What should I do to get my rm85 back running?

[Sniklefritz]

Recently my 2007 RM85 broke down and wouldn't start. When I kicked it over it felt like it had no compression, but wasn't seized. I took the top end apart and found the Piston totally screwed. At first glance the cylinder didn't seem to have any damage, but upon further inspection I found a chip on one of the intake ports.

The wrist pin bearing was missing two needles, and I found one just passed the reeds and I believe the other hit my foot when I removed the piston. I believe this to be the source of damage to my top end.

Judging by the pictures, what should I do next? Can I get my cylinder resleaved? Should I buy a new cylinder? Or should I start looking for a replacement motor?

[JFRM250]

I’m a rank amateur in this forum, and others FAR more knowledgeable than myself may disagree, but in my own opinion, I would recommend a new piston kit (approx $100) and you probably want to send your cylinder out to a machine shop for replating and repair (approx $200). $300 sure beats a completely new motor.

While you’re in there, take apart the power valve/exhaust valve assembly and clean it up real good. You need to take that out anyway for a replate job.

[mlatour]

I'd say it needs a full tear down (cases split) to fully evaluate as the failed small end connecting rod bearings bounced around

inside the crankcase before making their way up the transfer ports and damaging that piston.

 

Any up/down play in the connecting rod? Any play felt when tugging on the flywheel.

If so, even before a closer inspection those are signs the crank/rod need attention.

 

No guarantee a pre-owned 'replacement' engine of the same vintage will fare any better if it's due to overhaul.

Money better invested refurbishing what you have.

 

At first glance your cylinder doesn't look too bad but it should be measured. 

If the cross hatch is worn away, that's sign the plating useful life is done.

Replate it rather than have a sleeve pressed in.

 

Edited January 22, 2019 by mlatour

[JFRM250]

Good point re: check for up/down play in conrod. Bit of side to side ok.

When doing replate, ensure machinist includes crossshatching and send them the new piston as well to ensure measurements/clearance accurate for borepiston diameter.

Re: bottom end, agreed that can’t hurt to take a look ‘down under’ while you have the top end removed to ensure at least main bearings/seals in good shape. Can’t just do top ends and call it a day when crankcase may well need love too.

[Sniklefritz]

Thanks for the help. I'm in Phoenix AZ. Do you guys have any suggestions as to where I should send it to get plated? I'm having trouble finding someone local.

[JFRM250]

Thanks for the help. I'm in Phoenix AZ. Do you guys have any suggestions as to where I should send it to get plated? I'm having trouble finding someone local.

There are a few reputable ones out there (Google cylinder replate). Millennium will do a replate for around $200. I’m having my 2001 RM250 cylinder done for $225 (so maybe a bit less for a smaller cylinder?). I’m also having them rebuild my crank for $90 using my parts so if you dig into the bottom end as well and split the cases to check the bearings and seals which you should probably replace while you’re doing this, a crank rebuild is probably a good idea as well.

Take some pics and maybe a video clip or two, and send them to this guy at Millennium. He actually communicates via email very well, or you can call him, and he’ll quote you. He’s been straight up with me. Good luck.

Rodney Heaton
Technical Specialist/Sales
ASE Certified Master Technician
1404 Pilgrim Road
Plymouth, WI. 53073
920-893-5595 EXT 316
rheaton@mt-llc.com

https://www.millennium-tech.net

[Sniklefritz]

Update: sent my cylinder to millennium with the piston and ring. Rod estimated it to cost $300 because he said it needed welding. Hopefully it's no more than that.

[JFRM250]

Rod Heaton?  Good guy.  Prompt and courteous communication. He was my contact a couple months ago. I sent him my cylinder along with new piston (he said didn’t need to send the rings) for a 2001 RM250 that needed ‘repair’ along with the replate job.

 Repair estimate at $75

 Replate $225

 Got it back after about three weeks.  Turns out it only needed the replate.  They did not charge for any repair that might’ve entailed welding.  But of course your mileage may vary.

I got the cylinder back for just the replate estimate cost and it’s arguably better than brand new. They did an incredible job. You’ll be happy with the work. 

 

 

[Sniklefritz]

Finally got all the things needed to tear the bottom end apart. 

I need to know what the best way to remove the nut off of the crank and the magnet on the other side. 

Edited March 16, 2019 by Sniklefritz