Inside the GasGas Pro Cases - Fixing Noise-Vibration

Discussion in 'Trials' started by motobene, Aug 29, 2013.

  1. laser17

    laser17 Been here awhile

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    Everytime I see a pro engine on the bench, Im amazed by the minimal size of the thing.
    #61
  2. laser17

    laser17 Been here awhile

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    Wasn't the old bearing (one side) fairly loose? Seems odd the new ones would be extra tight. Were both sides real tight? Is the difference in the bearings? (hard to measure now I guess...) The few Ive done (or helped with) went in pretty easy after heating the case and freezing the bearings. I'd assume the OD of the bearing to be fairly tight tolerance - but maybe that's a bad assumption.
    #62
  3. motobene

    motobene Motoing for 44 years

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    I was wrong about the one being looser than the other. Up a bit in this thread I posted how I measured the bearings more carefully and found the lateral play to be about the same with the old and new bearings. You really can't accurately feel the difference with the seals in because the mongo clamp on the inner race.

    The hope is the main bearings were bad from the wear and grit wear I found under the microscope. I've been trying to contact the previous owner about why he went into the engine a time or two. It might explain the evidence of grit damage in the bearings.

    The vibration issue on this bike won't close out until I test ride it with the rebuild with the shiny new main bearings. Coming soon.
    #63
  4. motobene

    motobene Motoing for 44 years

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    An additional discovery regarding the similarity and difference between GasGas models. I found the kick start shaft to be about a centimeter longer on the later model Raga and wider round-tube frame. I assume this is to clear the wider frame/sub frame during kicks. I noticed this when my wood engine stand which I made for the 2010 Econo's TXT engine (2008 elliptical tube frame), had the Raga motor standing a bit high off the block I put in to keep the kick start mechanism from slipping out.

    The eliptical-tube Pros were narrower and more compact between the legs. Not by a lot. There was a transition around 2008-2009 with the first round-tube frames that had the more straight-sided sub frame. Not sure if that one used the longer kick start shaft or not.
    #64
  5. motobene

    motobene Motoing for 44 years

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    Just noticed this. As you know, in mechanics a good rule is to never assume a problem's cause is something bigger. Often it's just something littler. Like the call, "Help! My bike won't start!" Then you ask if the fuel cock is on :puke1

    Problem solved, the guy drove back happy I bet.
    #65
  6. lineaway

    lineaway Long timer

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    They real problem was the new tire. The Shinko brand tire has a very round profile, instead of a flat contact area. The outside knobs stick out quite a bit and rubbed the spring. For those wondering about this tire, the roundness (Like most street tires) actually gives you less contact patch with the ground . The tire would be a good cheap alternate besides this flaw.
    #66
  7. motobene

    motobene Motoing for 44 years

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    That's -1 for the Shinko.
    #67
  8. motobene

    motobene Motoing for 44 years

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    This is the latest update on this project. I now know the history of my 'new' 2011 Raga after discussing it with the previous owner today. As I suspected, my Raga had been gotten into twice before I took possession, from marks I could see. Not sure if I've gotten the story entirely straight, but it's something like this:

    The previous owner was incautious regarding slap kick starting the bike. He also ran the high-compression head resulting in high forces on the kick start pawl. Being very anal about changing the tranny fluid at one point he noticed some metal chips coming out during an oil change. Resulting was two disassembly efforts, one without changing main bearings and the second changing main bearings.

    These efforts were initiated by sharp uptick in noise and finding metal bits had passed through the kick start idler gear and primary gears. Some gears and many bearings were replaced, some of which were for 'just in case.'

    During the second entry when the main bearings were replaced, ne noticed that unlike main bearings of pre-2010 I think, the fit between the main bearings outer races and cases is now tighter despite the assembly trick of freezing the bearings and heating the cases. My experience and that of the previous owner and Stu is the press is a bit too hard now.

    Now I and two others are speculating that some time after 2009 GasGas changed the supplier for the main bearings and these newer main bearings are different in some details than previous ones.

    Anyway, the previous owner states his rebuild did the trick and the bike ran well thereafter. some hard hours later I got into it chasing the solution to vibration, as in more vibration than my aluminum-cases TXT 2009 motor.

    There have been some odd noises from a few 2013 Replicas in the UK and US. That noise is different than my Raga's uptick in vibration compared to my 2009-motor TXT. Mine was not a come-and-go rattling noise when the engine revs down. The cause of that rattling is being chased. Though it has been reported by a reputable dealer to not make the engine less reliable, it is irritating. Working on it.
    #68
  9. motobene

    motobene Motoing for 44 years

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    Update. the frame is now red and assembly of frame stickers then all the subassemblies I worked on over the last few weeks will commence today!

    [​IMG]
    #69
  10. laser17

    laser17 Been here awhile

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    Looks good Chris. I'm a fan of the red myself. Did you get it powder coated? How much does it run these days?

    I think GG should do a Jordi tribute bike with a chrome frame. $$$$
    #70
  11. Sting32

    Sting32 Trials Evangelist

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    Oh no! no longer looks "raga" or factory. But I have always liked red, like the 2008 raga and 2009-10 regulars... prettiest bikes they ever built.
    #71
  12. motobene

    motobene Motoing for 44 years

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    The reassembly has begun!

    [​IMG]

    Engine is in and the bits are going on.

    [​IMG]

    Stickers from GasGas are expensive but quality items that make a frame repaint job more classy:

    [​IMG]


    [​IMG]

    Of course during rebuild little poop pops up like the front brake guide snapped in half. So I repaired it with a PEX plumbing fitting:

    [​IMG]

    More to come!
    #72
  13. laser17

    laser17 Been here awhile

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    Sweet! The left side brake setup came out really nice. Your right about the stickers - really makes a difference. I especially like the high quality grease sneaking out of the upper triple clamp bearing :beer
    #73
  14. motobene

    motobene Motoing for 44 years

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    My greasing philosophy is this: A LOT!

