Topic: Hard starting

[rm56]

Hello, I have a 74 CB 750K4. I rebuilt the carbs (had to, there was rust in the tank). I have to use full choke to start it, then back it off 1/2 way. It sounds like its not getting fuel and won't idle. Once it warms up it runs fine, but every so often it "coughs" or makes a sputtering sound? Keyster kits were used, I've been told on another board that aftermarket rebuild kits are no good. That some of the jets are not the right size, etc. I paid a shop to sync my carbs and they went out of business. Any ideas? Thank you

RM

[mattcb350f]

Well RM, It's not uncommon to use full choke to start a bike, and then back it off to half while it warms up. However,  it sounds as if it could be a bit lean since it "should" run smooth after it warms up and I suspect the "coughs" are a sign of a lean condition at idle.

I'd suggest you have a read through the manual or search this site on the topic carb adjustments. Each carb has an idle mixture adjustment and should be set according to the specs in the manual. However, sometimes if a lean condition like this persists after adjustment, you may need to back them out a little more than the recommended setting to make it run nice.

Cheers, Matt.