Carb Boot Issues?

[TonimusMaximus]

When I cleaned the carbs, I sprayed carb cleaner into the pilot jet and watched it come out of the 3 idle holes of each carb. Does that change anyone's opinion?

[ratbyk]

Poor Idle

OK, then check that none of the idle mixture screws have broken tips blocking off the idle circuit and recheck the float level. If the float level is low it is hard for the carb to draw fuel when the throttle plates are closed. It can only get fuel through the idle circuit when the plates are closed.
Ken/Sooke
78E Ratbyk
82 FT500 "LilRat"

[scalded dog]

Will the carb boots on a special, fit a standard? tia. Later 'Dog

[mitch]

HTH

Tony , i dont know all the proper names but i just wonder if you cleaned the emulfication tubes, i missed them the first 3 times i cleaned my carbs! When you have your carbs apart where the needle jet goes into the seat that is the tube it taps out the bottom of the carb after you have removed the lower jet. If they arnt removed and cleaned my bike acted like yours. Just a thought hope this helps. There is a pic of the tubes in question on the maintance section.........MITCH

[TonimusMaximus]

Hey guys. Update. I coated the boots in liquid electrical tape, put them back on and ran the bike. She would idle with the choke half out instead of all the way out. I put my hand over the airbox intake and she jumped in RPMs and I put the choke all the way in and TADAAA! She idled! So now I'm looking at an air box leak to. She was just running way too lean, not because the carbs were clogged, but because she was sucking in way too much air. Does anyone have any suggestions for sealing up the air box?

[randy]

Tony,

There's a rubber gasket that runs the entire edge of the bottom half of the air box. Make sure its in place, it can get dislodged whilst trying to get the cover back on. Also check that the air filter element is complete. As they age, one of the first things to disintegrate is the foam at the top and bottom edges of the filter, which serves to make the seal between the airbox halves. This can cause a major air leak past the filter element, causing a lean condition. How's the car?

Randy

[TonimusMaximus]

I've got a brand new filter in it and I did suspect that cheesey gasket. I'll replace that with some weather stripping foam or something. As for my truck, Geico replaced the $300 window for free. They even sent a guy out to replace it at my home. Nice people. I was thinking #2 Permatex around the intake nozzle and boots on the airbox. Any other ideas?

[Ken Talbot]

Something still doesn't sound right about this.

If the carb boots were/are cracked, or if there is leakage between the boots and the cylinder block, or if there is leakage between the boots and the carbs, you lose engine vacuum. This causes reduced airflow through the venturi, which reduces how much fuel gets sucked up out of the float bowl. Reduced air supply and reduced fuel and the engine starves.

If there are no vacuum leaks and you stuff your hand over the air intake, the airflow through the venturi has to drop off. Now you've created stronger vacuum in the carb throat than the normal airflow through the venturi will. You get more fuel sucked up to run on, but still not a large enough quantity of both air and fuel to run properly.

I'm guessing the reason you're not getting enough fuel up when airflow through the venturi is normal is because there is some form of restriction in the passage the fuel has to come up through. The common name for this is dirty carbs.

I did a quick look back to the start of this thread. Forgive me if I missed it, but I didn't see any mention that you removed every last removeable part from each carb during the cleaning and verified that every single port, orifice, and passage in the body was absolutely clear, both by running fine wires through where possible and by blowing compressed air or cleaner through.

Some guys get lucky with a single cleaning, some get it right with a tripple cleaning, and others literally go through this 10 times (or more, eh Stickyfingers? ) before it finally comes together.

Then again, I could be on the wrong track entirely....

[TonimusMaximus]

Hey Ken. I did clean the carbs and verified that passeges were clean by watching cleaner come out the other end. I did have a vacuum leak, repaired temporarily by coating the boots with liquid electrical tape. Am I wrong in that if there was not enough of a vacuum created inside the airbox, that the idle would be very poor??? Forgive me if I'm missing something terribly obvious. If I completely seal the intake tube, she doesn't die. She idles rough, but refuses to die.

[randy]

Tony, What about checking the seal betwen the head and the manifold boots, try spraying wd40 ther while running, and if you get an increase in idle, you've foud your problem. if that IS the problem, either new gaskets $yikes$ or sealant is in order. I've used a product called The Right Stuff. It's a vulcanising rubber compound, heat, fuel, oil resistant that comes in a nozzle can that dispenses just like ready-whip. I've used it to seal everything but heads on engines as small as lawnmowers and as big as V-8's. Good luck.

[randy]

In case anyone is interested, the manifold to head gasket part# is 10M-13556-00-00. The price (NOS) from Speed and Sport is $6.10 EACH! This application is '82XJ but will fit 79-81 XS also. Interestingly enough, there is no gasket listed for XS's. I think Yamaha figured it out too late for the XS that the boots wiil seal better with a gasket and introduced it on the XJ?

Speed and Sport.com:

http://64.30.217.113/speedandsportinc/index.html

[Jerry]

I think Yamaha figured it out too late for the XS that the boots wiil seal better with a gasket and introduced it on the XJ?

Maybe the XJ is just a better bike? (Ducking and running...)

[randy]

I don't know, but the XS didn't need the gasket and the XJ did?

Ducking and running or trying to catch up??

[John]

Originally posted by Jerry

Maybe the XJ is just a better bike? (Ducking and running...)

But just a little slower!

[Jeff]

Even if you clean the emulsion tubes, there is still a tiny passage between the idle jet and main jet/emulsion tube bores. Spraying carb cleaner thru the idle jet shows that the passages from that jet to the carb throat are clear..... but it is the passage between the main/emulsion and idle jet bores that feeds the idle jet.... at least if your idle jets have the plugs over them. If there is crud in the emulsion tubes, the idle jet feed passage or the idle jets themselves, idle to low rpm performance will be really doggy. On my 78, it would idle and rev ok sitting still... but while riding.... it ran like a slug until about 3500 rpm. Since I run dual exhaust, I noticed a change in the exhaust tone on one side at 3500-4000 rpm and found that one cylinder was stumbling at idle and kicking in smooth at higher rpm because the idle jet for that cylinder was not being properly fed. With no load, it would idle just fine but off idle while riding really suffered.