MOTORIZED BICYCLES:   grubee 48cc; NEED SPARK! posted by: Melinda on 7/26/2005 at 3:57:09 PM

I just finished mounting my 48cc Grubee on the Schwinn Stingray chopper, and yesterday I tried starting my bike. (I tried twice and then decided to wait until later because it was just too hot to push my bike back up the hill again.)

I didn't get any spark the first time, and when I checked my coil connection wires I realized that I had disconnected them in the process of securing them to the frame. So after reconnecting them I went up the hill again. I didn't get spark the second time either. After I checked my coil wires and my spark plug connection and they seemed okay, I decided to take a break. Actually I'm not sure what to check besides pushing down to make full contact with the spark plug and making sure there are no obvious signs of corrosion on the plug. How else can I check this?

Later it occurred to me that maybe I didn't pedal far enough to get it started. I went about 20-30 yards downhill at maybe 5-8 mph. Should I keep pedaling further do you think? Also the second time I primed the engine again just in case. Could I potentially flood the engine? And if I do what symptom will it show?

One other thing I noticed was that as I rolled the bike with the clutch engaged the drive chain would make a cyclic kind of thunk or thwack. It wasn't very frequent, maybe once every time the chain went around. I'm wondering if it might have something to do with the chain section I put in or the original chain, in particular where the two are connected with master links. I've ordered two replacement master links just to have "virgin" ones to put in. But one link on the original chain is kind of difficult to put a master link on. It appears to be kind of warped outward so that the locking piece can barely fit on. I don't know if maybe I should get a new 415HD chain. Anyhow I thought I would check in case this was "normal".

Thanks in advance,

   RE:MOTORIZED BICYCLES: grubee 48cc; NEED SPARK! posted by Melinda on 8/1/2005 at 8:11:56 PM

I have made progress. With help, I tightened the chain which reduced the thwack. Although I purchased a couple of master links from (, I haven't installed them yet. I'm hoping they will eliminate that thwap.

I also got a suggestion for how to check to see if I had spark from a member of the discussion group. He said to remove the spark plug from the engine but keep it attached to the CD ignition. Then while pedaling hold the plug near the block (and avoiding getting shocked), watch for spark.

I propped up my rear fork so that my rear wheel could turn freely and taped the spark plug to the bike frame so that it was close to, but not touching, the engine block. Boy! Did I have spark! It looked good!

I put the spark plug back in and tried to start the engine again. It sounded like it was turning over, but when I stopped pedaling the engine stopped, too. (Bike was still propped up with rear wheel able to spin freely.)

I tried adjusting the choke while pedaling, and I tried getting an air bubble out of the fuel line. Still the motor doesn't continue to run on it's own.

Right now I'm optimistic, but taking a break,
Any suggestions are very welcome,

   RE:RE:MOTORIZED BICYCLES: grubee 48cc; NEED SPARK! posted by Harry Tutle on 9/2/2005 at 1:12:37 AM
I'm looking for a V belt pulley to fit on the rearwheel of
a 26" bike wheel. I intend to mout a 2HP B&S engine above the rear wheel. Can anyone tell me where to find about a
8-9" pulley for a 4L or 5L belt?


   RE:RE:RE:MOTORIZED BICYCLES: grubee 48cc; NEED SPARK! posted by Edward on 11/20/2005 at 6:58:02 AM
You might try a whizzer dealer for a sheave (pulley). The alternative is to weld another rim (with spokes removed) to your rim every 6 inches around the circumference. You'll have to widen the rear forks to accommodate the extra width of the doubled wheel.

   RE:RE:MOTORIZED BICYCLES: grubee 48cc; NEED SPARK! posted by Melinda on 11/28/2005 at 2:05:07 AM
I figured out shortly after posting while reviewing a photo I was sending (to the fellow who sold me the motor) that I had reconnected the wires to the CD ignition backward. (They had become disconnected on an earlier attempt to start the engine.)

Meanwhile with suggestion from Edward, who posts here, I also sealed the carburetor to the motor better using a permatex silicone product. Both this and the correct connection of the wires lead to a successful start.

I've been riding the bike regularly now for a few months, 15-30 minutes at a time. With suggestion from a friend at work, I tuned the engine until it had a better gas-air mix. Now it doesn't spew burnt feul, but it still fouls the spark plug enough to need cleaning before each trip in order to start the engine. To tune the motor, I turned the gas mix screw and the throttle needle position screw until I minimized the smoke coming out the muffler. Ultimately that was the gas mix screw all the way in and the throttle needle all the way up to keep the engine from running too rich. This seems a bit extrememe and so I'm wondering if I should check something else that controls gas flow. (The carburetor float when last checked was okay.) Or air flow. (I'm trying to find a replacement air filter. Haven't had much luck yet.)

I've also put in chain tensioners (two Surly Tuggnuts) and that has helped with adjusting the wheel position immensely. I had the chain to the pedal too tight and wore out the coaster bearing already.

I hope to get a pair of "ape hanger" handlebars soon (offered by Schwinn). Maybe then I can sit up straight instead of leaning over.

In the meantime here's a photo of my bike with the stock handlebars.


