Planet Minis

Jthomas7 · 11-10-2009, 07:46 PM

Well I built an MR50 engine today. I used the only bottom end I had with a good crank and built the top end with PW50 setup.

Being the idiot that I am I guess I forgot to make sure the bike shifted threw all gears before building it up. The bike seems to be jammed in first gear as it will not even try to change. Any ideas where to start? The engine does run.

mexicanyella · 11-12-2009, 07:44 AM

I don't know the 1st thing about MR transmissions, but I'd like to know more about this MR/PW hybrid thing you're talking about. What's the advantage, and what's involved in doing it, what's the plan for it, etc?

Jthomas7 · 11-12-2009, 09:06 AM

The advantage is PW50 piston kits are still available. Basicly it's just a quarter inch spacer because the pin to deck height is higher on the PW.

mexicanyella · 11-12-2009, 09:11 AM

Are you swapping the entire PW top end--head, jug, piston, etc.--or does the PW piston fit in the MR jug once you put the spacer under it?

Jthomas7 · 11-14-2009, 11:17 PM

Just the piston, it's a direct swap.

50rider340 · 11-14-2009, 11:56 PM

Man I have never heard of this I'd love to see pictures of the spacer used etc.

As for tranny I am just like mexicanyalla I have no idea about mr50 transmissions.

jmurray192 · 11-15-2009, 12:03 AM

Only thing I could say is you need to take it apart. Ether you forgot a washer or assembled the tranny wrong.

Jbrownkyr1 · 11-15-2009, 01:05 AM

Quote:

Originally Posted by 50rider340

Man I have never heard of this I'd love to see pictures of the spacer used etc.

As for tranny I am just like mexicanyalla I have no idea about mr50 transmissions.

I would also like some more info on this swap. Does anyone have a link showing some pics and describing this?

Jthomas7 · 11-16-2009, 01:09 AM

Basicly all you need to do is trace a base gasket onto a piece of 1/4 aluminum plate, cut it out and drill the holes for the cylinder studs. Install with a base gasket on top and on bottom of spacer, install PW50 piston onto MR Rod and roll with it.

I've figured out what's happening with my shifting problems but not really sure what needs to be fixed.

basicly the fingers that engage with the pins on the shift drum are sometimes getting pushed back and the springs not pushing them forward. Soooooooo sometimes they are jamming up and cannot make contact with the pins.

mexicanyella · 11-16-2009, 07:29 AM

Can an adult human ride an MR50, as in, is it scaled for an adult to fit on it pretty easily the way a Z50A is? Or is it scaled more for small kids, like a PW50? Do they hold up when pulling an adult around?

They are cool-looking little bikes, for sure. I guess you have to hunt for parts a bit.

Jthomas7 · 11-16-2009, 03:48 PM

I have 5 of them, parts won't be a problem

And no they suck for an adult rider.

11-10-2009, 07:46 PM	#1 (permalink)
Jthomas7 2nd Gear Member Join Date: Dec 2005 Location: Ponca City, Oklahoma Posts: 799	Where to start, MR50 stuck in first gear Well I built an MR50 engine today. I used the only bottom end I had with a good crank and built the top end with PW50 setup. Being the idiot that I am I guess I forgot to make sure the bike shifted threw all gears before building it up. The bike seems to be jammed in first gear as it will not even try to change. Any ideas where to start? The engine does run.

11-12-2009, 07:44 AM	#2 (permalink)
mexicanyella El rey de los puntos Join Date: Aug 2008 Location: Troy, MO Posts: 972	Re: Where to start, MR50 stuck in first gear I don't know the 1st thing about MR transmissions, but I'd like to know more about this MR/PW hybrid thing you're talking about. What's the advantage, and what's involved in doing it, what's the plan for it, etc?

11-12-2009, 09:06 AM	#3 (permalink)
Jthomas7 2nd Gear Member Join Date: Dec 2005 Location: Ponca City, Oklahoma Posts: 799	Re: Where to start, MR50 stuck in first gear The advantage is PW50 piston kits are still available. Basicly it's just a quarter inch spacer because the pin to deck height is higher on the PW.

11-12-2009, 09:11 AM	#4 (permalink)
mexicanyella El rey de los puntos Join Date: Aug 2008 Location: Troy, MO Posts: 972	Re: Where to start, MR50 stuck in first gear Are you swapping the entire PW top end--head, jug, piston, etc.--or does the PW piston fit in the MR jug once you put the spacer under it?

11-14-2009, 11:17 PM	#5 (permalink)
Jthomas7 2nd Gear Member Join Date: Dec 2005 Location: Ponca City, Oklahoma Posts: 799	Re: Where to start, MR50 stuck in first gear Just the piston, it's a direct swap.

11-14-2009, 11:56 PM	#6 (permalink)
50rider340 3rd Gear Member Join Date: Mar 2004 Location: CT Posts: 3,082 My Mood:	Re: Where to start, MR50 stuck in first gear Man I have never heard of this I'd love to see pictures of the spacer used etc. As for tranny I am just like mexicanyalla I have no idea about mr50 transmissions.

11-15-2009, 12:03 AM	#7 (permalink)
jmurray192 2nd Gear Member Join Date: Aug 2006 Location: AZ Posts: 976	Re: Where to start, MR50 stuck in first gear Only thing I could say is you need to take it apart. Ether you forgot a washer or assembled the tranny wrong.

11-16-2009, 01:09 AM	#9 (permalink)
Jthomas7 2nd Gear Member Join Date: Dec 2005 Location: Ponca City, Oklahoma Posts: 799	Re: Where to start, MR50 stuck in first gear Basicly all you need to do is trace a base gasket onto a piece of 1/4 aluminum plate, cut it out and drill the holes for the cylinder studs. Install with a base gasket on top and on bottom of spacer, install PW50 piston onto MR Rod and roll with it. I've figured out what's happening with my shifting problems but not really sure what needs to be fixed. basicly the fingers that engage with the pins on the shift drum are sometimes getting pushed back and the springs not pushing them forward. Soooooooo sometimes they are jamming up and cannot make contact with the pins.

11-16-2009, 07:29 AM	#10 (permalink)
mexicanyella El rey de los puntos Join Date: Aug 2008 Location: Troy, MO Posts: 972	Re: Where to start, MR50 stuck in first gear Can an adult human ride an MR50, as in, is it scaled for an adult to fit on it pretty easily the way a Z50A is? Or is it scaled more for small kids, like a PW50? Do they hold up when pulling an adult around? They are cool-looking little bikes, for sure. I guess you have to hunt for parts a bit.

11-16-2009, 03:48 PM	#11 (permalink)
Jthomas7 2nd Gear Member Join Date: Dec 2005 Location: Ponca City, Oklahoma Posts: 799	Re: Where to start, MR50 stuck in first gear I have 5 of them, parts won't be a problem And no they suck for an adult rider.

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