250 full rebuild

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Nov 28, 2020
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I posted a few pics in some other threads. Figured I’d start a new one for our build. I bought my son a blaster for Christmas 2 years ago.
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Was 100% stock except for the painted plastics and graphics kit. Was actually blue originally.
 
Bought him new plastics and a toomy pipe for it last year thinking that would be all…. Wrong, you know how it is when you start tearing into things. So off to powder coat the frame and all the smalls went.
 
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Set of banshee front hubs and spindles, rear blaster sprocket and rotor powdered.
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Surfaced the rotor and removed powder.

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Front assemblies with fresh bearings and seals.
 
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Engine - 240 vitos topend with a 3 mil stroker. I did the port work, pics to come tomorrow.
I still need to check squish to see if the head needs milled or not.

Also have a 33 PWK ordered from the boys at FAST.
 
What squish are most of you guys running? I’d be comfortable with .035 to .040.
 
So I got the carb yesterday. Two things need addressed, the boot, and clutch cable clearance. The boot I’m sure I could make fit with a heat gun or hot water. Just not sure if it’s gunna be restrictive.
The clutch cable clearance doesn’t look good.
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Would a new boot help with clutch clearance? Or am I gunna have to run a spacer?
 
Ended up ordering a UPP 34mm intake boot. I’ll see how that fits up then add a spacer or maybe bend the clutch lever a bit if it needs.
 
Bought a reed spacer, was about 3/8” thick. Way too much for me, put it in the mill and shaved it down to just under a 1/4”. Carb has plenty of clearance now.
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Checked squish on the Vito stroked big bore with supplied gaskets and spacer. Was about .118”

Took spacer out and only running one gasket now. Then shaved about .020” off the top of the jug.
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Exhaust height was sitting at 85 degrees before I took spacers out. So, dropping the jug that far I gave the exhaust port a little raising.
Squish ended up at .032”, perfect.
 
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Gave her a little test run, power is awesome even though it needs broke in yet. It vibrates terribly though, so much so that it affects the bowl in the carb. If you rev it in neutral to about 6k, the bowl flutters and spits a lot of fuel out the overflow.
Next step is to balance crank and piston.
More to come later fellas.
 
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Welp, Ever seen one burn on the intake side…. Centered on the ring pin?
 
Head gasket was leaking a bit, normally that doesn’t cause a lean condition though.
 
Head gasket was leaking a bit, normally that doesn’t cause a lean condition though.

Any air leak in a 2 stroke will cause a lean condition, some more worse than others depending on where and how severe the leak is, I see signs of 4 corner seize on that piston pictured, improper warm up prior to riding with an air leak will cause all kinds of piston wear/damage.