1995 KLF300 Not Taking Throttle and Revving High With Choke On?

[Ragsy]

Recently got a 95 KLF300 and have been fixing a lot of electrical issues and finally got it running. It ran good for a day then went to start it the next and it was already done for and not starting. Found that the plug had been fouled and replaced that and now it runs. The problem I have though is that It will only idle with just a little choke on. Will not start with no choke and when choke is applied it revs itself to extremely high RPMs. Before I adjusted the air mixture screw it would only run if the choke was OFF and afterwards it only runs with choke. If I try to give it any throttle it immediately bogs down and will stall out. Starts back up like nothing happened. Timing is dead on.

I have a brand new Chinese carb, old owner didn't have OEM on it. What could be the problem?

[Mech]

It could have an air leak, (either a holed diaphragm or into the inlet manifold), or a blocked jet, or you might have adjusted the idle speed and mixture incorrectly.

I'd probably take the carb off and clean it and check the float setting, and then  when it's warmed up I'd adjust the idle mixture to it's best running with the idle speed screw wound out as far as possible.

[Gwbarm]

I had a similar problem I put aftermarket on, I would have preferred to rebuild the OEM CARB BUT IT HAD ALREADY BEEN REPLACED with aftermarket,  I had to do some adjusting on the throttle cable to get it to idle, not a perfect fit. Since yours ran good for a day I would suspect you might have been some particles in the gas line that might have got into your new carb,, you might also check the vacuum lines   to make sure they are all going where they are supposed to go, I think I had an extra one I didn't have a place for and had to plug it. if you have a vacuum operated petcock that may not be working correctly.

[Ragsy]

Okay thanks. I'll check over everything Saturday and see if that fixes the problem.

[Ragsy]

Hey, I checked the carb out and the floats aren't stuck, jets aren't blocked, and the inside is near spotless. All doors are moving appropriately. Idle screw also seems to be doing nothing to the performance at all. Put the carb back on and it ran fine for a second then once it started idling about 10 seconds it gradually begun revving itself up again. The throttle however worked this time and it would rev it up but it would not go back down. It is also back to where it does not want to start on choke, only off choke will it actually stay running but it revs so high its like it will blow the engine up. I will post an attachment video of it when I can get back to it later.

Also didn't notice any vacuum leaks but who knows, I could've missed something.

[Mech]

If the idle mixture screw doesn't have any effect, then it's because either the idle system has a blocked jet or passage, the fuel jet by the sounds of it, or the throttle is too wide open for the idle system to operate..

You should check the slide is going right up and down, that the slide needle is fixed in place correctly, and that the throttle goes right back if it's a CV carby. The throttle cable may not be attached/sitting correctly. If that stops the high revving then the idle mixture will perhaps adjust. If it still doesn't adjust then it needs the idle jet cleaning again.

If you are taking it off again recheck the join to the manifold, an air leak could cause the problems. So could burning oil.. It's not smoking is it ?

It would be a good idea to check the valve clearances too.

[Gwbarm]

Make sure there is no load on the throttle cable they are not a perfect fit on an aftermarket carb, after everything else you have done I might check the timing, it should not be off, but to advanced could cause a high idle, the only other thing I can think of is running to lean, I didn't have this problem, but I have known guys who put on aftermarket carbs describe your problem, and ended up drilling out the jets.

[Ragsy]

Okay guys so I just ended up switching to another carb and it runs fine now. I need to adjust it a little bit then it'll be fine, thanks for your help!

[Mech]

The other carb won't have much wrong with it.. They don't break !

If you strip it down again and clean all it's air and fuel passages it will almost certainly be all it needs. 

If it's a diaphragm carb,  if you look really closely where the butterfly closes, there will be two or three small holes, some on the air cleaner of the shut butterfly, and some on the engine side of the butterfly when it's full closed. The hole/holes on the air-cleaner side will be really tiny and they will just look like tiny black specs in there.. They are probably the culprits. They will need a good blast of air from the butterfly.. not blown out from the idle jet side.

If it's a cable on slide type carby, they have the same arrangement where the butterfly touches down. On the engine side of the point where the slide touches the venturi there will be a small hole, and on the air-cleaner side of that same point there will be another tiny hole..  They need the same treatment, a good blast from the venturi side, not up from the idle jet side.

It would be worth another go..  A good rainy day job.. A spare carb is always handy.