apex/viper rider
Member
im gonna extend my 121 to a 136 been looking at mpi extension kit and tracks usa extension kit any input on which u prefer im leaning toward tracks usa kit my other question is can i get away with a 1.25 ripsaw with studs will it be a clearence issue any input on this is greatly appreciated thanks 
super1c
Super Moderator
MPI does not make extensions anymore. The track usa and hartman are both good kits. As far as the 1.25 lug track, the track will clear fine. You might have to trim the lugs at the windows so they dont rub on heat exchanger protectors. As far as studding do a search. Some do and get away with it and most say go to 8 tooth drivers. That will be up to you.
apex/viper rider
Member
hey thanks for the response very helpful save me some headache i think i will go with the 8 tooth drivers also thanks again
Suprx125
New member
I have some 136 Hartman extensions, but I'm also looking at the Tracks USA ones now. They have a cleaner look. I'll prolly end up buying those and offing the Hartmans. Good 8 tooth drivers aren't cheap by the way... You'll gain alot more traction going to a 136. But if you do alot of lake riding, then yea studs are primo.
Vt Srx
New member
You also have to factor in the expense of re-gearing when you switch to 8 tooth drivers.
super1c
Super Moderator
Vt Srx said:
If he's going 136/144 the gearing will be a wash. So stock gearing with 8 tooth drivers and 136 will be about the same as ive always understood it.
We have done the 136 extension as well as the 8 tooth drivers. The gearing is stock, the performance is much better. Actually the fuel economy is improved with the 8 tooth drivers as well as throttle responce. I suspect the clutching is running in a higher ratio now. Top speed may be lower by about 2 mph only. Al
alswagg said:
Well that makes sense now. When I 136'd my Viper and left the stock gearing I lost a good 8mph on the top speed but gained a much better ride.
apex/viper rider
Member
hey i really appreciate all the responses it deffenitly makes my like alot easier thanks again
snotwister
VIP Gold
with the 1.25 and hart. 136 do u need to remove the tunnel protectors too? even for a non stud application? some say yes. ...
I am aware I need to remove front cooler protectors. but the tunnel too?
I am aware I need to remove front cooler protectors. but the tunnel too?
Suprx125
New member
snotwister said:
No, you should be fine.
where can u buy the 8 tooth drivers??
Suprx125
New member
yamadogg said:
Hartman, Dennis Kirk, Mountain Performance. I know I'm forgettting a few places.