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Royal Enfield Motorcycles => Bullet Iron Barrel => Topic started by: JordanMix on April 04, 2008, 02:13:58 pm

Title: kickback / coughing carb
Post by: JordanMix on April 04, 2008, 02:13:58 pm
I reassembled my engine/transmission/carb/adjusted the timing last night and ran into some trouble trying to start it. First I should let it be known that I always had a problem with the carburetor occasionally couching out the air filter (K&N cone previous to winter engine work) when starting the bike up.  I am having two problems now… first is a very violent kickback of the kick start leaver. It kicked back on me 3-4 times out of the 10-12 or so attempts to kick it over. They were very hard kickbacks, one hard enough make me sit down while my ankle recovered. I did get the bike started twice and it seemed to be pretty good, just idling a bit fast.

The other problem I am having is sever coughing/spit back from my carburetor. This happens on the occasions when the bike does not kick back, maybe 3 times out of the 10-12 attempts to kick it over. This is not a little spit either. I now have the velocity stack fitted and it spits back so hard that it turned the wire/mesh screen of the velostack inside out.

My question is, is it likely that both of these problems can be attributed to timing that is too advanced? I used the TDC tool out host provides and a test light to set the timing right before TDC on the compression stroke. By all means I am not a seasoned mechanic. I have some experience with autos, but the RE is my first bike… I am learning as I go.

I have a 1999 bullet 500. Running a free flowing exhaust with no baffle, pilot jet is 30, main jet is 125, velocity stack as an airfilter. Valve timing is good, no up and down movement but I am able to spin the pushrods.
Title: Re: kickback / coughing carb
Post by: baird4444 on April 04, 2008, 02:39:12 pm
I would say that your pilot jet is to rich...   mine was doing the same cough on start. I went down to a 27.5 and all was well. Also check your points... are they to wide??  if you close them up just a little you are retarding the timing.
                      - Mike
Title: Re: kickback / coughing carb
Post by: deejay on April 04, 2008, 02:41:26 pm
Your timing is off, sounds advanced. I've found that the best way to set my timing is to ride it pinging, then retard it until it goes away. Finding TDC and setting it without the bike running never worked for me.
Title: Re: kickback / coughing carb
Post by: JordanMix on April 04, 2008, 07:23:00 pm
Thanks for the help. Am i correct at saying you will retard the timing if you turn the points plate clockwise and advance it if you turn it counter clockwise?

From everything i have read today and from your replies i believe once i get the ignition set properly and possibly purchase a richer carb slide most of my problems should disappear and then i can start fine tuning.
Title: Re: kickback / coughing carb
Post by: cyrusb on April 05, 2008, 12:13:26 am
You are right on the plate direction for advance and retard.  As baird4444 said earlier ,set the points correct first, then time it. You sound way advanced. Once this is done then get into  the carb.
Title: Re: kickback / coughing carb
Post by: Peter on April 05, 2008, 02:38:21 am
You got kickback and backfire. Kickback is backfire transmitted to the kicker because it is still engaged. Backfire is when your filter gets blown off and the causes are the same as for kickback. Now, if you follow kickstart procedure meticulously, the Bullet should not be able to kick back at all. But it still can backfire and take out a sprag clutch (not an issue with a KS) and damage the worm drive.
I do not believe that kickback cannot happen with proper procedure; I know this kickback cannot happen but I'm not a believer. I still have on and off problems with my right ankle because I was careless in 1979. Shattered the whole thing and I was limping for a year. These days I'm happy to kick anything you show me but I will kick with the ball of my foot very slightly behind the kicker pedal and being sure that the kicker lever will clear my shin if it slips out because of kickback. Takes some practice and patience to make it a habit. With the Bullet it's standing on the right and kicking with your right foot. So don't break your friggin' ankle and be reminded that what you experienced does not qualify as a "violent" kickback. It was just a taste of one.

Make sure that the points have the proper opening clearance and retard a little bit if they are ok. By the way, it's generally a lean condition contributing to backfire, not a rich condition. Getting the carb and timing sorted out at the same time is back and forth a little bit at a time and keeping accurate track of your changes. Patience is all that's required except for being really careful not to crash while you are sorting it out - I'm serious, this stuff is very distracting while testing on the open road.
As far as I'm concerned, static timing is just for getting the engine running and it's ping timing from there on.

Be safe, and good luck
Peter
Title: Re: kickback / coughing carb
Post by: geoffbaker on April 05, 2008, 03:44:38 am
When my RE got back to Tucson she was DOA.

I rebuilt the head, new rings, and rebuilt the carb. It was set for the richest mix and the float was WAYYY off.

