My jetting fun

Blaster72

Blaster72

New Member
Jun 30, 2011
98
1
8
Nebraska
I'm still working on getting my Blaster jetted properly. I have a full FMF fatty pipe system installed. I tried a 260 with the snorkel removed. The plug was wet. I removed the air box lid and leaned it out to far. At the time the biggest jet I had was a 280. I did a plug chop and it was all white. Fast forward I started with a 310 and then went to 320. I ran out of jets again. I have ordered a 330,340, and 350. I will try to post the plug chop with the 320. It is faint but chocolate brown. I know everyone will tell me to leak test. I wasn't having problems before. I did use a spay bottle with water and went around carb, intake, and head gasket while running. I didn't have any idle issues. I'll order a leak tester in the future.

406597691.jpg

406597690.jpg
 
anything over a 300 main jet is too rich for an FMF pipe and airbox lid off as the only mods.
either your not running it far enuf at WOT to gain color on the plug, or that rich of jetting is masking an airleak.
 
Awk08 said:
anything over a 300 main jet is too rich for an FMF pipe and airbox lid off as the only mods.
either your not running it far enuf at WOT to gain color on the plug, or that rich of jetting is masking an airleak.
Click to expand...

Again, my advice - Buy a leak tester NOW! (Awk sells them, hint*hint*)
 
Blaster72 said:
I'm still working on getting my Blaster jetted properly. I have a full FMF fatty pipe system installed. I tried a 260 with the snorkel removed. The plug was wet. I removed the air box lid and leaned it out to far. At the time the biggest jet I had was a 280. I did a plug chop and it was all white. Fast forward I started with a 310 and then went to 320. I ran out of jets again. I have ordered a 330,340, and 350. I will try to post the plug chop with the 320. It is faint but chocolate brown.
Click to expand...

Faint chocolate brown says to me that you could be rich, but not getting the motor to pull hard enough for long enough.

You will have a problem getting a motor pulling hard with your mods and such a rich jet.


If the motor is pulling well, as Awk said the big jet could be masking an air leak.
 
Awk08 said:
anything over a 300 main jet is too rich for an FMF pipe and airbox lid off as the only mods.
either your not running it far enuf at WOT to gain color on the plug, or that rich of jetting is masking an airleak.
Click to expand...

I bought it used 2 years ago. I'm not sure if there are any other mods done to the engine. It pulls really strong through the gears. I held it open for 10 seconds. Don't know if it helps but I'm at 3300 feet elevation. Pipe and air box were original equipment and the plug was a dark chocolate color. Machine ran good. That sucks that I have a leak somewhere. Oh well it's only money.:D
 
3300 ft. elevation requires leaner jetting than at sea level.
we ride between 1800-2400' elevation and my buddies with same pipe/open airbox runs great with a 290 main jet
 
Not saying you have aleak but with what's stated so far it sounds like a possibility. I myself have used the old soap and water trick and yes sometimes it works and most times it doesn't. Buy a leak tester or build your own.. The soapy water trick wont let you know of you have an intake leak unless it's a massive leak and you stall out.. Starting fluid on the other hand will work for an intake leak and you will hear it idle up.. but all honesty by the time you buy some starting fluid and mix up soap and water and all that for finding leaks you should just do it the right and easy way n buy one from a fellow member or build one yourself... ;)
 
Never use starting fluid. If you are going to attempt to find a leak without a tester use wd40. You will get the same results without sacrificing lubrication.
 
Awk08 said:
3300 ft. elevation requires leaner jetting than at sea level.
we ride between 1800-2400' elevation and my buddies with same pipe/open airbox runs great with a 290 main jet
Click to expand...

I don't understand why people are using anything over a 270 with fmf, lid removed, and premix. I will be plug chopping mine again. With the same exact mods it was cardboard color in 30-40 degree weather at sea level. This was done with a 270.
 
won't let me qoute ? /\/\ agreed,
we like to play it safe, we're not racing, so on the edge performance is unneeded, and he runs alot of back roads at WOT, where that 2 sizes larger main jet will protect his azz from siezures.
 
Wifesblaster said:
Never use starting fluid. If you are going to attempt to find a leak without a tester use wd40. You will get the same results without sacrificing lubrication.
Click to expand...

Yeah good point.. i just happend to be looking at starting fluid at the moment..
 
Don't know if it matters, but the jets I'm using are pro jet. I don't have access to authentic mikuni jets. I've been getting them from Rocky Mountain atv.
 
definately matters, you should only use genuine Mikuni jets. These other knock offs do not have the same tapers and angles. As minute as they are, they will never deliver the same rate of fuel as a genuine Mikuni jet.

Have you installed the small brass washer that goes under the main jet? #vital.
 
Re: Re: My jetting fun

Blaner said:
definately matters, you should only use genuine Mikuni jets. These other knock offs do not have the same tapers and angles. As minute as they are, they will never deliver the same rate of fuel as a genuine Mikuni jet.

Have you installed the small brass washer that goes under the main jet? #vital.
Click to expand...

Yeah. I used the washer that was installed. Where do you get genuine mikuni jets? Damn, I rated a few bucks on crappy jets.
 
Blaaster said:
If WD40 contains any lubrication properties, it is not suitable in the innards of a 2 stroke motor.
Click to expand...

Agreed. I have heard carb cleaner is used, but personally I dont like the idea of my engine running on aerosol. Just leak test it and you have no need to feed poison to cure a sickeness
 
Blaner said:
definately matters, you should only use genuine Mikuni jets. These other knock offs do not have the same tapers and angles. As minute as they are, they will never deliver the same rate of fuel as a genuine Mikuni jet.

Have you installed the small brass washer that goes under the main jet? #vital.
Click to expand...

#vital this isint tweeter lol
 
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