The scrambler-ization of an R80RT monolever.

Discussion in 'Airheads' started by CanadaBiker, Nov 23, 2014.

  1. CanadaBiker

    CanadaBiker Been here awhile

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    Hold your pitch forks, as I dutifully restored a '74 CB550 and a R100/7. Both were barn finds--the /7 especially so. Actually the barn that the /7 was stored in, horrifically burned to the ground two weeks after my recovery of said bike. The fire consumed the barn and all of its contents including a nice collection of BSAs. So the timing re: /7, in retrospect, felt preordained.

    In honesty, I restored the CB and the /7 because I was too chicken-shit to cut them up, but still, I hope I've paid my dues on advancing the cause for maintaining classic bikes for the future. (so this maybe gives me a pass on chopping up the RT?)

    I'd read that the monos had enough small, yet cumulative advances. I was looking forward to better shifting, cleaner electrics, and a smoother feel. I tracked down an RT that was stored away, and I visited with the owner over the next year to gauge his willingness to part with it. The bike was low miles, but had some issues. The owner, a great guy, was somewhat sentimental over the bike considering its past. But timing is everything, and literally the day he decided to sell it, I randomly stopped by. He had it in the driveway, carbs cleaned, running well, etc. That morning he awoke with the gut feeling that the bike could be sold, and just that day I was lazily running errands and decided to stop by. We shook on it, and he delivered to my house a few days later:s

    The sale included the original tool kit, tire repair kit (with German instructions) a rebuilt Valeo starter, and a box of oil filters, sparkplugs, and more.
    #1
  2. CanadaBiker

    CanadaBiker Been here awhile

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    I extensively toured the 550, and I knew I wanted another 'classic' bike for such trips. Like many others, I contemplated a new Triumph, and even a MGV7.

    On a 5k trip into Northern Quebec on my DR, I covered many hundreds of KM across rough logging roads, and some off-the-grid two track. The trip was incredible, and I pondered doing something like that on an older classic bike, setup somewhat scramblerized.

    The DR preformed flawlessly (KOW) and I love that bike, and really I should just leave things alone and run my DR when needed, but I can't shake the lust over something a bit more classic feeling.
    #2
  3. Jim K in PA

    Jim K in PA Long timer

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    :thumb

    I have a Lufty 2->1 exhaust I will probably be selling on, if you are interested (PM me). It is for a mono and I bought it thinking I could use it on a twin shock.

    Looking forward to watching the transformation. :D
    #3
  4. chollo9

    chollo9 Screwed the Pooch

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    Have at it (I hacked up an R90/6), but keep the DR, they're great.

    [​IMG]
    #4
  5. nmalozzi

    nmalozzi airheaded

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    DO IT and post lots of pics.
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  6. Houseoffubar

    Houseoffubar HoFmetalworks.com

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    BEAUTIFUL restorations! Can't wait to see your "cut up" bike :clap
    #6
  7. CanadaBiker

    CanadaBiker Been here awhile

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    Thanks for the support so far!

    Jim K, I may touch base regarding your exhaust.

    My overall plan for the bike is to remove everything I can, and especially shed weight when possible. I want the bike to be simple, functional, with some 'classic' looks. However, I also want the performance, when doable, to be 'better'. Especially, suspension, handling, and brakes. I hope this will rise above being an exercise in style, as I really want it to lean toward being a RTW scrambler.

    I first want to suss out any major mechanical issues before tearing it down. The F/D is leaking and needs to be addressed. I drained the oil: there wasn't enough of it, and it didn't look good.

    I know the bike only ran 10 miles or so on the low f/d oil, as its been sitting (and leaking for several years) so I hope that the gears / bearings are not knackered. I removed the f/d cover. There was no gasket, and some remnants of some silicone something. I cleaned it up, installed a gasket with a thin coat of sealant. I didn't know what to do with the brake cam tube. The fiche show no o-rings in this model. I put a thin coating of sealant on the tub and slide it in from the outside.

    I changed the rest of the fluids, cleaned up the front callipers, and set the valves.
    #7
  8. CanadaBiker

    CanadaBiker Been here awhile

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    The fairing, seat, and rear tail were not in as good of shape as the pics suggested. The bike had a previous tip-over of some sort and the bottom of the fairing was broken in several places and had been repaired--not very well. It also rattled and was not aligned symmetrically along the tank. I removed the fairing and headlight bracket, then used some aftermarket bucket ears and cheapo turn signals I had kicking around to keep it road worthy so that I could put some miles on the bike.

    I also temporarily moved the ignition to just above the airbox. I bodged it with some zip ties and electrical tape. Again, just so I could put some miles on the bike to see if there were any other major issues.

    It looks very trim already.
    #8
  9. motu

    motu Loose Pre Unit

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    I did exactly the same thing a few years ago, a classic bike that could do all things for me. Time to get off the XT600...

    [​IMG]

    And onto something that can do all roads. The bike can be converted back to stock, or any number of alternatives in 30 minutes. I have 2 sets of wheels, 2 rear seats/guards, 2 front guards, 2 screens/fairings, 2,3 or more exhausts and any number of handlebars, and 2 sets of panniers.

    [​IMG]

    [​IMG]

    I use Slideways bars, and the XR750 seat allows me to move around more, mainly forward for corners and back using the pillion pegs for higher speeds. Not really for off road, just gravel, but has been used on some not quite roads.
    #9
  10. gsd4me

    gsd4me 90% bluff Supporter

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    Which is probably all that BMW expected the production GS to do, anyway.




    .
    #10
  11. CanadaBiker

    CanadaBiker Been here awhile

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    Great bike Motu!