Once I got the carb rebuilt and running right, it was just a matter of retarding the timing till the kickback went away.
Title: Re: kickback / coughing carb
Post by: JordanMix on April 07, 2008, 12:45:58 pm
i got the kickback/backfiring issues sorted out for the most part this weekend. I haven’t had a kickback at all, and the backfiring out of the carb is not nearly as bad. I am still having carburetion/mixture issues i need to sort out (ran out of time over the weekend).

My engine is running what seems to me as dangerously hot (lean mixture right?). I installed a 125 main jet, 30 pilot and moved the clip to the second from the bottom on the needle and it still is running just as hot. It should be noted that i have had engine work done, new rings, piston (oversized +20 and a rebred as well as new guides and valve work.

I took off the velocity stack and put back on the K&N air filter and also put the small removable baffle back in the exhaust thinking this might help with my car being to lean but it didn’t seemed to help. At the current time i have a K&N filter, shorty style exhaust with the silencer fitted, 125 main jet and 30 pilot jet, second grove from the bottom on the needle, stock throttle slide and stock but new needle jet.
Title: Re: kickback / coughing carb
Post by: Leonard on April 07, 2008, 05:02:41 pm
  Sorry if you have already checked but make sure that the rubber hose connecting the carb to the head isn't leaking.
Title: Re: kickback / coughing carb
Post by: JordanMix on April 07, 2008, 06:00:48 pm
Leonard.

in my attempt to rule out all possibilities i replaced the hose with a brand new unit at the onset of my problems. It did not make a difference.

I have actually just become so frustrated me with inability to get the job done that i scheduled a service appointment with my local RE dealer. It does concern me a bit that they have only worked on a few RE's over their years. They are a Honda dealer and are accustom to working on newer technology bikes. I know both of the service techs are fairly young guys, i am hoping they have some knowledge/training in old technology bikes to get the job done. A further complication to this problem is that i have a new piston/rings/rebore/valve guides so you really cant go out and rip around on the bike to see if you have it tuned properly.
Title: Re: kickback / coughing carb
Post by: deejay on April 07, 2008, 06:39:04 pm
I'm running a 127.5 and a 30 pilot, needle is on the bottom notch, air mixture and idle adjusted to suit...

I'd try slowing the idle, a bigger main jet, and raising the needle before bringing it to some kid at a shop.
Title: Re: kickback / coughing carb
Post by: Peter on April 08, 2008, 12:04:07 am
Looks like your jetting is close to what works for others and you have ruled out intake leaks.
I would work with the mixture adjustment screw at this point (richer). Timing could still be too advanced as well.
I have an Amal so I can't give you specific advice for your carb.
You don't have to worry about the main jet much while opening the throttle only partially during initial break-in.
Also, remember that the engine will run much hotter for the first few miles with a new piston and rebore. I don't mean that you should ignore it, but what I do is to warm it up with little load and let it completely cool down right several times after a rebuild, especially with a cast piston. In fact you are concerned about exactly the right thing at this critical time.
How many miles do you have on it since rebuild?
Is your header pipe turning blue? How far down? Got ping?

Deejay is right, bad time to let someone else touch the motorcycle and possibly even test ride it.

Peter
Title: Re: kickback / coughing carb
Post by: cyrusb on April 08, 2008, 01:43:09 am
With those jets installed  you should have a black exhaust pipe. If not, you must have a float level or fuel starvation condition . A 30 pilot is a fat jet, What else could it be?
Title: Re: kickback / coughing carb
Post by: JordanMix on April 08, 2008, 01:25:26 pm
i am going to try the 127.5 / 30 jetting, clip in lowest position and see what that does for me.  I think i may have a problem with the float level/fuel starvation problem. I was messing around with it a bit last night and noticed fuel coming out of the overflow hose. I disassembled the carb to see if i had a bur or anything and the float did not seem to be sticking. I took measurements as follows: carb inverted with bowl and gasket removed, i measured 26MM from the surface where the gasket sits to the top center of both sides of the float mechanism. From there i hooked up a crude device to test fuel flow. I got my Nalgeen hydration pack bladder and filled it up with water, hooked up the tube from the pack to the fuel in line of the carb then placed my carb into a small rocks glass with the car resting on the rim of the glass to test the fuel flow. The gas seemed to flow well and stopped about 10MM from the surface of where the gasket would sit.

If i am missing something here please let me know. I also sprayed out all the holes, ports and nooks and crannies of the carb with cleaner.

To answer some questions:

I am pretty sure i am hearing some pinging but my timing is set about 1MM after top dead center just to make sure i am not advanced.

