Help me jet my blaster.

[Luni]

Ok, I know the help can only be as good as the modlist I have.

So, heres what I KNOW about the quad.

Its got an FMF fat pipe and a 36mm Keihin carb. It has a K&N filter right off the back of the carb (no stock airbox - its been deleted)

I also know its running a wiesco piston, and Im bored .040 over.

I know the engine has been rebuilt twice. Last time it got rebuilt I was riding it and the piston siezed on me. The quad then belonged to my girlfriends dad and he got it fixed.

Now, the carb hasnt been rejetted since it was fixed, and I suspect the piston siezed on me cause it was running lean.

It has the Keihin carb on it. I just pulled it apart and the main jet is a 132. That seems kinda small, I did a search and people are saying to start with a 145-155 depending, and go from there.

Also, how do you tell what kind of pilot jet you have?

And lastly, people keep talking about the needle adjustment but my needle doesnt seem adjustable.

One more thing. 132 seems too small, but the quad gets crap for gas mileage. I cant go near as far as anyone else in the group, and one of the quads in the group is a bone stock blaster (bone ass stock.. NOTHING done to it).

I had another thread open because I couldnt get the damn thing to idle, and I was able to adjust the slide stop screw to get it to idle, so thats good, but Im pretty sure my jetting is off.

I have a ride coming up next saturday, and I want to get this thing going. I know its better to be rich than lean, so Im thinking of just kicking up my jet size.

The jets that came with it are: 160, 155, 150, 138, 132 and the 132 is in there.

Im in Utah. My elevation is around 4200 feet, and I sometimes ride at elevations between 8000-10000 feet, but if I figure out my base jet for my elevation, I can also figure out which ones I need to move down, or back up to.

Thanks in advance. Im learning lots on here. Just wanna figure out how to jet this thing. Want at least to be able to get a rough starting point.

 

[Luni]

Anybody? I really need something to go on here.

 

[blasterman87]

that carb is way to big. put a fresh plug in it and run it for a few minutes and see what it looks like that will give u a idea, a plug chop will be better but just looking at the plug will get u close

 

[brandoz28]

thats the only right way to do it/\/\/\/\/\/\/\

 

[Luni]

I know the carb is too big. Im trying to see if anyone want to trade me for a 30 or a 32mm Keihin. I know there are some guys on here who can use it but it just seems overkill for me.

 

[brandoz28]

my 36mm mikuni was pretty fun on the pipe......it was a really really really really really really really narrow powerband....but it'd power wheelie in 4th gear

 

[Luni]

Yeah, mine is farkin FAST. Its quicker than stock thats for sure.

I think Im just gonna try and fight the jetting for this thing if nobody wants it.

In theory no matter what the carb size is, if its jetted properly, it will do what you want it to.

Im fairly certain my main jet needs to come up. My pilot jet needs to go down and I might need a different needle, or adjust my needle.

 

[Luni]

So, I figured out my carb for sure (details in this thread http://www.blasterforum.com/engine-13/help-me-identify-my-carb-26890/)

I cant see ANY writing on my needle though, so I dont know which one I have, but its adjusted to the top most clip (so its down the farthest).

My main jet in there is now a 150 and my pilot jet is a 55. Im thinking the Pilot needs to go down to something in the 40s, and my main prolly in the 140s as well (i have 132, 138, 150, 155, and 160 to choose from right now)

Im going riding this weekend. I figured too rich is better than too lean. Ill do a couple plug chops and see how it runs in various parts of the throttle. (ll do one for half and one for WOT and see how it does.)

 

[Luni]

Well, I think I got it sorted. 132 seems like the right main. If anything it seems a bit high. I tried 138, 145 and 155 and it ran way too rich on 155. 145 was way rich, but it didnt buck or stumble at WOT like 145 was. Not much difference between 138 and 145, but 132 seemed to pull the hardest and give me the prettiest plug.

My pilot jet was way too big tho, it was a 55, and I sized it down to a 42, and got it to idle with a mere 2.5 turns out of the pilot circuit screw.

Can anyone translate 132 Keihin to mikuni speak in terms of size relativity?

 

[royalt67]

Well, if the 132 looks ok and pulls the hardest, I might stick with it, especially since you ride higher, which will richen you up as you climb. But then colder air leans you out, so 138?

Judgement call, man. Only you can decide.

 

[Luni]

The ambient temp I jetted at was around 45 degrees last night.

So I figure if Im at 45 degrees and OK with the 132, it will only richen up as temp increases.

Im picking up a 135 and a 125 today so Ill have more range.

I think I can actually drop down a jet size as well, but Id rather be safe.

 

[Luni]

Fouled a plug, so I dropped my pilot to a 38 and my main to a 125 and it seems better, but I think I need to go less on the pilot.