engine doesn't run right

[nascar7613]

Have a 1997 Valk. It had been sitting for a while before I got it, would not take throttle without stalling. Removed carbs, disassembled, cleaned, replaced the bowl gaskets and o rings on the tubes, reassembled, installed on the bike. Hooked up my vacuum gauges to sync, seemed like I had too turn the idle screw in too far to make it idle, but it would idle and take fuel. Synced the carbs then put the vacuum lines back, 3 & 4 into a tee then into the pulse air control valve, and the 6 to the petcock. After that was done, started the bike, but it will not idle and doesn't increase rpms smoothly. Could it be the pulse air control valve is stuck, or would that cause the bike to run like this? It's like it has a huge vacuum leak . Also, it seems that it is sucking a lot of air in the holes on the top of the air box. If I partially cover the holes with my hand, the bike runs better. This is the first Valk that I have worked on, but I have done many carbs and I know I did them right. Any insight would be appreciated.

[hukmut]

One question: when you did the carbs, you DID replace the float needle valves?
The little springs have lost their "springiness" due to age .

Try some Berryman B-12.  This stuff works.

Ride safe...

[longrider]

Are your pilots adjusted to 2.25 open?  You can temporarily cap off the vacuum ports to the pair valve to see if there is any leaks in the hoses.  Also before carb sync the air filter should have been installed as the bike may not have the correct fuel mixture with the air filter removed  just thinking

Warren

[Patrick]

I just have to ask, did you replace the vacuum port caps ? Also, if you didn't replace the other vacuum lines they could very well be leaking.

You shouldn't have to move the 5 adjustment screws very far, having to do so is an indication that something isn't right.

If the pilots are the original size [35], then as mentioned, it'll run better if they are set at 2.25 turns.

[Steel cowboy]

Did you replace the intake manifold o rings too.

[nascar7613]

I did replace the float valves, the vacuum lines, did not replace the intake o rings. I sprayed the intakes with the bike running and it did not affect the rpms, so I figured they where ok. The bike wouldn't even start with the air filter removed, so I put it in the airbox and also screwed down the cover. I have the pilot screws set at 2 1/4. I don't understand why the bike would run ok with the vacuum gauges connected but won't idle when I reconnect the vacuum lines. The caps that are on the 1,3 & 4 intakes do not look great, but I think they are good enough to seal. Thank all of you for your replies!

[The emperor has no clothes]

I did replace the float valves, the vacuum lines, did not replace the intake o rings. I sprayed the intakes with the bike running and it did not affect the rpms, so I figured they where ok. The bike wouldn't even start with the air filter removed, so I put it in the airbox and also screwed down the cover. I have the pilot screws set at 2 1/4. I don't understand why the bike would run ok with the vacuum gauges connected but won't idle when I reconnect the vacuum lines. The caps that are on the 1,3 & 4 intakes do not look great, but I think they are good enough to seal. Thank all of you for your replies!

It sounds like it's got to be the vacuum caps. When I did my synch with the DigiSync I thought mine were good but they were toast. That's where I would start, especially since it ran good with the Gauges hooked up.

[DK]

You could have a bad diaphragm in the petcock?

Did petcock stay open with moderate vacuum while syncing or were you supplying fuel from an alternate source with the tank off?

[nascar7613]

I put a repair kit in the petcock. I ran the bike then pinched off the vacuum line going to the petcock while doing the sync and the bike kept running through the whole process.

[indybobm]

I would suggest to hook the DigiSync back up and see if it runs correctly again. Then remove one digiSync line at a time, rplacing the vacuum cap, until you have found the problem.

[salty1]

Are the rubber intakes from the airfilter box placed properly? Your mentioned the bike won't idle, how does it run otherwise? ???

[longrider]

By your last comment you said it runs fine when all vacuum gauges are on.  If that's the case you've narrowed it down to vacuum.  Are the new hoses routed and hooked up correctly.  If so the pair valve may be the problem.  I'd start it, run it for a minute to fill the bowls then cap off every intake nipple.  If it runs you'll know for sure

[Hook#3287]

If you're using the original OEM caps, I'd bet that's the issue.  They can look ok and still leak.  I found that out years ago by doing the human mouth vacuum pressure test. 

If you've got some small rubber hose and some bolts that will fit in them, you can use that as caps.

