Intro and question about metrakit mini GP50

EPR

23,451 posts · Joined 2009

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#2 · May 21, 2017

Welcome aboard, I would go to an auto parts store or.... and ask for Permatex Plastic Epoxy, mix some of the 2 tubes, CAM2 here cut a part of a plastic tank and welded something in its place, worked Great.

 

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johncg

1 post · Joined 2017

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#3 · May 22, 2017

A bit of a tangent but... how fast are these little bikes? I'm interested in learning what the absolute maximum speed can be with a long straight road and the right gearing.

 

EPR

23,451 posts · Joined 2009

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#4 · May 23, 2017

There are China bikes and Euro bikes ranging from 3 to 18 horsepower, 25 to 55 + mph, building a BZM 13 hp engine for my avatar bike now, Italian made GRC GP.

 

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Frankenmini50 Discussion starter

2 posts · Joined 2017

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#5 · May 23, 2017

Thanks for the advice - we ended up plastic welding the area to be more flush. I think we determined it is the coil/thread for the bolt has come loose so just spins and backs out as we tighten the petcock, causing the plastic to warp. But for now, our fix is holding.

As for the speed - none of our's are road legal, so getting them on a long straight to figure out how fast they go has proven to be a bit difficult. A few things factor into the speed that the bikes will actually go too - like your body weight, the jetting and carbs on the bike, any boring, if you can manage to keep it in the very tiny powerband, etc. We took our bone stock 7.2hp 50cc 2-stroke NSR out on the street once - my 180lbs husband on the minibike, and I followed behind on my CBR500, and he hit around 45mph after about half a mile. But I will say that the 12 year old kids in TMGP with super tuned bikes fly by on the track seemingly much faster... But also on that note, if you're racing these bikes as we do on a go-kart track, you'll never reach top speed because the straights are not long enough.

 

EPR

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#6 · May 23, 2017

I would put a bigger rear gear on it, you need more low end to get out of the corners and down the short straightaways. For my Italian GRC GP w/ all alum frame, avatar photo bike, I am bulding a 40cc water cooled BZM engine right now, with 690 racing cases, and silver crankshaft, about 13 hp, I just saw a BZM engine made with CS racing stuff 18 hp, $2.600.00 USD. You need to know the rules of what you can do to your engine and still stay in the class you want. If the kids are that fast you can be tthere engines have been work over.