I bought my wife an '01 Blaster bac in September. We went for a ride on some aggressive trails and she rolled it. Sucked an air bubble in the injector line and blew the motor. I rebuilt the motor, bored .040, shaved the head .010, installed injector block-off kit. It has a k&n filter that was just cleaned and re-oiled. I run my pre-mix at 20:1 cause my '86 trx 250r runs that, uses maxima 927. Today was the second ride on the fresh top-end and she blew the motor again. That's twice in less than a year. She doesn't ride wot either, she barely gets into third. The plug was a light grey and had 40 psi for compression. Do you guys think I need to re-jet a couple sizes bigger?

 

I feel your pain I leaned mine out a couple weeks ago and have been working on getting it running again. Do you know what jets are in there now? Does it have aftermarket exhaust, reeds, or open air box?? All of those should have some bearing on your jetting. Everything I have read says to start big and worst case you are fouling out plugs and could come down a size. If you decide to rebuild again probably would heart to go up a coupld sizes. I have aftermarket exhaust, reeds and an open air box and my jetting was at 310 and I am bumping it up to 330 just to be safe as I don't want to go through this all again. Good luck and hope this helps.

Chad

 

One other thing it could be are the crank case seals to. I have read alot about these causing the engine to run lean so that migh tbe something to look into. rydindirty.com has some info under the Blaster section that can walk you through it. Probably would be good to check if you invest the money on a rebuild.

 

I pulled the carb out Friday and found 230 main jet. Obviously the guy I bought the bike from didn't re-jet for anything. I bought a 300 and 320, I'll do like you suggest and go big first. I think the 320 will be about right for the mods done to the bike.

I have a full trenga pipe/silencer, bored .040, head shaved .010, k&n filter, 6 one inch holes in the air box lid, injector block off kit. Looking back at when I bought this, the guy said HE just rebuilt the top-end. Guess I should have looked at jetting before. Next time I won't assume the jetting is right.

 

sounds ike with the pipe piston head shaved more air to the air box you probably need to jet up but i have a 2004 blater and a 1999 banshee run them both 32:1 with synthetic oil have had no problems.once one takes a 2 stroke from its properly tuned stock form it takes some know how to get it right again.im 41 been playing with 2 stroke street bikes and dirtbike/atvs since i was a kid and still takes paitents to get one right.if i was you i would run a good synthetic oil that will also help you until you figure out this situation.with out seeing for my self what you got to me it sounds like you have an air leak.case leak or intake boot or something of that nature. good luck

 

After the re jet try running 32:1 for fuel. The motor makes the most power with that mix. Well thats what lrd claims. Yeah u were really lean.

 

32:1 ratio is what you want,but i would start off with either 20:1 or 24:1 untill you have addressed all your problems.when you feel like the bike is correct,jetting,timing etc and no leaks 32:1 is what i recommend with a 91 octane or higher priemium synthetic mix.there is a noticable difference in power on any 2 stroke when the mix is rite.