[JVS]

Hey everyone,

Hope you’re all well and enjoying the end of 2015 This topic is about the installation of a manual decompressor in a UCE Enfield. I had wanted this for a long time, as the auto decomp wasn’t enough for me. So before I go further and make you read all this stuff, I’ll summarise:

- Was the manual decompressor worth the trouble?

A big yes! Please refer to this video for the decomp in action: https://www.youtube.com/watch?v=jPaG6Lyshvo

- Will you be able to use the electric start?

Yes, the e-start is better off with this type of decomp as compared to the auto decomp. This is because the manual decomp releases more compression (as compared to factory auto) and disengages automatically as well. Harley riders have these on their bikes for making starting easier and saving their batteries + sprag.

The possible downside to not having the auto decomp is that when the engine is shut off, there is a risk of the piston going backwards and ruining the sprag. However, I’ve had the auto decomp removed for approx. 2500km and there have been no issues till date. Steve Thackery and a couple more members have also removed their bike’s auto decomp, and primarily use e-start. Everything has been fine till now for them.

With regards to the installation:

For the installation to be successful, obviously you’ll need to remove the auto decomp that comes with these bikes. You can refer to the following topic, in which I document the removal of the automatic decompressor: https://forum.classicmotorworks.com/index.php?topic=22173.0

With many thanks to ace.cafe and gashousegorilla’s (GHG) suggestion, a manual decompressor can be installed where the second spark plug goes in the Indian domestic market for the UCE. If you have this setup already, it might be easier to get the manual decompressor installed. Otherwise, what we have to do is: Get a threaded hole done where the second spark plug is usually supposed to be. On most of our export models, this side is blank, with a nice circular template.

Based on ace.cafe’s suggestion, the decompressor one can get (to vent to atmosphere directly) is the Harley push-button type. This requires minimal head work as compared to the older cast iron type decompressors, which vent through the exhaust port. The latter will require more head work and I don’t think any machinist can do it perfectly. Only professionals with enough experience will be able to do it. Also, the push button type will only make kick starting easier, it won’t be a good idea to try to turn off the engine with it as the hot exhaust gases will probably burn your finger and be harmful to the tank! But if you can get one done to vent to the exhaust port, you can use it to shut down the engine whilst causing minimal impact on the starter/sprag during kick-back. With the push-button type decomp, if you don't want it to disengage automatically, you can just pull the pin back up after positioning your piston just past TDC.

Sourcing the decompressor

I bought the manual decompressor off E-bay from the US. It arrived within a couple of weeks as I’m in Australia. It’s the one with 10mm thread and 1mm pitch, smaller than your RE key. Ebay link - www.ebay.com.au/itm/10mm-x-1-0-HARLEY-COMPRESSION-RELEASE-VALVE-FOR-HIGH-COMPRESSION-ENGINES-/151750403936?hash=item2355076760:g:Ea4AAOSwYGFUsw3c




Quick walkthrough

Because I’ve never done any engine work, and as I didn’t have the right tools for this, I had to take the cylinder head to the local bike shop to get the threaded hole done (Approx. cost $50-$100). A basic approach to the installation of the decomp is as follows (Assumption is that you have a nice basic set of tools for the removal of the cylinder head, which includes your wrenches/spanner/torque wrench set, allen keys etc.)

Step 1
It all starts off as an idea, and you don’t stop till it is done. Before you start any job, just admire your bike and realise that you’ll be back on it soon.




Step 2
Remove your seat (if it will interfere with your work), along with your fuel tank. This is straight-forward. For the tank removal, remember to disconnect the fuel pump and low fuel sensor connectors first. For a detailed procedure on the tank removal, you can refer to singh5g’s video - https://www.youtube.com/watch?v=m1mn2JVPmac




Step 3
Remove your exhaust header pipe + silencer combo




Step 4
Remove rocker cover bolts and mark them, because they are all different and you wouldn’t want to waste your time thinking where one belongs etc. Pull off rocker covers.






Step 5
Put piston at TDC. Remove the four allen screws each from the exhaust and inlet rocker bearing covers. Then pull off the rocker bearings and push rods. If they are stuck, give them a few light taps with a mallet. Again, mark them because they are both different. Be mindful of the dowels. There are two each for the rocker covers and two small ones each for the rocker bearings. Keep them aside if they don’t come out with the bearings, as these can fall in to the gap/hole towards the hydraulic lifter and can be a pain to get out.




