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Lee or any RM expert for a '92 RM 125

andymoto

C100_scottdavis2

Posts: 4533

Joined: 11/28/2007

Location: Carmichael, CA USA

11/11/2009 3:00 AM

I got this bike cheap; 1992 RM 125 in fair running shape.

I thought it had a stock piston because of the single ring vs. Wiescos two ring top end replacements and others I saw..

Just had notice the ART inside the piston, which is a Pro-X piston. They claim to have from Standard and A thru D pistons in like 0.002 increments; while Wiesco are think 0.005 or 0.010 increments. Cylinder had zero seize marks and the combustion chamber is a shoe polish brown; a bit rich. No carbon buildup; a minor amt where pipe/cyl meet.

I assume standard has no markings; which I cannot find any and the remainder are, but where? Top of piston like others?. I've cleaned the top gentely with no markings.

Or does Pro-X have a certain spot they letter their pistons other than crown? Ring had no markings like some OEMs for top of ring specific ones..

Cylinder doesn't appear to have even a scratch mark or is a pressed sleeve; comb chamber had a shoe polish look, a little bit rich. I was real surprised cyl was so clean that could still see crosshatch marks while powevalve was in pretty good shape; no carbon buildup like the head or trimming it to fit a pressed sleeve.

Also have a TMX Mikuni flatslide. The 17mm float bowl holds the bowl in place only.....but I also see what looks like a place to put two small screws close to the float bolt. My eyes aren't good, but looked like threads the same as the four corner tiny screws on float bowls of Keihins and newer carbs..

The point of where it looks like small screws should go in, it doesn't leak fuel; that puzzles me. Yet, when cold, no start, carb/brake cleaner on plug, put bit of WD and starts while revving way too high. Took carb apart is where I noticed what looked to be 2 screws missing despite the 17 mm holding the whole float. Stock jet were there... Reinstalled carb w/o where I think 2 screws go, it started with no 5 grand idle last time..

Pipe, Mr. Newmann, FTE, Pat327; those that can remember, I'd sure be awful greatful like if you know what I'm talking about with the carb and I've had horrid luck just me with Wiescos; and just have never liked them; their kits are more expensive for a $400 buck bike that I wish I could redo, but cannot. Needs a rear knob too...burb.

Thanks a ton for any help on the carb, piston ID location and anything else that sounded stupid at 3 am Pacific whatever Time; fall back; spring forward..


Andy Medin



90rm125

C100_99449110_1260751227

Posts: 104

Joined: 7/15/2009

Location: Clarks Summit, PA USA

11/11/2009 5:36 AM

To answer your carbuerator question my 90 rm 125's carb also has one screw and it appears that there are threads for others but looking at the parts list it only shows one screw

Halfast816

C100

Posts: 339

Joined: 4/1/2008

Location: USA

11/11/2009 6:37 AM

Only one screw to hold the bowl in place when you change just the main jet it doesn't fall off.

project racer

C100_scan0009_3_1391468080

Posts: 2887

Joined: 8/26/2006

Location: FL, USA

11/11/2009 7:14 AM

Take the cylinder and piston to a REAL shop and have them "miked". You will know precisely where you stand at that point, and be able to order the proper piston.

Nutty C

C100

Posts: 464

Joined: 10/28/2009

Location: Waterdown, CAN

11/11/2009 11:32 AM
Edited Date/Time: 11/11/2009 3:33 PM

Had one of them bikes. Stock they have a nikisil cylinder ( no Sleve) , Your eyes are bad. One of them screws is a dowl pin and the other is a screw. They ensure the float bowl goes on correct and do not effect anything related to the engine running. Stock Jetting is 320 main and 50 pilot.

andymoto

C100_scottdavis2

Posts: 4533

Joined: 11/28/2007

Location: Carmichael, CA USA

11/11/2009 8:28 PM
Edited Date/Time: 11/11/2009 8:29 PM

90rm125 wrote: To answer your carbuerator question my 90 rm 125's carb also has one screw and it appears that there are threads for others but looking at the parts list it only shows one screw

You also then have the same carb; the one the float bowl drain plug screws onto like a post in the carb that tightens the whole bowl on....then one small phillips is used incase the drain plug unthreads(not very likely that I see).