[nascar7613]

I am going to buy some new vacuum caps and see if that is the problem. Getting the tubes from the airbox back on the intakes all the way on both sides was a struggle, but they seem to be all the way on now. I don't know what is interfering with the installation of the airbox, possibly the radiator cover, it was hard to install also. Can the pair valves or the control valve create a vacuum leak?

[The emperor has no clothes]

I would do a desmog. But if you want to keep it stock, all new hoses, caps are in order. The air box is a pain, get a flashlight and a dental mirror in there and make sure everything is good.

[salty1]

I would do a desmog. But if you want to keep it stock, all new hoses, caps are in order. The air box is a pain, get a flashlight and a dental mirror in there and make sure everything is good.

Absolutely agree with Meathead! Desmog the bike and eliminate future vacuum leaks. 

[pancho]

Many people have had vacuum leaks from bad hoses and caps and didn't even know they had a problem,, sounds to me like you may have something more going on.      I'd be  thinking I still have carburetor problems if it was me Nascar. A good indicator is when you mentioned that the bike runs better when you cover some of the the air intake ports on the airbox.


The pulse air control cannot cause a problem like this, and I haven't heard a report of one with a vacuum leak, but just cap 3 and 4 intake ports to rule that out.

[longrider]

After reading the ops post over the first time I assumed he had the air box lif off.  Pancho how is right if the air box lid was on this could be a carb issue

[nascar7613]

I replaced all the vacuum caps, bike still runs the same. When you say it may still have a carb problem, what could the problem be. The bike did run much better while partially covering the air box air vents on the cover. The bike would not run at all with the cover off. I don't know how much suction there should be at the air box cover air vents, but mine tries to suck my hand inside it's so strong. The bike ran ok with the vacuum gauges hooked to it, but still didn't seem right. It would idle and I could get the carbs to read the same amount of vacuum between them, but I did have to turn the idle screw in almost all the way to make it idle at around 1000 rpm, although it seemed to idle fairly smooth.

[Rio Wil]

You mentioned covering some of the holes in the top cover of the air box......there should be only one air intake hole(slot) on the top about 2/3 way back and facing to the rear....do you have other holes also? If so, your bike won't like it....

[Mr.BubblesVRCCDS0008]

You might try to open the pilot screws up to 2 and 1/2 or 3/4. No all bikes run the same I had to get mine up 2 1/2 turns om my interstate before it idled right and starts without throttle or choke.

[pancho]

FIrst thing I would check is the pilot screws nascar,, make sure they are not closed down. Like others have said, initial setting of 2 1/4 out should make the bike run satisfactorily,,, if not that I would suspect the pilot screw passages and/or the slow jets being clogged up.

[nascar7613]

I took the carbs off again and found that the pilot jets were clogged. I had cleaned them when I had the carbs off before, but then the bike sat while I was waiting for some parts. I guess the ethanol fuel must have caused the jets to clog. I've put them back on, but I can't get the air box tubes to go all the way flush on the intakes. I can't see where anything is under it, it looks like it's all the way down. I can force the tubes on the intakes but they are not flush in the backside.

[Bone]

Haven't had any problems with the slow jets in my 98 Tourer. I have read more than one post where the guys just replace
the jets saying they are difficult to clean.

[nascar7613]

Finally got the air box on. What a pain that thing is. Had to make sure the tubes weren't rolling under on the backside, so I put the backside on first then took out the roll under from the front. Also had to use a tie down strap to get them all the way down, they are all flush now. You were spot on about the carbs being the problem, Pancho. I didn't want to take the carbs off again, but it made sense there was a problem there. I haven't taken it out yet, not going to until I wash the months of dirt off, but it fired right up, idled smooth and takes throttle well. Thank all of you guys for your input, you are fantastic!

[pancho]

Glad to hear all the progress is in a positive direction......

[nascar7613]

Took the bike out for a ride. Runs very smooth, except at full throttle, it breaks up a little bit. Only rode it a few miles, possibly needs a good long ride. Any ideas would be appreciated.

[salty1]

Put a full can of Chemtool to a tank of gas and run it through. Did you set your pilots at 2 1/4 turns out? Have you synchronized your carbs? The latter two items shouldn't influence full throttle operation. How are your plugs? What rpm are you noticing the miss? Sorry for all the questions.