Step 6
Remove the six flanged hex nuts from the cylinder head. These are the main ones that are torqued to 25Nm. Be mindful of two of these flanged hex nuts, as they are close to the hydraulic lifter side and can also fall in to the gap where the pushrods go. Disconnect the intake manifold, cylinder head temperature sensor and head steady.

Step 7
Give the cylinder head some light taps with a mallet throughout its circumference. Then, pull the cylinder head upwards with both hands. It should be removable without too much trouble.

I had a fair bit of carbon build up on the piston.






Now is the time to decarbonise your piston, and head/valves. Because I had never done this before, I took a small screwdriver and started scraping the larger carbon deposits. Obviously this wasn’t a good idea as it left some scratches/scuff marks on the piston crown.






Thanks to GHG, what one can do is use some WD40 and let it sit on the piston crown for a while. Then, a scotch brite type pad can be used to scrape off the deposits. Since the cylinder head seemed okay to me, and because I didn’t want to mess up with the valves, I just left them stay as is. Only thing I did was to kind of clean them with fuel/gasoline. I didn’t touch the cylinder wall at all. I just used a very light cloth to get any debris out near the top of the cylinder wall.

Step 8
This is the critical part. Now you have to make the decision whether to take the head to the shop or do this yourself. If you can’t do this yourself, I would really recommend you take it someone who really has done this type of stuff before or has a lot of experience/know what they’re doing. As per ace’s recommendation, the best way without altering the combustion characteristics is to drill a larger 10mm threaded hole from the top of the head, then leaving enough cylinder thickness to a smaller 2mm normal hole that will go in to the combustion chamber.

I couldn’t do this at all so I took it to my local bike workshop who said that they will be able to do it. So I left the cylinder head with them and collected it in a couple of days. Unfortunately, their machinist apparently couldn’t do a 2mm hole from the bottom of the larger hole towards the combustion chamber. So I was left with a 9mm threaded hole in to the combustion chamber! I was a little scared now…would this affect the performance? Would I notice any change?










Step 9
Now is the fun part. Reassembly! Make sure you clean everything properly first. I had a lot of debris in the cylinder head after I got it back from the shop. Again, I used gasoline/fuel and used a small paint brush to get the debris out. Then I used a vacuum cleaner to get rid of the minute particles, followed again by a thorough clean.

Remember also to clean the piston crown properly and try to leave minimal deposits. Use a fine sand paper to make the mating surfaces clean and flat (where the head gasket meets the cylinder head and barrel). Before you put the head back on, get the piston towards BDC using the kick lever, and give the cylinder wall a small coating of oil. Then bring it to TDC and put a thin film of oil around the edge of the piston. Remember to keep the piston at TDC before re-assembling. Thanks to GHG for telling me this.

Preferably use new gaskets for everything. Head gasket – MLS, inlet rocker cover and exhaust rocker cover.




Put the six flanged hex nuts back on and tighten them diagonally. They require about 25Nm of torque.




Step 10
Install the rocker bearings, push rods and associated screws. Clean them and then give them a slight coating of oil by hand before installation. Thanks a lot to GHG for this advice: After the re-assembly, leave the motor at TDC overnight, so that the lifters are bled down. Then, in the morning, give the pushrods/rocker arms a nudge downwards towards the lifters and see if they can be rotated slightly. This will allow the lifters to set the lash automatically once the engine is started.




Step 11
Install rocker covers using the new gaskets. Reconnect cylinder head temp sensor, head steady, header pipe + exhaust, spark plug and HT lead. Then the usual tank mounting and seat (if applicable).

Step 12
Check for leaks, see if your decomp is working like it is supposed to. Push the decomp button and kick it over. Just after TDC, you’ll hear a loud ‘swoosh’ of air coming out the decomp, and it will be 100 times easier to kick the engine over.

Step 13
Start it up and let the engine idle for a while. The decomp should disengage itself once it cranks. Check for any oil leaks. Do a quick oil + filter change.

