XJ750 requires choke for a LONG time

I'm assuming this is caused by less-than-perfectly-clean carbs, but wanted to check with you guys to see if anything else could cause it. My bike is starting fine with the choke on, but once it has warmed up it will only idle with the choke off for about 30 seconds before it starts to die. Revving the engine keeps it alive, or adding a little choke. After a 30 minute ride or so, it will idle just fine with no choke. Any ideas?

EDIT: Now with poll. Do you think seafoam in the gas will help the carbs, or cause clogs and make 'em worse?

 

Carbs :wink: ...

skillet

 

Then I've updated my post with a poll! I plan on taking the carbs off in winter and giving them a proper cleaning, but for now I'll live with it... I want a good riding season before I tackle anything major.

The question is, will seafoam make it run better or just cause trouble?

 

it's been my experience that every time my own carbs aren't synced. the idle is never stable. it gets higher as the engine gets hotter.

sync the carbs and your idle should perform better.

 

Has it gradually begun to do this or always done it? All stock induction and exhaust? Have the idle jet adjustment plugs been removed and re-adjusted yet?

 

I've only had it for a month, and it's done it since I got it. Not stock exhaust, it was a straight pipe and I replaced it with a baffled 4-1 system... cut out the lean pops, but idle remained the same. Air intake is stock, I don't know about anything else. I haven't touched the carbs, and don't know if PO did.

It idles at around 1k. What is it supposed to be? I don't have my service manual handy.

 

You answered the BIG Question with a statement.

You don't know if the PO did the Carbs ... and you know you didn't.

You're due!

 

have you tried turning up the idle screw? I'm not sure if its the same on your bike, but mine has a fatty screw in between the 3 and 4 carb, at least it will be consistent and you won't have to ride around with the choke on.

My bike takes forever to warm up, I fiddle with the main idle screw for a good 30 minutes at every stop light before she's perfect(although I don't have a choke)...just old bikes I guess...

 

I haven't touched the idle adjuster yet, but I was going to try bumping it up a bit with that if nobody knew a magic solution here.

I know it's due for a carb cleaning, that's not even a question, but since it rides just fine right now and I can get around the idle problem, I'm going to delay that until winter so I can actually get some saddle time on my new bike!

Any word on the seafoam? I know it can dislodge build-up in the carbs and clog needles, so it worries me. I have no idea what condition they're in, but off-idle the bike is smooth and strong and pulls hard well past any posted speed limits so they aren't horribly screwed up at least. The crankshaft and final drive drain plug were both magnetic. I believe the PO was a chump (he owned it for a year and never changed the oil), but the PPO took care of it.