Vacuum leak? crazy rpms, and now it won’t start.

I started a thread and I've been updating it a lot. If you have the time please check it out I'd appreciate any advice.

 

Had the same issue as you. The three things required for your engine to run are spark, pressure, and fuel/air mixture. When this happened to my xj650 I started by running a compression test and checking the sparks. Compression test is pretty simple, if you have an autozone near you they loan out the kit and you get money back when you're done. Spark tests are also easy (check youtube), just make sure you ground the spark plug (put the tip of it on your engine) or you'll get a nice shock. Added bonus when you pull out the spark plugs you can inspect them to see if you're running rich or lean. Both of these are much simpler than going through the carbs so I recommend doing those first if you really want to be thorough. That being said your problem only seemed to arise after working on the carbs, so it's up to you. Just sharing what worked for me.

 

Initially it was due to a vacuum leak so I did a full strip down of the carbs but I have taken them to church and replaces nearly everything that should have been replaced. My current issue as of now seems to be fuel levels and getting those to spec.

 

It's not something totally unrelated, like a clogged pick up screen in the tank or blocked petrooster, is it? How much rust and gunk was in the float bowls when you first removed them?

 

Oh a ton lol but I have cleaned the inside of the tank coated it with por-15 had a few pin hole leaks pop up and then used an epoxy on the outside of the tank. It should be pretty rust free. The carbs are off the bike and I’m using an external tank while I work on it. When I measure the fuel levels I am making sure the carb body is level In two different directions

 

That may be part of your problem. Service fuel level is meant to be set on the bike, on the center stand. Carbs installed on the bike are not level front to back - they are tilted down at the front.

 

I was under the impression that you do the wet levels off of the bike... I have read through the article several times and even made a stand for it.
Update: after taking the needles out and blowing compressed air through the gas line they are now over flowing with fuel, so the problem may be close to being fixed.

 

There are probably 3rd party procedures for that, but the factory procedure, and level, are based on the rack as it is sits on a complete bike. I'm not sure how the floats behave when on a level stand - effectively tilted back from their normal orientation. Maybe you still get the same reading as long as you read in the center of the body? Maybe not...

When I've been forced to do carb wet sets, I've done them on the bikes. (I also converted to fuel injection, though, because I mostly hate carburetors). The two carbureted bikes I have now only have two carbs each, which is about 4X easier than having four of them.

 

Ok so I have gotten the wet fuel levels as close as I can, carb 3 seemed to fill up a tad slow but it did end up getting into specs or close enough. I put them back on the bike and after some trying it eventually started up and shot straight up to 6K rpm with the choke on. I tried to let up on the choke to get the rpms down and it kind of worked but was all over the place or died. I am not sure what to do next but am officially done for the day. I assume I have to adjust the idle screw? I had turned that all the way out. It was suggested that after my bench sync I may not have had it open enough. any advice would be very much welcomed. I want to get this bike ready for the post COVID world

 

Are you sure the idle knob is backed out all the way? Did you do a bench synch? This is how I do it in take two business cards , cut in two , put one under each carb , turn the synch screw starting on the number one carb turn in until you get a slight drag pulling on the card leave it in place, go to second carb repeat , go to number four do same. Now turn in idle knob till on number three carb you get a slight drag on all four cards. Remove the cards hold carb up to a strong light you should see a slight crescent shape on the bottom of the butterfly plate, this should get you close till you can do a vacuum synch. Good luck.

 

could you elaborate on where you put the cards? Are they feeling drag from the movement of butterfly valves?

 

You put one each of the cards under the butterfly plates , adjust the synch screws till there is a drag by pulling on the card .

 

I ended up using a paper clip for mine and had done it that way. When I put the carbs back on and it didn’t work someone suggested turn the mixture screw out as a possible solution. Turns out it was fuel levels that were the issue and now I have to mess around and undo the mistake.

 

You don’t have to play the card game OR use paper clips

1. Set carb 3 with the butterfly juuust on the back edge of the hole at the top of the butterfly.use the idle screw to do that
2. Now, use the sync screws to adjust the other three to the same spot.
(3. I snap the linkage a dozen times at this point)
4.back the idle screw out until carb 3 hole is covered HALFWAY
5. Double check that the other three are also half way. Now fine adjust until all are half covered after snapping again several times.

you are now bench-synced. It took you longer to read this than it takes you to do it. It usually takes about 1 minute to do.

I haven’t used paper clips or cards in years. It takes longer to get the clips unfolded and inserted, or pieces of cards cut and inserted than it does to just do it the way I described.

dfox

 

which hole? there are three...

 

Hello ladies and gents, finally got the wet levels set and a decent benchsync, the bike started up!!!! my new issues are that I sometimes get a single click from the solenoid when I try to start it up. other times the engine turns over. my plan for that is to rebuild the starter but I am unsure how to test connections and resistance and grounding??? so there is that fun new learning opportunity, any links for good walk-through s would be much appreciated. my next issue is that when the bike starts up it only starts on choke and revs up to 3-6k but can slowly be brought down, but dies if I take the choke off... am I supposed to sink the carbs while the choke is on? do I mess with the idle screw while the choke is on? any advice on this issue will also be much appreciated! thanks in advance. getting this far on my own work and everyone's advice has been a real satisfying feeling!!

 

Sounds like there are some clogs somewhere yet

 

like in the carbs? any recommendations on how to test?

 

I blow air with my mouth to verify air is moving through. Yes the passages are tiny, but you can feel it. A tiny open passage feels different than no air moving at all. Before all that, there is plenty of soaking, cleaners, compressed air.....

Upon first hit of compressed air, you can also see any carb spray still in passages get blown out.

If I can see, feel, and hear the compressed air going through, I know it’s clear. If I can’t see, hear and feel ALL THREE, I don’t reassemble until I CAN. THEN I know all passages are clear. Time-consuming?? Yup, but I wanna make DARN sure that a rack is totally clean and clear before continuing.

 

I did everything, short of using an ultrasonic cleaning. I soaked all parts, used an air compressor, I shouldn't need to break the rack down at least then. back to the board then. so when that is fixed ideally how should the bike be running when I start it?

 

It should start and run well enough that you can get it to warm up and idle on its own without the enricher on. You may have the idle a bit higher than you want at first, but get it to idle without the choke. THEN do the running sync after it’s warmed up.

 

Thank you! It’s been too long since it has run properly!

 

Make sure the jet in the enrichment well in the float bowl is clean, with a wire.

 

That's exactly what I am going to be doing next, buying a wire set from chacal and going through the carbs again.

 

checked the starter motor and it works, so it must be in the wiring!

 

Gotta lock auto correct ( blocked petrooster) made my day!