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Old 11-07-2013, 01:12 AM
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mapbike mapbike is offline
Motorized Bicycle Elite Member
Join Date: Mar 2010
Location: Central Texas
Posts: 5,379
Default Re: what did you do to your motorized bicycle today?

Originally Posted by Danschutz View Post
Recently installed the sbp exhaust and replaced the 44t sprocket with a 41t. My low mid power is unbelievable, there is a hill near my house that I test my bike on. The bone stock motor struggled about 15-17 mph with a top speed of 22 (unknown that i had a cylinder issue) then after installing the hi head, ported cylinder and notched piston I was sustaining 22 mph up the hill with a top speed of 31 while four stroking like crazy.

With the addition of the expansion pipe (and 41T sprocket) I can take that hill at 27mph. Here's the twist, I can only get about 28mph top end, tonight I hit 30 mph.

Cruising at 20-22 mph is hardly a chore for the motor right now and it gets there in a hurry. I can't believe I'm about to say this but you can feel it shove you right along. I rode with my buddy Brian and his very nice running Arrow 4.5 hp motor and was eating him up around the hills and leaving him in the dust up to 28-30 mph then eventually he catches and blows by me.

I added one 45 degree elbow to the Sbp kit so I'm guessing I need to shorten the pipe somewhere to get back some top end OR do I get a 36t sprocket?

Also upgraded the stock bolts on the sprocket, so much nicer lol.

A 36T rear sprocket and a well tuned carb will likely get you at leas 5mph more on top end, the RT carb from dax is an excellent upgrade that makes a felt in the seat of your pants difference all the way around and will likely put you at 35+ mph on top end and a good cruise speed of 30-32mph maybe better jst depends how well balanced your engine is.

I dont always ride WOT, but when I do..I do my best to keep the rubber side down..Ride safely my friends!
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