The 22" rears are robbing power, 20's are stock size. Your top end is ready for a rebuild 150 is min, 165-170 is normal. The tires and comp are why it won't pull 6th...

 

^ exactly..... By the way if you put smaller LIGHTER rear tires on and rebuild it you will 1- have more get up and go, 2- will be faster threw every gear. I WOULD NOT put a 45 tooth on the back!! In general you would have better luck with changing the tires, and rebuilding it or at leat puting on a thiner head gasket (raises comp.)...

 

I am at 3000 feet above sea level. That may afffect the compression. Why wouldn't you go with a 45 tooth on the back? I can't go with tires any smaller, i do lots of riding in mud and muskeg and climbing the side of mountains, once a year i go to the dune in St. Anthony. I thought a bigger sprocket would be better because sand is so power robbing. Where is the compression limit for 92 octane gas?
Thanks for the input so far.

 

True your altitude will lower the comp reading but your still giving up hp, on 92 octane you can run 170psi. The gearing change is huge going from a 39 to a 45, you won't have a very high top speed but it will surly pull 6th gear..

 

Yes, 6th gear at 40mph probably lol

Are you sure you can't goto 20's? Is there a skid plate on your R?

 

it would cost half as much to buy a counter shaft sprocket than a rear sprocket. 22's is too tall for your gearing to pull 6th, go down to 20's or buy a 11-or-.12 tooth front sprocket $25 bucks.

 

I have been told that running a smaller sprocket on the front will where the chain out faster. I think it will go faster that 40mph. 3 teeth on the back should equal in increase in tire size from 20 to 22. So really all I am doing is gearing it down 3 teeth from stock. I run 12/44 on my raptor with 22inch tire and it goes plenty fast enough, It was 13/40 stock. After I do some motor work to it I may just goto a 41or 42 on the back.

 

if your biking is laying down on the top you could be lean.

86-89 gear ratios only changed from 3rd to 4th. 88's had a different spread

 

oh,dabeachman proves me wrong again. I learn something new every day. Maybe I should stop posting[img]i/expressions/face-icon-small-frown.gif[/img]

 

^^ yeah, no kidding. DaBeechMan - why do you always come in 'ere an be all smart n stuff

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