I have two extra threaded areas that aren't on the gasket sealing area; that was my concern what are those for, if anything?

andymoto

C100_scottdavis2

Posts: 4533

Joined: 11/28/2007

Location: Carmichael, CA USA

11/11/2009 10:24 PM

Nutty C wrote: Had one of them bikes. Stock they have a nikisil cylinder ( no Sleve) , Your eyes are bad. One of them screws is a dowl pin and the other is a screw. They ensure the float bowl goes on correct and do not effect anything related to the engine running. Stock Jetting is 320 main and 50 pilot.

Appreciate your post. The carb I had a 350 main/ 30 or 35 pilot when first tore into..

Use to have bags full of mostly mains, but lots of pilots and multiple carbs. Not anymore.

Thank you.

Andy

andymoto

C100_scottdavis2

Posts: 4533

Joined: 11/28/2007

Location: Carmichael, CA USA

11/12/2009 12:58 AM

project racer wrote: Take the cylinder and piston to a REAL shop and have them "miked". You will know precisely where you stand at that point, and be able to order the proper piston.

I went the feeler gauge route. I worked for a National rider for some 10 yrs and can't tell ya how many things were stolen and loaned never returned; so I did it that way.

Was hoping someone here might use Pro-X piston kits and I just wanted to know their sizing methods; like Yam use to stamp in blue A, B, etc. on the crown.

That is my main question; how Pro-X marks their stuff for sizing.

Thanks for your post. I appreciate everyones answers or suggestions.

Andy.

ThePipe

C100_115277520_1244048412

Posts: 1765

Joined: 8/2/2006

Location: Hell WI pop 1, WI USA

11/12/2009 6:38 AM

Get yourself a Bore Gauge / I got one in 1986 and use it all the time.
Those things come in handy.

PitRacer

C100_rm125avatar

Posts: 190

Joined: 4/1/2008

Location: Valley City, OH USA

11/13/2009 5:36 PM
Edited Date/Time: 11/13/2009 5:37 PM

I just talked to Eric Gorr today about my '92 RM125. Gonna start tearing it down in a few weeks and send him the topend to make it a 144.

I'm going to need to paint the frame, does anyone know the correct yellow?

Looking forward to getting this thing ready for next summer, would love to find a technosel seat as I want to emulate Donny Schmidt's works bike look if I can:

http://www.pitracer.com/ubbthreads/images/185273-schmidt125.jpg">

90rm125

C100_99449110_1260751227

Posts: 104

Joined: 7/15/2009

Location: Clarks Summit, PA USA

11/13/2009 7:13 PM

yea what is the correct yellow?

andymoto

C100_scottdavis2

Posts: 4533

Joined: 11/28/2007

Location: Carmichael, CA USA

11/13/2009 11:12 PM

I forgot Jan Houtermans didn't live that far; so I went and he measured the thing;

Man I'm lucky to have a stock spec'd nikasil cylinder in primo shape and a piston that needs no replacing(even though I'd like to); just don't have the $$$. Just needs a new ring for now and a hone thru it.

The one thing this bike has is JB Weld on the clutch basket cover itself. You had one Lee, but I'm late to that date on that one....saw one a month ago on E bay and started at $5 with a day a few hrs; forgot all about it....duhhh.

Didn't the '92 RMs has while rear fenders? I had a new '92 250 and it did with those blotch color stickers; think '92 stock bikes were only yr with while rear fender.

Wish could find just stock seat cover; whole seat almost $250 and think one outfit(forget which has it). I thought either stock or the Schmidt rep look both nice.

Guts has an off yellow with black sides on their replacement '92 RM covers.

I also wish to know the color question.....Lee knows.....Mr. Newmann prob too.

Andy Medin

Nutty C

C100

Posts: 464

Joined: 10/28/2009

Location: Waterdown, CAN

11/14/2009 11:29 AM
Edited Date/Time: 11/14/2009 11:30 AM

92 American bikes had white rear fender and rad plastic . The Canadian bikes were all yellow.
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