kitted minarelli v1, wont start when warm

I recently put a kit on my bike, along with exhaust and a mikuni carb. It started right up and ran fine for a couple days. Now, if i go to start it for the first time in a while it will start but if it has been running almost any length of time its near impossible to start. When its cold you can hear the engine turning over, when its warm it sounds like its turning over much slower. I took the cylinder off and checked for any damage and the rings and walls look fine. Any ideas? Is it the clutch?

Re: kitted minarelli v1, wont start when warm

you might just be jetted to rich. A hot engine won't start with the choke on cause the mixture is to rich, same things happens if you jet it to rich.

Re: kitted minarelli v1, wont start when warm

yeah exactly how big is that carb, and what jet are you running?

Re: kitted minarelli v1, wont start when warm

On mine with the kitted engine (Polini) when it gets warm the compression seems to be higher. Maybe because of expansion or maybe because the rings are nice and lubricated.

Anyway, my starting clutch wants to slip when it is warm.

What I do is pull in the starting clutch and bring the pedal to about the 10:30 position and lightly press on it. The piston goes to top on the compression stroke and then I wait for about 5 seconds. What I believe happens is that the compression bleeds off and then when I run it through, the engine is free to start to spin.

Re: kitted minarelli v1, wont start when warm

It's probably electrical.

Re: kitted minarelli v1, wont start when warm

i've noticed the same thing here with our kitted V1 as well, its much harder to kick over when its hot and you have to get it just right or get a running start on it. usually when its warmed up she just pedals up and hits the clutch and vrooom there it goes. when its cold it usually fires on the first or 2nd kick. doesnt help that the starter clutch is weak sauce on these engines, you really have to crank down on that lever, and you cant adjust it too far because it will stay on a little all the time then. maybe theres a way to weld a little tab onto the arm to make it longer so you got more torque when you pull it? theres just soo little room between the arm and the frame though. it sucks!

speaking of our kitted V1, we're going back to a high compression (210-230 psi) 50cc setup for the rest of the summer. this fall i'll be trying to make her intake for the 19mm dellorto and get that thing working. the brass choke rod is seized into the carb body..which means i need to pull ti all apart and heat it gently to see if i can free it. if i cant...i dont know what the heck to do! anyone want to donate a 19mm carb to a chesty girl with a love of mopeds?

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