Almost giving up on my first 4-stroke build

Idlandz

New Member
Joined
Dec 11, 2019
Messages
11
So last summer I saw a video about a motorized bike build on YouTube. Seemed simple enough. Just slap that old 4-stroke on there and bam, cheap motorcycle.

I found my dad's old trash mountain bike and bought the standard Huasheng 4-stoke all in one kit on Ebay. After putting everything together, making sure the chain was tight, and hooking up wires and fuel lines, I was ready to ride off into the hazy sunset of a hot South Texas suburb.

I hoped on my glorious invention, settled back into the insanely small and hard mountain biking seat, and gave the throttle a twist. (had already let it run idle and reved up a bit for an hour to break in) The first mile went well until it didn't. Cruising at maybe 20mph down a flat road was all fun and games until the drive chain committed suicide, with no warning whatsoever the chain ripped in half and wrapped its self around the rear sprocket. This happened about 5 more times, with many attempts to figure out the problem. I checked the chain tension, all good there. Realigned the rear sprocket? Yep... many times.

Eventually I found that the pineapple mount on the rear wheel was the problem child of the whole build. It would come loose or shift no matter how tight I made the nuts, or how much thread locker I put on it. The solution after that was to buy an $80 CNC adjustable sprocket adapter that would clamp onto the rear hub.

That expensive part turned out to not fit my rear hub as it's not a standard hub size. So now I have an expensive paper weight, can't return it with out paying almost more than its worth in fees and shipping. So now I'm left with a bike that's been sitting in the garage taking up space for months and I only got to ride it a mile or two before it died. It makes me so mad because it was so much fun for that short time, and I have so much money put into it just for it to sit and get dusty.

The whole community seems so great, and one time I broke down on the side of the road some guy on a 2 stroke cruiser stopped and helped me unwrap the mangled chain.

So yeah any advice would be greatly appreciated. I really want to get it running, but don't have much more money left to throw at it. Not that I did in the first place lol.

91766

Bad picture, sorry.
 


FNTPuck

Well-Known Member
Joined
Jul 2, 2018
Messages
879
Judging by the picture you may just need to go tighter on those sprocket bolts. It shouldn't move around even with a bigger stronger motor than that.

If you are adamant about upgrading it though, mic the rear hub and let us know the diameter.

What country are you in? Mzmiami on ebay sells the CNC adapters in both 1" and 1.5" for like $35, identical to the CDH ones but without the engravings. I've gotten three from them.
 

GreasyChris

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Joined
Jan 3, 2019
Messages
1,377
Dont give up yet, you're almost there. Like puck said there are lots of places to get the hub adapter for much cheaper and probably free shipping but you need to measure the diameter of your hub first. You've already experienced how fun it was to ride if only for a mile.
 

RB55

Active Member
Joined
Sep 18, 2019
Messages
168
I’m surprised you’re having issues with the sprocket wheel mount. I’ve gone through a ton of issues but never had any trouble with a properly installed rear sprocket with factory parts, even thought it’s extremely crude.

You don’t need to return that hub, just sell it on eBay for a few dollars cheaper then the next lowest price and it’ll be sold fast. That’s what I do when I have to return stuff, honestly it’s such a pain that I just sell it and only lose a few $$.

I would try the stock mount again. When you install it, tighten the bolts to at least 12 ft-lbs or torque (I just use the 12 number on my drill). It’s alright if you break a bolt or strip a nut considering the price of a new hardware. Blue Thread lock is what I use. If that doesn’t work then tighten those bolts down like hell and try again. They really need torque to grip the tire spokes.

If all this doesn’t work, then go ahead and get a new bike wheel off and old bike or something and use the CNC mount on that, or the old one if you’ve already sold it.

Once you get it working, you’ll be glad you did!!
 

Idlandz

New Member
Joined
Dec 11, 2019
Messages
11
Hey thanks for all the replies. So I grabbed some calipers and measured the rear hub. I don't know exactly how to use these calipers but if I'm reading it right the hub is 1 and 1/10th U.S. inches. (living in united states btw to answer your Q) The real problem arises from the fact that going up to the spokes is a sharp inverted cone slope on the hub. (if that makes any sense). So the diameter climbs up to around 2 inches by the time it gets to the edge of the hub. So to get one of those adapters to fit I've realized I'd have to cut a reverse cone into the aluminum of the adapter. Sorry if that's a bit confusing.

Are there any place's I could get a rear wheel that has the standard one inch hub size? Before buying a new wheel or anything I'm going to try RB55's and Puck's suggestion of trying the original mountings again before I buy anything new. Might have to buy some better nuts and bolts but will definitely tighten to 12 ft-lbs. I might also try a larger, tougher chain as the one that came with it has a very tight tolerance with the sprocket.

Thanks all for the advice so far; I really didn't want to give up on this project as it was so much fun for just that little bit of riding. I will be selling that cnc sprocket on Ebay If I can't find a good rear wheel that works. But either way I have some renewed hope now about my bike project.
 

