after carb clean balance all cyclinders are hot now for the rest of the bike

[His Dudeness]

I fucked about tried cleaning my low mile originals 3 times with they've only done 10,000 miles !
Tried 4 other sets until I got some that worked perfectly,I found out its not just jets there's a few tiny orafaces inside that clog too.
The jets also get yellow/green gunge inside them you cannot easily clean or even get to,the best option is to buy new emulsion tubes, jets etc & replace the rubber parts too.
My low mileage set needs about £80 or so spent to make them good,we've got the EU & the shitty petrol they sell to thank !

Those tiny orifices are the transfer ports. If you look at the carbs on the airbox side you see two air jets. The one on the left is the pilot air jet


At idle air is drawn through that jet down a small orifice and it goes into the holes in the side of the pilot jet and out the narrow end of the jet.



That draws fuel up from the bowl at the slotted end of the pilot jet and up through the center of the jet and the air fuel mixture goes down another orifice and comes out of the small holes on the engine side of the butterfly valve called transfer ports. The transfer port orifice is joined to the the mixture screw orifice so the air fuel mixture also comes out at the mixture screw hole. Turning the screw in blocks the hole and turning it out lets more fuel through.



That's how the idle circuit works and all of the passages have to be clear not just the jets.

There's a good diagram of what I'm saying. The left side is the airbox side

[psyfi_1]

i  was pretty sure i had cleaned them....... i will wait for carb cleaner to some and do it again with a guitar string and see if that does anything....

[bikemad]

I blow air though & make sure all the carbs sound the same though each oraface,if not it's not clean enough !
The problem I had was a flat spot about 1.5-2k so it's just where the idle jet crosses over to the main jet circuit,the main jet emulsion tube is also prone to the green/yellow coating inside.


You can buy the exact new parts for these carbs,because their commonly used in other models.


I did read that paint thinners can soften the gunge but I've never tried it myself.

[His Dudeness]

I edited that last post to make it a bit clearer.

I blow air though & make sure all the carbs sound the same though each oraface,if not it's not clean enough !
The problem I had was a flat spot about 1.5-2k so it's just where the idle jet crosses over to the main jet circuit,the main jet emulsion tube is also prone to the green/yellow coating inside.


You can buy the exact new parts for these carbs,because their commonly used in other models.


I did read that paint thinners can soften the gunge but I've never tried it myself.

It's more about throttle position than rpm. If the flat spot is at 1.5-2k you'd only have the throttle open a tiny bit so I'd estimate 90% or more of your air/fuel mix would be from the pilot circuit. If you're having a flat spot there and you think it's fuel related you should clear out the pilot air jet, pilot fuel jet, mixture screw and very importantly the transfer ports because that's where the fuel comes out. If the transfer ports are blocked cleaning out the jets isn't going to solve the problem. The transfer ports are so small that carb cleaner or an ultrasonic cleaner is the best way to dissolve the crap and old varnished petrol. After everything is clean adjusting the mixture screws and balancing the carbs would also help but everything has to be clean first

[Bretty]

Electrical faults can create flat spots with throttle position. As the mixture resistance changes you can find opening the throttle with a weak spark will make it misfire, back off on the throttle and the engine picks up.

[His Dudeness]

Electrical faults can create flat spots with throttle position. As the mixture resistance changes you can find opening the throttle with a weak spark will make it misfire, back off on the throttle and the engine picks up.

Yea I've experienced that where a cylinder was dropping out because of water around the spark plug caps causing arcing to happen but only at low revs. Then as you're saying the mixture resistance must have lowered as you opened the throttle because the arcing stopped as the revs went up and the bike ran normally.

[psyfi_1]

right the top of cylinder 3-4 are hotter now defintatley but they still dont seam to be as hot as the other two..... i will put balance on them later and see whats going on...... if the balance is out will it give  a diferent tempreture reading??

[His Dudeness]

right the top of cylinder 3-4 are hotter now defintatley but they still dont seam to be as hot as the other two..... i will put balance on them later and see whats going on...... if the balance is out will it give  a diferent tempreture reading??

It can do. But how is the bike running is the important question I don't think you mentioned that. What is it doing? Is it lumpy at idle? Is it mis firing when you open the throttle? Does it feel down on power when you're riding? If you've got a mis or a cylinder that isn't contributing you can use the water on the exhaust trick to show which cylinder is the problem cylinder. If the bike is running ok and there's no mis and there's still a difference in exhaust temperatures it can be caused by a rich or lean mixture. The leaner the mixture is the hotter it burns and the richer the mixture is the cooler it burns so if you do the water on the exhaust trick and it can give you an indication of rich vs lean on each cylinder, also if you take out the spark plugs and read them. Black and sooty is rich, white is lean, wet is no spark, and you combine that with the exhaust temp you can get an idea of the problem.

[psyfi_1]

okay idling is fine is happy at idleing when when warm okay just after a few mins needles a little jumpy though okay riding is pretty smooth until you give it some then the engine shakes she looses power then if i let of the revs a bit she settles and i can pull back to higher reves but cant blam the throttle basily....

[His Dudeness]

It could be fuel/air related or it could be spark related (ask Red98 about his stutter ). You'll have to rule things out with trail and error. But from your description it sounds like it runs ok until you open the throttle suddenly and a lot then it stutters and stumbles. The water on the exhaust is suggesting that 3 and 4 are the cylinders stumbling so it could be a problem specific to them. Did you check the diaphragm rubbers for holes when you had the carbs apart? If there's holes in the diaphragms the slides won't lift so your main jet won't come on when you wack the throttle open. That could be the problem. A blocked air filter could be the problem causing a restriction in the air flow. It could be blocked jets on 3 and 4 carb. It could be a spark related problem that only happens up the rev range.

[psyfi_1]

okay i have balanced the carbs now the pipes are the same now and all are hot........ fuck yes when i get her back on the reoad legaly i will give her a test run and see what happens but for now just front rear brakes to do and fenders to paint also some touch up on the front fairing bolts cause there rusty lol