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1974 Honda MR50 minibike

Bike preparation, class eligibility, technical questions.

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1974 Honda MR50 minibike

Postby jerry smith » Mon Dec 14, 2020 4:56 pm

Got the bike in boxes from a friend. Have it all back together. Scrounged parts, ebay , fixed carb leaks , Built an exhaust and air cleaner. New crank bearings and seals. I have everything working. Good spark on plug but won't fire. I think you 2 stroke guys are in some kind of cult. The compression was 60# so got a rebore and now have 95#. On this bike it seems everything is grounded (not sure how that works). Usually when the stator grounds it's no good, but not this one. Can't check continuity on points etc 'case all grounds but still get a good spark at plug. Are 2 stroke guys into voodoo or something.
Seriously though my buddies son had this bike as a kid and 2 years ago took his life and his dad wanted me to get it running for his grandkids. Brocks coming by Wednesday and we're going to see if we can figure it out. I'm not familiar with 2 strokes and wonder if a crankcase leak would be a problem. It looks like it should be so simple but I can't figure it out.
Thanks. Jerry.
jerry smith
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Joined: Mon Apr 11, 2005 8:00 pm
Location: Creemore

Re: 1974 Honda MR50 minibike

Postby carbio12 » Tue Dec 15, 2020 2:34 pm

Had a MR50 for several years , it is now with a bike repair guy named Garth whose shop is called CNC Ware located between Meaford and Owen Sound . 519-374-7343 . He does lots of 2 stroke work .
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Joined: Thu Nov 24, 2016 6:09 am

Re: 1974 Honda MR50 minibike

Postby Paul Brubaker » Wed Dec 16, 2020 6:32 am

Hi Jerry,

I am not a 2 stroke expert but I understand a compression check alone will not tell the whole story on a 2 stroke.

2 strokes really need a pressure check. There is lots of explanations online and YouTube as well.

Here is a link to a good explanation ... sstest.pdf

Not sure if this will help but after the pressure check you are at lease sure that you have no leaks.

Good luck and let us know how you solved it please.
Paul Brubaker
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