I have only put about 1.5 miles on the bike because it was running so hot i was worried to ride it any longer. i went straight back to my garage. My header pipe was always blue/golden at the top, maybe the first 15-20 centimeters.

when you say "with those jets installed you should have a black exhaust pipe". do you mean i should have black smoke coming out of my pipe? I didn’t notice any, which could mean that you are correct in your assumption that i am having a fuel starvation problem. I am hoping to get some time to look at it this week or weekend. My appointment is not scheduled until the 18th, so maybe i can get it sorted out before then.
Title: Re: kickback / coughing carb
Post by: Leonard on April 08, 2008, 01:53:46 pm
 With the timing retared that much you shouldn't get any ping.  According to Snidel:
Spark is too late: The flame front has to "chase" the descending piston down the cylinder, catching up with it at some time, resulting in some burning of the fuel. The exhaust valve opening will be greeted by a burn that is still well in progress, with lots of burning left to do in the exhaust pipe,resulting in overheating of the entire engine, and signalled by a flatter exhaust note, burning of the chrome on the pipe, and generally poor efficiency. Retarded timing will also burn your exhaust valve, necessitating a valve job at minimum.

I am pretty sure i am hearing some pinging but my timing is set about 1MM after top dead center just to make sure i am not advanced.
.
Title: Re: kickback / coughing carb
Post by: cyrusb on April 08, 2008, 02:09:01 pm
Black soot inside the exhaust pipe, or at least blackish. Not black smoke.
Title: Re: kickback / coughing carb
Post by: deejay on April 08, 2008, 04:35:19 pm
Black soot inside the exhaust pipe, or at least blackish. Not black smoke.

I've never seen an exhaust pipe that was clean on the inside.
Title: Re: kickback / coughing carb
Post by: cyrusb on April 08, 2008, 04:57:05 pm
Then you have never seen  a lean unit. I have seen white. Grey is a good color.
Title: Re: kickback / coughing carb
Post by: Foggy_Auggie on April 08, 2008, 08:42:45 pm
Leonard's reply #14 is right on the mark.

Retarded timing generates excessive heat.

Set it using the ammeter kick (for points opening) at 0.8mm BTD.
Title: Re: kickback / coughing carb
Post by: Peter on April 09, 2008, 12:03:06 am
That static timing thing may not get you anywhere. One mm after TDC or 0.8 mm before may each get you into the ballpark. You can already start the engine so you can also dynamically check the timing.
If you have a timing light, you can take off the timing side cover, somehow mark TDC on the magnet and the alternator and 32 degrees advance from there, also on the alternator.  After you have made the marks, start the engine and rev it a little bit while shining your light on your marks. Your TDC mark on the magnet should hover around your 32 mark. Adjust as necessary.
With a fancy timing light you don't need the 32 degrees mark, just make the TDC marks line up after setting the advance dial to 32 (or 64, you'll see what I mean when you shine it on there, has to do with the timing gears and no wasted spark). 32 degrees is definitely in the ballpark and takes timing out of the equation for now. Then troubleshoot the mixture. And then ping time it. You are not going to load the engine much during initial break-in, so don't worry about being exactly on the spot for now. Again, this is not an alternative to ping timing, but you can measure advance with your light AFTER you have ping timed the engine for future reference.

You haven't increased compression, or have you?
I'm asking because that changes the timing thing significantly.

Peter
Title: Re: kickback / coughing carb
Post by: Foggy_Auggie on April 09, 2008, 02:07:56 am
That static timing thing may not get you anywhere. One mm after TDC or 0.8 mm before may each get you into the ballpark. You can already start the engine so you can also dynamically check the timing.

Peter

This engine is obviously not a high tech state of the art racing engine.  I'll concede that 1.0mm BTDC static timing won't hurt it.  Anymore advance, there can be occasional kickback issues.  My own engine is an example.

And the 1.0mm ATDC - there will be higher heat generated.

Peter - you go into great (and good) detail about using a degree set up and timing light.  Then you go into "PING" timing after all the good stuff - I've never "pinged" timed any engine in my life.  "Ping" timing is about a shot in the dark as anything.  With all the variables of heat, humidity, octane and static load being just the highlights.  It's too fine a line to tread for an engine of moderate output and long use.

Years ago I used to build and tune racing engines for drag racing.  I'm not some pilgrim.

The iron engine goes to full advance, anyway, very quickly.  And the average rider is not going to be able tell if his engine is static timed correctly or "ping" timed as far as performance.  And if the centrifugal advance is sticking and doesn't go full advance - and the engine is "ping" timed that way - what happens when it "unsticks" while riding...

