Improving the 2005+ Montesa 4RT

Discussion in 'Trials' started by motobene, Oct 27, 2013.

  1. motobene

    motobene Motoing for 44 years

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    Wow. I'm increasingly surprised at how many places this basic clutch design is used. One could assume more recent would be better, and that the new part number -KA3-710 should subsume the older ones if you tried to order the others?

    Too bad all those Mitani options are hard to come by in North America, and they sound interesting.

    If it were my dollar, I'd go Sureflex and avoid Honda clutch plates. Honda has a longstanding reputation for too-quick clutches. Sureflex has a lot off trials history.

    As for dimpled or not, who knows what that really does? We assume trapped oil, but who has been small enough to ride around in a dimple and watch what happens?

    On the flats between all those dimples, the plates could have a wide variety of surface conditions and that may be more important than dimples. I've found clutches will be a little less grabby after sanding all the metal and fiber plates by hand with 80-grit emery paper in random directions. It's been my way in the past to put a little bit of new feeling back into a clutch and to get plates to stop sticking together after storage time.

    My 300 Raga clutch (from my Econo 280) has gotten a bit faster with use. I'm thinking of disassembling it to scratch everything up, as soon as I can find the 8mm 12-point socket to fit the goofy little screws GasGas decided to use on their clutches.

    Oh and I noticed when looking at both GasGas clutches assembled that one of the fiber plates seemed to have a slightly different color. I wonder if they do a multi-material thing as well?
    #81
  2. Thats_a_Five

    Thats_a_Five Adventurer

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    Great stuff guys! I can't wait to get back stateside so I can apply some of these improvements to my '05 4RT.

    Have you done anything to reduce the throttle braking? I know, "learn better throttle control" and I am trying.
    #82
  3. motobene

    motobene Motoing for 44 years

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    One way is to raise the idle. In the old days when the clutch was used little, the idle on bike was sometime very low so you could brake by shutting off the throttle. Like high ground clearance, that technique is now out of favor because it causes other problems, like stalling.

    I run the idle fairly high on my GasGas such that when cold the engine won't die easily with clutch in creeping around slowly. When the engine warms the idle will be somewhat high, but that reduces stalling tendency.

    On a 4RT the idle is naturally quite high to run the FI without a battery. That reduces the throttle-closed engine braking effect.

    The latest model 4RT comes with claims of managing crank case pressure pulses to reduce engine braking, if I understand that right. Still a mystery as to HOW they'd do that. And I don't get it. If you pressuring the crank case on the down stroke, you get the energy back on the upstroke. Aha! Maybe they seal the crank case better so they don't lose energy in both directions through leakage?
    #83
  4. motobene

    motobene Motoing for 44 years

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    It's been quiet on this thread. I'm wondering if any of you other than our test case:

    - Did the 4-clutch-springs mod

    - Sped up the forks with Redline 2.5 extra light

    Some of you are waiting for deep winter to send me the shock for revalve.

    I'm asking because I want to know if the time I spend here is effective (resulting in change).

    Thanks.
    #84
  5. laser17

    laser17 Been here awhile

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    Does anyone have any info on the new crankcase decomp on the latest 4rts? Im wondering what they did and haven't seen any specifics yet.
    #85
  6. lamotovita

    lamotovita Ageing Adventurer

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    I probably won't do either of those things on my 4RT, but I appreciate reading about it. I was already planning on experimenting with clutch springs on a different bike so your posts were encouraging in that case.
    The thing with 4RT mods is that you're working with a six+ year old bike. Those of us that have been riding them have already either modified the bike or adapted our riding to suit the bike to some extent. It's also a fair assumption that most of us that are competing on six+ year old bikes are not top level or even very serious competitors. I'm always interested in hearing about others experience and solutions though.
    You never did address my question about flywheel weight in post #36. I was hoping your background would enable you to provide some insight on that issue.
    #86
  7. Thats_a_Five

    Thats_a_Five Adventurer

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    Motobene,

    I have not made any mods yet.... I fully intend to.

    I really appreciate the detailed descriptions of what you did and how it worked. I just got my 4RT this summer and love the bike. Especially the rear suspension. WOW. I will post my reaction once I make some mods.

