2007 yz450f hard to start now

Hey guys ... just wanted to check to see if I'm missing anything.

I just had the bike into the shop to replace my crankcase cover due to it being cracked from the guy I got it from. The replaced the bearings, piston rings and all the gasket while they were in there. While the bike was at the shop, I took the opportunity to clean and rejet the carb for the exhaust he put on. It was running a little lean. I also put a fuel mixture screw and the boyesen quick shot 3.

Before I took it in, the bike relatively easy after just a few kicks with the it choked. Now it takes forever even with the choke. I found that if I hold the throttle open it will normally start after a few kicks, but that doesn't seem normal.

What would be causing this? Is it the carb tuning or valve issue?

Once the bike is running, it runs great. I have about 10 hours on the bike since the work was done.

check the valves

Could being too tight result in that? Is there an easy way without taking the top cover off?

Timing off a little. That's my guess

Yeah my gut tells me something like that too. I just don't want to tear the bike down to fix the shops mistakes again. Live and learn I guess

It's more likely the carb than anything, and if it likes the throttle slightly opened during starting, it usually indicates a rich condition.  Try the fuel screw in a half turn from its current setting to begin with. 

Thanks! That would be ideal! I'll give that a shot

Would having the quick shot on the carb be causing it too? That replace the leak valve, so I don't think that would affect starting

Would having the quick shot on the carb be causing it too? That replace the leak valve, so I don't think that would affect starting

 

It can affect starting, but only if you grab several hand fulls of throttle before starting, squirting too much gas into the intake.

 

Unlikely the issue.

Cool thanks...will try the fuel screw, then tackle the timing and valve clearances

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