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**Wingnut** · 03-20-2005, 11:44 PM

Paul,

Excellent detailed post. You did everything I would have done in pretty much the same order. I think you hit the nail on the head yourself when you said, "Fuel in the bowl just not getting to the engine." I would have guessed valve adjustment at this point but you noted the compression was good. To prove a point I would swap two carbs between cylinders to see if the problem follows. Sounds like you still have a carb problem and the blue pipe is indicating that.

**ptm** · 03-21-2005, 11:10 AM

Thanks for the reply, Bob. Not sure how to swap two carbs. I guess the middle two could be switched since they both have fuel inlets on both sides. I think the next thing I'm going to try is to keep turning the fuel pilot screw out and see if it starts letting some gas through before it falls out.... At idle I think it should be the main source of fuel.

**earlfor** · 03-21-2005, 12:35 PM

Re: high idle and #3 not firing

Paul, the problem is vacuum levels and your air and fuel screws are all over the range. Some slight differences in screw settings is normal due to induction layout and manufacturing, but your setting are way out of the ballpark. The guy that set it up before you didnt have a clue. :-)
Set the pilot air screw to 1 3/4 turns out on each carb. Set all your fuel pilots at 1 turn out. Set your float heights at 24 mm. You must synch the carbs with vacuum guages. A manual synch is only good enough for getting the engine run so you can do a vacuum synch. You need to reduce your vacuum levels. I will assume you have corrected any induction leaks. Set your vacuum levels to 25 cm hg at 1500 rpm. Then with clean plugs, take the bike for a ride and then pull the plugs and take a lookie see. If they are all too dark, resynch your vacuum levels a couple points, to say about 22 cm hg at 1500 rpm, and take another check ride. Once the plugs are close, as in two are about right, maybe one is a touch lean and the last is a touch still rich, then you are in the range that a slight adjustment on the fuel pilot screw settings will clean things up.

It is your vacuum levels that are giving you fits. :-)

Earl

**ptm** · 03-21-2005, 01:41 PM

Thanks, Earl, I'll have another go at it tonight. It is strange that the one cylinder wouldn't fire even when I had all the air screws set to 1 1/4 turns out and all the fuel screws set to 1 turn out. I'll try 1 3/4 for the air screws tonight.

I have set the floats to 24 mm (and I'm checking both sides)

I'm confused about the steps, though. I thought you were supposed to let it warm up (choke off), then set the pilot air screws for highest idle (resetting it back to 1500rpm after each) and then do the sync with the vacuum gauge. When mine gets warm enough to take the choke all the way off, the idle it still too high and the #3 exhaust is just barely warm (I assume from the heat of the other cylinders). Is the idle too high because the vacuum levels are too high and adjusting the slides will bring the idle down so I can set it again to 25cm at 1500?

Thanks for the help. It was a really frustrating weekend. I paid way too much for this bike, I've been working on it for over 3 months, and am just now finally starting it for the first time and nothing seems to be making sense...

](*,)

