Engine upgrade, 88 YZ 125

[Daniel]

Hi All

I have a 1988 Yamaha YZ125,

Just putting a word out there, does anyone know if you can swap to a later 125 motor, something a little more modern maybe a 90's type.

Thanks in advance

Daniel

[cnrcpla]

Welcome to the forum  If your a good welder you can put anything in the frame  As far as motors that would mount up to the original mounts with out having to move them, you should be able to get an 89 motor in there. But, if this motor is in good shape, I wouldn't even bother. Yamaha motors have changed so very little that I personally wouldn't even bother going through an engine swap to another yz motor. If its more power your after, I would say re-weld the mounts and make it fit a yz250 engine in

[2T Institute]

Welcome to the forum  If your a good welder you can put anything in the frame  As far as motors that would mount up to the original mounts with out having to move them, you should be able to get an 89 motor in there. But, if this motor is in good shape, I wouldn't even bother. Yamaha motors have changed so very little that I personally wouldn't even bother going through an engine swap to another yz motor. If its more power your after, I would say re-weld the mounts and make it fit a yz250 engine in

Except is 94 or so the YZ swapped from a 56 X 50mm bore and stroke to 54 X 54.5.

Hi All

I have a 1988 Yamaha YZ125,

Just putting a word out there, does anyone know if you can swap to a later 125 motor, something a little more modern maybe a 90's type.

Thanks in advance

Daniel

Worked on a few early YZ's and the absolute best thing you can do is swap to a 110mm rod and a alternate piston. Then all you have to do is jet it correctly and it should be a right flyer.

[cnrcpla]

Except is 94 or so the YZ swapped from a 56 X 50mm bore and stroke to 54 X 54.5.

Yes, but seeing as that year engine wouldn't fit in with the original motor mounts on the '88, would it really be worth re welding and moving brackets and mounts for the '94 yz125 engine?

[Daniel]

Hi Guys,

Thanks For your input & information, i was tossing up the idea if it was simple in a way, the motor is in good shape(just have to re-do the power valve needs new seals), iv'e had the bike for about ten years, rode for a couple of years the put in the shed and forgot about, the pulled it out done a full rebuild new plastics, fuel tank, rims, tyres, spokes, bearings etc the list goes on, & the profile picture is what it is today, its nothing spectacular but fun.

Thanks Daniel

[cnrcpla]

Nice  Ride the wheels off it 

[Daniel]

Thank's Mate,

it's a good old ride, lots of fun