Unofficial Royal Enfield Community Forum

Royal Enfield Motorcycles => Bullet Iron Barrel => Topic started by: LarsBloodbeard on October 29, 2012, 02:17:06 am

Title: Engine/tuning issues
Post by: LarsBloodbeard on October 29, 2012, 02:17:06 am
When I slowly crank over my engine it blows a fair amount of air out the carb right after intake.  It does close fully and has good compression (can stand on the kicker and it supports my 250lbs).

ace.cafe suggested the cams might be off a tooth.  Pulled the timing cover.  Looks fine, except some rust and the oil in there was really watery and green for some reason...

I'm wondering if maybe the intake pushrod is getting hung up.  Don't know where else to look, really.  The pushrods are adjusted right.  When cold they will rotate by hand, but not move up and down (checked 4 times).

Edit: changed title to match how this thread progressed.
Title: Re: Intake not closing soon enough?
Post by: ace.cafe on October 29, 2012, 02:09:00 pm
If it's doing it just during the very slow kicking procedure, that isn't necessarily indicative of a real problem because the engine activity is too slow. Any closing of the intake valve after BDC could cause that in a very slow engine rotation, and all engines close their intake valve after BDC.
It only matters if it's doing it during running.

The other possibility you might see during idling is exhaust related. If you have an exhaust pressure wave reflected back up the exhaust pipe, that arrives at the cylinder during the overlap period when the intake valve is open, it can cause a reversion up the intake tract like that. Typically you can see this reversion as "stand-off", which is a little mist cloud of fuel-atomized vapor standing still outside the mouth of the carburetor during idling. This is commonly seen when people run "straight pipe" exhausts.
Usually you can cure this with a wave-breaker, such as a muffler with baffles, or a megaphone, or something like that. Preferably one that changes the overall length of the exhaust system too.
Title: Re: Intake not closing soon enough?
Post by: Vince on October 29, 2012, 04:27:52 pm
      Check your ignition timing.
Title: Re: Intake not closing soon enough?
Post by: LarsBloodbeard on October 29, 2012, 04:48:07 pm
I have the stock exhaust.  It actually idled really, really nicely without the silencer on (only the header) when I briefly started it for testing purposes.  So it could be that it's too restrictive.

How do I adjust the ignition timing on this bike?

2002 Bullet 500 ES (now 535), btw.
Title: Re: Intake not closing soon enough?
Post by: barenekd on October 29, 2012, 05:41:55 pm
See PM
 bare
Title: Re: Intake not closing soon enough?
Post by: LarsBloodbeard on October 29, 2012, 06:02:34 pm
Don't know if you got my PM, it said it had a server error when I sent it.

Anyway, I will check whether it's 180 degrees out and adjust the ignition timing/gap.  I have a TDC finder, so it makes that fairly simple.  Timing cover is still off too, so I can see where the cams are at.  I will try this tonight and see how it goes.  I just wasn't sure where to set the gap.  I'm used to adjusting ignition timing with a timing light.

Spark did look slightly weak (though acceptable), so I think I'll buy one of those Bosh coils from nfieldgear just for the heck of it.

Here's a vid of it.  I had the throttle open, then backed down so as to capture it sneezing without it just dying.  http://youtu.be/4d36ZX4BRnw

Excuse the poor quality, I sprayed wd-40 in the carb to help start it (jetting was too lean --now fixed) and kicked it, while filming.  I really needed 3 hands for that.  Then when it died I tried the ES, which sucks, before finally kicking it again... didn't realize the camera was still rolling.
Title: Re: Intake not closing soon enough?
Post by: ace.cafe on October 29, 2012, 06:12:44 pm
If it was 180 out, it wouldn't be running.

I think you just have a tuning issue.
You have a very restrictive exhaust silencer on there, which is about like a potato in the pipe. If it ran well with the open pipe, then it's going to run like shit with that muffler on it.
Try unscrewing your air bleed screw a half turn, and see if that helps it.
I think you're just too rich with that muffler on it.
Title: Re: Intake not closing soon enough?
Post by: barenekd on October 29, 2012, 07:41:33 pm
Yeah, seeing the video, the timing isn't that far off. Go with Ace's recommendations. Pull the muffler first and see what happens.
Bare
Title: Re: Intake not closing soon enough?
Post by: LarsBloodbeard on October 29, 2012, 07:57:44 pm
If it was 180 out, it wouldn't be running.

