SPB Jackshaft Problems...

GoldenMotor.com

jolfstn

Member
Oct 30, 2011
112
2
18
Seattle, WA
I see now why SPB on their website advises that one has already built a motorbicycle prior to trying to install their shift kit. Although I've ridden a colleague's bike I've never built one myself. I purchased a beach cruiser, 66cc motor (that I have yet to turn over, but that's a different matter) and SBP HD Deluxe Shift Kit II. After much wringing of hands and cursing, I got the thing together. As previously mentioned, I'm having issues with my engine not turning over, so there has been much pedaling and releasing the clutch. First the chain on the left side, from the engine to the sproket broke, I think maybe it was too loose. I removed a link and it seems tight but not too tight. Then, the chain on the right side, from the sprocket to the freewheel came off, when the shaft the sprockets are on came loose somehow, I allen wrenched those locks on the sprockets almost until the wrench bent. I don't see how I could have made them any tighter, and I did grind the shaft where the sprocket is screwed onto, as directed. It doesn't seem I could have made it any tighter and it still came off. Could it be that the chain was too tight? I suppose it's a good thing that I'm having these chain issues before I get the motor working but I have to admit I'm getting frustrated, having spent so much time and money on this project and have yet to have had even one ride. I think I have to get the jackshaft right before I can address the engine-not-starting problem. Anyone else have issues like this with a shift kit? What did you do about it?
 

jolfstn

Member
Oct 30, 2011
112
2
18
Seattle, WA
correct, the engine won't start. I've tried everything, given up and my bike is now at the small engine repair shop. He's been working on it for 2 days and can't get it started either, so I feel better about the whole thing in the sense that if a professional is having that much trouble, perhaps I, with such limited experience, didn't give up too soon. Ugh, I honestly believed this would be a fun, inexpensive, easy way to get around! Hah! For the amount of funds I've spent on this, I could have had a crappy albeit drivable car!! Not to mention the time spent. Let this be a warning, never NEVER buy a used motor. Only asking for trouble.
 

The_Aleman

Active Member
Jul 31, 2008
2,653
4
38
el People's Republik de Kalifornistan
The thing is, those 2-strokes are so inconsistent and tend to be real needy when it comes to tinkering. Especially with a shift kit.

I've bought used "problem" stuff from people quite a few times and was usually successful in getting it to work and then kept it or resold.

Don't give up yet! It's probably something in the ignition, CDI or magneto.
 

camlifter

Active Member
May 4, 2009
1,033
16
36
acme labs marion ohio
you must keep pedaling hard to start it, bump starting can't happen with a free wheel kit. as for the sprocket, the area where the set screw tightens to the shaft you have to grind or file a flat spot on the shaft or it will never stay tight.
are you getting spark. failure to start on china girls about 90% of the time is a bad spark plug wire.
 

jolfstn

Member
Oct 30, 2011
112
2
18
Seattle, WA
Mechanic says he got it started. He said too much compression. He shimmed the head, said he got it started. My thinking now is to add a pull start/centrifulgal clutch. This is a Grubee GT-5, where do I buy a conversion kit? I've checked Pistonbikes.net, Gasbike.net, Sickbikeparts.com, etc. I don't know how to install this, I'll let my mechanic add it. He's agreed. He also said he should add another shim to the engine head, but the bolts aren't long enough. anyone know where I could purchase longer head bolts? I'm so dissapointed, there is dirt all over the bike, said he had fun driving it after he got it started but I've NEVER ridden it powered! I've spent enough to buy a crappy car and countless hours assembling this darned thing and have yet to have even a moment of joy. Despondent in Newport, OR.
Also, I live on a ship, I don't want this thing to rust, I've purchased a cover for this, it's a steel frame, how does one protect their bike if very near the sea?
 

RadicalxEdward

New Member
Apr 19, 2013
14
0
0
Chicopee, MA
How did your project ever turn out? Mine has been almost the exact same story. very disappointing. At most i've gotten it to run for like a minute or two then something breaks. I was thinking of adding a pull start and all that but to do that i'd have to add wider cranks and this and that and it just ended up making me think, hey i already regret how much i've spent on this thing, maybe I shouldn't dump more money into it than I have to.

I'm now rebuilding the entire thing cause my rear motor mount is complete bent now and nothing will line up obviously.

my bike also did the same thing of spewing it's exhaust guts somewhere as well as the magneto cover flying off. I've yet to be able to get replacement bolts for the cover so i've left that off and I have no idea where the exhaust parts came off so I have no clue where they are. Another problem is that it's been raining off and on for WEEKS on end now so even though I have it covered as much as I can, the jackshaft sprockets are rusted onto the shaft and now I can't get them off to unbend the engine mount. So I can't even set it up without the jackshaft (which really isn't worth the headache to anyone wondering)

I gotta say, if anyone I knew ever asked me about building one of these, I'd say just take the money and buy a used motorcycle (which is what this was supposed to help me save up for)
 

Sidewinder Jerry

Well-Known Member
Dec 19, 2011
1,996
928
113
61
Rockwood, TN
With these kits you get what you're willing to pay for. There's two building philosophies: 1) Spend the money for a quality kit. 2) Buy a cheap kit then spend money upgrading it.
 

maniac57

Old, Fat, and still faster than you
Oct 8, 2011
4,484
22
0
memphis Tn
Buying a SBP deluxe shifter kit without any experience almost never works out well.
Just sayin. Thats like getting a Bugatti Veyron for your very first car.
The stock china kit would have cost half as much and been MUCH easier to assemble.
You might ask yourself just exactly WHY SBP states that in their ads...
 

BMS420

New Member
Jan 18, 2012
26
0
0
54
Hawaii
I'm also having problems keeping chain tension on the righ side drive chain, I also have bent the jack shaft assembly I believe due to dropping the engine off the bench smh ( no fault on SBP) I did file the shaft as to keep the sprockets from coming loose, I also have a theory that the engine is not sitting close enough to the seat down tube, this is my third bike build but my first with a shifter kit, I don't mind buy a new assembly from sbp and ect. But I also feel like giving up on gears and go back to single speed , yet the gears are fun ... idk what I will do help!:-||