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Rm Trans problem

  1. #1
    boom shackalaka catch2otwo's Avatar
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    Rm Trans problem


    I posted a problem with my 2000 Rm 125 earlier this summer. The problem is when my bike is totally at a stop in first gear with the clutch pulled in, i am having a problem taking off. On a regular bike you can slowly ease the clutch out to get going. Only way i can get it go to is to basically rev it up and dump the clutch.

    Bike runs and shifts fine once its moving. Never pops out of gear or anything.

    When i do this, i feel the bike catch a little bit then nothing over and over again. Its not so much a smooth engagement, but rather a real "mechanical" miss as if the chain is skipping off the sprocket then engaging again.

    Some suggested i check the clutches and fluid level. This past weekend i pulled the bike completely apart. Clutches and plates were checked. All calipered to well within spec of my manual. The basket looks new almost no grooves. Hub and all teeth are fine.

    Dealer suggested checking shift drum and shift fork for wear and maybe a bent fork or something. So we split the cases and drum looks new, all forks were calipered and checked out to spec called out in the manaul. None of the gears were damaged or even worn for that matter.

    Everything in that motor looked brand new. No metal anywhere, ring is stock and well within gap. Theres barely any carbon anywhere.

    I am pretty much stumped. any ideas before i put everything back together? im pretty sure ive looked at just about everything.

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  2. #2
    Lifer R1's Avatar
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    Re: Rm Trans problem

    I had this happen with a KD 80 i had years ago, turns out we overtightened the rear axle.........

    Stupid i know!

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  3. #3
    boom shackalaka catch2otwo's Avatar
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    Re: Rm Trans problem

    Quote Originally Posted by R1slowflyer View Post
    I had this happen with a KD 80 i had years ago, turns out we overtightened the rear axle.........

    Stupid i know!
    dont think thats its, axle is greased and the nut was torqued to spec. anyone else?

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  4. #4
    Lifer
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    Re: Rm Trans problem

    Is the bike stock, or did you buy a used race bike that someone ported?

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    For every action there is an equal but opposite reaction - and sometimes a scar...

  5. #5
    boom shackalaka catch2otwo's Avatar
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    Re: Rm Trans problem

    bike is bone stock with the exception of a pipe and silencer. Jets are still all stock, heat and jug have not been ported or polished. all internals are stock.

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  6. #6
    Lifer
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    Re: Rm Trans problem

    Just checking basics here...
    Are the chain and sprockets in good shape?
    Was the chain slack in the right range when this was happening (not excessively loose)?

    With the cases already split -
    Check the old bearings in the transmission, especially the ones on the ends of the main shafts, and the output shaft. You're replacing the main bearings, trans bearings and seals since you have it apart - right?
    Check for the gears sliding smoothly on the shafts.
    Make sure all the snap rings are in their grooves.
    Check the alignment on the clutch forks - both fingers should be parallel.
    Check the drive and driven gear on the clutch basket.
    Check the clutch engagement linkage for smooth operation (including the cable and lever).
    Measure the height of all the clutch springs.

    Hope this helps...

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    SSearchVT

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  7. #7
    boom shackalaka catch2otwo's Avatar
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    Re: Rm Trans problem

    [QUOTE=SSearchVT;448445]Just checking basics here...
    Are the chain and sprockets in good shape?
    Was the chain slack in the right range when this was happening (not excessively loose)?
    both Sprockets and chain were replaced and problem was still there, slack was set to spec

    With the cases already split -

    Check for the gears sliding smoothly on the shafts.
    Gears rotate fine with no binding when i spin them by hand. I also was spinning the shift drum to change gears and again no binding or harsh rotation

    Make sure all the snap rings are in their grooves.
    reassembled them myself

    Check the alignment on the clutch forks - both fingers should be parallel.
    When you say clutch forks, do you mean shift forks? and what do you mean that they should be parallel?

    Check the drive and driven gear on the clutch basket.
    Drive and driven gears on the basket are perfect no chips, no missing teeth, no real wear


    Measure the height of all the clutch springs.
    Measured height of springs with calipers and they were all within service spec provided by the manual

    this motor and trans is so simple i really cant find anything else to look at. its got to be something stupid

    Would weight of trans oil cause this? even though i dont think its even possible to get a "mechanical cluncking/catching" feeling due to weight of oil

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  8. #8
    Lifer
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    Re: Rm Trans problem

    yup - mis-typed with clutch forks - meant shift forks...
    By parallel - The two fingers should both be perpendicular to the through shaft (i.e. the fork shouldn't be twisted).
    Within reason the oil weight shouldn't bother it - the transmission will work mechanically the same with gear oil or 10W/40...

    Examine every gear and bearing for any type of damage before putting the motor back together. With it together, no plug, and on a stable workstand - put it in first gear and turn the motor through a bunch of cycles slowly by the counter shaft - both directions. If the piston goes up and down smoothly - the problem lies outside the mechanicals of the motor...

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    SSearchVT

    For every action there is an equal but opposite reaction - and sometimes a scar...

