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carb tunning
Posted: Sun Jan 08, 2012 3:57 am
by FullRace808
how do u know if ur main and pilot jet are to big or small?
Re: carb tunning
Posted: Sun Jan 08, 2012 10:08 am
by evilone
Plug chop, running condition, cylinder head temps.................
Re: carb tunning
Posted: Sun Jan 08, 2012 10:17 am
by Mystic
depending on what size your setup is i would start with a good sized pilot and leave the main jet out once you have a good steady idle and throttle response up to 3/4th then put the main jet in. start bigger than you think you need and decrease until you have a good strong steady throttle response from idle to full then do a plug chop as well as constant monitoring of temperatures. if you get sputter in the midrange of hte throttle but a good full then adjust the clip position on hte needle
Re: carb tunning
Posted: Sun Jan 08, 2012 2:06 pm
by Bear45-70
Plug chop and then read the plug (see Wikispreedia for instructions.
Plug readings;

Re: carb tunning
Posted: Sun Jan 08, 2012 2:09 pm
by FullRace808
Wat is plug chop?
and I will try to adjust the clip. Kuz I have a little sputter from idle to 3/4.but to full its good
Re: carb tunning
Posted: Sun Jan 08, 2012 2:13 pm
by Mystic
what size bore, exhaust, and carb are you running? also what size pilot and main are you using now and what oil mixture and air filter? all these things are a factor for jetting
Re: carb tunning
Posted: Sun Jan 08, 2012 2:22 pm
by Bear45-70
FullRace808 wrote:Wat is plug chop?
and I will try to adjust the clip. Kuz I have a little sputter from idle to 3/4.but to full its good
What part of this did you not understand?
Bear45-70 wrote:Plug chop and then read the plug (see Wikispreedia for instructions).
Re: carb tunning
Posted: Sun Jan 08, 2012 8:26 pm
by FullRace808
Not to sure wat size.but my bore and crank(50mm fully counter) equals to a 107cc.
1st gen pg long
30 oko(142 main, 58 pilot)
Re: carb tunning
Posted: Sun Jan 08, 2012 9:07 pm
by Bear45-70
FullRace808 wrote:Not to sure wat size.but my bore and crank(50mm fully counter) equals to a 107cc.
1st gen pg long
30 oko(142 main, 58 pilot)
If you do not know what the measurements are how the * do you know what the cc's are?
Re: carb tunning
Posted: Sun Jan 08, 2012 11:29 pm
by FullRace808
Kuz my frend is the guy who built the motor.and he said its a 107cc
Re: carb tunning
Posted: Mon Jan 09, 2012 12:08 am
by bakaracer
Mystic wrote:depending on what size your setup is i would start with a good sized pilot and leave the main jet out once you have a good steady idle and throttle response up to 3/4th then put the main jet in. start bigger than you think you need and decrease until you have a good strong steady throttle response from idle to full then do a plug chop as well as constant monitoring of temperatures. if you get sputter in the midrange of hte throttle but a good full then adjust the clip position on hte needle
you better go back to reading on how carbs work. there will ALWAYS have a overlap at some point. the main jet starts to over lap before 3/4 throttle.
Re: carb tunning
Posted: Mon Jan 09, 2012 12:22 am
by Bear45-70
bakaracer wrote:Mystic wrote:depending on what size your setup is i would start with a good sized pilot and leave the main jet out once you have a good steady idle and throttle response up to 3/4th then put the main jet in. start bigger than you think you need and decrease until you have a good strong steady throttle response from idle to full then do a plug chop as well as constant monitoring of temperatures. if you get sputter in the midrange of hte throttle but a good full then adjust the clip position on hte needle
you better go back to reading on how carbs work. there will ALWAYS have a overlap at some point. the main jet starts to over lap before 3/4 throttle.

Re: carb tunning
Posted: Mon Jan 09, 2012 2:30 am
by ottoman
Bear45-70 wrote:Plug chop and then read the plug (see Wikispreedia for instructions.
Plug readings;

The above chart is good but not the best way to read plugs.
I was taught how to read plugs by one of the Champion Spark plug tuners. Back in the day the company sent a tuner to all the big races to help teams get the tuning right.
Its really an art and I only know the basics any more but what your really looking for is the soot ring at the base of the porcelain. Looking the the tip of the porcelain can lead you wrong! You should have a plug reader, a magnifying flashlight tool made to look in at the base.
The size of the soot ring will tell you your mixture at WOT... the tip of the porcelain will tell about the heat range too hot/too cold... detonation and other things.
Re: carb tunning
Posted: Mon Jan 09, 2012 3:27 am
by Bear45-70
True, but most guys will never disassemble a plug to read the properly or get a real and proper plug reading tool.
http://www.ebay.com/itm/Nitrous-Outlet- ... _504wt_952
Here is a more reasonable one like I used back in the dark ages.
http://compare.ebay.com/like/1406646479 ... si=y&cbt=y
Re: carb tunning
Posted: Mon Jan 09, 2012 10:07 am
by Mystic
While I understand that baka, it would take more than a paragraph to fully explain
