The Air Cooled Monoshock Thread

Discussion in 'Trials' started by Brewtus, Feb 19, 2018.

  1. Norman Foley

    Norman Foley Devotee of the Husqvarna Supporter

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    Almost put this in vids, but decided it's ACM material!
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  2. Huzband

    Huzband Team Dirt

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    I rode a couple of trials back in the day where one section was nothing but a turn then a hill climb. Funny thing, they were always set in the wet season. :hmmmmm
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  3. Norman Foley

    Norman Foley Devotee of the Husqvarna Supporter

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    Before the rain....
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  4. Slow Joe

    Slow Joe Yep, that's me

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    I have a couple of questions on my recently acquired Beta Alp 240(TR34). I realize compared to most 2 stroke off road bikes that trials bikes have a lot of flywheel weight. But I still expected the throttle response to be more crisp than it is. a quick crack of throttle is a very smooth increase in revs, no wheel spin no lift of front wheel. There is no bogging just slow increase in rpms. Also slow to return to idle speed. Not a hanging high idle but a slow decrease in engine speed.

    If it were a regular 2 stroke off road bike I might possibly suspect leaky crank seals.

    Thank you,
    Joe
  5. lineaway

    lineaway Long timer

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    Throttle response on a trials bike is taken from a stop. It is measured how quick from stopped or almost stopped in first through third gear. When I got my `89 TR34 I was amazed how quick it was, in trials bikes terms. If you are moving and gas it, it is not going to hit a powerband. You have to compare it to another trials bike.
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  6. Junglejeff1

    Junglejeff1 Long timer

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    Try a richer pilot jet.What carb is on that bike?.
  7. Slow Joe

    Slow Joe Yep, that's me

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    Still has original Dellorto carb. I think I just need to ride it a little bit more. It has been on static display in climate controlled show room for about 15 years. Shows 1152 kilometers on odo.

    Thank you for everyones help.
    Joe
  8. tomatoe333

    tomatoe333 Long timer

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    Should be a Dellorto PHBH26 on that bike. The engine doesn't rev quickly, due to the large flywheel, but it should rev smoothly right off of idle. If you need to take off quickly, you have to learn how to use the clutch along with the throttle to control the power.

    With my SuperTrial, it ran best when I adjusted the air screw to be slightly rich at idle - not enough to cause it to bog down, but a little bit on the rich side of fastest idle.

    Also, that particular DellOrto will clog its pilot jet if you look at it funny. It's not hard to clean, just annoying. I got into the habit of running the carb dry of fuel before putting the bike away.
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  9. Slow Joe

    Slow Joe Yep, that's me

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    The acceleration and deceleration are smooth and linear. Yes Dellorto PHBH26. The more I ride it the more I like it.

    Thank you,
    Joe
  10. Norman Foley

    Norman Foley Devotee of the Husqvarna Supporter

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    I might go partners with Mike Komer on a Beta TR34, that he just took in trade. Both of us would like to ride maybe one air cooled series trial a year, and this would be a good bike for that.
  11. Brewtus

    Brewtus Buffoonery, Inc.

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    Now just what the heck am I getting from Scooters West?? I don't do Vespas! :lol3

    20200113_120734~2.jpg

    Huh. Looks like a Motoplat Dinosaurio flywheel for an Air Cooled Mono Montesa....

    20200113_121027.jpg

    So what gives? Glad you asked! :wink:

    Christmas Eve, I was having yet another bout of insomnia, Lt. Joe marathon on the tube, and I was trolling the interwebs bored out of my mind at 1:30 am. I was looking for Cota 25C fuel tanks and 304 ignition/stator bits. Somewhere I ran across a post (Trials Central I think) about how some of the '80's Motoplat flywheel would lose magnetism over the years, and if one could locate the correct shop they can be recharged.

    You don't say.

    So that started another search, who does such work, or could I rig something up? Lots of homemade Rube Goldberg-type contraptions came up, and another random pic with a professional-looking rig had the caption that it could charge dead flywheels. Huh. Who are these fine folks, and please tell me that they are in the U.S.!

    Scooters West, in Southern California. :D

    The Monday following Christmas I called, they said no problem (the ID of the flywheel would play nice with their machine), and it got shipped out the following day. It showed up in todays mail, I reinstalled the ignition system that had been removed a year and a half ago to be sent to a Motoplat expert in Detroit (that is only open in the warmer months and is always swamped). A quickie kick revealed spark!! Another quickie carb clean, some fresh fuel and.....

    20200113_133835.jpg

    Now where the heck did I stash the box containing the shock, side cover, and shifter...:scratch

    More to come! :thumb
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  12. lineaway

    lineaway Long timer

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    So did this bike break while near the Roswell crash site? :rofl The Aliens stole your magnetism.
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  13. Norman Foley

    Norman Foley Devotee of the Husqvarna Supporter

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    :photog
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  14. Brewtus

    Brewtus Buffoonery, Inc.

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    Or it was shaky QC from the tumultuous '80's Spanish industry, and too many birthdays. The Scooters West website showed a (I'm assuming a Vespa) flywheel on end supporting a 19mm wrench with the magnets. I tried that with the Dinosaurio, and it would barely support an 8mm wrench. Since I had Lt. Joe on the tube when I ran across the information -

    [​IMG]

    it was a shot in the dark, but I never could find any real reason stator/points/condenser wise why it had little to no spark. It cost a whopping 47 bucks (plus shipping), and yes the flywheel will now support a 19mm wrench. :D I knew it was good the first time I kicked it, and it kicked back a bit. It NEVER did that since I've owned it. Time to do some actual tuning on it, put the front brake system back on it (I stole it for the Rat 315 over a year ago), and actually compete on it.

    Somewhere. :lol3
  15. lineaway

    lineaway Long timer

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    Got it! A good quality19mm test wrench. That`s awesome. :lol3
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  16. Norman Foley

    Norman Foley Devotee of the Husqvarna Supporter

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    If the bike never runs again, you have a cool wrench holder!:beer
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  17. Brewtus

    Brewtus Buffoonery, Inc.

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    I have (several) big red wrench holders. I wanted a running 304. Now I have one. :D The tech I spoke with at Scooters West said that some of the magnets were almost dead, and the others were just weak. Now all are "Gaussed up" and ready to go...... :lol3
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  18. PSchrauber

    PSchrauber Long timer

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    Good to here the bike is running again and the rotor is fixed too.

    You still might switch the carb, ...
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  19. tomatoe333

    tomatoe333 Long timer

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    Bring it up to CATRA for the NYACT event there. You can test your mettle against Kurt Spoonogle and Chris Arnold.
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  20. Brewtus

    Brewtus Buffoonery, Inc.

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    Planning on it. I've never been a fan of Amal carbs. :nah