Topic: Hot start problem

[longshanks]

So my buddy just got his K4 overhauled and everything in the motor was done. Carbs was gone through, cleaned, jetted and synced. His problem is the bike won't start when hot. It will turn over and over and it takes forever to finally come to life. Once its running though, it is perfect, so smooth. I should mention that when its cold he says it starts just fine. Any ideas gents?

[Dimitri13]

Gas cap vent clogged?

[longshanks]

Gas cap vent clogged?

any other reasons?

[fire113]

...if it starts without choke when cold it is running toooooo rich, check the air screws.

Good luck...Georg

[windwalker]

valves to tight?

[iron_worker]

x2 on the over-rich problem. Did whoever went through the carbs change jets or adjust the idle mixture?

I have a K4 and if I remember correctly the idle mixture should be 1 1/2 turns out... that is if it's stock.

IW

[flybox1]

^ +1
plug deposits will confirm.

[longshanks]

So should my buddy be more worried about the air bypass screw, idle jets, or mains? What's going to affect it the most? Like I said the bike runs AMAZING when its going. Good power, idle is smooth and responsive. It's basically a new, rebuilt motor.

[iron_worker]

Starting issues will be primarily caused by the idle jets and the idle mixture screw. The mains don't really come into the picture until at least 1/2 throttle and up.

Does the bike have a stock airbox and does it have stock exhaust? If so you should check to see if you have the correct size pilot jets/idle jets. If it does then the stock idle jet should be a #40 and the the air screws should be 1 1/2 turns out.

If the exhaust or airbox is changed then you are looking at doing some custom tuning.

IW

[longshanks]

Stock airbox and Mac 4-2 drag pipes. I'll have to find out what the pilots are.

[iron_worker]

The drag pipes will definitely have way less back pressure than the original exhaust and you'll likely need to rejet / retune your mixture screws and needle position.

IW