Step 14
Be on your merry way! Enjoy the thump

I haven't noticed any downfall in the engine performance. On the other hand, maybe because of decarbonising a little bit (or because of the placebo effect), I actually felt that the bike was running a bit more smoother Lol.

Many thanks to GHG and ace.cafe for their generous help, without them this wouldn’t have been possible. Thanks for your time.

Have a great Christmas/holiday season, and a happy new year to you all. Ride safe.   

[malky]

Thanks for the post. I will do that when I need to take the head off.

[heloego]

Great Post, JVS! 
Thanks for all the info!

[mattsz]

Cool, thanks JVS!

I was tossing this idea around awhile back - my decompressor was noisy and clattered for a long time unless the engine was really hot.  A dealer "fixed" it by disabling it - either by mistake, or purposefully but without telling me.  I liked the idea of having a decomp that would ease fears of kickback when shutting the engine off, but obviously that's problematic here for the reasons you mentioned.

So now you have 3 valve seats in your head.  Since this decomp is only open when the engine isn't running (is that true?), hopefully there won't be a problem with carbon buildup potentially holding the decomp open while the engine is firing...

Speaking of which, how does the "closure" mechanism on this thing work?  If you activate it and kick the bike through once without it starting, do you have to press it again for the next kick?

Same question for the e-start - sometimes some of our engines crank through a number of cycles before they start - is it just the first cycle that is "relieved", or does the decomp stay open until the engine fires?

I suppose for e-starting, easing even just the first cycle would be helpful to get that heavy crank moving - and once it's spinning the starter motor can better deal with full compression.

As an aside, I had carbon buildup in my cylinder... worse than yours, and - interestingly, perhaps - in different spots.  Mine was heaviest closest to the intake, on both the piston and the head.  When I cleaned it up, my bad pinging problem was instantly cured.  I can't say I noticed any other change in performance, though...

[gashousegorilla]

   Awesome job and right up JVS. 

[caricabasso]

Can you tell me how many kilometers has covered your bike?
This is to know the amount of carbon residue on the chamber and  when the decarbonise  is recommended.

[Ice]

 The Factory Service Manual recommends de carbonize every 30,000 KMs under normal use conditions.

[GSS]

JVS,
Nice job! Very nicely done.

GSS

[SteveThackery]

I agree, it is a nicely done job.

I just don't think it's necessary if you use the electric start.  You claim it gives the electric starter an "easier" life?  So what?  Who cares, so long as the electric start lasts as long as the rest of the bike?

I can see the point in earlier bikes with their troublesome sprags, but the recent UCEs?  No, of course not.

How can it be a good thing if no other road bike on the market has decompressors?  That should be a VERY major clue that decompressors are completely unnecessary!  (Provided the starter and sprag are correctly specified, of course, and I assume the current ones are.)

[gashousegorilla]

I agree, it is a nicely done job.

I just don't think it's necessary if you use the electric start.  You claim it gives the electric starter an "easier" life?  So what?  Who cares, so long as the electric start lasts as long as the rest of the bike?

I can see the point in earlier bikes with their troublesome sprags, but the recent UCEs?  No, of course not.

How can it be a good thing if no other road bike on the market has decompressors?  That should be a VERY major clue that decompressors are completely unnecessary!  (Provided the starter and sprag are correctly specified, of course, and I assume the current ones are.)

  I completely agree with this.   I think JVS's decomp... just like the stock one. ONLY makes it easier to kick start. And I think when people remove the stock decomp for whatever reason... different cams , troublesome etc. They miss that  VERY easy kick starting they had with the stock decomp.   The original spags that came on the early UCE's were crap.  With or without the auto-decomp they went bad.  No kick starter on mine,  E-Start only, newer designed sprag, much higher compression then stock, no huge strain on the battery or starter, starts on the first hit.  And I guess that's going on around three or four years now with the new sprag ? 

  And I think in the event of a "kick back" on the bike..... which shouldn't happen if it is tuned correctly or it is stalled by the rider etc.  But it happens ?.... The spring that retains the sprags in the newer design, will allow them to move outward without damage.   With the old design, the sprags were housed in a cage with metal tabs that retained them in place.   once those tabs were bent up, or progressively bent up over time from kick back, there was nothing to hold the sprags in place.     That's my take on it anyway...