  9. #9
    boom shackalaka catch2otwo's Avatar
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    Re: Rm Trans problem

    Quote Originally Posted by SSearchVT View Post
    yup - mis-typed with clutch forks - meant shift forks...
    By parallel - The two fingers should both be perpendicular to the through shaft (i.e. the fork shouldn't be twisted).

    Examine every gear and bearing for any type of damage before putting the motor back together. With it together, no plug, and on a stable workstand - put it in first gear and turn the motor through a bunch of cycles slowly by the counter shaft - both directions. If the piston goes up and down smoothly - the problem lies outside the mechanicals of the motor...
    shift forks are perfect, measure the thickness and also the "flatness" to make sure they were not bent because thats what we suspected to be the problem.

    when i get gaskets ill put it back together and turn it on the stand. i suggested maybe it was an ignition problem on the BORN site..

    ME: "A wild thought, could it be an ignition thing? if ignition cuts out intermitently would it feel like that clunk? but then again the bike runs fine once you get going....."

    Response:
    "not having experienced the issue myself i can't really say if it might be an ignition issue.. but it is plausible.
    ignition misfire (hard miss) can feel like a slip/grab kind of condition
    i guess if the gearbox is that clean (i presume no metal fragments anywhere) then its most likely not in the box"

    any comments on it being maybe the ignition? not sure what it is but there were wires going into my air box attatched ot the black box. It was super greasy covered in an oily sludge. not really sure what it is or why its so dirty being in the air box.

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  10. #10
    Just Registered wylee's Avatar
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    Re: Rm Trans problem

    Do you use the clutch when shifting or only when taking off? I'd assume you're using the clutch constantly since it's an MXer but thought I'd ask anyway.

    Sounds like something binding/slipping when the clutch is slowly engaged...had that happen on my first street bike. When you "dump" the clutch, it's able to go by the binding point, but when released slowly it sticks.

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  11. #11
    boom shackalaka catch2otwo's Avatar
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    Re: Rm Trans problem

    Quote Originally Posted by wylee View Post
    Do you use the clutch when shifting or only when taking off? I'd assume you're using the clutch constantly since it's an MXer but thought I'd ask anyway.

    Sounds like something binding/slipping when the clutch is slowly engaged...had that happen on my first street bike. When you "dump" the clutch, it's able to go by the binding point, but when released slowly it sticks.

    depends on what kind of terrain im riding on. sometimes ill clutch, sometimes i wont.

    Are you suggesting i check the cable or something? if its not the cable is there anywhere else it might be "binding"?

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  12. #12
    Lifer
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    Re: Rm Trans problem

    Quote Originally Posted by catch2otwo View Post
    depends on what kind of terrain im riding on. sometimes ill clutch, sometimes i wont.

    Are you suggesting i check the cable or something? if its not the cable is there anywhere else it might be "binding"?
    Check out the cable, the lever, and the entire mechanism on the engine case/into the center of the clutch basket... You should be able to easily pull the clutch in with two fingers and have it snap right back out.

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    SSearchVT

    For every action there is an equal but opposite reaction - and sometimes a scar...

  13. #13
    boom shackalaka catch2otwo's Avatar
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    Re: Rm Trans problem

    Quote Originally Posted by SSearchVT View Post
    Check out the cable, the lever, and the entire mechanism on the engine case/into the center of the clutch basket... You should be able to easily pull the clutch in with two fingers and have it snap right back out.
    yep i can pull it in no problem and it snaps right back out no problems.

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  14. #14
    Lifer
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    Re: Rm Trans problem

    While you've got it apart - take a look at the reeds (cracked, frayed ends, etc), the intake boot, and the jets in the carb (A plugged pilot jet will drive you nuts). IMO - An ignition problem would show up in all the gears.

    When I was practicing, and racing - the air filters were changed a few times a day - with a grease seal between the airbox and filter. I'd clean the inside of the airbox about monthly and it was gross. The black box in the airbox is most likely covered with air filter oil (and crud).

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    SSearchVT

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  15. #15
    boom shackalaka catch2otwo's Avatar
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    Re: Rm Trans problem

    reeds are fine, no chips, cracks etc, carb was taken apart and cleaned already, air box and intake boots are all good with no cracks or leaks.

    i figured the ignition would happen in all gears as well, if it misses, it would miss all the time.

    good to know the crap in the air box is normal..


    i am stumped haha

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  16. #16
    Just Registered wylee's Avatar
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    Re: Rm Trans problem

    Quote Originally Posted by catch2otwo View Post
    depends on what kind of terrain im riding on. sometimes ill clutch, sometimes i wont.

    Are you suggesting i check the cable or something? if its not the cable is there anywhere else it might be "binding"?
    When I had the problem it was the release mechanism in the case. I'm not familiar with the RM's setup, but I would look very carefully at all the parts related to the clutch release.

