YZ465 hard start

[chrisnoel]

Looking into getting my YZ465 to start easier after rebuilding the top end. Was hard to start before the top end rebuild and has not improved since. It was new to me so I tore it down only to find a practically new piston and rings in it that are vintage .040 wiseco. The ring end gap was slightly larger than spec so I did hone and re-ring it. Has new manifold rubber, stock reeds, and stock jetting with stock air box plus foam filter.

Runs great after kicking it till I'm exhausted. Doesn't seem to start much better when warmed up.

I'm at about 5K here in Colorado Springs CO and will probably ride at 8K on a regular basis is you have any jetting recommendations?

the exhaust is solid but the seal at the engine is questionable. Will be replacing it soon.

 

[2strokerfun]

Have you inspected and cleaned the carb? If you're getting spark, carb is the usual culprit for hard starts. Make sure the pilot jet is not clogged up. I've had good luck using the wire from the middle of a bread tie and carb cleaner to ungunk them if they are clogged. Fresh fuel mix and plug are also helpful.

 

[chrisnoel]

Thanks. Dipped the carb and parts then blew everything out before replacing the manifold as well. This was all done before the top end. After the top end I took the carb apart again, removed the jets, and sprayed everything plus blew it out again.

Yesterday I re-did the foam seal on the side cover and restricted the air intake vent. Started a little better plus I'm getting better at finding TDC before giving it the boot. Still cold natured but with starting so restricted I'm probably too lean. Suppose I'll have to play with the jets one at a time to richen things up. If I go straight for the pilot I could go too far right away but I'm thinking this is the culprit.

 

[Danno's 465]

As a friend once said, when stating the venerable 465, kick it like you would somebody who slept with your sister.

Mine is a toughie to cold start....but I am slowly dialing in the carburetor. Matter of fact...I am replacing it with a new one; carrying over the jetting and such. Once it is warm,2-3 kicks gets it going again.

Fully leaned, she ran like a champ...so I figger it's time to boot the old carby. Plus, it looks non-standard. The choking apparatus is all wrong.

All let you know how the new carby does. It is a Mikuni VM38-9.

 

[2stroke]

Ive got one. I know what you mean, you get half worn out starting the damn thing!!!!

Play with the jetting all you want. The root cause is this.

It has so much compression that it is hard to kick it over with enough revolutions to draw fuel into the cylinder.

Pull it out after sitting a week, and there is of course, NO fuel left in the jug at all. Sucking a fresh charge from the carb takes more revolutions than an average kick will get you.

Ive done many things. Bump the kicker little by little til it gets tight, then just a HAIR more. Then jump up and kick it HARD.

Spray some carb cleaner into one of the T vent hoses...that works well also.

Ive gone so far as to place a small petock inline with my boost bottle hose, and I have a lab style squirt bottle with some premix in it, so first start of race day, I twirl the petcock open, give it a squirt, twirl it shut and two kicks tops.

Mine still knocks a bit when hot...gonna try some 110 octane next time out.