    Thanks again for all you knowledge and sharing of this info.
    #87
  8. jonnyc21

    jonnyc21 Trials Ninja

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    For what it's worth I have committed to having my rear shock reworked by motobene (unexpected expense so will be early to mid December). And am looking forward to seeing how much it changes the bike.

    I am considering doing the springs when the shock is out for service but not 100% on that as the ELF I have left seems to make it work fine for me. However I will be running some different oil for testing for sure as I don't have as much ELF as I would need for the life of the bike...

    Might be a few befor I have a ride report on the changes but I will do my best to give a report worthy of the level of bene's efforts once I have the bike updated and know a bit more about the other oil in comparison to the ELF.
    #88
  9. motobene

    motobene Motoing for 44 years

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    Thanks for the report back, guys. I've been spending significant hours on this forum because I like it, but it may not be the wisest use of my time, especially if my work is having little apparent effect and isn't profitable beyond recreation time for the brain.

    At a recent board meeting and continuing education, I came across Daniel Pink's Flip Manifesto. It's one of those management books in pre-book form with a list of neat concepts that run contrary to many assumptions. One neat bit is the concept of to-don't and to-stop lists. Everybody thinks in terms of the to-do lists, but enhancing personal success requires avoiding some things and stopping doing some things. These can be as simple as, "Don't go to bed after 11 pm."

    I have been wondering lately about the wisdom of sinking some of my precious morning hours into this forum, which is why I asked.

    BTW, look at this for a bit of Daniel Pink's work:

    https://www.youtube.com/watch?v=u6XAPnuFjJc
    #89
  10. jonnyc21

    jonnyc21 Trials Ninja

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    Thanks for sharing that Motobene... The video was intresting, now I am going to have to take some time and look more at Dan Pink's information. :norton
    #90
  11. motobene

    motobene Motoing for 44 years

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    I like guys like that. Good change often creeps in from the fringes!
    #91
  12. jonnyc21

    jonnyc21 Trials Ninja

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    It took a few to get everything together but... I ordered up some Red Line, shipped my rear shock yesterday, and pulled the front out to drain them. So motobene will be re-valving soon. :clap

    Once I get it back and have a chance to ride it I will give a ride report. Should have it back in the bike in about 3 to 3 1/2 weeks. I am sure it will take some adjustment on my part before I am use to the change in the settings but should have some good ride info between weeks 4 and 5 for everyone. :deal

    Next on the list... the clutch... I am thinking I should leave it tell the suspension is done so I don't have to many changes at once and can report on each change by them self.

    Clutch:
    Round 1 take out 2 of the 6 springs then hen ride with my current ELF oil to see the change.
    Round 2 will be a change to some "MAXIMA MTL Extra Light Transmission Fluid"
    Round 3 set to what I liked best (unless I can think of something else before then)

    lets see where this takes me. (FYI: I am all ears for other changes :ear I may or may not try things depending but still open to hear them all)
    #92
  13. motobene

    motobene Motoing for 44 years

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    Assuming nothing goes pfft (like a shipping foible), I should have the shock back to you and revalved inside of the 10th.

    I suggested last night to johnnyc21 to not change tranny oil yet, but try the -2 clutch springs with the ELF oil. It's a simple procedure:

    Lay bike on side opposite the clutch. Remove the cover. Remove the screws progressively to back off on spring pressure. Set aside the steel plate the slave cylinder pushes on and remove two clutch springs on opposite sides. Replace the plate, putting all six clutch screws back in progressively. Refit cover and enjoy a clutch you can forget about even after you get tired in a tough trial.

    The 4RT we have here has been running four springs a long time and the owner continues to state adamantly he'll never go back to six spring. I rode the bike a while Saturday, doing some 4th gear WFO clutch dumps to launch over a gap and rock after slamming a kicker. Still no slipping when the lever is released fully.

    One more thing. The shock johnnyc is sending me is off an `07. That'll provide a direct view of the valve stack specs on the `07. I doubt HRC changed it from `05 because his suspension is described as slow responding like the `05. But better to assume nothing until proven.
    #93
  14. Thats_a_Five

    Thats_a_Five Adventurer

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    I finally got to start making some of the mods listed in this thread. First thing - turned front rebound to minimum. Didn't notice a big difference so thorough cleaning and lighter oil are on the list.

