Jackshaft Speedster

[kdaddy1980]

i just got my jackshaft in the mail today from bikeberry. im already confused about how this crank is going to fit on my huffy santa fe. it comes with a 3 piece crank and it looks like its too small to fit into the crank case of the bike. do i have to have a bike that comes with a three piece? how to i get this mounted to my cruiser? ive seen it done but not sure how they put the thing on there.

 

[MotorBicycleRacing]

i just got my jackshaft in the mail today from bikeberry. im already confused about how this crank is going to fit on my huffy santa fe. it comes with a 3 piece crank and it looks like its too small to fit into the crank case of the bike. do i have to have a bike that comes with a three piece? how to i get this mounted to my cruiser? ive seen it done but not sure how they put the thing on there.

You need these high quality aluminum adapters to convert your 1 piece bottom bracket (BB) to the standard 3 piece
http://www.sickbikeparts.com/catalo...ucts_id=104&osCsid=f4oglb54mm74lrkuhqrn7va464

 

[kdaddy1980]

i went through bikeberry because it was cheaper, plus i got a few extra parts on the same order so i could get free shipping

 

[MotorBicycleRacing]

i just got my jackshaft in the mail today from bikeberry.

I am curious why you bought that jack shaft kit from BB instead
of buying it from Sick Bike Parts?

 

[Pablo]

i went through bikeberry because it was cheaper, plus i got a few extra parts on the same order so i could get free shipping

Well actually the Bikeberry Chinese knock-off kit at $149 sale price is more expensive than our made in USA kit. And that's not even counting our current sale price $139!

So a China knock off with essentially no support or warranty, doesn't really work great, costs $10 more than the real USA version and comes with less parts (vital parts!). Not starting a war here, but it seems basic unless I'm missing something. Please let us know how your experience works out and we will support you. motorized bicycle Racing got you the link for the adapters, let us know if you need anything. Thanks.

 

[silverbear]

I have to put in my vote for the SBP parts even if they were more expensive, which they are not. If the parts aren't made well or you need technical help you're in for a world of headaches. The shift kits need to be made well to withstand the stresses of geared riding. Pablo and Ghosto are our guys, part of this forum and came up with the idea and followed it through to the benefit of us all. Thanks again, you guys.
SB

 

[kdaddy1980]

Well actually the Bikeberry Chinese knock-off kit at $149 sale price is more expensive than our made in USA kit. And that's not even counting our current sale price $139!

So a China knock off with essentially no support or warranty, doesn't really work great, costs $10 more than the real USA version and comes with less parts (vital parts!). Not starting a war here, but it seems basic unless I'm missing something. Please let us know how your experience works out and we will support you. motorized bicycle Racing got you the link for the adapters, let us know if you need anything. Thanks.

well they gave me a discount for spending over 60 bucks and it came out to $119 with no shipping. I did notice some differences in the kit like there is no spacer to keep the chain from falling in between the gears on the front freewheel but ill improvise something for that. do you guys recommend a grip shifter for this kit? I was going to use regular shift knob but not sure if it will work right..

 

[Pablo]

Grip shifter is the way to go. Super easy shifting.

 

[KCvale]

I did notice some differences in the kit like there is no spacer to keep the chain from falling in between the gears on the front freewheel.

It's called a 'Jump Stop'.

I was going to use regular shift knob but not sure if it will work right..

What gears do you have?
It's a Huffy with what 3-speed coaster brake or a '7-speed' with real V brakes front and rear?

If it's the latter I find this to be safest easiest to operate handlebar refit.

I am curious to see how well your pedal crank freewheel bearing holds up, that is the expensive (~$75) part of a good shift kit.

 

[Pablo]

You need a wider box

 

[kdaddy1980]

It's called a 'Jump Stop'.
What gears do you have?
It's a Huffy with what 3-speed coaster brake or a '7-speed' with real V brakes front and rear?

.

im using a shimano 7 speed cassette with rear disk brakes

 

[KCvale]

im using a shimano 7 speed cassette with rear disk brakes

Sweet, you'll be able to stop the beast ;-}

 

[kdaddy1980]

Sweet, you'll be able to stop the beast ;-}

yeah i fugured if im going up to 55 miles an hour i better be able to stop this thing, and those old school brakes arent gonna cut it.

