Messages

1

General Two Stroke Talk / Race gas - what to get?

« on: July 29, 2012, 01:29:21 AM »

I run avgas too mostly to get away from stupid Cali pump gas and all the additives. My CR250 starts first kick and my YZ465 is 2-3 kicks. Ithink it's mostly because the carbs stay way cleaner with no oil/gas separation. My YZ was a nightmare on pump gas.

2

General Two Stroke Talk / CR250 build

« on: July 29, 2012, 01:26:03 AM »

All this info came from Thumpertalk from some pretty knowledgable guys.
.025 to .030 milled from the base of the cylinder or have RB Designs or Eric Gore mill the head for pump gas. The squish is way to big for pump gas. Milling the cylinder will give more bottom endand correct the squish volume without messing with the head.
Keihin Air Striker carb. I got mine from CarbPartsWarehouse and it came with the correct 03 carb cable. You can use a carb from a late model YZ250. The difference is the back to front length and fitment but it's not a problem either way. Either carb you won't be running the TPS.
The stock pipe seems to be the way to go with a PV Shorty on it but I am running a full PC set-up because my CR had a crushed leaky pipe.
Race gas unless you can get non ethanol gas or 50-50 to handle the slight boost in compression. I run avgas 100LL with no problems. I was running 100 street racing pump gas but it was almost $10 a gallon. Avgas is $5.50
These mods will get the bike running way better, probably the way it was intended to run but this is plenty for most people.
Good luck and keep us posted. It's cool to see whats up with other peoples CR250's.