Time to cvhange top-end in my 01 YZ125
- Thread starter menaceg21
- Start date
- Nov 25, 1999
- 7,926
- 43
Clean the bike and engine.
Have a clean work area.
Remove the tank, seat, sub-frame, carb/intake/reeds, and exhaust.
Drain your coolant from the radiators and water pump.
Disassemble the top-end with the appropriate wrenches. Pay particular attention to the powervalve assembly taking pics for reassembly. IMPORTANT: Be sure to coverup the bottom end to prevent anything from falling into the cases!!! Shop rags work well for this.
Clean everything thouroughly!
Besides gaskets, you will need to inspect the bore/plating and overall dimensions. This requires some specialized micrometers and is best done by a reputable mechanic.
Once you have the dimensions and plating inspection, you can order parts. Being an 2001, your cylinder may need to be bored and replated. If you do not have a manual, order it now.
Reassemble per the manual and break in. Work time will likely be several hours your first time. Other work will be dictated by the inspection and ordering parts will likely be several weeks.
BTW, if a top-end has not been performed on the bike before, a bore a replating is almost assured. Failure of a piston skirt can cause catastrophic engine failure and be MUCH more expensive to repair. Don't put this off!
Have a clean work area.
Remove the tank, seat, sub-frame, carb/intake/reeds, and exhaust.
Drain your coolant from the radiators and water pump.
Disassemble the top-end with the appropriate wrenches. Pay particular attention to the powervalve assembly taking pics for reassembly. IMPORTANT: Be sure to coverup the bottom end to prevent anything from falling into the cases!!! Shop rags work well for this.
Clean everything thouroughly!
Besides gaskets, you will need to inspect the bore/plating and overall dimensions. This requires some specialized micrometers and is best done by a reputable mechanic.
Once you have the dimensions and plating inspection, you can order parts. Being an 2001, your cylinder may need to be bored and replated. If you do not have a manual, order it now.
Reassemble per the manual and break in. Work time will likely be several hours your first time. Other work will be dictated by the inspection and ordering parts will likely be several weeks.
BTW, if a top-end has not been performed on the bike before, a bore a replating is almost assured. Failure of a piston skirt can cause catastrophic engine failure and be MUCH more expensive to repair. Don't put this off!
truckster225
Member
- Jun 11, 2009
- 58
- 0
And never reuse ANY little clips, or gaskets. Once you remove the piston, that little C-clip cant go back in! There like 2 bucks! Its just not worth NOT replacing all the little parts. It will save you some serious problems down the line.
I only say this cuz I re-used that little damm clip the first time I did a top-end. RUINED the engine, completely.
And I agree with BSWIFT, get the manual, it will make a world of difference!
Good luck!!
I only say this cuz I re-used that little damm clip the first time I did a top-end. RUINED the engine, completely.
And I agree with BSWIFT, get the manual, it will make a world of difference!
Good luck!!
There is an awesome video on youtube by rockymountainatv that shows you how top end work is done.
They don't go into the real details, but they show you how to do it.
watch?v=-FFIWtqU5Zc&feature=channel_page
Combine that with the advice your going to get here and you'll be set.
I can't post links so your going to have to add the last bit of the link above to a youtube URL
They don't go into the real details, but they show you how to do it.
watch?v=-FFIWtqU5Zc&feature=channel_page
Combine that with the advice your going to get here and you'll be set.
I can't post links so your going to have to add the last bit of the link above to a youtube URL
you gonna need this: http://ymenvom.nl/manuals/M5MV30_1.PDF
Read the section to rebuild the top end it will answer your questions.
Read the section to rebuild the top end it will answer your questions.
