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    SuperTrapp resto
    #1
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    Always wanted to mess around with one of these and never had the opportunity until I spotted one on e-bay a couple weeks ago. Listed as having been on an early '80s RM250, its a standard universal fit style. Looked to be a good match for my 250. Didn't look too bad in the picture, so i figured for $50 bucks it was worth a shot.

    Unfortunately, taking the "before" pics with no SD card in the camera isn't conducive to creating usable eye-candy.

    Anyway, it arrived and first off, the bike had been laid down at one point. damage wasn't real bad, but the discs have taken a couple hours of tlc with hammer and dolly to get back in shape where the edges were flattened.

    Next up was core inspection. that however turned out to be a real battle as the core's slide-over internal pipe was pretty well rusted to the inlet pipe. tried knocking it apart using a wood rod, but that just started pulling the disc/tail cover bolts out of the core.

    Slice and dice ended up being the only option. With the shell off, muffler clamped a piece of tubing into the inlet and PB soaked, heated and hammered the hell out of it to break it apart. 4 sessions of that and it finally gave in.

    Some pics of it after clean-up and the packing showing just how rusted up it was inside.















    I've also taken the worst disc, cut the center a little larger in diameter and ground down the OD so that it fits inside the tailpiece of the core. going to weld stainless washers and nuts to that to create a stronger nut plate for core removal purposes. Still have to pick up some new packing, nuts and washers. when finished, the disc bolts will get a second locking nut once i have the stack height dialed in.
    Last edited by Xbird; 01-20-2014 at 02:51 PM.
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    Re: SuperTrapp resto
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    Just about got it wrapped up.

    After taking it apart, there were only 2 of the press-in nuts left in the core's end, so I knocked those out. The notches let it clear the core retainer nuts. drops right around the core and nests against the end plate. Just gotta remember to stick it in BEFORE wrapping the core! (2X)



    Took an afternoon of phone work to find the 1 shop that had some packing -- most places had no clue what i was asking about. Most of the quad/cycle shops around here did not survive the recession. First attempt (shown) was too fat, trimmed it down. decided to use a full wrap of heat-rated duct tape as a rust barrier.



    Old setup I had rigid mounted to the frame, both the pipe and muffler. Too much heat and vibration transfer, so i went with the universal auto type hangers. nothing pretty, but it works.





    First test drive, four discs and as lean as I expected it would be.



    Just ran it again with nine discs and she's too rich. going to go with 6--followed by double nutting the stack, welding the hangar and bar-b-que black spray bomb. Final tuning will be with the carb jetting.
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    Re: SuperTrapp resto
    #3
    Intense Moderator Rat4020's Avatar
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    How many HP is your motor . A rule of thumb for tuning a super trap is 1 disk per 7 HP
    Last edited by Rat4020; 01-20-2014 at 03:22 PM.
    The question is not if its gona roll. Its when ..

    That be some kind of church cruzzer or commuter bike thingy ?
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    Re: SuperTrapp resto
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    Have no clue as to HP, not much, probably about 15-20 max. That's one spec that I could not find, even with inside help from suzuki. Given the carb, intake and exhaust changes I've made, this is pretty much shooting in the dark for a baseline that i've been doing with the carb and exhaust.

    Quick vid, idle, unloaded rev and maxxing out 3rd gear ( 9-disc rich session).

    STTEST - YouTube
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    Re: SuperTrapp resto
    #5
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    Had to head back to the drawing board with the disc stack nut-n-screw situation. ... Twice

    Don't know if it was stainless to stainless (nuts n screws) galling together when they got hot or fiberglass getting into the threads, but I ended up with seized/stripped hardware when i went to change discs. Royal PITA to remove and retap two of the screws and nuts. They'd loosen about 1 turn, then lock up and strip.

    To figure out what was causing it, i decided to "enclose" the nut and protruding screw in a sealed tube to keep any glass fibers out of the threads.



    Repacked the core, sealed the end of the tubes with aluminum duct tape and went for a test ride.

    Went to make a change and all 6 screws/nuts were locked up. As far as torque goes, I'm not going magilla gorilla on them, supertrapp calls for about 15 inch pounds, doing it by hand with an allen key and making sure i don't crush the discs.

    So after another screw snapping teardown I finally got the big light bulb lit and reversed the setup. Welded the screws into another modified disc so that the nuts tighten outside the muffler. Also makes the repack a lot easier since the screw no longer extends up into the packing. Used ones long enough to provide extra room for disc tuning. Spacers are inner chain link pins (50 series) that the chain rollers ride on. This time, the nuts are plain steel to also take the question of stainless-stainless galling out of it. Originally, the nutserts in the core were plain steel and the screws stainless.

    So if you ever have to restore/repair one of these, and don't want to pony up the $$$s for a new core, I think this final one is the way to go.





    Last edited by Xbird; 03-01-2014 at 07:20 AM.
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