[JVS]

Cheers guys, it was a team effort like always 

So now you have 3 valve seats in your head.  Since this decomp is only open when the engine isn't running (is that true?), hopefully there won't be a problem with carbon buildup potentially holding the decomp open while the engine is firing...

Speaking of which, how does the "closure" mechanism on this thing work?  If you activate it and kick the bike through once without it starting, do you have to press it again for the next kick?

Same question for the e-start - sometimes some of our engines crank through a number of cycles before they start - is it just the first cycle that is "relieved", or does the decomp stay open until the engine fires?

I suppose for e-starting, easing even just the first cycle would be helpful to get that heavy crank moving - and once it's spinning the starter motor can better deal with full compression.

As an aside, I had carbon buildup in my cylinder... worse than yours, and - interestingly, perhaps - in different spots.  Mine was heaviest closest to the intake, on both the piston and the head.  When I cleaned it up, my bad pinging problem was instantly cured.  I can't say I noticed any other change in performance, though...

Matt,

I'm not sure if these bikes should be called "lean-burn", but based on my engine and others, it appears that the combustion pattern is always "rich" at some place or the other within the chamber. It's good to know that cleaning the carbon helped you with your pinging issue. I guess the key is to ride these bikes for longer distances and not just a lot of 2mi runs 

With regards to the decomp, it is more like a second spark plug  You can have it "engaged" or "disengaged" while you kick over the bike, the choice is yours. When "engaged" all you have done is pushed down on the decomp, which lets out the compression. I wish I had taken more photos of the decomp by itself. However, you can refer to the following image which I got from the net:



In the above pic you can see the button is pushed on the decomp lying on the left of the cylinder head. Air escapes now through that cavity, then exits from the hole you see on the hex side.

So, if you're kicking over the bike gently to get past compression (refer video above), it doesn't close by itself. However, if you kick with just enough effort on the compression stroke, it can close by itself as long as the right amount of compression did build up (in-rush) to bring the mechanism back up with a 'pop'. That's what you hear in the video I posted above as soon as the engine cranks up.

This is primarily for kick-starting as Steve mentioned. However, I did try it on the e-start as well. It's hard to see/hear/notice on which 'cycle' it disengages by itself, but I could tell it did make the first crank relatively easy for the starter motor to actuate the engine.

Can you tell me how many kilometers has covered your bike?
This is to know the amount of carbon residue on the chamber and  when the decarbonise  is recommended.

caricabasso, the bike has only covered 22,000km. I just haven't got a chance recently to go ride as much as I would like to.

I agree, it is a nicely done job.

I just don't think it's necessary if you use the electric start.  You claim it gives the electric starter an "easier" life?  So what?  Who cares, so long as the electric start lasts as long as the rest of the bike?

How can it be a good thing if no other road bike on the market has decompressors?  That should be a VERY major clue that decompressors are completely unnecessary!  (Provided the starter and sprag are correctly specified, of course, and I assume the current ones are.)

I agree, Steve. I always use the kick start. That's why I wanted to get this installed. Now, it is so much easier to get it started. I can once again bring the engine to life by kicking whilst sitting on the bike (one foot on the ground, other on the kicker). Just past compression, even with half a kick it starts up 

The e-start for me is only for emergencies, hence 'emergency' start 

  I completely agree with this.   I think JVS's decomp... just like the stock one. ONLY makes it easier to kick start. And I think when people remove the stock decomp for whatever reason... different cams , troublesome etc. They miss that  VERY easy kick starting they had with the stock decomp.

GHG, with this manual decomp, it is so like 50 times easier to kick-start, as compared to kick starting it with the auto-decomp in place 

[SteveThackery]

I always use the kick start. That's why I wanted to get this installed.

May I ask why you always use the kickstart?  Personally I always use the electric start, simply because it's quicker and easier.  I'm puzzled as to why you'd choose a slower and more difficult method!   

[Ducati Scotty]

The Suzuki S40 has an automatic decompressor.  I don't think it has a kick start so it's just to ease the strain in the electric start system.