**KEITH KRAUSE** · 03-21-2005, 03:34 PM

I agree with Earl. Let me add in my own words:
The carb synch and pilot fuel screws are all off. It's very easy to incorrectly adjust the vacuum levels until the bike idles high without the pulley even touching the idle adjuster tip. The pilot fuel screws are commonly set a little differently from each other after fine tuning, but never at your differences. I read your previous posts, but I may duplicate something you've already checked. If it was my bike, here's what I'd do.
I think you should take the carbs back off and do a manual synch in preparation for the vacuum tool synch. You risk over-heating the bike if you try to adjust the levels while running, they're that far off. I also think you may need to inspect a few things better.
I believe your jet needle e-clip may be in the wrong position. I don't have a manual for your bike, (Earl does I think) but I think your e-clip should be in position 3, if the intake and exhaust are stock, including the air box lid still on. For example, if your info says: jet needle, 5DL36-3, the "-3" means the e-clip position. I may be wrong, but thought I should mention it.
You should also check the tips of the pilot fuel screws to be sure no tips have been broken off and check the 2 tiny holes that enter the carb throat to be sure they're both open. Verify with flashlight or carb spray.
You say the floats are adjusted, o-rings inside are new,(especially the needle jet o-rings?) carbs are clean, and manifolds and manifold o-rings are good. The ignition timing and valve clearances are also good?
I would check/clean the connections for cylinder 3 at the coil and plug cap and check the lead itself for cracking.
Then manually synch the carbs. Do you know how to set the slides for the fully closed and fully open positions? I believe your carbs should be synched both manually and by vacuum tool, starting with carb #3 first. That is, adjust the slides to match # 3.
As for the pilot circuit, for starters, turn the pilot fuel screws (underneath) out 3/4 to 1 full turn. Turn the side air screws out to 1 1/2 turns. Now adjust the idle adjuster knob up several turns so the bike should start and hold an idle.
Warm it up first on the centerstand. Adjust the idle to 1,100 rpm's with the idle adjuster knob. Now, starting with any carb, adjust the side air screw slowly in either direction and listen for the highest rpm possible. After fine tuning, the screw will generally end up between 1 1/2 and 2 turns out. Now set the idle back down to 1,100 rpm's and repeat with the next carb until all 4 are set and the rpm's are about 1,100.
You should be able to vacuum synch without too much difficulty now. Hook up two fans and your vacuum tool. If you did your manual synch well, the levels will all be within their "range", with only balancing needed. Adjust any higher levels down to the lower ones. It's easier that way and you avoid the bike "running off the idle adjuster" again. Get the levels as close as you can. The difference between the highest and lowest level should be no more than 1/2". Don't over-tighten the throttle valve adjuster holding nuts, 3.5 lb/ft is correct. Double check your levels after setting in case of any throttle valve's sticking slightly. I personally set my levels at about 3,000 rpm's because that's closer to where I'm riding. Avoid over-heating. If you want, after synching, you can re-adjust the side air screws for the highest rpm, but don't expect much change, if any.
To get plug reads for the pilot circuit and to make any pilot fuel screw adjustments, I ride the bike in 4th gear at a steady 30/35 mph for a couple of miles and chop the bike off and read. You want as little effect from the jet needle as possible. Fine tune your pilot fuel screws according to performance/plug reads. Once you get the plugs burning good at that minimal throttle position, you can do a final adjustment to your side air screws.

**ptm** · 03-21-2005, 05:15 PM

Thanks, Keith. I appreciate the input. I'll give it another try tonight.

I have a manual so I'll check to see what it says about the position of the needle jet. And I'll go through the wire and plug cap for #3 again. The bike is all stock - muffler, airbox, etc.

Most of the rest I've checked or have been doing - manual sync, checking the pilot fuel tips and holes, ignition timing, valve adjustment, using fans to prevent overheating - but I appreciate the reminders.

I think your tip about doing the sync will help the idle - I've been taking the low one and bringing it up to the higher ones instead of the other way around.

Thanks, again, I'll keep you posted.

**ptm** · 03-22-2005, 01:46 AM

Well....

According to the manual the jet needle is 5F21-3. What's actually in the carbs are 5DL36-3. I don't know what the difference is, but I set the clip to the 3rd slot on each carb. Interestingly the manual also says the carb should have 450 13 stamped on the side of the throat on the engine side. Mine have 450 30...
I set the pilot air screws to 1 1/2 turn out and the pilot fuel jets to 1 turn
I did (another) careful manual sync.
I inspected the #3 wire and plug cap again and it looks OK.

Put it all back together and started it and it seems to be firing on all four cylinders - a little rough and an occational miss, but all four exhaust pipes were getting hot. (fans on to keep it from getting too hot) I ran it for a minute or two slowly reducing the choke until it was off. I set the idle to 1500, and tried adjustments to the pilot air screws, but going a half turn in either direction seemed to make no difference, so I put them all back at 1 1/2. Cautious optimism, so...

