I just posted that my sbp exhaust gave me incredible low to mid torque, a real hill puller but I'm sure I lost some high end. I'm not certain high much I lost because I swapped out sprockets also.
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.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.
Dan.
Shan,
Dan
My motor has cleaned intake an exhaust ports, they have been smoothed slightly enlarged, the combustion chamber is polished, head is milled down. .016 copper gaskets, NT speed carb,with air filter & .66 jet from SBP. ngk iridium plug, jag cdi and coil, accel 8mm plug wire.
Which fred motor did you get? I've got one of his engines BNIB in my basement that i keep pushing to the back of my parts stash. Idk why, but I just really dont want to run that engine. Something about my BS cobbled together grubee variant makes me happy. and FWIW my buddy has a fred motor on his bike, 36t and i still romp a few mph faster.today I met the anesthesiologist and the whole medical staff that will be transplanting the Fred motor into the body of blue , she will be in room 66 C , the smokers unit.
LMAO
By bog, if it just looses power and seems to be running flat while you are riding at top speed, it is tuned too lean. It needs a larger main jet.
You absolutely confirmed my sneaking suspicion.... I had a feeling I needed to switch back to a .68 jet, seeing as both my crank and head compression have been raised some, that and I noticed it more after I installed the jaguar CDI. I perhaps didn't realized that I had equipped the engine to finally handle the potential of the small NT speed carb....
I can't really see how changing the gap by a few thousandths of an inch is going to have any significant effect on the millisecond(s) it takes for a spark to jump the gap. At a level beyond common measure there may be a difference, but to find it I'd suggest you get good walking shoes and turn right at the decimal point.
I note that it may be the case that a larger gap could cause the spark to wait fractionally for the voltage to climb higher to jump the gap - in fact, a too large gap may cause the spark to wait forever.