[wildbill]

nice work jvs

I think with the later bikes and the duel option kicker and electric -you have the best of both worlds...lol
kicker to look  and the electric for the easy way out! I too always use the electric but would be complaining if I didn't have that kick start lever on the right side which I think on the past 3 bikes I never even tried

[gizzo]

May I ask why you always use the kickstart?  Personally I always use the electric start, simply because it's quicker and easier.  I'm puzzled as to why you'd choose a slower and more difficult method!   

Just because you don't use it, doesn't mean someone else shouldn't  . If it makes you feel good, do it.

[gremlin]

May I ask why you always use the kickstart?  Personally I always use the electric start, simply because it's quicker and easier.  I'm puzzled as to why you'd choose a slower and more difficult method!   

For the same reason he chose a slower and less-well-engineered motorbike.  It's all about FUN !

[Ice]

May I ask why you always use the kickstart?  Personally I always use the electric start, simply because it's quicker and easier.  I'm puzzled as to why you'd choose a slower and more difficult method!   

 Kick starting is less wear and tear on the battery and cranking system, extends their service life dramatically.

 

[malky]

If you ask a mountaineer why they climbed a mountain the answer is " because it was there"
Ask a motorcyclist why they fitted something to their bike, the truthfully answer would be " because it wasn't there"
I like the idea of a manual decompression, but a bar mounted actuator, for me, is a must. I'm working on it.

[Ice]

 IMHO the unit machines are begging for a bar mount operated de comp.

 Why else would there be a ready made place on the head for the de comp valve and that silly enrichener things cable connected to the already exiting de comp lever on the bar at the left switch control house ?

[malky]

IMHO the unit machines are begging for a bar mount operated de comp.

 Why else would there be a ready made place on the head for the de comp valve and that silly enrichener things cable connected to the already exiting de comp lever on the bar at the left switch control house ?

It has to be one of these.

[SteveThackery]

Just because you don't use it, doesn't mean someone else shouldn't  . If it makes you feel good, do it.

I didn't say they shouldn't.  I asked why.

[SteveThackery]

Kick starting is less wear and tear on the battery and cranking system, extends their service life dramatically.

If they are correctly specified, their service life should be as long as the service life of the rest of the bike.

I'm talking about the starter, of course, not the battery.  Are you saying the starter system isn't correctly specified or manufactured?

As for the battery, are you sure the battery's life is shortened by using the electric start?  Is that what ages a battery, or are there other ageing mechanisms that swamp any effects from using the starter?

If someone says "I use the kickstarter because I like using it" then I can totally buy into that.  If someone asserts that it greatly extends the service life of the starter and battery, alarm bells start ringing, the phrase "unsubstantiated assertion" comes to mind and I immediately have to ask "How do you know?".

[JVS]

  It is exactly because I like using it. That's how these bikes were used to be, no e-start. I'm just replicating those times. And because I like to keep my knee in shape for now, before arthritis 'kicks' in or something 

I also wanted a bar mounted actuator, just like the old decompressors. However, as I mentioned in my original post: That will require extra machining to guide the air towards the exhaust port. If your local bike workshop guy/girl can do it, then go for it. I barely got this one done by the workshop and really wasn't confident about the job after I saw what they did.

Maybe in the future I'll try to retro fit a spring mechanism on this decomp somehow and run a cable to the bar.

[Ice]

If they are correctly specified, their service life should be as long as the service life of the rest of the bike.

I'm talking about the starter, of course, not the battery.  Are you saying the starter system isn't correctly specified or manufactured?

 As for the battery, are you sure the battery's life is shortened by using the electric start?  Is that what ages a battery, or are there other ageing mechanisms that swamp any effects from using the starter?

If someone says "I use the kickstarter because I like using it" then I can totally buy into that.  If someone asserts that it greatly extends the service life of the starter and battery, alarm bells start ringing, the phrase "unsubstantiated assertion" comes to mind and I immediately have to ask "How do you know?".

 I say you're spot on about starters.  Let me add  in support the Prestolite starter of my (E/S only) Shovel Head. What differentiates it from other like starters in like bikes of similar usage is an annual tear down and servicing. 118,000 trouble free miles and counting.

  Your question on batteries is quite fair Steve. On that topic I offer empirical observation of my own and many other similar bikes under similar usage and similar maintenance among our group of friends and our acquaintances, over a span of forty plus years. 

 Damned internet and its lack of vocal inflection and facial expression. I'll risk being misconstrued anyway.

