Idle Problem

Hi guys, I haven't had a chance to take anything apart and check specs, but last summer my bike had a problem where it would warm up and idle around 1000 RPM's, and then into my ride whenever I would pull in the clutch and it would die. I didn't really know where else to post this question, and seeing as how I think it may be a carburetor problem I decided to post it here. Any insight would be much appreciated. Thanks:)

MN400 wrote:

Hi guys, I haven't had a chance to take anything apart and check specs, but last summer my bike had a problem where it would warm up and idle around 1000 RPM's, and then into my ride whenever I would pull in the clutch and it would die. I didn't really know where else to post this question, and seeing as how I think it may be a carburetor problem I decided to post it here. Any insight would be much appreciated. Thanks:)

Am guessing the bike is a 1977 KZ400.

Including information about bike year and model may elicit better responses. And it's easy to put in your signature where it will automatically appear in posted messages.
When done, the signature information appears in all posts, past and future. And may be changed as often as desired.

Here's how to do it:
Click here > kzrider.com/index.php?option=com_kunena&...d=8&id=382004#382317

As to the reported problem, too tight valve clearances might be causing loss of compression as the engine warms.

If not already done, would check and assure valve clearances are set to specs.

Acceptable cold compression figures are not enough, and don't necessarily continue as the engine warms.

Good Fortune!

Another cause might be a sticking ignition timing advancer unit.

It's easily checked with a strobe type timing light, and watched moving back and forth as rpm is varied by blipping the throttle.

When the advancer is sticking, lubing alone is sometimes enough to cure it.
But might require removal for a good cleaning and lube.

Good Fortune!

As to carbs, might be improperly adjusted pilot circuits and/or carbs out of sync.

Imo, carbs should be the last items addressed, after first ruling out other possible reasons.

Would first assure valve clearances to specs, and verify ignition timing, and install new spark plugs after visibly observing a fat blue spark on each plug, and then adjust carb pilot circuits and idle thumb screw position.

Good Fortune!

If it has a points style ignition, the contacts should be first dressed and cleaned, then the points gap set, and lastly the ignition timing adjusted.

Oh yeah, I apologize for not mentioning the specs on the bike, but you were right on. And thanks for the info, once I get time (currently at college) I will go home and start checking specsl