RB55

Active Member
Joined
Sep 18, 2019
Messages
168
Hey thanks for all the replies. So I grabbed some calipers and measured the rear hub. I don't know exactly how to use these calipers but if I'm reading it right the hub is 1 and 1/10th U.S. inches. (living in united states btw to answer your Q) The real problem arises from the fact that going up to the spokes is a sharp inverted cone slope on the hub. (if that makes any sense). So the diameter climbs up to around 2 inches by the time it gets to the edge of the hub. So to get one of those adapters to fit I've realized I'd have to cut a reverse cone into the aluminum of the adapter. Sorry if that's a bit confusing.

Are there any place's I could get a rear wheel that has the standard one inch hub size? Before buying a new wheel or anything I'm going to try RB55's and Puck's suggestion of trying the original mountings again before I buy anything new. Might have to buy some better nuts and bolts but will definitely tighten to 12 ft-lbs. I might also try a larger, tougher chain as the one that came with it has a very tight tolerance with the sprocket.

Thanks all for the advice so far; I really didn't want to give up on this project as it was so much fun for just that little bit of riding. I will be selling that cnc sprocket on Ebay If I can't find a good rear wheel that works. But either way I have some renewed hope now about my bike project.
Don’t give up! I’ve gone through everything from the internal engine drive gear falling off to the exhaust pipe bolts not going in to a bad crash where I had to rebuild half the bike. The more effort you put into it, the more you’ll love and enjoy riding it!
 

FNTPuck

Well-Known Member
Joined
Jul 2, 2018
Messages
879
Hey thanks for all the replies. So I grabbed some calipers and measured the rear hub. I don't know exactly how to use these calipers but if I'm reading it right the hub is 1 and 1/10th U.S. inches. (living in united states btw to answer your Q) The real problem arises from the fact that going up to the spokes is a sharp inverted cone slope on the hub. (if that makes any sense). So the diameter climbs up to around 2 inches by the time it gets to the edge of the hub. So to get one of those adapters to fit I've realized I'd have to cut a reverse cone into the aluminum of the adapter. Sorry if that's a bit confusing.

Are there any place's I could get a rear wheel that has the standard one inch hub size? Before buying a new wheel or anything I'm going to try RB55's and Puck's suggestion of trying the original mountings again before I buy anything new. Might have to buy some better nuts and bolts but will definitely tighten to 12 ft-lbs. I might also try a larger, tougher chain as the one that came with it has a very tight tolerance with the sprocket.

Thanks all for the advice so far; I really didn't want to give up on this project as it was so much fun for just that little bit of riding. I will be selling that cnc sprocket on Ebay If I can't find a good rear wheel that works. But either way I have some renewed hope now about my bike project.
The "reverse cone" would also have to coincide with the distance from the spokes it needs to be for proper alignment as well to maximize contact.
 

Communistic

New Member
Joined
Dec 15, 2019
Messages
9
hang in there. my 4 stroke kit is being a massive pain in the a** as well. my original chain tensioner bent a full 90 degrees and obliterated my backj wheel at 20 mph making me fishtale all over the place and then walk the wreck home about 3 miles. I had to completely tear mine down because a piece of gasket material got lodged into the exhaust valve. I've burnt out two clutches and a chain already and the carb is peeing fuel all over the place at random. IF i still have the patience to not launch my entire bike through a window (tempting) I'm sure you can too! lol
 

DistantWolrld101

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Joined
Aug 11, 2018
Messages
679
hang in there. my 4 stroke kit is being a massive pain in the a** as well. my original chain tensioner bent a full 90 degrees and obliterated my back wheel at 20 mph making me fishtale all over the place and then walk the wreck home about 3 mile
If the bike your riding is the one you posted in your media you don't need a chain tensioner if you know how to set it up i can tell you that right now.

Take the chain tensionor off, wrap the chain around the sprockets, put master link in(don't put the pin in cause your gonna take the link out) where you have a PERFECT length fit where there is some wobble that you'd just the tensioner to get rid of, now take chain off back sprocket and take one and only one link out and put the master link in and put chain on top half of sprocket and SLOWLY rotate tire backwards to put chain on, you'll notice it will get tight and it will seem like it doesn't want to go on but as you apply pressure it will just POP on and once it does POP on the chain will have little slack on top and bottom that you will want and this is achieved without a chain tensioner that can cause wrecks and other problems :p also it just looks nicer without a chain tensioner more cleaner in my book
 

Idlandz

New Member
Joined
Dec 11, 2019
Messages
11
hang in there. my 4 stroke kit is being a massive pain in the a** as well. my original chain tensioner bent a full 90 degrees and obliterated my backj wheel at 20 mph making me fishtale all over the place and then walk the wreck home about 3 miles. I had to completely tear mine down because a piece of gasket material got lodged into the exhaust valve. I've burnt out two clutches and a chain already and the carb is peeing fuel all over the place at random. IF i still have the patience to not launch my entire bike through a window (tempting) I'm sure you can too! lol
My chain tensioner came loose one test ride and was about a half inch from catching the wheel. I bought a spring tensioner so hopefully that helps plus doing a better job of tightening the chain like Distant said.

But I totally get wanting to throw it out a window lol, happens after a whole day of working on the bike just for it to fly apart again on the road.
 
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