I shut it off and put the adaptors on for the vacuum sync, started it up and... 1, 2, and 4 are all at about 22-24cm, but #3 is sitting at about 8-10cm!! After about a minute of running I checked the pipes and #3 is cooling off... I tried reducing #4 down to where #3 was, but ran out of adjustment. So I tried to adjust #3 up to where the others were and also ran out of adjustment.

I'm thinking I've got a major air leak somewhere on #3. It shouldn't be that far off after the manual sync. This is the second time that it seemed to be firing and after shutting it down and doing nothing but removing the screws and installing the sync adaptors, it stopped firing and had much less vacuum than the others. Hmmmm just had a thought - maybe I should also look at the hoses on the gauge or at least swap the #3 hose with another and see if the problem moves - it's a brand new Motion Pro, but maybe I broke something or put it together wrong and it's the gauge that is leaking air and causing the problem...

I may not be able to get back to it for a day or two. Let me know if you have any more ideas, I'll keep you posted on the progress.

Thanks again for your help. I'm sure glad I'm not on my own...

**KEITH KRAUSE** · 03-22-2005, 03:56 AM

As for you not having much luck with the side air screw adjustments, you should start the adjustments at 1,100 rpm, not 1,500. 1,500 can be above the range that the screws can effect the rpm's. If you have them at 1 1/2 to 1 3/4 turns out, that will be close enough for the time being.
Your carb synch findings are interesting. You should be able to lower the high levels to match the lower level if you wish and vice-versa. During the manual synch, did you use the #3 carb slide as the master and match the other slides to it? Did the small nick in the slide look identical in adjustment to the other 3? I know it may not make sense, but the throttle shaft can be rotated 180 degrees and the throttle valve arm screws re-installed and this can POSSIBLY help as a last resort idea. Then you have to re-synch/ vacuum synch again.
I'm also wondering if you're getting too much fuel and wet fouling the plug at #3? No combustion will effect the vacuum. Any chance your vacuum line is drawing fuel from a failing petcock diaphragm? Your description of (after carb work is done) how that cylinder stops firing after a minute or two fits this thought. Test the petcock for leakage. You can put the petcock to prime, but a more positive test is to cap the vacuum nipple and turn to prime at your next synch/test.
If your needle info says position 3 at the end (-3) then the needle e-clip should be in position 3 on a stock bike.
Are you sure the manifold at #3 is not cracked? Any chance the o-ring slipped out of its groove a little during re-assembly? Always coat the o-rings with some hi-temp' bearing grease to help them last and torque to 6 ft/lb.

**ptm** · 03-26-2005, 09:00 PM

Well, a little progress, but I still can't get #3 to fire.

I redid the manual sync and, by first unscrewing all 4 slides, and starting with #3, I got a better manual sync. The idle is no longer a problem and the idle screw doesn't have to be screwed in so far before it touches the throttle arm.

I can sometimes get #3 to fire for a while when it is first warming up and the choke is on. After that it just doesn't fire.

It is getting a good spark, and I've tried several spark plugs.

When I pull it after trying to get it to run, the #3 plug is not wet from fuel.

I replaced the fuel pilot screw.

I've had the carbs off several times and cleaned and recleaned. Today I tore #3 down and soaked it in Berrymans again for several hours and then gave it another good spraying with carb cleaner and blew it out with air. I can't find any holes that even hint at being blocked. Those puppys are CLEAN.

I tested the vacuum gauge and it has no leaks.

I can't find ay evidence of a crack in the manifold.

I checked the o-ring on the rubber boots that bolt to the manifold and they looked fine. I even swapped two boots - no difference.

I have been running all tests with the petcock on prime. I don't have a hose of the right diameter for the vacuum that's long enough to reach the tank.

It seems to come down to no fuel. I've got spark and there's fuel in the bowl, but none getting to the combustion chamber.

I have thought about trying to swap the middle two carbs. I think it would work since they both have fuel inlets on both sides. The pilot air screws would be pointing the wrong way, but I could at least see if the problem follows the carb...

