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I could really use help finding a bore kit that should fit my engine.

I have a jn1p39qmb motor. The fact that it's not 139qmb is making it tricky. Is it practically the same interchangeable parts as 139qmb?

If someone could help me that would be amazing!!

* I'm getting promoted with the company I'm working for and they said I'll have to do a bank deposit in the morning. Scooter red lines at 8k + 35 mph only. Kinda normal, but I need a boost for going to the bank. Also so cars won't run me over and kill me. Also so I can attempt to get away from someone chasing me down for the money deposit >.<. Versus just pulling over and handing them the money..

Long case, I think I can fit put a 13 inch wheel on "14 max".

The belt seems almost perfect except for the slack in it that could be caused by heat, I could be wrong

I ordered that bicycle mph gauge.

But; I have been looking at a few other alternatives to make it more wanted when I sell the bike.

I plan to remove the entire speedometer and create a basic custom plate.

Then I'm just manually going to add gauges, once done I want to cover my custom speedometer with plexiglass, then screw it in.

I'm going to document part numbers for exact replacements.

I'm pretty good at making stuff like this so if this day comes soon I'll take pictures, document parts, maybe add simple instructions. This way someone could do the same or very similar.

From what I've configured with name brand parts it's going to cost 30 - 40 dollars. Not bad, and practically the same price as OEM clusters

I was considering on doing something like that for a tachometer.

I know I could configure once I pickup speeds, 8,000 rpms equal 35 mph etc. Of course this varies upon roller weighs etc.

6,000 rpms with 3 - 4 gram rollers could be 15 mph.

6,000 rpms with 6 - 8 gram rollers 'could' be 25 mph or lower. All depending on the riders weight etc etc.

*just something to fiddle with.

As for faults, there's a possibility of a bad gear puck "I think that's what it's called".

I had a guy tell me in the past the cable becomes stretched and weak, causing it to become sensitive. I think it's bs.

I also read that there's a plate inside the cluster that can be adjusted by bending it..

I've had my eyes open for a dirt cheap replacement " under 20", but nothing so far.

I've also considered getting a digital speedometer, something you might buy to make a dirt bike street legal. Haven't found anything cheap under 100 yet. And I prefer not investing money like that in this crap bike >.<.


Do you oddly have a amazon link to the one you bought?

I'm not entirely sure where to start poking at the bike.As some people know it's a new motor so everything is factory set that I know of. I inspected the variator, there's no washer.I probably should look into a fatter belt width? "if there is one".The motor still has the pair system. I do not currently have the proper tools to do what's needed so I'm just leaving that alone for now.Is there a true speed difference without it?Originally, the stock rollers made the rpm's hit 6000 with only going 12 mph, fresh build. With using 8.5 gram roller weights, I achieved 27 mph at 6000 rpms, I tested it only once at 7,200 and I achieved 32 mph.But there's a few issues, I down jetted the bike to stock. I still have a slight backfire flame sometimes.Wide open throttle sounds like an old farm biplane passing low "bhurrrn". Lightly let off and the noise is gone. I adjusted the pin on the needle to be as lean as possible.There's an issue going up long hills, might need slightly lighter rollers, not sure. As my speeds can go as low as 15 mph. It still moves lol. I plan to drain the gear oil out tomorrow. Might be needed during the break in dunno.The odd part is, I tried pumping the throttle as if it's a two stroke with a oil tank reservoir. It seems like after pumping the throttle for more fuel it runs faster and better. But if I make it more rich it runs like hell.. Any helpful checks/changes are much appreciated

Well the worst that could happen is the other side cracking/splitting..

I did what I will consider a flex test on the side that currently does not have a shock, seemed to favor slightly twisting on the side I was pushing on, and that's the side without a shock.

Is there anyone here that has a stock 50cc scooter, that could take a picture of where the rear shock bracket is on there frame? It would be nice to do a compare to a frame with one shock. It's possible it might need to be moved a little, maybe not.

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The other thought if this is a disaster, would i run into issues if I wanted to attempt a crankcase swap? From my new motor to the old one? Then there would be no issue technically..
If not I might just order a new crank case, preferably an exact replacement