    Every faster thread and electrical connection on the bike gets grease. Contrary to intuition, greased fastener don't tend to loosen more easily under vibration, and they never get stuck when you want them loosened. They are easier to torque so gorilla mechanics should back off on "if tight is good, way too tight must be better."

    Wheel bearings are packed full with no air space. Swing arm pivot... dog bone bearings, etc. also are packed full. Full packing means you can pressure wash and creek ride without water inclusion.

    Steering head bearings really gunked up, but I can't pack the stem full - too heavy. Lower steering head bearing is especially vulnerable to infrequent or no maintenance. I see GasGas saying in 2014 they will seal the lower bearing area better, as with Japanese bikes, with something other than a single O-ring.
    #74
  15. motobene

    motobene Motoing for 44 years

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    Ride Report! This will cover the vibration solution and other rebuild results. Overall I have now a VERY sweet ride, very smooth, plush, light, and super gutsy running. Very pleased!

    Recall much of this effort was to get into a newer bike and not lose what I had gained in the 2010 Econo's excellent setup and riding characteristics like smooth power, low vibration, and very precise handling with great lateral stability or 'plantedness.'

    HANDLING

    Finished the bike 1-1/2 hours before I had to leave for Peru, KS 2-day, then burned half an hour fiddling. Got to Peru and the rain-soaked Saturday and fiddled more. I had ridden the Econo the week before and found again its remarkable lateral stability. I felt that was somewhat lacking on the plusher Raga, but had trouble figuring out why. I had a clue weeks before during comparison rides when I moved the grips forward (rotated bars forward a bit) and oddly gained lateral precision. At Peru I hopped on Dale's 2013 Replica. Dale's a great mechanic and knows setup well. The bike was very nice... and very planted in a practice section. I came back and was commenting on the slight difference, his bike to mine in plantedness and he said, "Try moving the bars forward a bit more. That's a very important setting on these bikes."

    I did, and that made mine like his. Odd. Such a little adjustment. Bar rotation is very individual thing, so I won't make absolute statements about it, especially against all the other setup variables, but it's something to pay close attention to, at least to experiment with.

    I'll add a photo on that later so you can see where I ended up.

    VIBRATION

    The problem before, as documented by the video at the beginning of this thread, was more than typical vibration for a 300, enough so to make the fork springs buzz in the tubes. Thus started the process of testing assumptions, swapping parts with the 280, etc.

    Happy to report vibration is now normal for any 300 GasGas. I went through a process of elimination. Was it a piston mass difference between the 280 and 300? No. The Raga's 300 piston is lighter than the 280's piston, and when I put the 300 top end on the Econo it got even smoother.

    Was the crank or flywheel being unbalanced? No. The Raga's crank, flywheel, primary gears are in the Econo and it runs just the same. The Raga has all the Econo parts (they are the same parts) and work well.

    Was it the magnesium versus stiffer aluminum cases? Probably not. The 2013 Replica 300s and all the other GasGas models now all have aluminum cases. The magnesium cases are bye-bye. They vibrate the same as my magnesium-cased Raga, so that's not it.

    Bike mass. Yes, probably has some effect on making the Econo a bit smoother. The Econo is at least 11 pounds heavier so whatever engine vibration there is will be modified by more bike mass.

    The Kokusan ignition module's map. Can't confirm this is a factor or not. Dustin Land said it might be. The idea is the advance could affect engine pulses thus vibration. I have both and if I have time I'll check this out.

    Was it the main bearings? Yes, confirmed. I found some wear in the crank bearings from TDC in crank rotation to about 40 degrees ATDC. not much wear but apparently enough. The bearings were replaced with bearings from the same manufacturer and possibly the same lot.

    Now I can ride!
    #75
  16. laser17

    laser17 Been here awhile

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    After all that work - Im glad to hear your noise went away. Damn bearings. Thanks for keeping us informed. I just changed the oil in my bike - even included a flush cycle as the old stuff was dirtier than I would have liked to see. Feeling better now.:1drink
    #76
  17. motobene

    motobene Motoing for 44 years

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    I've gone to changing oil after each event. It's so easy with my gear lube tip bottle, why not?

    Oil came out clean after the rebuild and 2-day event. There was the usual ferrous wipe-off fuzz on the two magnets.

    And I got a surprise at the Peru 2-day. It was maximum 80 degrees. I found the 'new' 300's clutch was just a tiny bit fast engaging during the event. Maybe KrAzy's adjacent 4RT passed some evil fast-engage cooties? This oil change I added 30% Rotela 15W40 to the ATF+4 to increase viscosity and slow the clutch engagement a smidgeon.

    I think I know what happened. I had to dump the drug store mineral oil I used after the rebuild. I did not know it was thicker than clutch mineral oil. So I used some Redline suspension fluid called Like Water. Very thin, and I think that quickened the clutch engagement. More on that else where.
    #77
  18. neilking

    neilking Been here awhile

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    Refrigeration mineral oils come in different viscosities just in case you want to try them. 150 sus, 300 sus and 500 sus.
    #78
  19. neilking

    neilking Been here awhile

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  20. motobene

    motobene Motoing for 44 years

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    Fantastic! Thanks Neil. 150 SUS (Saybolt Universal Seconds) is about 30 something cSt (centistokes at 100 degrees C), and 300 SUS is about 65, and 500 SUS is about 110. Relating this back to SAE number is a hard because SAE numbers aren't really viscosity numbers.

    The 150 SUS is probably the stuff closest to what's used in clutches, and if you had some 300 SUS stuff you could proportion it to tweak clutch engagement speed behavior.
    #80