jet size question?

[spyk276]

my blaster has a fmf gold series head pipe, fmf power core silencer, and a 240 kit. the jet i'm running is 250, and the fuel mixture is pretty rich. it barley runs. it won't hit power band at all. always bogs up a hill or when you don't down shift early enough. i wanted to know if i needed a bigger jet, or what else could be wrong with it? we think the rings are going bad to. so?

 

[Joey_Stacks]

first question is it bored .40 over or is it an aftermarket top end kit. Second when you did all this stuff did you do anything at all with the carb or just rode it out?

 

[spyk276]

not really sure, i think its just bored. bought it like this. with pipe and everything. carb is stock i believe i just know on the jet the number is 250 and the spark plug is pretty black. and it runs like crap, with hardly any power.

 

[Luni]

If its black its too rich.

 

[brandoz28]

you have to do a plug chop to really tell, but i would think 250 would be about where you need to be

 

[blasterfreek30]

is the airbox lid on or off, how does the kicker feel, is it real easy to push down??

 

[spyk276]

we tried with lid on and off, both ways ran like crap. it kicks pretty easy. seems like it should be harder. we took the guts out of the pipe and it ran a little better. but still crappy.

 

[royalt67]

Soooo, time for a compression test. All the best jetting won't help if your comp is low.

 

[spyk276]

well we decided that it was blown up. guess what? one ring was missing with a big chip in the piston and the other was fried. gotta buy new piston and rings, just gotta figure out what size piston to get first. it was bored before we got it and we have no clue. how do you measure it? i can use calipers on it. about what measurements should i be looking for?

 

[tyler1blaster]

it will say on the piston

 

[spyk276]

it doesn't. the guy we called said if its been bored then it won't say it, but if its still stock it will. i dunno if thats true or not. and sounds a little backwards to me.

 

[royalt67]

Yeah, that does sound backwards. Every aftermarket piston I've seen says the size or gives a part number you can figure it out from. Your best bet is to take it down to a shop (jug and piston) and ask them to measure it for you. A good shop would do that for free and also tell you whether the cylinder needs to be bored.

You said a ring was missing? Better clean out that lower end real good. Hose it out with brake cleaner while holding it upside down and maybe you won't have to split the cases.

 

[spyk276]

yeah it might be covered up with the black soot on the piston. lol. i will clean it up and see what it says. i'm suprised that it had a chip like that in the piston and didn't hurt the cylinder wall. i will get i picture soon.

 

[xJust_Causex]

yep should be on the top of the piston, or you can measure the inside of the cylinder, do this in a couple place just in case it is out of round. Then I would take it to a shop and have them run a bore bar through it to the next size up.

 

[spyk276]

this is the front side of the piston. there are no markings on it. only the arrow pointing to the front. the crack is pretty bad lol. there are pits and stuff in the piston and the head. but i didn't see any metal and the cylinder wall is fine.

 

[98blasterworked]

find out whats its bored to... is a 240 kit or is it bored .040 over?

 

[Awk08]

dude by by the looks of that piston that cylinder will need some work too, better get that to a shop, or one of our builders, kenoconnorracing.com will hook you up!!!!
done 2 of mine so far!!!!!

 

[spyk276]

its not a 240 kit. and i have no clue if its bored or not. i found a code on the inside of it after i got it off. 37f01. it also says ART with an S and a 2 under it. havent got the chance to measure it yet, i'm looking for something to measure it with right now.

what i sorta think this kid did is bored it and put the stock piston back in with new rings. probably why the top ring was just completely gone.

 

[spyk276]

dude by by the looks of that piston that cylinder will need some work too, better get that to a shop, or one of our builders, kenoconnorracing.com will hook you up!!!!
done 2 of mine so far!!!!!

amazingly the cylinder walls don't look bad at all.

 

[spyk276]

so i measure the piston and the cylinder with a ruler. i know its not exact but its close enough to tell. i measured the top of the cylinder to be 68.00mm and the pitson to be 65.00mm so the piston is stock. and the cylinder is suposedly bored .080 over. so i'm starting to think my theory is correct. this stupid kid bored it because it blew up and then put the stock piston back in it. with new rings of course.

still amazes me that the walls are fine.