 In Harley E/S service we'd get an rough average of three good years from AGM batteries before the performance would begin to drop off while our K/S friends would get seven or more. In our liter bikes we would get a bit better for the same / same.  FWIW the AGM battery in my Bullet was dealer installed upon un crating.

 The consensus was and is that the higher loads and deeper discharge demanded of a battery from E/S coupled with less than optimal re charge cycle of the bikes charging system impose more electro chemical wear and tear on a battery than it would be subject to in K/S only service. The repetitive discharge/ charge or undercharge cycles tax a cumulative toll.


 
 

[SteveThackery]

The consensus was and is that the higher loads and deeper discharge demanded of a battery from E/S coupled with less than optimal re charge cycle of the bikes charging system impose more electro chemical wear and tear on a battery than it would be subject to in K/S only service. The repetitive discharge/ charge or undercharge cycles tax a cumulative toll.

Fair enough, and useful information.

There is another important factor to add to the mix.  One reason a battery will last longer on a k/s-only bike is because it doesn't need to be as healthy in order to start the bike.  It could have a high internal resistance and very small capacity and still start the bike, because it only has to power the ignition system. 

The battery on the e/s bike has to be able to provide a hundred amps or so, which is much more demanding.

My point is that even if the batteries degraded at exactly the same rate in the k/s and e/s bikes, it would come up short on the e/s bike sooner because of the greater demands upon it. 

Personally I've yet to be convinced that electric starting itself plays a significant part in wearing out the battery (unless the bike is a bad starter, of course), but I'm open-minded to this and happy to change my mind in the light of evidence.

Meanwhile, though, I wouldn't mind if I had to change the battery every three years if it meant I had the convenience of electric start.   

[gremlin]

Let's put this to bed.

IF you discharge a standard auto battery more than 20% each use (and the electric start does just that) you substantially shorten the battery life.

[Narada]

That graph refers to "low-solar antimony", which sounds a little too close to "ex-wife alimony to me!

My 2015 UCE E/S C5 starts in about one second.  I don't believe that discharges my battery 20 percent or prematurely wears out my starter motor.

That argument is UCE-less.

Manual decompression is fine for those with the older weak sprag, or those with "restless (kick-start) leg syndrome".

One day, I may add it for easier kick starting but so far I am preferring the E/S option.

That being said... nice work JVS. Impressive quality and excellent write-up.

[gremlin]

I agree the OP is a really good write-up on Decomp install in a UCE. 

have a look at the lower-most curve .....  That would be the lead-calcium generic auto battery chemistry.

I'm not saying E/S will kill your battery any faster than under-charging it and letting it sit for days on end.  I'm just giving the evidence requested by the questioner ......   

"Personally I've yet to be convinced that electric starting itself plays a significant part in wearing out the battery (unless the bike is a bad starter, of course), but I'm open-minded to this and happy to change my mind in the light of evidence."

[Ducati Scotty]

FWIW, the starter on the UCE Enfields is the same one used on some 800cc V-twin Suzuki cruisers.  I have one sitting on my shelf that I got some time ago. 

Scott

[SteveThackery]

Let's put this to bed.

IF you discharge a standard auto battery more than 20% each use (and the electric start does just that) you substantially shorten the battery life.

You're obviously having a joke.  Let's assume the starter draws 200 amps for three seconds (mine starts much faster than that).  That is 600 amp-seconds, which is 10 amp-minutes, which is 0.17 amp-hours, which is 1.4% of its capacity.

That's why I find it hard to believe it contributes anything much to ageing the battery.

[gremlin]

auto batteries are seldom at 100%

I saw a listing on eBay for an OEM compression release kit, complete with cable.  looked like it could be adapted to the bi-starter lever.

[Rattlebattle]

While I would have preferred a manual valve lifter, having been used to these on all the old Brit iron I've owned over the years, personally I don't see a need to remove the auto decompressor or to install a decompressor in the way described, though I do appreciate the write-up. FWIW I like to use the kickstart; it's not the only bike I have so equipped. I use the electric foot when the engine stalls (not that mine does this very often) or for when it doesn't start on the kickstart, which now that the engine has loosened up is quite rare. It is just a little bit different in these days of uniformity and is, after all, why I like my RE. I don't see why using the electric foot should be detrimental to the battery, or at least to a good one. The vast majoirty of vehicles have electric starts don't they? It is cranking amps that matters ie how many amps can be delivered by the battery in short bursts. The alternator should restore this in fairly short order if it and the r/r are working properly, so I don't see what the issue is now that the sprag clutch is sorted.

