Missing When Started Cold

[signaramatn]

Hey guys Ive got a 2000 Kat 750 with 45K on odometer. Within the last six months when I start her up after a week or so of not riding, for the first 5 minutes or so she's only firing on three cylinders. Once I get out on the road and warm her up (slowly) she starts running fine. FYI - Im way overdue to check valve clearances. Without blasting me for not doing this what is the likelihood that valve clearances being out of spec is causing this? If unlikely could someone provide some feedback as to what the culprit most likely is? Much appreciated!

[arsenic]

Let me rephrase your question. "Hey guys, I didn't do a maintenance item that can cause an issue. I'm now experiencing said issue. Is there something I can do besides fixing it to make it work?"

[Yoyosten]

Fire it up. Feel by hand or use a temp gun on the exhaust headers. Find out which cylinder isn't firing. Turn it off. Take the plug out check for fouling. Is it getting spark and fuel. A good indicator of fuel is some popping from the exhaust. That unburnt fuel get ignited causing a backfire afterfire. Sometimes it's easy to skip right over the easy stuff and assume the worst. There's plenty of culprits thay could cause your issue. You just have to go down the list man.

[92xjunker]

Afterfire, not backfire. I bet the carbs are gummed up.

[Yoyosten]

Afterfire, not backfire. I bet the carbs are gummed up.

I always forget, and you're always there to let me hear about it. =)

[92xjunker]

Just think after- as in Forward through the engine. Back-as in backward through the carbs. FYI after fire is carb related. Backfire is timing related, Kats aren't prone to it because the timing is fixed, no mechanical advance. Now if you screw up a valve adjustment, yup it will happen but, valves are timed so, it is still timing related. You'll hear puffing at the carbs before you get it to back fire if you goofed a valve adjustment.

[signaramatn]

@92xjunker - Thanks for the response. Thought about that and took the carbs off/apart and checked. Clean as a whistle.

@Yoyosten - Good point but the bike only misfires for a few minutes. Ill try but I don't think it lasts long enough to detect a difference in temp. at the headers. Hopefully Im wrong. Thanks!