schmanman

Mi. Trail Riders
Member
Jan 9, 2007
437
0
it's strange, the bike is a beast, runs perfect, until you hit full throttle.

it's like a switch. the bike bogs and slows like you hit the brakes.

I think I need to go down a couple sizes on my main jet.


how much does a jet kit run? (I know, they're carb specific)

I've never tackled jetting before.

any suggestions? anything else it could be?
 
Last edited:

inotocracy

Member
Apr 22, 2008
208
1
My girlfriends XR100 will do that if it isn't warmed up (throttle acts like a kill switch if you crank it all the way), but once its warm there isn't an issue.
 

destructo

Member
Feb 24, 2006
100
0
It could be one of 2 things, a lean air bog or a rich bog, I had a Husky dirtbike that had a lean air bog, aggravated the sh*t out of me, try and lean it and see if it crispens up, its easier to raise or low the needly clip setting and you can tell, the closer you raise the needle clip to the top the leaner it will be on topend, the lower you go with the clip raises the needle higher when you nail the throttle, the richer on topend, each clip setting is equivelent to 1/2 a main jet size. You dont need a jet kit for a 2 stroke, I always just order mains and pilots, I would reference stock jet settings and reinstall for that bike and adjust from there. Heres a really good site to order your jets from.....www.motorcyclecarbs.com
 

schmanman

Mi. Trail Riders
Member
Jan 9, 2007
437
0
inotocracy said:
My girlfriends XR100 will do that if it isn't warmed up (throttle acts like a kill switch if you crank it all the way), but once its warm there isn't an issue.



I'll have to ride and check tomorrow. :P

destructo said:
It could be one of 2 things, a lean air bog or a rich bog, I had a Husky dirtbike that had a lean air bog, aggravated the sh*t out of me, try and lean it and see if it crispens up, its easier to raise or low the needly clip setting and you can tell, the closer you raise the needle clip to the top the leaner it will be on topend, the lower you go with the clip raises the needle higher when you nail the throttle, the richer on topend, each clip setting is equivelent to 1/2 a main jet size. You dont need a jet kit for a 2 stroke, I always just order mains and pilots, I would reference stock jet settings and reinstall for that bike and adjust from there. Heres a really good site to order your jets from.....www.motorcyclecarbs.com

so, just to clairify, the more of the needle that sticks into the needle jet tube, the leaner it will be, right?

so, adjust the needle down? wont that make it leaner throught the whole throttle pull?
 

2strokerfun

Member
May 19, 2006
1,500
1
schmanman said:
so, just to clairify, the more of the needle that sticks into the needle jet tube, the leaner it will be, right?
Correct

so, adjust the needle down? wont that make it leaner throught the whole throttle pull?
It will lean it out roughly from 1/4 to 3/4 throttle
 

kx125412

Member
Mar 30, 2006
341
0
Rich bog - bleh bleh bleh bleh just sputters and doesnt clear out

Lean bog - booooowaahhhhhhh

If its already lean and you lean it more say goodbye to your motor. First things first, clean the carb, remove all jets and blow them out and make sure they're clear. Find some stock jetting specs and go from there.
 

dirt bike dave

Sponsoring Member
May 3, 2000
5,349
3
schmanman said:
it's strange, the bike is a beast, runs perfect, until you hit full throttle.

QUOTE]

I'm not sure I understand this part.

So if you are riding along at middle rpm in 3rd gear, and whack the throttle full open, what happens?

Does the bike just instantly bog, gradually work through the bog and then accellerate to high rpm?

Or does it accellerate great until you get to high rpm, and then it falls on its face?


Which bike in your profile are you talking about? FWIW, both of them are non-power vavled, small displacement two strokes. If the bike 'runs perfect' most the time, the current jetting might be the best compromise, as long as you don't open the throttle full when the motor can't pull it.
 

schmanman

Mi. Trail Riders
Member
Jan 9, 2007
437
0
I have cleaned the carb with a can of solvent and my air compressor several times. it's a rich bog, since it kind of sputters out.

I'll clean it again, it sure cant hurt.
 

schmanman

Mi. Trail Riders
Member
Jan 9, 2007
437
0
dirt bike dave said:
schmanman said:
it's strange, the bike is a beast, runs perfect, until you hit full throttle.

QUOTE]

I'm not sure I understand this part.

So if you are riding along at middle rpm in 3rd gear, and whack the throttle full open, what happens?

Does the bike just instantly bog, gradually work through the bog and then accellerate to high rpm?

Or does it accellerate great until you get to high rpm, and then it falls on its face?


Which bike in your profile are you talking about? FWIW, both of them are non-power vavled, small displacement two strokes. If the bike 'runs perfect' most the time, the current jetting might be the best compromise, as long as you don't open the throttle full when the motor can't pull it.


the yz/it frankenstien.


whenfoxforks-ruled said:
Timing is okay? When it starts bogging, pull in the clutch and kill the engine. Look at the plug, wet or dry? Cut the threads off your plug, rich or lean?

yep, timing is good.... would'nt it run rough throughtout the entire rpm range if the timing was off?

I'll check, but I am 99% positive the biek is rich......

of course, it's that 1% that can easily kill your engine, so it's worth a look-see....
 

whenfoxforks-ruled

Old MX Racer
~SPONSOR~
Oct 19, 2006
8,129
2
Merrillville,Indiana
If it gets to a point retarded, I believe the top end will suffer first. The tip of your electrode should have a shiny end about 1 mm or a little less. That fine tunes it after you verify the marks are lined up on the magneto plate. If it is all dark, it is retarded.
 

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