Why do guys do the jackshaft stuff on these? All the cage kart guys just put them in gear and push start them.Thanks Mike. I have a fuel injected crf450 that’s ready to bolt on and go. Jackshafted by Westerfeld and comes with the clutch, gears, etc. I’ll take $4000 for it. All you will need is a starter and new chain to hit the track tomorrow.
Because we see peak torque at 10-11,000 RPM’s and restarts/cautions have us around 6-8K before we hit the loud pedal. 1, it’s far lighter than a transmission and the engines from the factory don’t have them to begin with whether it’s a sudam, reedjet or BRC, 2, we have pipes built to compliment our jackshaft/clutch setups and the engines themselves turning upwards of 15K make no sense of being direct drive when we’re stuck under 8K under caution. Maybe if we were on super speedway size tracks it’d make sense but we’d never see the pipe come in if direct drive or a transmission was mandatory. Also keep in mind that a jackshaft is a torque multiplier.Why do guys do the jackshaft stuff on these? All the cage kart guys just put them in gear and push start them.
crf450 we were told by the builder 10k was target rpm and rev limit is set at 10500.Because we see peak torque at 10-11,000 RPM’s and restarts/cautions have us around 6-8K before we hit the loud pedal. 1, it’s far lighter than a transmission and the engines from the factory don’t have them to begin with whether it’s a sudam, reedjet or BRC, 2, we have pipes built to compliment our jackshaft/clutch setups and the engines themselves turning upwards of 15K make no sense of being direct drive when we’re stuck under 8K under caution. Maybe if we were on super speedway size tracks it’d make sense but we’d never see the pipe come in if direct drive or a transmission was mandatory. Also keep in mind that a jackshaft is a torque multiplier.
Oops, didn’t see you were asking about the 450, I thought you were asking about the 2 cycles. it’s mostly to save weight. Push starting isn’t an option, must be able to start on the grid via onboard or external starter. Some guys like the transmissions for the compression braking when you let off, others want the motor to respond like a normal kart engine when they let off to maintain good roll speed. I’d imagine that all that weight with the 450’s regardless of what you do, the chassis doesn’t like it and getting good transfer/unloading on entry and exit is hard to nail down. It’s really just preference and getting the scale numbers right.crf450 we were told by the builder 10k was target rpm and rev limit is set at 10500.
Price and pics 607-382-5051BRC 150 built by Seay
After talking to a couple other cage kart guys it looks like they are pretty much just taking them off the bike and putting them on, while its not cheap its cheaper than a jackshaft, clutch and all the rest of that stuff that goes with itOops, didn’t see you were asking about the 450, I thought you were asking about the 2 cycles. it’s mostly to save weight. Push starting isn’t an option, must be able to start on the grid via onboard or external starter. Some guys like the transmissions for the compression braking when you let off, others want the motor to respond like a normal kart engine when they let off to maintain good roll speed. I’d imagine that all that weight with the 450’s regardless of what you do, the chassis doesn’t like it and getting good transfer/unloading on entry and exit is hard to nail down. It’s really just preference and getting the scale numbers right.
On the flip side, I’m yet to see a jackshaft 450 or 500 setup on a cage kart. There’s no rules in cage racing mandating push start only, but there’s got to be an advantage cutting weight on the engine by going jackshaft and external starter. I don’t know one thing about how cage karts scale out or if they even scale their karts but I am curious to say the least. Pretty sure Red bluff/cycleland (california) and millbridge in North Carolina don’t mention jackshafts or external starters in their rules.After talking to a couple other cage kart guys it looks like they are pretty much just taking them off the bike and putting them on, while its not cheap its cheaper than a jackshaft, clutch and all the rest of that stuff that goes with it
i have talked to alot of different qrc guys(oklahoma area) and it sure seems like the majority dont scale, especially as they get into the 250/500 classes. "we just eyeball it" thats the answer from caster, camber, wheel offset, all of it.On the flip side, I’m yet to see a jackshaft 450 or 500 setup on a cage kart. There’s no rules in cage racing mandating push start only, but there’s got to be an advantage cutting weight on the engine by going jackshaft and external starter. I don’t know one thing about how cage karts scale out or if they even scale their karts but I am curious to say the least. Pretty sure Red bluff/cycleland (california) and millbridge in North Carolina don’t mention jackshafts or external starters in their rules.
I personally think there’s speed left on the table with not scaling especially since they are using fully adjustable chassis, even more so with them running spec treads. I’d be trying to find the most speed possible aside from a clapped out engine. Seems like there could be advantages to being numbers and setup savvy but I’ve also never seen an open engine cage setup with lead or guys addressing setup. Started racing at tracks with them back home on the west coast and always noticed they just roll the kart out of the trailer and race with the same tires all day. @CarlsonMotorsports what say ye?i have talked to alot of different qrc guys(oklahoma area) and it sure seems like the majority dont scale, especially as they get into the 250/500 classes. "we just eyeball it" thats the answer from caster, camber, wheel offset, all of it.