 

[mew905]

yeah i fugured if im going up to 55 miles an hour i better be able to stop this thing, and those old school brakes arent gonna cut it.

I find V brakes have far superior stopping power in good conditions, however in the rain or snow they cant stop at all, and they require readjusting frequently to keep your stopping power good.

Disc brakes I find have less stopping power (I cant lock the wheels with em), but far more consistent. You dont have to readjust them all the time and they work (apparently) in rain or snow, but use em too much and they fade quickly (I only run a front disc, no rear brakes, so the front disk heats up pretty rapidly).

 

[KCvale]

yeah i fugured if im going up to 55 miles an hour i better be able to stop this thing, and those old school brakes aren't gonna cut it.

Best get new nice speed rated tires and tubes and both wheels balanced if you plan on topping 50MPH because at those speeds everything matters and the last thing you want is a tire to fail.

 

[ivan H]

55mph, man thats gunna take some doing. Wot do u plan on doing to get u there. A jackshaft adds some extra resistance that the motor has to overcome, from 3 chains, 3 small radius sprockets (a small radius bend in the chain creates more resistance than a large one) & 3 extra bearings it has to spin. It isnt heaps, but it all adds up. (yes, I have an SBP jackshaft, wouldnt be without). I have a reasonably worked over 66cc, reeds, piston is ported, crown ramped & 5mm off skirt on intake side, cylinder boost ported, intake floor lowered 5mm at cylinder wall, (othet port work done as well), RSE head, quality bearings throughout, SBP chamber, mikuni carb (properly tuned), adjustable CDI, SBP jackshaft & 8 speed shimano hyperglide cassette, all on a steel mountain bike with road tyres & I weigh about 83 kilos. Now admittadly I have it ported & tuned more for midrange torque, & I dont have an accurate means of determining true speed, (I dont think a phone app is "accurate") but I can tell ya, 40mph, no sweat. In all probability 45 & maybe some if I wanted to wring it right out (& blow the sucker up), but 50,,, no way, I'm probably being optimistic as it is. Good luck with, if u get 55 out of it (& it lasts) ur one **** of a 2 stroke builder/tuner. Cheers

 

[MotorBicycleRacing]

[QUOTE="ivan] I have a reasonably worked over 66cc
reeds,
piston is ported, crown ramped & 5mm off skirt on intake side, cylinder boost ported, intake floor lowered 5mm at cylinder wall, (othet port work done as well), RSE head, quality bearings throughout, SBP chamber, mikuni carb (properly tuned), adjustable CDI, SBP jackshaft [/QUOTE]
The bottle neck in your motor is that the Rock Solid reeds are way undersized.
They are the right size for a 25 CC motor, maybe a 31 cc at the most.

 

[mew905]

The bottle neck in your motor is that the Rock Solid reeds are way undersized.
They are the right size for a 25 CC motor, maybe a 31 cc at the most.

depends what RPM, they're good for a 66cc at around 6000 RPM, keep in mind high RPM for a 2 stroke is closer to 12k, not 6k. They'll handle a 49cc at 8k RPM rather effortlessly. It's about flow rate, not strictly engine size, a 25cc will suck twice as much air as a 49cc at twice the RPMs. However you are correct, they are undersized, but the best bolt on for these motors as you dont have to stuff the crank, all ya gotta do is reed port and it's good. Arrows drop the compression so much I, personally, highly recommend stuffing the crank to gain back your pressure, but they provide the flow needed for a high performance screamer. Your other bottlenecks may be the intake size itself. I emailed Arrow, I'm awaiting a reply, if they can do custom intake sizes for bigger carbs. 25mm would be perfect for a 21mm Dellorto. If not, make your own, shouldnt be difficult if you can weld. Don't use a shim as your intake will be bottlenecked by the SMALLEST area it can flow through (in the case of RSE reeds, about 7300 RPM with a 15mm runtong carb).

If you can, I say open up the intake port (wider, lower) to maximize your intake, match it to your exhaust basically (open your exhaust to 30mm as well, though standard 30mm spacing jugs wont be able to for obvious reasons). 40mm spacing (GT5-a and perhaps others?) should allow 2mm between each stud and the port opening.

These motors greatest downfall is they can't breathe properly (carb too small for the 66cc), their piston is too heavy (110g, crazy heavy and off balance) and their transfers are garbage (no respectable 2-stroke engine aims its transfers toward the exhaust like these things do). Fix those 3, and you'll be able to fly. Then you can add reeds, a pipe and compression to boost power.

