my motors done!

[Honda4life05]

as most of you know my motor took a crap on me about 2 months ago. i had to get a new head,jug,piston,crank/rod, and all new bearings in the motor, new valves an a bunch more... my shop cleaned the whole motor, dissasembled, and put it back together for $400. i didnt think that was too bad for all that they did. i went with a mostly stock setup except for a 11:5:1 JE piston. my question is, will the jetting be the same with the higher compression? since i had a stock piston in there before. i ask this because i went to brake it in, an it runs really rough, alot of popping, shooting flames, ext.... is this normal when you start it for the first time? i only ran it for about 2 min so far... any help is great!

[kenny450er]

if you didn't change the cam then you shouldn't need to rejet higher compresstoin just gives you more bang for your buck sounds to me like your cam timming wasn't set right or your valve,s arn't adjusted right.

[wckedclownz69]

x2 and lucky you im still waiting on my hotrods crank....

[eastside 400]

higher compression greatly affects jetting! with your setup i wouldnt worry becuase you didnt really go much higher, if you go from a 14:1 back to stock the bike barely wants to run. higher compression is able to pull more fuel and burn more

[kenny450er]

the piston will only pull in more fuel an air if you run a longer duration camshaft and more lift

[Honda4life05]

yeah i'm was too impatiant to wait for the hotrods! but i did narrow it down to the jetting, it is running a little lean. And what could also be a factor is when i last ran it with the stock piston it was 80F and now it's around 40f so it"s def running lean. thanks

[miles Machine]

ok heres what you do...(you do need to re jet for compression differences that's common sense) but for your application you didn't raise it much, a simple way to richen up your mixture without taking the carb off is to run a higher octane fuel in it if it runs better you need to rejet it richer.

[Honda4life05]

people are 50/50 on wether you have to rejet or not do to compression change.. but i"ll try that.

[kenny450er]

we all do things alitle differant all the replys make senes if we all crossed the finish line at the same time it wouldn't be fun anymore.

[miles Machine]

very well put, I do agree in application were you bump it a half a point even a point 98% chances are you wont have to rejet but in application were your going from 11.5 to 14 + its needed

[rt20ps]

Did you clean your carb while the engine was being rebuilt. I see this happen alot when people bring me engines without carbs. The carb sits for weeks or longer with fuel in them and everything gums up. Carbs need to be rebuilt (or at least disassembled and cleaned) regularly.

[Honda4life05]

yes i had them clean the carb, as well as the oil cooler an lines. i also drained the tank an put fresh gas in it. it's just wierd because it was running good before. it runs good if i keep pumping on the gas, but when i hold it in a steady place, it shuts off.along with the compression bump, it is much colder now so that might have something to do with it.

[pro-rider46]

that sounds like something is gummed up in the carb, or something is working right in there, you might want to go throught and clean it all yourself.

[250rPRIDE]

not sure what the some guys are talking about and i am a 2 stroke guy but yes you HAVE to rejet a carb for higher compression, go a lil richer on the needle and up with the main about 3-5 sizes.. at least, and as stated before which everyone should know run higher octane!!!!!!

when your pumping the throttle its shooting in more gas everytime you hit it when you hold it steading it doesnt have enough fuel to keep running its to lean and like you said cold weather will make it lean as well
good luck

[Honda4life05]

i'm going to get into the carb an bump it up a few jet sizes. i'll keep ypu guys posted.