[gremlin]

...... The alternator should restore this in fairly short order if it and the r/r are working properly,......

Only if one goes for quite long rides ~ its a known peculiarity of lead acid batteries that they take a long time to "top-up"  in reality, most automotive batteries on the planet are running around at 80 ~ 85 percent charge ......

[Ducati Scotty]

I don't see why using the electric foot should be detrimental to the battery, or at least to a good one. The vast majoirty of vehicles have electric starts don't they? It is cranking amps that matters ie how many amps can be delivered by the battery in short bursts. The alternator should restore this in fairly short order if it and the r/r are working properly, so I don't see what the issue is now that the sprag clutch is sorted.

The battery is not really the problem, it's the borderline charging system and how the bike gets used.  The charging system on these bikes is adequate, not great but adequate, if you run at a good cruising speed for extended periods.  If you make short stop and go trips and have that extra bright halogen headlight, the system just can't keep up.  Combine that with the fact that a standard wet lead acid battery self-discharges fairly fast just sitting there if you don't ride every day. 

These alternators only work well at moderate speed or above.  At idle and low RPM you are losing charge.  This is not unique to the RE, many bikes up to the early 80's behaved this way.  For someone who commutes daily down the highway with some nice uninterrupted stretches, no problem.  For a rider who takes the bike out once a week on the weekend for a putt through town with stop signs and lights, that battery will die an early death. 

All the modern bikes I've owned had no problem keeping the battery charged so long as I rode them every few weeks or so.  The RE did not play like that.  The combination of a borderline charging system and a sprag that tends to fail if the starter isn't getting all the juice it should changed my habits.  If the bike sat for more than a few days I'd put it on the charger overnight before I planned to take it out.  I had the early C5 with no kicker so I had only one way to start it.

Scott

[Rattlebattle]

Even if most batteries on the planet are running at 80% charge the fact is that for the most part car or bike engines usually start. I've had lead acid batteries that have lasted more than eight years, though it's longer than that since I've bought a new car or bike with one and I was surprised to find my new C5 has one. I shall change mine to a Motobatt when it conks out. Not using the lights unless visibility is poor I've had no bother with the charging system keeping the battery charged though I do give it a trickle charge every now and then if I haven't ridden the bike. Of course, if one must add heated grips, extra running lights and other accessories that consume more current than the alternator can supply the battery will gradually discharge in use. I thought that one of the benefits of an alternator over a dynamo is that it delivers a good charge from relatively low revs, especially a three phase alternator, so I'd expect it to maintain the battery in normal use. I'd be interested to know what the rated output of the alternator is supposed to be.

[Ducati Scotty]

Most car alternators and some on bikes do not have permanent magnets.  They use electromagnets powered by the alternator itself. They are lighter, and at lower RPMs you can push more electricity to them to make them more powerful, effectively generating the same power at lower speeds.  The RE and many bikes have fixed magnets.  They're better at low RPMs than a generator but they're not magic.

[no bs]

alternator output approximately 18 amps. rather underwhelming...

[gremlin]

and yet, the RE amp-meters are 8 amp.

[rtillery02]

Yup Scotty, I've been put'n off that HD alt upgrade to give an LED with dc rectifier a chance. Draggin that halogen upgraded headlamp bulb every runnin moment probably aint helpin the situation.

[Rattlebattle]

and yet, the RE amp-meters are 8 amp.

Yes, but putting the full output of the alternator into the battery would fry it, which is why there is a regulator.

[gremlin]

Yes, but putting the full output of the alternator into the battery would fry it, which is why there is a regulator.

Yep, just like us humans, too much internal pressure will kill.

[ace.cafe]

The old Iron Barrel Bullets had barely enough alternator output to handle their basic needs. Some would say not even enough. It was often a problem trying to use an up-rated halogen headlight. The lights would always dim down to a dull yellow tint at idle.