 

[ivan H]

Actually, I dont believe that the reeds are resyricting the motor. Putting RSE reeds into a normall 66cc intake port, the port roof will not allow the upper reed to open much at all, so pretty much most of the breathing is done thru the lower petal. My port roof has been opened up as much as possible to a depth & width of just more than wot the reeds protrude into the port, allowing the upper petal to properly open. The standard intake manifold ID is about 15mm. Mine is 16mm to match the carb. The apeture on the carb side of the reed block is 16 x 20mm & with the port roof opened right up the open area of the reeds outlet is equal (at least) to the area of the apeture of the manifold. The petals are low tension fiberglass & quite flexible. With the same port arrangement etc b4 reeds & with, top rpm is the same. Low & mid torque increase was substansial.
I do have a question tho. U say the RSE reeds r only sized big enough for a 25 or 31cc. Can u tell me wot the RSE reeds flow? The area of the apeture of my manifold is 201.06 square mm. The area of a rectangle is length x width, so u see, if each petal can open 6mm, the area of the reeds outlet equals the area of the manifold apeture. When u take into account the fact that the reeded motor is intaking to the crankcase thru close to 180 degrees as opposed to the 60 degrees, resulting in greatly reduced velocity, I dont think the RSE reeds will be restrictive unless ur trying for really big revs, so long as u open up the port roof to allow the upper petal to properly open. Of course, if this isnt done I can see how wot u said would br true as flow volume woyld be seveerly compromised. Then again, if looking for big revs u wouldnt use low tension fiberglass reed petals or u'd get flutter, so the RSE reeds arent designed for big revs so dont need that flow capacity. Cheers

 

[kdaddy1980]

55mph, man thats gunna take some doing. Wot do u plan on doing to get u there. A jackshaft adds some extra resistance that the motor has to overcome, from 3 chains, 3 small radius sprockets (a small radius bend in the chain creates more resistance than a large one) & 3 extra bearings it has to spin. It isnt heaps, but it all adds up. (yes, I have an SBP jackshaft, wouldnt be without). I have a reasonably worked over 66cc, reeds, piston is ported, crown ramped & 5mm off skirt on intake side, cylinder boost ported, intake floor lowered 5mm at cylinder wall, (othet port work done as well), RSE head, quality bearings throughout, SBP chamber, mikuni carb (properly tuned), adjustable CDI, SBP jackshaft & 8 speed shimano hyperglide cassette, all on a steel mountain bike with road tyres & I weigh about 83 kilos. Now admittadly I have it ported & tuned more for midrange torque, & I dont have an accurate means of determining true speed, (I dont think a phone app is "accurate") but I can tell ya, 40mph, no sweat. In all probability 45 & maybe some if I wanted to wring it right out (& blow the sucker up), but 50,,, no way, I'm probably being optimistic as it is. Good luck with, if u get 55 out of it (& it lasts) ur one **** of a 2 stroke builder/tuner. Cheers

well, i just heard somewhere this thing can get you up to 55 mph, but i think they are exaggerating a little bit, i didn't plan on doing any motor mods besides a boost bottle. im using a bikeberry jackshaft, which seems to have less of a rating then the sick bike parts jackshaft, but hoping it works ok. i really didnt plan on riding 55 much but a cool 40 would be good..right now my bike does a good 30 maybe 32 at most..so i was just looking for a a decent increase, just reading the other guys comment i see that this can get really involved and intricate. like , reed valves.. im still fairly new at bike building so i havent even actually seen one of those but little by little im learning what it takes to build good bike. this forum helps a lot, and thanks for all youre input.

 

[KCvale]

well, i just heard somewhere this thing can get you up to 55 mph, but i think they are exaggerating a little bit, i didn't plan on doing any motor mods besides a boost bottle.

Just a tip, you will get a better performance enhancement from an $8 Iridium spark plug than a 'joke bottle'.

i really didnt plan on riding 55 much but a cool 40 would be good.

Unless you ride a lot on big long flat straight open roads with little traffic I think you'll find 40ish is plenty fast.

 

[ivan H]

I agree with KC, 35 ~ 40 is a reaonable speed. Remember, these are bicycles, not motorcycles. Cheers