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Cutting out on top end, jetting or timing???

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#21 ·
I was having the same problem with my OGM 140.

The bike will get up in 1 to 2nd. then when i'd pull the clutch to shift into third it would bog out.

The issue ended up being my aftermarket gas cap and stubby hose with the little one way vent, it was creating an airlock in my gas tank.

if you have the same cap setup try taking the little vent off and running just a hose for about ten minutes. see if that helps. worked perfect for me and my bike was doing the same thing your bike is.

it's worth a shot if you haven't found a solution yet, most things turn out to be something really stupid.
 
Discussion starter · #23 ·
I have a vented gas cap? but i'll check anyway. If the cam timing was off, then it would crack and pop all over the rpm range, right? I don't think it would be running this good if the timing was off... I dunno...



I also found a very small O-ring gasket for the cap on the carb. that I didn't have in, I put it in and will see if there's any change tonight at splitrail. I went through the intake last night as well and couldn't find any leaks..
 
Discussion starter · #29 ·
So... I just got done putting the ignition/flywheel on, it runs better, but still cuts out badly, which leads me to believe that it is jetting, my original suspicion.... Plug now looks very dark/black... Is it possible that I am that far over-jetted with a 115 main in 30 degree weather?
 
Discussion starter · #32 ·
WOW! Finally got it figured out this weekend. After 3 months of trial and error... and the help of many people, finally figured out that the cam shain was retarted one tooth on the cam-sprocket... unbelievable. It took me all weekend tinkering and then rejetting.



The bike deffinitely grew a set!.. its insane with this new head.



Thanks for all the help and input guys, and def. props to robinsondb22!!!
 
#33 ·
good to hear you got it sorted out!



The cam timing is what i was trying to illustrate to you on page 1 !!!!



The timing marks on the china motors arent precise. so the cam gear mark is usually slightly above the mark on the head.



so now that it's running insane, ho wwould you compare it to any of the other motors or setups youve had?
 
Discussion starter · #34 ·
yeah... your right! page one... but now the marks look WAY off!!! oh well, it looked right before I changed it, like you illustrated... who knows why it would be soo far off..



the motor rips better than any I have ridden/owned, I haven't ridden anything bigger than a 170 v2 though... I think it could have been dialed a little better, and other than that it was stock. but this thing pulls front wheel in 4th!!
 
Discussion starter · #37 ·
I will have to do so... If the case notch matches the "T" on the flywheel, then the dot on the cam sprocket is roughly .5cm above the mark on the head... one tooth retarded (original setting), the dot on the cam matched the mark on the head... maybe even a little above then too.
 
#38 ·
yeah my setting is usually the cam dot is slightly above the mark on the head. i've also tried setups with the mark slightly below the mark as well with no noticable differences. maybe your setup is more sensitive to cam timing with the combination of the bigger valves, cam & porting you have done to it.
 
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