   RE:RE:RE:MOTORIZED BICYCLES: grubee 48cc; NEED SPARK! posted by Melinda on 11/30/2005 at 12:30:21 AM
Trying the picture again


   RE:RE:RE:MOTORIZED BICYCLES: grubee 48cc; NEED SPARK! posted by Melinda on 11/30/2005 at 12:45:47 AM
Trying to post a link without the tilda symbol in it:


MOTORIZED BICYCLES:   Clutch problems on 60cc Grubee posted by: David on 7/22/2005 at 6:23:33 PM
I installed a 60cc grubee and am having trouble with the clutch being tottally stuck in the engaged position so that I cannot pedel freely. When I unscrew the clutch nut enough for the wheel to actually spin the clutch lever is extremely stiff. Anybody have any ideas?

Thanks in advance...

   RE:MOTORIZED BICYCLES: Clutch problems on 60cc Grubee posted by Melinda on 7/26/2005 at 3:07:43 PM
Hi, David,

I just put together a Grubee 48cc Skyhawk with the new Stingray Chopper frame, and I ran into a similar question. Fortunately the guy who sold it to me helped me out. With the clutch lever screwed on, have you tried pushing the clutch arm toward the bike frame? The clutch is a very stiff spring. It may take two thumbs at first (or at least it did with my small hands).

Then getting the clutch adjusted involves putting the brass sleeve in a position close enough to disengaging the engine that the handlebar lever will allow the chain to move freely when pulled. For me this took a lot of trial and error. I also had to cut off a lot of that small spring to allow the clutch lever to move without buckling that spring. Finally I did what I should have from the start which was use a Sharpee to mark the cable where I intended to put the brass sleeve. That helped me more successfully move the sleeve forward or back from the last attempted position.

Also forget the 1/16" freeplay they mention in the instructions. When I was concerned that the engaged position involved some tension on the clutch lever, the guy who sold it to me said don't worry about the risk of wearing the clutch out. Also I ultimately took the opposite approach from the one in the instructions. I pushed the clutch lever all the way in and pulled the handlebar lever in, too, and then marked where I wanted to put the brass sleeve. This initially made the cable too short, because the bike still rolled freely when the handlebar lever was let out, but I could just bit by bit move the sleeve down the cable and finally find a good position for it.

Good luck! I want to keep in touch because right now I'm troubleshooting, too. :)

   RE:MOTORIZED BICYCLES:   Clutch problems on 60cc Grubee posted by Don Mussell on 8/22/2005 at 1:53:47 AM
Your problem is very easy to solve.Replace your cluch outer cable with a good quality bicycle cable.Your free play is bering taken up by the low qualitey chinese cable buckling under tension. Don [email me if you want more tech.advice.]

   RE:MOTORIZED BICYCLES: Clutch problems on 60cc Grubee posted by carlos davila on 6/18/2007 at 9:59:10 AM
i owen a 48cc skyhawk lowrider bicycle and for some reason i can push the bike with out holding the clutch. do any body knows what is that happen,it's because the clutch is gone?

AGE / VALUE:   malvernstar autocycle posted by: steve on 7/22/2005 at 11:49:35 AM
did the malvernstar autocycle come in two models if so did one have pedals and the other not i believe my grand father had one that didnt have pedals but had akick start

MOTORIZED BICYCLES:   Progress on '63 Schwinn Moto posted by: Rif on 7/8/2005 at 3:55:00 PM
Hey all,
My shipment from Mike Simpson (simpson motorbikes) came yesterday A.M.
I spent all day wrenching on my two projects-
The main one being my '63 Schwinn Typhoon with Hercules tank.
It now has an 80cc Grube mounted!
Interesting install. I fabricated a front motor mount extension from some mild steel plate that I had laying around, and it came out sweet!
the engine is solidly mounted with NO clearance issues.
The only troubles I'm having is with the clutch and the rear wheel. The clutch is stiff and the arm doesn't 'snap' back freely like on the 48cc I have. It feels wierd. The rear tire is being pulled out of line by the different chain tensions and the rear drive sprocket; I ran out of daylight and have no lighting in my workspace so I had to stop.
BTW- the clutch is going to be activated by a bendix three speed, positive lock stick shift. The Standard handlebar mounted clutch lever just wasn't doing a thing for me. I've already mounted the stick shift on the down tube (jockey shift style); this is not to be trendy or cool, but because that's how the inspiration hit me while digging through my parts bins. I am merely a vessel through which Art and Inspiration travels. The bike sort of 'tells' me what it wants and I build it to my vision...
Well, I'll post pic.s as soon as I can snap some and down load them.
The Faux antique 1902 California(2)/1905 Mead replica now has it's center stand and hairpin saddle, and is looking great in it's 'mock-up' stage; pic.s of that one soon too...]


   RE:MOTORIZED BICYCLES: Progress on '63 Schwinn Moto posted by rif on 7/9/2005 at 3:17:31 AM
Never mind, got it taken care of!
I got it to fire up but unfortunately, the wheel and drive sprocket
are out of true, so my next day off I'll throw it on the trueing stand
and get that all taken care of...
Man, does that engine sound GOOD; Snappy on the throttle too!

AGE / VALUE:   Two people on A Motobike??????? posted by: Mike Schneider on 7/5/2005 at 2:06:23 AM
Looking for advise - experience on hauling two people on a motobike.

Been emailing Riff Addams, Don Grube and Mike Simpson. Mike gave me some excellent advise: 70 cc engine, 24" wheels and a 50 tooth sprocket.

Any experience or advise out there?

BITW (Brothers In The Wind)