Basket case? First 4stroke build

[CrazyDan]

Aleman is 100% correct in everything he said. The flywheel cover can come in black, red, green and yellow. You have a straight shaft 142f, there were no 144s made with a straight shaft as far as I know. You can shim the pulley a little with thin washers. The mount and tranny are from the gasbike ghost racer kit, so it's a 7g tranny. I've modded tugs meant for horizontal dropouts to work on my forward facing diagonal dropouts since finding some made to work can be hard. I've found one mentioned on an ebike forum called a batavus chain tensioner that looks good, but I only see it for sale in europe... I too am running a sbp shift kit with my 4 stroke, and love internally geared hubs. I'm running the nexus 3 speed. More brakes are a must before you get that thing going fast. A suspension fork would make for a smoother ride if you have potholes.
So yeah, I'm basically repeating what aleman said, just as confirmation lol .

 

[Obsessed biker]

The flywheel cover color is just an option. I've seen them in red, yellow, green, and black over the past 10 years.

You may have nothing but trouble with that mount on that frame. It will require grinding out the bottom of the front mounting block in order to get it to sit at an angle that will let you mount the plate on it level. My brother and I experienced the same issue with that type of mount, and so did the person who mounted your engine - that's why it's mounted so cock-eyed. Alternatively, you could replace the mount, or tack on a couple bars of angle iron to use as a mount instead. Angle iron will let you mount the engine lower, as well.



You have the straight shaft Huasheng, they are 142F. Basically a copy of the Honda GXH50.



I do not think that is a real Grubee 4G, but some kind of copy. Your trans plate is an unmachined casting, judging from the back side of the plate. I have never seen a 7G in person, but that could be what you have.



Possibly. The rear pulley can be removed and shimmed to bring it out a bit to help line it up.



Those are semi-horizontal front-facing dropouts. There's a couple chain tugs that work for that application, such as these.



SickBikeParts sells a 4-stroke shift kit that can be made to work with your engine and trans combo. I did that back in 2010. The obstacle you might run into is the box muffler hitting the cantilever bars because the engine would be mounted farther forward. You'd need a different exhaust and also a different rear wheel. Coaster brakes don't work with shift kits.

I recommend a Sturmey 3-speed hub or the like with a strong rear brake. I've used X-RD3 and X-RD5 on my setup, and the integral drum brake itself isn't quite enough for my taste. I run 2 brakes on each wheel (Sturmey drums + V-brakes). You'd definitely need a front brake for your bike and the easiest way to go about that is to install a better fork with a mount for V-brake or even disc.

The flywheel cover color is just an option. I've seen them in red, yellow, green, and black over the past 10 years.

You may have nothing but trouble with that mount on that frame. It will require grinding out the bottom of the front mounting block in order to get it to sit at an angle that will let you mount the plate on it level. My brother and I experienced the same issue with that type of mount, and so did the person who mounted your engine - that's why it's mounted so cock-eyed. Alternatively, you could replace the mount, or tack on a couple bars of angle iron to use as a mount instead. Angle iron will let you mount the engine lower, as well.



You have the straight shaft Huasheng, they are 142F. Basically a copy of the Honda GXH50.



I do not think that is a real Grubee 4G, but some kind of copy. Your trans plate is an unmachined casting, judging from the back side of the plate. I have never seen a 7G in person, but that could be what you have.



Possibly. The rear pulley can be removed and shimmed to bring it out a bit to help line it up.



Those are semi-horizontal front-facing dropouts. There's a couple chain tugs that work for that application, such as these.



SickBikeParts sells a 4-stroke shift kit that can be made to work with your engine and trans combo. I did that back in 2010. The obstacle you might run into is the box muffler hitting the cantilever bars because the engine would be mounted farther forward. You'd need a different exhaust and also a different rear wheel. Coaster brakes don't work with shift kits.

I recommend a Sturmey 3-speed hub or the like with a strong rear brake. I've used X-RD3 and X-RD5 on my setup, and the integral drum brake itself isn't quite enough for my taste. I run 2 brakes on each wheel (Sturmey drums + V-brakes). You'd definitely need a front brake for your bike and the easiest way to go about that is to install a better fork with a mount for V-brake or even disc.

Thank you Aleman! Been away for a bit, but am ready to get back to work on it. Excellent info, just what I needed to know! Regarding the mount, I do have a couple pieces of angle iron, but am having trouble imagining what you envisioned on how to use them and I don't have much welding experience. Do you mean just replacing the silver plate with two pieces of angle iron?

The plastic cover i was referring to was the engine casing around the pull cord, not the flywheel cover. Most of those I've seen are in red or black, so i thought that might indicate if it were a 142 or 144.

From what I've heard, the straight shaft is on the older models? Does that also mean it's without a governor?

Unfortunately the rear pulley is the one that's sticking out farther. Upon closer inspection, it looks like if I flip it around, that may bring it in closer. I'll post the results. If that doesn't work, is it possible to shim the clutch side to bring it out farther?

