Does this look normal? 05 RM 250

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12/19/2017 7:53 PM

Picked this smoker up last year and after rebuilding it, I put 13 hrs on it this past summer. Winter is here so looking to do a fresh top end. Does this look normal or do I have bigger issues? Thanks.

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12/20/2017 12:08 AM

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

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18 Yamaha YZ450F
94 Honda CR 500
90 Honda CR 500
81 Yamaha SR 500
68 BSA Thunderbolt
69 Triumph Tiger 100

12/20/2017 4:08 AM

Looks a little rich.

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If you're not mixing gas, you're not haulin ass.

12/20/2017 6:12 AM

Looks likes its running rich but not too bad.

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2009 Kawasaki KX450F
2009 Kawasaki KX250F
2002 Suzuki GSXR 600

12/20/2017 10:32 AM

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.

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12/20/2017 11:33 AM

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

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12/20/2017 3:27 PM

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.

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12/20/2017 3:32 PM

No problem, a lot of people get it mixed up

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12/20/2017 4:46 PM

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

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12/21/2017 8:10 AM

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

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12/21/2017 9:58 AM

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.)

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Braaapin' aint easy.

12/21/2017 7:52 PM

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

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12/22/2017 11:30 AM
Edited Date/Time: 12/22/2017 11:31 AM

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.

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12/28/2017 3:55 PM

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?

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12/28/2017 4:29 PM
Edited Date/Time: 12/28/2017 4:30 PM

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?

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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.

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12/28/2017 4:46 PM

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

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12/28/2017 5:03 PM

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?

Photo

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.

Photo

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12/28/2017 5:14 PM

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.

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1/6/2018 10:20 PM

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...

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1/7/2018 8:50 AM

^^^^^^^^

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

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1/7/2018 11:27 AM

FWYT wrote:

^^^^^^^^

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

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

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