I think you just have a tuning issue.
You have a very restrictive exhaust silencer on there, which is about like a potato in the pipe. If it ran well with the open pipe, then it's going to run like shit with that muffler on it.
Try unscrewing your air bleed screw a half turn, and see if that helps it.
I think you're just too rich with that muffler on it.

Sorry, meant 360 degrees. 
I didn't say it ran well without the silencer.  Any amount of throttle would kill it... but it did idle very smooth and consistently.  Heck, I'd leave the silencer off if the header would stay put without it and I wasn't afraid of damaging the valves.

I've adjusted the hell out of that carb with the exhaust on now... including changing jets.  Haven't messed with the needle position though.  I really should check the timing anyway, so I'll give that a crack tonight.

I still think it's really bizarre that the intake stays open so long, but if you guys say that's nominal, then I trust you.
Title: Re: Intake not closing soon enough?
Post by: ace.cafe on October 29, 2012, 08:31:35 pm
The spec for the intake closing is 60 degrees After Bottom Dead Center.
That's not really a very late timing.
We use 78 degrees ABDC for the  Fireball, and it NEVER spits back. That's 18 degrees later than stock!

The problem with the Bullets is that they OPEN the intake too early, when the exhaust pressure is still high and the piston is still coming up on the exhaust stroke, and it pushes back up the intake system. The overlap triangle is way to wide on the stock bike, for it's state of tune. It's always been a problem.
Title: Re: Intake not closing soon enough?
Post by: LarsBloodbeard on October 29, 2012, 09:29:39 pm
That gives me more peace of mind.  Thanks.

Is the idle mixture purely controlled by the two screws on the outside and not any jets?
Title: Re: Intake not closing soon enough?
Post by: ace.cafe on October 29, 2012, 10:03:49 pm
That gives me more peace of mind.  Thanks.

Is the idle mixture purely controlled by the two screws on the outside and not any jets?

The idle mixture is set by the pilot jet and the air bleed screw, together. The pilot jet sets the amount of fuel and the air bleed screw sets the amount of air, for the idle mixture.
The large-headed thumbscrew is the idle speed adjustment, and all that does is lift the slide by small amounts to get the idle speed where you want it.

If you unscrew the air bleed screw, it lets more air in, making in leaner. If you screw the air bleed screw in, it lets less air in, making it richer. You have about 3 turns allowable movement from all-in to 3-turns out, with that screw. Outside that range, you need to change the pilot jet.
Title: Re: Intake not closing soon enough?
Post by: LarsBloodbeard on October 30, 2012, 03:42:30 am
Thanks for the tips, guys.  I adjusted the timing and it made a world of difference.  It now runs fairly decently, though it does need more tuning.  It could be smoother, and if I open the throttle quickly it will die. 

Check it out: http://youtu.be/N_RJs2u6RNA

After I get the higher flow silencer I might just take it to an expert for tuning, just to get some peace of mind.
Title: Re: Intake not closing soon enough?
Post by: baird4444 on October 30, 2012, 04:08:45 am
Timing seems still off a bit....  try opening the points just a bit. In the old country they often fine tune the timing by opening or closing the points. to open advances....   close = retard...
           - Mike
Title: Re: Intake not closing soon enough?
Post by: Vince on October 30, 2012, 04:19:42 pm
     If it dies when you open the throttle quickly, that is indicative of it being a big, long stroke single. At low engine speeds a quick blip of the throttle will drastically change engine vacuum, but there isn't enough air velocity through the carb for the carb to work. Gas won't be picked up through the jets so it runs lean and stalls. Learning to roll the throttle on will eliminate most of this.
     This feature is why car carbs had an accelerator  pump to pump in more fuel at low engine speed/large throttle openings. You can tune some of it out, but eliminating it requires an accelerator pump or jetting it so rich that you almost instantly foul plugs.
     When properly jetted you will never notice this issue with proper throttle technique.
Title: Re: Intake not closing soon enough?
Post by: LarsBloodbeard on October 30, 2012, 04:38:16 pm
     If it dies when you open the throttle quickly, that is indicative of it being a big, long stroke single. At low engine speeds a quick blip of the throttle will drastically change engine vacuum, but there isn't enough air velocity through the carb for the carb to work. Gas won't be picked up through the jets so it runs lean and stalls. Learning to roll the throttle on will eliminate most of this.
     This feature is why car carbs had an accelerator  pump to pump in more fuel at low engine speed/large throttle openings. You can tune some of it out, but eliminating it requires an accelerator pump or jetting it so rich that you almost instantly foul plugs.
     When properly jetted you will never notice this issue with proper throttle technique.

