Breathing noise with Mikuni upgrade

[Olderasteroid137]

I’m not sure what to set the fuel mixture screw or idle screw at. My idle screw is currently screwed out pretty far, only because its the only way I can get the bike started.

 

[Minimichael]

Roughly speaking, the mixture at 1.25 turns out, idle out so slide is just 1-2mm off the bottom. Choke off unless it's cold.

You should be able to run like this.

 

[Minimichael]

This might help you understand better.

 

[Olderasteroid137]

Have idle set at this. I turned the fuel mixture screw all the way in and then 1.5 turns out. With choke on/off, engine doesn’t start.

 

[Minimichael]

Try restricting air flow with your hand over the intake - not too tight

 

[Olderasteroid137]

Try restricting air flow with your hand over the intake - not too tight

I got the engine starting by adjusting idle. It doesnt run to great though. It runs with choke on but dies out when I turn it off. *I can get the bike running on choke but it dies when I give throttle with choke off. Any suggestions? https://youtube.com/shorts/Fj_BKMjy2Io?si=QUhlMhoJfF9fos6_

 

[Minimichael]

Somebody else has to chime in here about choke. Some say up, others say down.

Seems to me it should run either way, tho choked (aka "enriched") should run too rich and sputtery

 

[Minimichael]

Do you know what # is your pilot jet? You could try dropping the needle clip position, so as to shorten the needle length - and let fuel in more easily during early throttling.

 

[Olderasteroid137]

I put a 120 jet in

Do you know what # is your pilot jet? You could try dropping the needle clip position, so as to shorten the needle length - and let fuel in more easily during early throttling.

 

[Olderasteroid137]

I’m not sure why the bike dies when I turn the enricher off. Currently it exhausts smells pretty bad and I can tell that it shouldn’t be runner with enricher on, I’m not sure what to do to get it running with enricher off

 

[Minimichael]

I put a 120 jet in

Pilot. You put a 120 main in. What's your pilot?

 

[Minimichael]

I’m not sure why the bike dies when I turn the enricher off. Currently it exhausts smells pretty bad and I can tell that it shouldn’t be runner with enricher on, I’m not sure what to do to get it running with enricher off

I'm still suspecting air is leaking in at your manifold gaskets. So much so that enriching is only way to meet fuel needs.

 

[Olderasteroid137]

Pilot. You put a 120 main in. What's your pilot?

120 pilot jet (the smaller jet)

 

[SAS289]

Somebody else has to chime in here about choke. Some say up, others say down.

Seems to me it should run either way, tho choked (aka "enriched") should run too rich and sputtery

Plunger up enrichment on. Plunger down enrichment off. Been this way on Mikuni's for decades.

I wouldn't use that black insulator spacer. There are 3 places to leak air instead of 2.

 

[massacre]

You're going to have to do some investigation. We can give suggestions but you'll have to do the actual checking of stuff. I'd start with valve lash and see if that frees up the flywheel at all. Then remove the carb and start over. Reinstall it, taking care to make sure everything is sealing good and tight. Spray the carb with ether and see if it fires. Then start working on the carb.
having a tach would help.
Top speed is about a lot of factors but that is the least of your problems at the moment

 

[Olderasteroid137]

This gasket is probably the culprit of the air leak.

 

[Minimichael]

120 pilot jet (the smaller jet)

How about the other jet? The long one..

I'm thinking that should be about 17.5.

 

[Minimichael]

This gasket is probably the culprit of the air leak.

Was that o-ring pinched? Replace that with a couple paper gaskets.

 

[Olderasteroid137]

Bike is running with fuel enhancer fine but still evantually dies when I turn it off. And it immediately dies when I give it throttle. I’m still unsure of why this is happening.

 

[massacre]

How is it on the pull rope? Is it still tough to spin over? I wouldn't run it too long like that. Improper valve lash could be causing your issue
Glad you found the air leak