Aftermarket Part Jetting?

[Sum0n3]

I just rebuilt my engine and to my surprise i found a 230 jet in my carb. I also bought a carb rebuild kit which has a 230 jet with it (which I'm assuming is the stock size).

Now to my point.. The quad has a FMF gold series pipe, K&N filter and boysen reeds. Is the 230 jet the right one for my setup, or is that why my engine blew? Can somebody recommend the right size? Also the engine is now bored .020" over along with the other mods.

Oh and one more thing. I run the quad at about 1,000' above sea level.. How much effect would the altitude have on the jetting.

Thanks in advance for the help.

 

[blasterboy91]

go to 260

 

[xjma]

260 or 270. Maybe 260 since you're at 1,000 feet. 270 would be safer!! Try em both and see which one works better for you.


higher altitude means thinner air (less oxygen content per volume). So, holding temperatures as a constant, if you're dialed in at sea level and you go to a much higher elevation, you're gonna be rich. It's better for your motor to err on the rich side!!

 

[CC&Fabb]

I think FMF recomends that you run a 270 main for that set up. go to their website FMF Racing - Technical Support and, check it out. And yes, if you were running a 230 main jet it could cause your quad to blow up b/c then it woudl be running way lean.

 

[hickskateboarder]

read the diy on doin plug chops. you definately don't want to run lean.

 

[Mrbrocco]

can you rejet without changing the carb?? cuz im getting a port and polish and im running a vitos fat bastard exhaust..

 

[djack12]

yes you can change the jets without changing the carb. however the vitos fat bastard pipe is a high volume pipe built to run on 240 stroker blaster motors. i wouldnt run that with your mods.

 

[Sum0n3]

Cool, thanks guys. I'll just grab the 260 and 270 to be safe.. Looks like I learned the hard way this time. Even tho it was the previous owner that ran on a 230, but i should have known better and checked it.

 

[Sum0n3]

One more question.. How much do main jets usually cost at the dealer? I believe I heard it's only a few bucks, but bike bandit has the stock one listed for $10.

 

[tproblemc]

what size jet would u guys recommed with a ported engine runnin without the muffler with an fmf pipe

 

[89custom]

^^ i wouldnt suggest running without the silencer. you need that back preasure. mind you, it isnt were it all comes from, but you should have it on. isnt it loud as all hell? thats sick but like, to a point lol.

 

[Sum0n3]

Hmm.. I just looked at the fmf jetting thing and got another question. They say to set the needle to the 3rd groove. Now that would be from which direction? The bottom(pointy side) up, or the top(blunt side) down of the needle?

 

[oldskool0317]

this has been my question also.

i ordered the VITOS jk200 kit and the smallest main jet in the kit is a 290.

is this just to big all together?

 

[tproblemc]

^^ i wouldnt suggest running without the silencer. you need that back preasure. mind you, it isnt were it all comes from, but you should have it on. isnt it loud as all hell? thats sick but like, to a point lol.

well my silencer is in bad shape so i was tryin to get around rebuildin it and i live in the middle of nowhere so the sound isnt a problem im just tryin to find out the right jet size this is the third rebuild for this engine