Good to know that's normal.  Would a larger carb (like a vm32) overcome this at least somewhat?

I'm more familiar with car carbs, which like you say have accelerator pumps among other differences, so I was a bit baffled by this little vm28.
Title: Re: Intake not closing soon enough?
Post by: Arizoni on October 30, 2012, 10:30:21 pm
A larger carb will make things worse if we are speaking of the engine dieing with quick blips of the throttle.

That's one reason small carburetors are often put on street bikes where fussy engines aren't tolerated by the owners.
Title: Re: Intake not closing soon enough?
Post by: LarsBloodbeard on October 30, 2012, 11:12:26 pm
A larger carb will make things worse if we are speaking of the engine dieing with quick blips of the throttle.

That's one reason small carburetors are often put on street bikes where fussy engines aren't tolerated by the owners.

Interesting.  There's really no reason for me to blip the throttle like that, other than checking how it performs.  It just seemed possibly abnormal to me.  It's good to be wrong.  :)
Title: Re: Intake not closing soon enough?
Post by: LarsBloodbeard on October 31, 2012, 02:47:24 am
Advanced the timing and it runs better. Drove it up and down the street and it had decent power and throttle response.  Still needs some tuning though.  Runs rougher than I'd like.

https://www.youtube.com/watch?v=FcRd6lkCCt8&feature=youtube_gdata_player

How do I more precisely set the timing?  I'm lost without timing marks.
Title: Re: Intake not closing soon enough?
Post by: ace.cafe on October 31, 2012, 09:07:37 am
Advanced the timing and it runs better. Drove it up and down the street and it had decent power and throttle response.  Still needs some tuning though.  Runs rougher than I'd like.

https://www.youtube.com/watch?v=FcRd6lkCCt8&feature=youtube_gdata_player

How do I more precisely set the timing?  I'm lost without timing marks.

Most people use "ping timing" to see how far it can be advanced before "pinging" occurs. The hemi has a big combustion chamber, so it likes plenty of spark advance to help it have time to burn the fuel in such a large area.

To "ping time", you bring the bike to a fairly substantial long hill, and start riding up it and get into top gear at around 2800-3000 rpm. If you don't have a tach, but have standard final drive sprocket, it's around 45-48mph in top gear.
If the bike doesn't "ping", then you can advance it a little bit. You can keep doing this until you start hearing some "ping". That's as far as you can advance it safely. It will only "ping" under worst case conditions, which are to be avoided if possible, since you don't ever really want to have any "ping". This is just telling you how far you can advance until you get it.
Ping is detonation, so you don't want to be having it, but you can use it to determine your limits. Then you can back it off a hair in the retarded direction to keep it safely out of "ping" territory.

If you don't know what ping sounds like, it's that metallic rattling noise that you hear when you try to go up a hill in top gear at a very low rpm, and the engine starts making that noise. Or if you got low octane fuel by mistake, and the engine is pinging. That's the noise.
Some people call it "knock" or "engine knocking". Same thing, different name.
Title: Re: Intake not closing soon enough?
Post by: LarsBloodbeard on November 01, 2012, 05:32:37 pm
Pushrods are bent.  This is probably the source of my rough idle problems.  I might just try straightening them myself rather than wait several weeks for an exchange.

Update: Can't fix it.  :(
Just the exhaust pushrod is off.  And it's not actually bent.  The threads are tapped crooked.
Title: Re: Intake not closing soon enough?
Post by: Vince on November 02, 2012, 06:34:18 pm
     CMW should have them in stock. It should not take weeks to get. That being said, most of them are not "perfectly" straight. Sometimes the adjusters are slightly off. This may be an issue if you miss a shift and over rev the heck out of it-it would be somewhat more like to spit a push rod. In regular use you will never notice it. This will NOT cause a rough idle condition. Improper valve adjustment-too tight especially- can cause rough running. So being too bent to properly adjust will affect running. But these bikes are actually pretty forgiving of small valve mis-adjustments. So if they are BENT, that is an issue. If there is a slight mis-alignment that you have to search hard to find, then probably not.
Title: Re: Intake not closing soon enough?
Post by: LarsBloodbeard on November 02, 2012, 06:53:39 pm
I would say it is too off to properly adjust.  I adjusted it to the point that I can rotate it quite easily 1/3 of the way, then it gets tighter, then won't budge (with fingers).

