Help! Not running on back two cylinders!!

[dannymax]

Just out of curiosity, the jet block gasket should be reusable correct? I know it’s a paper gasket, but when I removed these they were in great shape. No tears or damages. Or should I have replaced them?

Yes replace them they get compressed and harden with age.

 

[dannymax]

Run them on a good engine to see if these problems persist

 

[kx250gs1100]

Update

Well I got the new carb kits in and installed them in all the carbs. New orings, and new gaskets in all. Got it all back together and on the bike. Fired it up and no popping!!! Idled decent! Still needed a lil tuning though. Equaled out the fluid levels on my schronizer then hooked it up. Carbs were a lil off. Figured they would be still the carbs were split. Started synchronizing the carbs and that sob started popping out of that same damn cylinder again. Idles great now but that one damn MF ing cylinder is popping again.

 

[Fire-medic]

FYI, I recently had a cold LF cylinder, and it was a combination of a bad O-ring on the VBoost manifold, and crud in the small jet block (pilot jet) #42 on a carb fiche which was only fixed after I replaced the gas tank. I found the leaking VBoost O-ring using starting fluid on the area of all four VBoost O-rings, and the revs picked-up on only one area. Since it was coming off, I just ordered 4 new ones. Synching the carbs and making sure the float levels are correct, as you have done, should also help.

https://www.ronayers.com/oemparts/a/yam/50045c0ef8700209bc7942f3/carburetor

What is your # of turns-out on your air bleed screw, something around 2.5? I have always treated popping as an indicator of leanness.

 

[dannymax]

You check mixture screw sensitivity?
All purge jets clear?

 

[timbacharly]

How did this end up? I am currently having a hard time : After carb rebuild (disassembly-clean-assembly), I got both right hand cylinders cold..

 

[Fire-medic]

Do they come-in when you rev it?

 

[timbacharly]

No they don't... spark comes ok. Fuel levels somewhat equal when I drain them

 

[Parminio]

Are you SURE you got them properly seated into the boots?

To test it, fire it up, get some carb cleaner or WD40 and shoot small squirts at the base of the carbs. If your idle goes bonkers, you didn't get them seated all the way.

If it turns out they're not in, reinstall them. In my personal experience, you should always get the right side seated in the boots first. It may be because I'm left handed, but I've always found there to be more room to get more oomph on the carbs on the left side.

So what I do is stick the right front carb in first, push it in (you'll feel it "pop" in) then the rear right, the push the left side carbs in and they normally both pop in together.

 

[timbacharly]

Are you SURE you got them properly seated into the boots?

To test it, fire it up, get some carb cleaner or WD40 and shoot small squirts at the base of the carbs. If your idle goes bonkers, you didn't get them seated all the way.

Ok, trying about now. I just bought CRC starter spray. U mean, seated the needles?

 

[VMAXXIMUM]

No he means the carb bodies into the boots.

 

[timbacharly]

Start pilot has no affect to two dead cylinders.... (Should I mention, the two working ones stall when I spray it them when running . And YES it is a proper spray)

 

[dannymax]

Did you sync them?

 

[timbacharly]

Did you sync them?

Yep

 

[timbacharly]

Going now for a test drive if those wake up

 

[timbacharly]

Do they come-in when you rev it?

Actually yes, something was happening when I drove it. Like 1/2 or 3/4 throttle , it feeld like all four would be firing! Only a couple of times tho. Idle and full throttle always in V2 mode...
What could it be Could it be too rich? I do not know the aize of main jet, but this ia canadian model (1991) , the needle has 6 notches, now it is set to 2nd. I think I have clogged idle circuits. I tried to remove A/F mix screws, (with pressured air to Pilot Air Jet, didn't succeed.)

 

[timbacharly]

Actually yes, something was happening when I drove it. Like 1/2 or 3/4 throttle , it feeld like all four would be firing! Only a couple of times tho. Idle and full throttle always in V2 mode...
What could it be Could it be too rich? I do not know the aize of main jet, but this ia canadian model (1991) , the needle has 6 notches, now it is set to 2nd. I think I have clogged idle circuits. I tried to remove A/F mix screws, (with pressured air to Pilot Air Jet, didn't succeed.)

Found some dirt ("black gold") in the small line inside the cover..But didn't solve the dilemma.

 

[Fire-medic]

I suspect a tear-down of the carburetors, to the removal of the jet blocks, removing the pilot jets, and poking-out the plugs of crud in the pilot jets is going to be needed. An ultrasonic cleaner big-enough for soaking a pair of carbs (you split the carbs into two pairs) at a time, at the minimum, is what I've found to be effective. If you cannot see daylight through the pilot jet, it is not clean.

https://www.vmaxforum.net/threads/got-a-carb-question.50303/#post-504218
Be sure to open the carburetor enrichment gland nuts which retain the pistons, to drain the soaking fluid, and to lubricate them upon reassembly with 5-56, WD-40 or similar. You do NOT need to remove the steel rods which tie each pair of carbs' enrichment pistons together, nor do you need to remove the forked followers which are attached to the rods, which move the starting enrichment pistons up/down. If you leave those gland nuts on, and you soak the carbs, and then you DON'T drain the liquid out of the piston area, they will quickly corrode, which can be a big problem to fix.

 

[timbacharly]

I suspect a tear-down of the carburetors, to the removal of the jet blocks, removing the pilot jets, and poking-out the plugs of crud in the pilot jets is going to be needed. An ultrasonic cleaner big-enough for soaking a pair of carbs (you split the carbs into two pairs) at a time, at the minimum, is what I've found to be effective. If you cannot see daylight through the pilot jet, it is not clean.

https://www.vmaxforum.net/threads/got-a-carb-question.50303/#post-504218
Be sure to open the carburetor enrichment gland nuts which retain the pistons, to drain the soaking fluid, and to lubricate them upon reassembly with 5-56, WD-40 or similar. You do NOT need to remove the steel rods which tie each pair of carbs' enrichment pistons together, nor do you need to remove the forked followers which are attached to the rods, which move the starting enrichment pistons up/down. If you leave those gland nuts on, and you soak the carbs, and then you DON'T drain the liquid out of the piston area, they will quickly corrode, which can be a big problem to fix.

Yep.... Actually splitting is not a promblem, I just had the carbs in pieces and for cleaning, this was the first start after re-assembly Maybe there were some dirt left somewhere.

I also need a genuine carburettor repair/jet kit, where could I get one? (Finland)

 

[Fire-medic]

Sean Morley [email protected] and CaptainKyle [email protected] have shipped overseas. They can provide carburetor kits.