All this engine needs is correct static timing and plug readings after short bursts of WOT and hitting the kill switch.  The plug readings are for carb jetting and settings.  The Champion Sparkplug website has excellent pictures of plugs in all states of use.  And also pictures of plugs that have been "pinging" or even under detonation loads.

My three pence worth.  8)
Title: Re: kickback / coughing carb
Post by: Peter on April 09, 2008, 12:15:13 pm
I'm not talking about about timing the stock Bullet in general which is not a big deal at all.
Jordan had a problem with backfire and retarded to 1mm after TDC to get rid of it.
That is the problem and the easiest and quickest way see if there is any issue with the ignition and to get it in the ballpark is to shine a timing light on it.
A timing light is cheap and comes with instructions and answers all timing questions in about ten minutes worth of work.
Nothing complicated about it and also nothing complicated about ping timing.
I would't underestimate the "average Bullet rider".

Peter
Title: Re: kickback / coughing carb
Post by: Peter on April 09, 2008, 12:23:29 pm

... The iron engine goes to full advance, anyway, very quickly.  And the average rider is not going to be able tell if his engine is static timed correctly or "ping" timed as far as performance.  And if the centrifugal advance is sticking and doesn't go full advance - and the engine is "ping" timed that way - what happens when it "unsticks" while riding...


That is precisely why ping timing is such a good thing to know how to do.
The Bulleteer who has ping timed the engine, knows ping.
And what would an advance coming unstuck cause? Right, ping!
Time to investigate and correct.
What would a stuck advance do to a statically timed engine? Right, burn the exhaust valve and cause other overheating disasters.

Peter
Title: Re: kickback / coughing carb
Post by: JordanMix on April 10, 2008, 02:28:22 pm
Gentlemen.

Thank you for all the help and advice. I am going to have a go at it this Friday night and Saturday to see if I can get it in proper riding state. I have never used a timing light or wheel before. Since I have purchased the Bullet I have been using a test light and a top dead center tool (which I think it less than precise). I do have an appointment scheduled next week to have to bike looked over. I had pretty much everything apart this winter and sitting on my garage floor/work benches. I just want a professional mechanic to give it a once over before I go out on the road and end up spilling it because of a simple error.

One questions I do have is there some certain parameters I should give them mechanic in regards to timing other than the .8mm before TDC? This may have been answered in Peters reply, but I just don’t understand it because I have zero experience with a timing wheel/timing light. Should I just tell the mechanic that it should be statically timed at 32 degrees before top dead center? Or should I just print out Peters reply and give it to the mechanic? This is of course if I can not get it sorted out by myself this weekend. The shop I am going to is a Royal Enfield dealer, I just do not believer their maintenance team has any real experience with Enfields as my bike is the only one I have ever seen around my town area and they have told me the Enfield has been a very slow mover for them.
Title: Re: kickback / coughing carb
Post by: Peter on April 10, 2008, 07:24:55 pm
You only have to tell the mechanic that FULL ADVANCE should be about 32 degrees, not static timing.
The only issue is that the Bullet does not have TDC and timing marks.
You need to put at least a TDC mark on the magnet and a TDC mark on the alternator then make another mark 32 degrees clockwise (to the RIGHT) of the TDC mark also on the alternator. Then you have to tell the mechanic which mark is which.
However, once you have arrived at that point you don't really need a mechanic anymore. Just shine the light on it and rev to 2-4000 rpm. The Bullet advance unit fully advances below 2000, so you don't have to go crazy with revving.
Timing lights are available at any auto parts store and come with simple instructions for hookup.
You don't need a fancy wheel to determine full advance, just something to measure an angle with.

Peter
Title: Re: kickback / coughing carb
Post by: JordanMix on April 10, 2008, 07:59:27 pm
Peter, thanks for the help. I will let everyone know how it goes. Hopefully by next saturday all the wrinkles will be worked out of my bike and i can fianlly get on the road with no issues for the first time since purchaseing it last August.
Title: Re: kickback / coughing carb
Post by: Foggy_Auggie on April 10, 2008, 09:20:13 pm
The dealer will know the difference between dynamic timing for total advance and static timing for initial advance.

Initial advance is where it sets with the engine shut off.   

The dynamic advance is the point cam rotor mechanically being turned by centrifugal weights the higher the engine RPM.

With the point cover removed and grasping the cam rotor - it can be rotating in one direction while observing the springs, weights and slot mechanism of the centrifugal advance.  This will be easier to understand  then a few more paragraphs!