carb rejetting

[89blaster89]

ok so awile ago i was having problems with my blaster i thought i heard a knocking at low rpm's but i wasent sure so i made a post about it and everyone told me i was problally running lean so i did a leak down test and didint find any leaks. and i took the head off and i looked at the piston and combustion chamberand cylinder walls, i didint find any prblems there either, the piston and cobustion chamber looked pretty clean there wasent much black build up on anything, and when i wiggled the piston back and forth there bearly any movement. so i then took my carb apart and checked the main jet and it was a 370! WAY to big for my mods. so what im asking is for my mods what jet should i put in i bought 270-300 jet sizes and the needle and eclip was set for the 370 jet so what jet should i put in and what else should i adjust to fit my mods?

 

[EZRider76]

How do you know the 370 was too big? Did you plug chop and get a too rich reading??

 

[89blaster89]

How do you know the 370 was too big? Did you plug chop and get a too rich reading??

everyone told me it was to big of a size for my mods and i did do i plug chop and the whole tip under the plug threads was pretty dark colored

 

[EZRider76]

everyone told me it was to big of a size for my mods and i did do i plug chop and the whole tip under the plug threads was pretty dark colored

Ok...depending on how dark and how lean vs rich YOU want it to run, you just heretic start stepping down in main sizes. jlsparky just posted a great video of carb jetting on here. he explains the theory of the carb systems really well. 15 mins of your life for peace of mind.

 

[89blaster89]

Ok...depending on how dark and how lean vs rich YOU want it to run, you just heretic start stepping down in main sizes. jlsparky just posted a great video of carb jetting on here. he explains the theory of the carb systems really well. 15 mins of your life for peace of mind.

yea i watched it well would would you do should i just throw in a 270 and then startit up and do a plug chop do i need to adjust idle or airscrew or anything

 

[Blaaster]

yea i watched it well would would you do should i just throw in a 270 and then startit up and do a plug chop do i need to adjust idle or airscrew or anything

Before you plug chop the idle must be adjusted correctly as any discrepancies will affect the main and needle settings, and will affect the plug chop readings.

 

[89blaster89]

Before you plug chop the idle must be adjusted correctly as any discrepancies will affect the main and needle settings, and will affect the plug chop readings.

ok sorry didint see you posted this i sent you pm. so just adjust the idle wile its on and will i need to adjust the clip or anything

 

[Blaaster]

Warm up the motor to riding temp and adjust idle.

Do not stuff around with the needle, leave it on the middle clip.

I would prefer to start with a #290 and work down to be on the safe side, a #270 seems a little lean for me.

 

[EZRider76]

ok sorry didint see you posted this i sent you pm. so just adjust the idle wile its on and will i need to adjust the clip or anything

First thing is first, get the idle set, don't worry about anything else.

After that, warm up your machine by just cruising around in 3rd and 4th gear. Then depending on what you want to check, plug chop that range on the throttle. If you want to check the needle, run at 1/2-3/4 throttle for a plug chop. That should tell you your needle setting is rich or lean (AWK told me that, I'm not having much luck with it myself). If you want to check your main, WOT for your plug chop. Depending on your readings, that will tell you what you should be changing....if anything. To get a lighter stain, go leaner, to get a darker stain, go richer.

 

[89blaster89]

Before you plug chop the idle must be adjusted correctly as any discrepancies will affect the main and needle settings, and will affect the plug chop readings.

wheresthe idle screw i dont see one isint it suppost to be on the carb cap

 

[Blaaster]

You still have TORS or not?

 

[EZRider76]

wheresthe idle screw i dont see one isint it suppost to be on the carb cap

Should be right next to the air screw. :-/ What carb are you running? Pics? There has to be an idle screw AND an air screw.

 

[89blaster89]

You still have TORS or not?

no tors , its removed by the last guy who owned my blaster

 

[89blaster89]

oh and im running a stock mikuni carb

 

[EZRider76]

Then there definitely has to be an idle screw, somewhere near the air screw.

 

[89blaster89]

Then there definitely has to be an idle screw, somewhere near the air screw.

is it on the side of the carb or the top on the cap

 

[scotj77]

so he didn't drill and tap the hole for the idle air screw? there is a long nipple sticking out beside the mixture screw. it should be filed flat bc it comes cut on an angle then you drill and tap for an idle screw. if not you can adjust it with the cable on the top of the carb. I would suggest starting your jetting no lower than a 290. 270 will be as lean as ya want to go probably

 

[EZRider76]

I would think on the side of the carb, here is my 28mm, air screw is to the right and the idle screw is the big brass circle in the middle.

 

[Blaaster]

On the side to the left of the air screw, unless the PO adjusted it with the throttle cable.

 

[scotj77]

I would think on the side of the carb, here is my 28mm, air screw is to the right and the idle screw is the big brass circle in the middle.

stock blaster carbs dont' come with an idle screw it is on the tors unit. so you have to drill and tap the carb for the screw that comes with the tors delete cable. if this wasn't done you have to use the cable