Does this look normal? 05 RM 250

Looks like on right side inside cylinder scratch. Take off cylinder and check it out properly or take better pictures.

Looks a little rich.

Looks likes its running rich but not too bad.

I ran 32:1 motul 800 at the beginning of season. Noticed it running rich so went to 36:1 and leaned out the air screw a half turn. Spark plug was a nice Golden brown at the tip but a little bit of splooge on the threads. I agree, I could go leaner. Sorry for the bad pics. I will take the piston out and further inspect and clean the cylinder and PV.

Going from 32:1 to 36:1 is actually making your bike run richer, granted not much but rich and lean does not mean amount of oil. When a bike is rich it is from too much gas to air ratio not oil in the gas ratio

ktm-5 wrote:

Going from 32:1 to 36:1 is actually making your bike run richer, granted not much but rich and lean does not mean amount of oil. When a bike is rich it is from too much gas to air ratio not oil in the gas ratio

I get that confused. I need to lean out the fuel to air mixture through jetting, not by changing my oil to fuel ratio. I got it...thanks for clarifying.

No problem, a lot of people get it mixed up

if i was you i would leave it. any leaner and you are pushing it.

I would want to see the underside of the piston to make sure it is not a leaking crank seal giving you issues.

Paw Paw

ktm-5 wrote:

Going from 32:1 to 36:1 is actually making your bike run richer, granted not much but rich and lean does not mean amount of oil. When a bike is rich it is from too much gas to air ratio not oil in the gas ratio

This.
Also, leaning out the air screw only works in your slow circuit (idle and just above idle at low throttle openings.)
For most riding scenarios, your needle position is what controls the jetting, in combination with the main jet size. I would start by leaning out your needle by a click and see if that gets cleaner. (Move the clip up the needle one position so the needle projects out of the throttle slide farther.)

Paw Paw 271 wrote:

I would want to see the underside of the piston to make sure it is not a leaking crank seal giving you issues.

Paw Paw

^^^^ this

Paw Paw 271 wrote:

I would want to see the underside of the piston to make sure it is not a leaking crank seal giving you issues.

Paw Paw

Pulled the top end off and your suspicion seems correct. Saw some oil under the piston and on the exposed part of the crank. I probably should have done a bottom end rebuild when I first bought it, but everything seemed tight and it ran excellent this summer. Will be doing one now and glad I purchased a crank puller/case splitter last winter. It will be my first experience splitting the cases. Thanks for the help.

Working on tearing the engine down and ran into some stuck screws. 1) how do i remove these without stripping them? 2) can I replace these with something easier to remove?

Teej317 wrote:

Working on tearing the engine down and ran into some stuck screws. 1) how do i remove these without stripping them? 2) can I replace these with something easier to remove?

I just ran into this with a RM125. Impact screwdriver is what your supposed to use to remove them. The stripped screws (I had two) I used a Torx bit socket that I hammered into the screw head. They all have blue locktite on them. Heat will help.

The clean areas on the piston are called wash, safe wash is 1/4 -1/2 inch. How did the plug look?

A impact screw driver (not a powered on but one you hit with a hammer) will help loosen the screws.

impact driver

Teej317 wrote:

Working on tearing the engine down and ran into some stuck screws. 1) how do i remove these without stripping them? 2) can I replace these with something easier to remove?

As said above, heat to loosen the loctite and then an impact driver. Key is getting a good fit on the screws before trying to undo, but by the looks of the heads on those, you’re going to need to drill a pilot hole and hammer in a torx bit or use an ‘easy out’ screw extractor.

That said, if you’re just doing main bearings and seals, you don’t actually need to remove either of those parts (powevalve actuator arm and selector paw). Here’s a picture of an RM125 engine I split, where I left the powervalve assembly in place.

Schmidt452 wrote:

The clean areas on the piston are called wash, safe wash is 1/4 -1/2 inch. How did the plug look?

A impact screw driver (not a powered on but one you hit with a hammer) will help loosen the screws.

impact driver

Plug was golden brown on the tip with some splooge on the threads.

So I managed to get the cases split and pressed the crank out. As I was getting it out, I heard a little metal piece fall. This is what I found...what did I do? I have no idea what that is...

^^^^^^^^

Looks like a roller bearing cage. Inspect carefully!!!!

FWYT wrote:

^^^^^^^^

Looks like a roller bearing cage. Inspect carefully!!!!

That sounds very likely. Will more closely inspect the bearings to confirm. Thanks.