Those are nice axle tugs, but they don't look like they'd hug the curved back of the dropout. I'd be concerned they may slip and swivel up or down. I suppose if there's enough room, a short bolt could go in the second hole to keep it lined up in the dropout, but that would limit how much it could pull.

I figured to make the most out of a jackshaft kit, I'd have to install it on a multiple speed bike. Maybe on my next build.

I agree about the brakes and I don't think the coaster brake is very effective, so I'll likely go with a long reach side pull brake since there aren't any bosses on the rear. I did change the front fork to a suspension one with brake bosses and put v-brakes on. The only issue is it made the front taller so the handling will be different.

Thanks again! I was beginning to think the number of questions might've scared away some responders.

 

[CrazyDan]

The plastic cover i was referring to was the engine casing around the pull cord, not the flywheel cover. Most of those I've seen are in red or black, so i thought that might indicate if it were a 142 or 144.

The flywheel is behind the pull start, the plastic shroud covering that side oft he engine is also known as a flywheel cover. They come in different colors, the person buying from the factory in bulk can request whatever color available.

From what I've heard, the straight shaft is on the older models? Does that also mean it's without a governor?

The straight shaft isn't age dependent and doesn't tell you if it is governed or not. The shaft shape and if it is governed or not is all dependent on what the buyer requested. The only thing shaft shape tells me is it's not a 144f, I never heard of a straight shaft 144f, they have all been tapered shaft.

Unfortunately the rear pulley is the one that's sticking out farther. Upon closer inspection, it looks like if I flip it around, that may bring it in closer. I'll post the results. If that doesn't work, is it possible to shim the clutch side to bring it out farther?

You can shim the inner side of the rear pulley (on the side of the plate where the output sprocket is on) with washers to bring the pulley inwards.

I agree about the brakes and I don't think the coaster brake is very effective, so I'll likely go with a long reach side pull brake since there aren't any bosses on the rear. I did change the front fork to a suspension one with brake bosses and put v-brakes on. The only issue is it made the front taller so the handling will be different.

Glad you got a front brake . You can chop the horseshoe off of a cheap fork with the brake bosses, and bolt/ strap that on to add v brakes to the rear.

 

[Obsessed biker]

Aleman is 100% correct in everything he said. The flywheel cover can come in black, red, green and yellow. You have a straight shaft 142f, there were no 144s made with a straight shaft as far as I know. You can shim the pulley a little with thin washers. The mount and tranny are from the gasbike ghost racer kit, so it's a 7g tranny. I've modded tugs meant for horizontal dropouts to work on my forward facing diagonal dropouts since finding some made to work can be hard. I've found one mentioned on an ebike forum called a batavus chain tensioner that looks good, but I only see it for sale in europe... I too am running a sbp shift kit with my 4 stroke, and love internally geared hubs. I'm running the nexus 3 speed. More brakes are a must before you get that thing going fast. A suspension fork would make for a smoother ride if you have potholes.
So yeah, I'm basically repeating what aleman said, just as confirmation lol .

Thanks Dan! As i mentioned to Aleman, I meant the plastic around the pull cord, not the flywheel cover. I'm still curious how you identify the 142 from the 144 if the color of the plastic is not an indicator. I've no experience with the different trannys, but it sounds like 7g is a newer version of the 4g. Does that mean i don't need to worry about the same issues that made folks recommend upgrading to the Grubee? That internally geared hub sounds like a winner. Are you happy with the jackshaft kit? Imo, all bike engines should've been designed to run through the existing drivetrain. I did upgrade to a suspension front fork. I didn't think it would change the handling as much as it has, but it's worth it to have the good brake options.

Edit... Well you responded before i got to post the reply to you lol. Ok, I thought the flywheel was the large wheel on the tranny. Terminology can be confusing cause I still think of a car's transmission when "flywheel" is mentioned.
Oh, good idea to take the horseshoe from a cheap fork!

 

[CrazyDan]

The 7g is a knockoff of the 4g, gasbike was hoping to stir the same thoughts you have. They hoped a higher number value made it sound better, but it is a cheap knockoff with more issues than the 4g had originally (those problems have mostly been addressed with the 4gs). You can make the 7g work, you just need to fix things that might be out of tolerance. The rear pulley not being in line with the front is one common issue, and shimming it with washers can fix that. A bad issue that can't be fixed is when the plate is bored, it might not be fully square causing the pulleys to not be on the same plane. You might want to upgrade the clutch, the stock ones with the gasbike kit chatter bad and wear out fast because they try to engage too early and slip forever.
I love my jackshaft kit, lets me accelerate quick and reach a high top speed. If I run single speed, I can only choose quick acceleration and low top speed because I live in a really hilly region. If I tried to gear for high speeds without my shift kit, I'll be burning my clutch to 20 mph from stoplights, and large hills will kill my speed to the point I am only burning my clutch the whole way up.