    I took 2 of the springs out of the clutch and rode the bike today while setting up an event for next weekend. Wow, huge improvement! It is now possible for me to slip the clutch in a (semi) controlled fashion. Now, I need to learn how to use that technique.

    Thanks Motobene. Or should I say "multo-bene."
    #94
  15. motobene

    motobene Motoing for 44 years

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    Cool. You got the Italian word play ('motorcycle good' from 'very good').
    And you are welcome!

    A great help to learning clutch slipping better is to not have a hyper-active clutch intruding on the learning process. Optimization is getting machine quirks out of your way so you can do the most with what you have. At zero cost (except a few minutes of labor), the 4-springs mod is perhaps the most cost and effective mod you can do to a 4RT. And there's no substitute for objective peer review, so I really appreciate you reporting back on your results. "Huge improvement" and nothing blew up... hmmm.

    Modern, faster action out of the older model 4RT forks with adjusters working in a useful range requires a re valve or significantly lower fork oil viscosity. The Redline 2.5 and Redline Like Water are great tools to avoid the cost and work of developing a re valve.

    I believe I recommended earlier in this thread to use some or all 2.5 in the spring (compression side) to slow things a bit for hot weather. Given I am a busy fellow like most of you, I prefer all-seasons settings over seasonal fiddling, especially not having to change fork oils for seasons. The Like Water will span all seasons with just clicks of adjusters, but half or all 2.5 in the one side may be a tad more optimal when it's 95 degrees outside.

    There is weight, and perception of weight. The 4RT is a heavier bike, and with the older suspension specs the older models also impart more perception of weight. The suspension's ability to respond to rider input better from the fork oils mod will really improve the perception of weight issue, but you need to mod the rear to get at 60% of the improvement. I should receive another shock to mod any day now.

    I assume the 2014 models have modernized suspension specs, because not changing that would be stupid beyond belief for Honda/Showa (and Olle 16V). The 4RT is substantially unchanged since its intro 9 years ago. It's still a heavier bike at 70kg dry (Cota) and 73kg dry ('Racing' model). The more affordable model gives you 3kg to come down to the 2014 FIM weight minimum if that matters to at all to the rest of us (it doesn't).

    Here is a link to titanium and carbon bits by an Italian company who will be happy to trade money for weight reduction:

    http://www.vitititaniowtc.com/en/mo...s/light-part-ddm-prodotti-per-moto-trial.html
    #95
  16. KrAzyOSUcOwBoY

    KrAzyOSUcOwBoY kRaZy

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    I have to chuckle at the resistance to the clutch springs removal. My experience is much improvement as well with NO slipping. I am tempted to remove 1 more for only 3 remaining and test the results. You can't know until you try. :wink:
    #96
  17. Thats_a_Five

    Thats_a_Five Adventurer

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    Part of my previous resistance came from reading the factory manual about getting to the clutch and it stared with "drain the coolant, remove the water pump, remove the kick lever, ......). Then I looked more closely at the bike and saw I could simply remove 5 or 6 bolts and the smaller cover over the clutch basket was removable. Whipped that bad boy off, took out two springs and slapped it back together. Simple and very effective change.

    You are correct MotoBene that I struggled in the past with learning because the clutch was too jerky (or maybe it was just me being jerky). Now it works so much smoother.

    I'll probably go to the Red-line "Like Water: in the forks because it just doesn't get to 95 degrees in Seattle.

    Ride on! Thanks again for all the work you guys did to uncover these improvements.
    #97
  18. jonnyc21

    jonnyc21 Trials Ninja

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    Getting excited, my shock is almost at motobene's! :evil

    As indicated before I will play with the bike for a week or two with the new suspension update. After I have a better feel for the bike the way it is I will update the clutch -2 springs and rid it like that using my ELF oil tell the next oil change. Final update will be to try the Maxima extra light to compare with the ELF.

    Report to fallow with each change. :freaky
    #98
  19. KrAzyOSUcOwBoY

    KrAzyOSUcOwBoY kRaZy

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    I tried a variety of light (no ELF) to very heavy gear box oils and have had the best luck with....dramatic pause....Silkolene 10w40 Off Road engine oil. I did have to wait for it to work into the plates for maximum effect, took a couple of hours.
    #99
  20. jonnyc21

    jonnyc21 Trials Ninja

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    Thanks I will add that one to the list as one to try. :D