Shift kit recommendations :)

GoldenMotor.com

UTmotorbiker

New Member
Oct 12, 2014
16
0
0
Utah
Hey guys, looking for some recommendations on a shift kit. I'm a newbie here so I could use some guidance but I'd like to be cruisin 30mph or so instead of always being WOT and barely getting 28-32mph downhill. I'd be nice to be in a mid-gear range/throttle to get around town. I know the break-in period isn't quite done yet but I'd like some ideas. Also, I'm putting on the RT carb later this week so hopefully that'll also help get some more speed out of it.

Here's what I have on it so far:

PK80 motor (150 miles on it)
RT carb (will install in next few days)
41T sprocket
26" wheels

Any ideas for kits would be awesome. Thanks!
 

MotoMagz

Well-Known Member
Aug 2, 2010
1,817
1,154
113
Michigan
I can't help you with setting up a 2 stroke shift kit ...but I can tell you to buy it from Sick Bike Parts. They will always answer any questions and there kit is the best out there. Good luck with your build!
 

maniac57

Old, Fat, and still faster than you
Oct 8, 2011
4,484
22
0
memphis Tn
I agree. SBP makes the best quality kit available. Be sure to get the HD front freewheel as the standard is (more) failure prone.
I would also suggest you try a 36 tooth with a decent tuned pipe to gain speed and reduce revs at your particular happy speed. I'm 250lbs and the 36 works great, especially with a good tuned pipe to help the low end.
 

UTmotorbiker

New Member
Oct 12, 2014
16
0
0
Utah
I'm about 170lbs and I'm currently using a 41T but 30mph seems to be a bit out of reach unless going downhill at a decent slope. I am thinking about getting one of those expansion pipes from SBP to help increase power and efficiency as well as attaching the RT carb. I'm thinking those will help quite a bit but I'm still new to all of this and I don't really have a workspace to install everything. I'd just like to not have to be WOT everywhere I go to get anywhere at a decent speed (25+).
 

NEAT TIMES

New Member
May 28, 2008
1,964
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PENSACOLA, FL
UT

Look at my posts in last couple days. A very good flexible system from Staton-inc.com.

Have bought SBP kit, they are good also. They make a 4 stroke & 2 stroke kit.

Ron
 

DICYRUL3S

New Member
Sep 21, 2010
14
0
0
Guelph
I use a shift Kit from sbp. It's great. I've had so much fun modifying my bike. I've hit a top speed of 56.3mph and I still have room to go faster. Preventative maintenance is the biggest problem, there is a lot to keep in good condition.
 
Last edited:

abeha

New Member
Apr 1, 2015
1
0
0
china
I agree. SBP makes the best quality kit available. Be sure to get the HD front freewheel as the standard is (more) failure prone


_____________
emma
 

KCvale

Well-Known Member
Feb 28, 2010
3,966
57
48
Phoenix,AZ
The KEY part and difference between a cheap kit and a $200 SBP HD kit is the freewheel bearing that isolates your pedal cranks from the engine drive sprocket.

The $20 bearing is OK for a stock 48cc or ~350W electric but shred in short order with anything bigger.

I have seen this first hand twice, one was a 48cc shifter build I did long ago and when his motor died (put regular gas in it) I replaced it with a 66cc.

He didn't get 10 miles before the cheap freewheel went out, and they don't go out friendly.

You can't unscrew the bearing from the special threaded crank arm without a special tool, and that is the part that gets destroyed so there is no way to get the bearing off thus rendering the entire assembly except the inner sprocket you can get off garbage.

Actually I was just noticing yesterday SBP has a new Ultra HD Freewheel Bearing coming soon for you high performance engine guys.
I haven't been able to take out an HD bearing yet but there are some pretty mean engines out there.

One other note is the actual jackshaft housing you attach to the engine.
The cheap shift kits use the old original SBP style 3 part system.
What a pain in the ass in so many ways.

The replacement design is one solid U shaped piece so the actual jackshaft can't wander with mount movement.

Yes they take a lot of adjustments during chain break-in and they are not easy or friendly to make, and sometimes you simply have to use a tensioner.

Another issue is your bikes gears...
Though a 7-speed will work they are far from ideal, and 9 sprockets is just asking for trouble.

Throwing engine torque at 9-speed chain that isn't even in straight line just isn't going to be trouble free, you will miss a shift eventually and you'll snap that chain right in half and without the kits Jump Stop you will find the chain simply won't like first or second gear.

I try to use an internal geared hub whenever I can.
I love the things.

Just one fat sprocket on the rear wheel you can align perfectly with the freewheel bearing sprocket and get tight using fat single speed HD 410 or even HL710 chain.

Bikes have a bunch of close gear ranges to help your measly .2HP legs stay within your body's tiny power band.

Your 2HP engine has a vast power band, enough that you can run them direct drive.

I find a simple Shimano NEXUS 3-speed to be simply ideal.

For a 26" wheel...

2nd gear is pretty close to the gear ratio and speed as a stock direct drive kit with 41-44T sprocket.
1st gear is ~33% gear reduction, sort of like having a 63T rear sprocket for torque.
3rd gear is ~33% gear overdrive, sort of like having a 27T rear sprocket for speed.

All those ratios can differ of course by the hub and sprockets used but you get the point...

You can get going from a dead stop much quicker, and have a faster top speed than direct drive.
 

BOYGOFAST

New Member
Sep 28, 2013
124
0
0
Citrus Springs Fl.
Sure I've got one or two clues, first you better have a pair of double wall wheels with throne resistant tubes to start with.Once there you can nearly rely on doing 45 or more mph easily and brake within some reassurance.Your best bet is simple and most will disagree.Take off the clutch cover find the pressure plate the flowernut removed you will need to weld an extension on the end of that stud I'd recommend no less than a 1/4'' diameter high quality bolt that's been cut or find a stud that will suffice. You'll need to fasten a # 35 sprocket I'm using # 35 on this attempt you may use whatever.Yeah got to be welded to the pressure plate then bolted.OK once there you can double the pressure plate or run single they will move and can be adjusted if you are careful about the welding taking place it's not much but must be correctly done.OK the cover over the clutch must be spaced to allow the chain to ride the new sprocket location.You can use the single 3 4 5 8 whatever speed hub with coaster or without problem is to do so you will need to pull start the engine or place an extra pair of sprockets you'll see when you get that far along and you'll need a freewheel front on one side or the other your choice on how you set it up. Any way to get the bike to move will be more or less the same manner of link. There is an advantage to having a few tools around this is the least expensive, lightest and likely the best of any link you ever install good luck I'm sure there are a few who have the same link I've purchased the Deluxe kit but I'm not using it I've reached the weight limit without it this is a best or all offers made solution ...Again good luck I' think I've got the setup correctly explained.