I brought it by an engine specialist and his words were "wow, that is way off."
Title: Re: Intake not closing soon enough?
Post by: Vince on November 02, 2012, 11:33:51 pm
     There you go. Call your nearest dealer or CMW. You'll have a set in a few days. In the mean time try adjusting it at the tightest spot. Just for testing purposes, not for normal riding. This will insure that the valve fully closes. Does that help your idle? If so, you found the problem.
Title: Re: Intake not closing soon enough?
Post by: LarsBloodbeard on November 03, 2012, 02:04:59 am
I've got the idle better.  It just doesn't run right though.  Kind of puzzled at the moment.
Title: Re: Intake not closing soon enough?
Post by: Vince on November 03, 2012, 04:29:36 pm
     You haven't mentioned if you made other changes. Do you have the stock air box and filter? Did you remove the crank case vapor catch can? Have you drained it? Is the crank case vent hose clogged? Have you changed gas stations lately? Was it left out in the rain? How old is the battery? Is it charging correctly? How is the connection and resistance for the plug cap? Do you have an Autolite  (NO!!) plug or an NGK? Did the issue start suddenly or has it been building for a while? Have you checked for air leaks in the intake hose and manifold?
Title: Re: Intake not closing soon enough?
Post by: LarsBloodbeard on November 03, 2012, 07:05:22 pm
Thanks for the input, Vince.  This thing has me demoralized at the moment.  It does run, just not like I feel a rebuilt engine should.

This is after a top end rebuild.  535cc alloy cyl, 2mm spacer, forged piston, valve job.  Stock air box & filter as far as I can tell.  I cleaned the filter.  Catch can is there.  I have drained it but not recently -- I'll do that just in case.  Hose is clear, brand new actually.  Fresh gas.  Battery is new.  Can't find any air leaks.  Plug is NGK, but I haven't checked the resistance -- will do that.  Gap is slightly larger than it should be (~.02")  I think I'll throw in a new one and a bosch coil just for the heck of it.  I'll see how it runs once those arrive in the mail... My local dealer is less than helpful when it comes to parts for the iron barrels.

I took it to an engine specialist today.  He said he wouldn't worry about it until the rings are seated.  He also said I should really split the case and check out the lower section soon, he thinks something is amiss down there.  I was hoping I could wait on that... But my bike does shake like it's trying to erase an etch-a-sketch.
Title: Re: Intake not closing soon enough?
Post by: ace.cafe on November 03, 2012, 07:21:02 pm
Yes, it will take quite a number of miles before those rings are fully bedded-in.
The basic sealing gets done early, but the rest of it takes quite a few miles.
Idling won't do it. You need to load the rings up with some acceleration and deceleration with some real road riding. You don't have to rev it way up or be hard on it. Just give it some loading on some hills and stuff, at moderate speeds.
That will help. You are probably running on lower compression than you expected, until the rings seat better.

If it's shaking like a paint-shaker downstairs, that's not good.
It usually is a sign that the crank was not trued well at the factory. The ones that are trued better don't shake as much.
These bikes are not inherent shakers, just because they are singles. They can be a lot smoother than many people think, if the crank just gets trued properly.
Title: Re: Intake not closing soon enough?
Post by: Vince on November 03, 2012, 08:43:06 pm
      FRESH REBUILD!!!!! These engines take a long time to break in. City driving is excellent for this. It will run progressively better with time and miles. HOWEVER... This affects some of the previous answers. You might benefit from a new carb. Carbs operate on the principle of volumetric efficiency. That is- they are efficient within a range of air volume and velocity. A larger piston changes both velocity and volume. You may need one larger or even smaller that is compatible with the changes you made. You may also need a new air intake system to accommodate the new volume potential. That larger piston also affects the combustion process. The ignition flame front may not reach the edge of the piston. You may have incomplete combustion or prematurely complete combustion. This may require reshaping the chamber, or perhaps larger valves, or both. Then you have to address the exhaust system. It needs to be compatible with the changes in flow. An engine with valve overlap needs an exhaust system that will scavenge the combustion chamber, then create a reverse wave to block the open exhaust valve to keep the incoming charge in the chamber rather than dumping out the still open exhaust valve. Volumetric efficiency applies to exhaust systems also. So you may never get the smooth idle you want.
     Or it just might need to break in. As long as it is not running lean to cause engine damage, you might just try running it for a while.
     Or... I have concerns about you bottom end. This should have been addressed before the over bore. I have seen many bikes blow out the crank with a new top end. The tired bottom end could not take the extra power. A marginal main bearing will cause the crank end to oscillate- rough running condition. A bad rod bearing could allow the piston a little farther into the combustion chamber at TDC. This could affect flame front consistency. I'm talking .001" imperfections.
     At this point it needs a professional evaluation. He said to wait and see. I would say the same, but I will add that you should look over the points I raised above and formulate a plan to at least investigate these points when the break in is much further along.
Title: Re: Intake not closing soon enough?
Post by: baird4444 on November 04, 2012, 12:22:12 am
"But my bike does shake like it's trying to erase an etch-a-sketch."

