I have a yamaha blaster i put a motor together for and its detonating like a s.o.b. The motor has vitos big bore kit,vitos 3mm stroker crank,mild port work,carbon fiber reeds,ricky stator adjustable timing plate and im running the stock carb and also running a fmf fatty pipe.I want to run pump gas also but i need a baseline for jetting and how much do i retard the timing should i also go with a colder plug?
any input will help please i dont want to destroy a brand new motor and im so frustrated im thinking about selling it.So i need helpp

Go to your local airport and get 100LL AVGAS. I run it in all of my bikes it is only about $5gal and it is 100 octane. It is pinging because the fuel you are running is too low octane. What is your compression ratio?

Also, if you have that much work done to your blaster retarding the timing will take all of the extra power away. And there is no way jetting could affect pinging unless it is running super lean. Buy a JD Jetting Kit for the pipe and 240 kit. I believe vitos has a jetting chart on their site anyways so you should check it out. Im sure you can search thumpertalk and you will get your answer on the jetting.

Edited by bobbyw1200, 04 August 2012 - 10:26 AM.

stock compression on a stock blaster is 130 to 160. and when i checked my compression im at 190psi

You will need to start running a higher octane fuel. It will keep pinging unless you do. Have you rejetted the bike for th 240 kit? If not that should be the first thing you do. And if you do not have a small airport nearby you can always find race fuel even online. I was running c12 for a while before i switched to avgas. Avgas will also store for a longer time and it wont gum up the carb.

thats what i was afraid of i didnt want to have run race fuel but i guess at this point im gonna have to.I work at a local speed shop and i can get c16 but its 75 bucks for 5gallons i didnt want to spend that much just to go riding. maybe ill just cut the fuel down like a half gallon of pump gas and half a gallon of c16 and advance the timing.

You could also get c12 and sunoco or cam2 as its called here for much cheaper. Get that fuel and make sure you jet for it and you should be good to go.

i decide to rechamber the head so i can drop compression some and so im able to run pump gas.Mixing gases and spending gu-ku money every weekend to ride my wallets hurting already so rechambering the head is what im gonna do

before I sold my blaster I jetted the carb with a 35pj and a 300mj. Way to lean with the stock 230mj. It was a tad rich though but ran real good and could notice a power diff. with the jetting. If you haven't already, take off the air box lid to compensate for this jetting.