I'm getting pretty discouraged. Anyone know of a good mechanic in the Portland area?

I should have bought those carbs on eBay from the guy with no feedback...

Any thoughts or suggestions are greatly appreciated.

**KEITH KRAUSE** · 03-27-2005, 03:16 AM

First of all, you can't swap any of the carbs. #4 carb has a floatbowl vent that also feeds #3. If you swap #2 with #3, you'll have no floatbowl venting to #2. That will cause fuel starvation.
I re-read your previous posts and as you say, it must be fuel not getting to the cylinder.
I'll go back and read what you say you've done and see if you missed anything. I'm so darn computer stupid, I don't know how to save my message as I'm making it. If I go back now to read your posts, I'll lose what I've typed so far. Back in a bit.

**KEITH KRAUSE** · 03-27-2005, 04:19 AM

Well, your bike seems to run temporarily after you've played with the carb. So it's not a problem of no fuel getting to the cylinder... the fuel flow is not sustained. It's possible fuel is not entering the bowl as fast as it should. So after a minute or so, the bowl level gets so low the jets can't draw fuel. This could be a blocked passage to the valve, sticking float needle valve, or the float not operating smoothly and sticking.
You can easily find out if this is happening. Prime the bowls as you've always done and start the bike. As soon as the cylinder stops firing, turn off the petcock FIRST, and turn the motor off. Quickly take off #3 bowl without spilling and set it aside. Take off #4 bowl and compare the amount of fuel in each. Though it is possible that fuel can still trickle in from the fuel line and fuel passages, if you quickly remove the bowl at #3 first, you should get a fair check of the fuel amount.
If the amount is noticably less in #3, then it's the passage to the valve, the valve, or float causing the problem. The valve sometimes develop a burr on a side that hangs it up.
If the fuel amount is the same as the #4 bowl, then the dry cylinder has to be caused by a blocked jet or passage to the carb throat, or a loss of vacuum to carry fuel to the cylinder.
This may sound dumb, but are you remembering to plug the vacuum nipple at #3 during your tests?
If the vacuum nipple is capped, then it's a blocked passage or jet.
When you test and that cylinder stops firing, are you always idling (on the pilot circuit) or do you ever try holding the throttle at about 1/3 so you know you're on the needle circuit? If the cylinder started firing again at 1/3 throttle, that would prove the blockage is in the pilot circuit.
Because that cylinder does fire temporarliy, I really don't think it's a blocked passage or jet though.
So as long as you did plug the vacuum nipple, I'll go with the bowl level check and see what you find.

**ptm** · 03-27-2005, 09:23 PM

Originally posted by KEITH KRAUSE

This may sound dumb, but are you remembering to plug the vacuum nipple at #3 during your tests?

Bingo!!!!

I made a very bad assumption - Since two of (what appear to be) vacuum nipples vent to atmosphere, I assumed that they were all the same. I was running a hose from the #2 vacuum nipple to the petcock, I had the normal hose on #4, and #3 was just sitting there.

So, I put the two hoses on #2 and 4 and ran the hose from the petcock to #3 (just like it is when it's all put together), and IT WORKS!!!!

All cylinders are firing, it idles nicely and I got it sync'ed. WOOO HOOO!!

Now if you could only do something about the rain that is forecast to last for at least another week.

Thanks so much for helping me with this. Although I've done a fair amount of wrenching before I hadn't ever done carbs to this level.

By the way. If you are replying to a post and want to see what is already in the thread, just scroll down the reply page. Right below the Preview and Submit buttons for your reply there should be a 'Topic Review' section that shows all the posts in the last page of a thread. They're in reverse order with the last post on top.

Thanks again

**duaneage** · 03-28-2005, 12:04 AM

The bright side to this is your a freakin expert on those carbs and we get a very good post to learn how to work on carbs. I see the good in everything, it's my greatest flaw.

**KEITH KRAUSE** · 03-28-2005, 09:29 AM

Glad to help Paul. Enjoy the bike!

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high idle and #3 not firing

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