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    Last edited by wylee; 01-08-08 at 11:23 PM.
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  17. #17
    boom shackalaka catch2otwo's Avatar
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    Re: Rm Trans problem

    Quote Originally Posted by wylee View Post
    When I had the problem is was the release mechanism in the case. I'm not familiar with the RM's setup, but I would look very carefully at all the parts related to the clutch release.
    ill look it up in the manual tonight. thanks

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  18. #18
    Soul Rider Paul_E_D's Avatar
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    Re: Rm Trans problem

    I'd replace the cable. I had one that had streched out, and it gave really notchy starts. I'd also pursue the ignition angle. No wires should go in the airbox, so I'd start by figuring that out. Then, I'd try a new coil, plug wire, plug cap (usually included with a new coil) and plug. These parts are prone to failure on 2 strokes. Lots of vibes.

    It also sounds like fouling. Hows the plug look after low rpm use? Is there lots of spooge at the tailpipe?

    One more thing: clutch steels can measure out OK, but still be warped. Check them for flatness by laying them on a thick piece of glass (coffee table?)

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    boom shackalaka catch2otwo's Avatar
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    Re: Rm Trans problem

    paul:

    ill throw a new cable on if all else fails, need to check one thing at a time.

    The wires that go into my airbox are attatched to a black box. doesnt look aftermarket or anything, but i havnt checked the manual to see what it is yet.

    flatness was checked on the disks as well

    ill be throwing a new plug and wires in there too. and yes theres a ton of splooge on the silencer, that was going to my next problem to fix. Since we are on this topic, the bike seems to fall flat on its face and bog when I gas it. then after a couple seconds it will spring alive. I know its a 2 stroke and has a "powerband" but there is def a problem. i was planning to fiddle with the adjustments on the side of the carb later on. I know its probably a carb issue but carb has been throughly cleaned.

    I hesitated to state this problem earlier since we didnt think the two were related but since most of the internal mechanicals seem ok, we think they might be associated.

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  20. #20
    Soul Rider Paul_E_D's Avatar
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    Re: Rm Trans problem

    Uh, yeah, that was important info. I think you're trouble shooting everything BUT the problem, which is simply jetting. Forget about evberything else, and re-pack the silencer, THEN get a few pilot jets in smaller sizes and go down one at a time. Also lower the needle one notch at a time, and set the air screw to 1.5 turns out. You could also go down on the main one size at a time, as it will also have a small effect on the lower circuit.

    You've been fouling the plug.

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  21. #21
    boom shackalaka catch2otwo's Avatar
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    Re: Rm Trans problem

    Alright Paul, you have officially proved im a moron. i tried not to complicate things by solving one problem at a time, but hey i learned how to split the cases haha.
    %0

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    Last edited by catch2otwo; 01-11-08 at 08:13 AM.
    Tuono

  22. #22
    Soul Rider Paul_E_D's Avatar
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    Re: Rm Trans problem

    OK, not a bad idea, BUT the method is to start with the easiest things one at a time, and work towards the more involved. Most 2 stroke issues are reeds/jetting/plug. Always start there. Next look for vacuum leaks, then inspect/clean power valves, followed by taking off the head to inspect piston burn patterns, only then do you go deeper into the cases.

    Plus, I haven't solved your problem, just pointed you to the highest probability fix.

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  23. #23
    boom shackalaka catch2otwo's Avatar
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    Re: Rm Trans problem

    well i know you havnt solved my problem, but we started to figure it was going to be something simple since everything mechanical inside looks great. we'll see, dealer should have my gasket set this weekend or early next week so i cant wait to get it back together. sick of seeing it in pieces in the living room + im loosing my seat on the couch to this lol


    one thing though, how would the wrong jet size give me these problems? also before i go buying jets, the bike has a pro circuit pipe and silencer on it. Do you still suggest going down in size or up? also when i go to trouble shoot this, do i change 1 jet, put it together and ride it, then do needle adj. , or do i do the jet and needle adj. at the same time?

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  24. #24
    Soul Rider Paul_E_D's Avatar
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    Re: Rm Trans problem

    Since you haven't blown up your bike yet, we can assume from your symptoms that things are too rich, especially at low rpms.

    Do one thing at a time.

    set the air screw 1.5 turns out to start. I'd go down one size with the pilot first, then ride. If you felt some improvement, then drop the needle one clip position and ride. Things still improving, go down one more pilot and ride.

    Pay attention to zero to half throttle response. spooge factor should diminish, and throttle response should get lots better making take-offs smooth and easy.

    if you go too lean on the pilot, the idle will hang up before settling down to normal. If you go too lean on the needle, it will feel totally gutless from half to 3/4 throttle

    You can even mark your throttle housing, and then mark the grip flange at 0, 1/4, 1/2, 3/4 and WOT so you can learn where the bike stumbles, and where it's running clean and strong.

    Once you have decent performance off the bottom, do a WOT run and a series of roll-ons from lower rpms to WOT. You can hold stedy throttle at each mark and note how the engine responds.

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    boom shackalaka catch2otwo's Avatar
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    Re: Rm Trans problem

    thanks paul, ill give that a shot once its back together. should be a good weekend.

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