Blaster Jetting

[KawaBoy]

My buddy has a 2001 Blaster with DG pipe/Silencer, K&N Filter, Boyesen Power reads, and bored .20 over with wiseco piston. Does anyone have any suggestions on what to jet it too? sometimes when your riding it its like it dies then you have trouble starting it like it isnt getting gas. After you kick it for about 5 Min it starts and runs just fine. It has a 240 main jet and i think that way too lean. Anyone have any suggestions what to jet it too with all the stuff hes put on it? Thanks

Justin

[KawaBoy]

Anyone?

[dirtmomma]

Hmmm well we have a 300 jet in ours but we have a big carb on it, have you checked the plug?? What's it look like?? I think we run a 270 or so when we go over to Idaho which is about 5000' & above where we go.

[cals400ex]

i would probably run a 250 or 260. remember that the needle may need to be adjusted too. also, the pilot jet may need to be increased while your at it. if it was me i would probably try to lower the clip on the needle one position and put in a pilot jet one or two sizes larger. also, as the temp changes, so does your jetting. if it dies at idle, its more than likely your pilot jet. however, i am almost sure that carb has an air skrew on the side of it. turning it in will richen the mixture at idle and turning it out will lean out the mixture at idle. i would also make sure you don't have an air leak anywhere. clean the carb out really really good. blow out the hoses on the carb to in order to make sure no dirt or other debris is in them.

[ss440ex]

240 with a pipe and silencer and filter sounds LEAN..
We are running a 290/300 with pipe/silencer in Texas.
Good luck.

[KawaBoy]

He put a new plug in it before we went riding. I dont mean to sound dumb here but what exactly does it do by moving the needle up or down? And whats the pilot jets purpose? Sorry guys im not good with carbs. It doesnt die at an idle. I think it may be getting too much air from the air screw probably b/c it started idlleing real high today. It is ok through mid range but it is REALLY flat on top and isnt revving out near as good as it should. Thanks for the help cals400ex,dirtmomma and ss440ex.

Justin

[ss440ex]

Kawaboy,
pilot jet is for right off idle to about 1/4 throttle.
Then the needle jet (needle) comes in,lowwer the E clip lifts the needle and richens the mid range. raise the E clip lowwers the needle and leans out the mid range.
If you are flat on top end that is your main jet.
Good Luck.

[cals400ex]

Originally posted by KawaBoy
He put a new plug in it before we went riding. I dont mean to sound dumb here but what exactly does it do by moving the needle up or down? And whats the pilot jets purpose? Sorry guys im not good with carbs. It doesnt die at an idle. I think it may be getting too much air from the air screw probably b/c it started idlleing real high today. It is ok through mid range but it is REALLY flat on top and isnt revving out near as good as it should. Thanks for the help cals400ex,dirtmomma and ss440ex.

Justin


i just wouldn't recommend going huge on the mainjet. the richer you go, the less power you will have. the needle will have a clip on it. this clip is adjustable on the needle. i can't remember on the blaster, but my 400ex needle has 5 adjustments. so, you can put this clip in any one of the 5 places to fine tune your jetting. when you lower the clip, your richen the mixture from 1/8 to 3/4 throttle. when you raise the clip, your lean out the mixture from 1/8 to 3/4 throttle. the pilot jet is for the idleing circuit. so, the pilot jet and air skrew work together. the pilot is used from idle to 1/8 throttle. the air skrew is like a fine tune adjustment for the pilot jet. now, don't get confused with air skrews and fuel skrews. these are not the same. the blaster will have an air skrew. so, the more you turn the skrew out, the leaner the air/fuel mixture gets between idle to 1/8 throttle. the more you turn it in, the richer the it gets from idle to 1/8 throttle. however, you can only go in so much and out so much with air/fuel skrews. the fuel skrews work opposite of this. turn out for richer and turn in for leaner condition at idle to 1/8 throttle. you either have to go larger or smaller with the pilot jet if the skrew doesn't have enough adjustment and you should never max the adjustment out.

the mainjet is used between 3/4 and full throttle. i would try a main one or two sizes larger and see how it works. do you have stock gearing? do you have stock sized tires?

for the fluctuating idles, i would clean the carb really good with a carb cleaner, make sure your carb is on tight so you don't have any air leaks, make sure your reeds look good and aren't cracked, and finally blow or squirt out the hoses running off of the carb.

by the way, i assume your running mikuni jets??? because mikuni jets are not the same as dynojets.

[KawaBoy]

ok thanks guys, ill try that tonight. It has the stock gearing with 18" Razors on .190 wheels on back. Ya, there is mikuni jets in it with the stock carb. Ill post back and tell ya if it runs better. thanks alot

Justin

[cals400ex]

those 18's will probably hurt your top speed pretty much. i would raise your gearing unless you only want low end grunt.