this may sound silly but have you checked to be sure ALL mounting bolts and
the head steady are all tight??
sorry, gotta ask. I always start with the simplest and never overlook the  obvious....
       - Mike
Title: Re: Intake not closing soon enough?
Post by: Arizoni on November 04, 2012, 01:22:34 am
"...I always start with the simplest and never overlook the  obvious...."
-----------

You mean like the time I sit there looking at the end of the rear motor mount stud for a minute and then said, "Whoa!  Isn't that supposed to have a nut on it?  It looks like it sheared off!"  :(

 ;D
Title: Re: Intake not closing soon enough?
Post by: LarsBloodbeard on November 04, 2012, 06:15:41 am
Yes, it will take quite a number of miles before those rings are fully bedded-in.
The basic sealing gets done early, but the rest of it takes quite a few miles.
Idling won't do it. You need to load the rings up with some acceleration and deceleration with some real road riding. You don't have to rev it way up or be hard on it. Just give it some loading on some hills and stuff, at moderate speeds.
That will help. You are probably running on lower compression than you expected, until the rings seat better.

What I'm hearing is I should take it out on the Norton ride tomorrow... :)

Oh and I checked the compression today too.  It was 90, but I forgot to open the throttle when I did it.

Regarding the shakes: I wouldn't be surprised if something terrible is going on with the crank.  Just about every component was in awful shape when I got this bike.  However, I took it on a test ride later today and heard a loud clatter at certain RPM's that scared the wallet out of my pants.  Poked around and discovered the head stay was loose, just like baird guessed.  Oops!  Guess I neglected to torque that down.  :P  The shaking is reduced, but still very prevalent.

Anyway, I think I'll just plan on ordering a new crank and bearings in a month or so.  In the meantime I'll break it in and hope for the best.

As usual, thanks for all the advice, guys.
Title: Re: Intake not closing soon enough?
Post by: ace.cafe on November 04, 2012, 09:00:19 am
A word of advice about the bottom end.
You need very good bearings from a known top brand bearing company. OEM bearings really are not up to the grade.
When you get the crank, you cannot assume that it is trued. Even if it was trued at one time, that is no guarantee that it will arrive at your house in trued condition. Shipping often knocks them out of true. It would be VERY advisable to use dial-indicators and v-blocks or a lathe to check that it is under .002" run-out total.

Next, if you plan to build this bike beyond stock at all, you need to address the con-rod problem when you do the bottom end rebuild. The con-rod in the 500 is generally not  best-suited for handling higher power or more rpms.
My usual advice is that if you are going to go through all that work of a bottom-end rebuild, then build it up as strong as you can, and do it once, so you don't have to go in there again for a long time.
Title: Re: Intake not closing soon enough?
Post by: LarsBloodbeard on November 04, 2012, 08:50:05 pm
A word of advice about the bottom end.
You need very good bearings from a known top brand bearing company. OEM bearings really are not up to the grade.
When you get the crank, you cannot assume that it is trued. Even if it was trued at one time, that is no guarantee that it will arrive at your house in trued condition. Shipping often knocks them out of true. It would be VERY advisable to use dial-indicators and v-blocks or a lathe to check that it is under .002" run-out total.

Next, if you plan to build this bike beyond stock at all, you need to address the con-rod problem when you do the bottom end rebuild. The con-rod in the 500 is generally not  best-suited for handling higher power or more rpms.
My usual advice is that if you are going to go through all that work of a bottom-end rebuild, then build it up as strong as you can, and do it once, so you don't have to go in there again for a long time.

I will definitely follow your advice when the time comes.  According Hitchcock's, the modifications I made aren't supposed to stress the stock components too much.  I would like to do a bit more though.  Ported head, better performing cams, etc.  Nothing real crazy.
Title: Re: Engine/tuning issues
Post by: LarsBloodbeard on November 05, 2012, 08:00:57 pm
Problem solved!

I replaced my coil and spark plug, and as soon as I fired it up it ran great.  Tweaked with the idle screws a tiny bit but that's all.  It now will idle really slow and smooth.  Thump........ Thump.......  Thump.......