    I will have 2 sets of wheel as well. The original 18" pair, plus an 18" rear spoke, and a 19" front spoke. (changing the front end to a DR650 setup) What are you running for rubber on your 18" cast pair?

    I need to figure out what rubber to install. I don't think I want to use a 110/80 of the front, and would prefer a 100/90. I like the the Shinko 705 but the 19" only comes in 110/80. Looking at Mefo, but I might consider the old school Dunlop K70. I had them on previous bikes and they work great, but I told myself I would put 'real' dual sport tires on this bike. If the 705s or even the Shinko 700 had a nice 18 / 19 combo, I'd go with that. I'll guess keep looking, and I think I'm deciding to scratch the K70s off the list as I the type, since the 'rules' of the build need to lean toward performance over style.
    #11
  12. Jim K in PA

    Jim K in PA Long timer

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    I have the K70s on my '79, and they are surprisingly good in the gravel. My Scramdurally project will get knobs, possibly DOT Conti TKCs, or perhaps some non-DOT knobs. I am running my 18R/19F snowflakes. Just because.

    Keep the pics coming.
    #12
  13. CanadaBiker

    CanadaBiker Been here awhile

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    I really liked my K70s. They are better tires than they should be. They can track grooved concrete sometimes, but you just go with it. I will also have a 21" front option, so that would open up some possibilities. But I will be starting with a 19/18 combo. I won't be doing hardcore single track, and I will need to hit the highway to get to trails and back-water logging roads, so the 19" front will be nice for that, although I have zero issues running my DR650 on the highway with the 21.

    Does the the TKC come in a 100/90 - 19"?
    #13
  14. CanadaBiker

    CanadaBiker Been here awhile

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    While I have a long ways to go on the build, I’ve put a whack of miles on the bike and I now have a few initial thoughts on the (newly naked) R80 mono:

    The bike feels vastly different without the fairing. Handles quicker, lighter, and more nimble. What a difference.

    The bike starts super easy, ideas well, and runs great. The spot in the rpms where airheads seem to chug when lugged, is much narrower than my 100/7 was. That’s good news for me, as I enjoy lugging when I’m on back highways that go through small towns.

    Shifting is also much smoother, and I find that I don’t have to short shift into second as quickly, plus the shift lever pre-load trick isn’t really needed compared to my old /7. The engine has less vibes overall as well.

    The dual front brakes work very well, almost too well. They can be grabby and have less lever feel than I would prefer. It has the 14mm mc, which I think is the one for duals? But overall they feel a bit on or off. I cleaned up the pads, and callipers, and everything seems to be moving well. I would install new pads, but I have a different front end in mind, so it’s somewhat moot to dig into the from end too much.

    Now for the rear suspension: The shaft jacking on this bike is much more pronounced than my old twin shock bike. It feels like the damn shock is connected to my tail bone. And the overall throttle action as it turns the rear wheel feels almost like an FI bike. I don’t love it.

    I have a few theories as to why the shaft jacking is much ‘worse’ on this bike, but everyone please chime in your thoughts:

    1) The rear shock could be knackered. An old timer I spoke with, said that when the jacking seems to be bad, it’s time for a new rear shock. It seems to be bad regardless of the preload setting.

    2) The shock is connected directly to the main frame vs. having the energy pass through two shocks, mounts, and a bolted on subframe. Maybe the energy gets somewhat eaten up by the flex of the subframe on the twin shock bikes, so the shaft jacking could feel worse on the mono lever?

    3) 37/11 f/d. Maybe the low gears of this drive exacerbate the speed and forcefulness of the upward push? On the highway when I’m getting hot in slower twistys and such, I can really feel that low end grunt of the 37/11 and with it comes the shaftjacking. Maybe a 32/10 would not ‘wind’ up so fast and would feel like it reduces the jacking. I know it doesn’t change the physics, just the intensity?

    The 37/11 might have made sense to propel a heavy RT with a smaller engine, but now that the bike is being stripped, it might feel too low. I know many guys love the 37/11 on their GS's when doing off-off-road stuff. I will be doing much more highway, and unimproved gravel vs crazy single track. Maybe I’ll consider hunting down a 32/10 mono lever drive?
    #14
  15. Jim K in PA

    Jim K in PA Long timer

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    Rebound damping on the shock is probably nil. Increasing spring pre-load will only increase the jacking effect. Rebuild or replace the shock and it should make a substantial difference.
    #15
  16. motu

    motu Loose Pre Unit

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    I have 2 sets of cast wheels, on one I run street rubber, on the other I use tyres for gravel roads. Currently on K180's, 120/90x18 front and rear. Race compound and very sticky on seal, wet or dry, wear out fast. I have used K70's previously, 4.00x18 front and rear, and hard to beleive, but they are far better on gravel than the K180's, they just hook up and drive, there is a lot more wheelspin and sideways action with the K180's....I don't mind that, but if you want to go fast, you need to hook up. Having done a small amount of dirttrack, on a local clay car track, I like my bike set up like my dirttracker, this works well in gravel, the fat front tyre is really planted, and on seal I can really push the front like on the dirttrack.
    #16
  17. CanadaBiker

    CanadaBiker Been here awhile

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    Yeah I was exaggerating the feeling (I'm bad for that:). I was just surprised at the force of the jacking through the rear end as I whacked the throttle. If we were in person I could make suitable vroom vroom sounds while twisting my right wrist to illustrate the experience. I think that's a universal language for "something not right". :lol3

    Sounds like both you and Henry lean toward a knackered shock. Any ideas on a replacement. I've found lots of options for the GS, but it's a shorter shock than the Mono. Bob's has a nice OEM style repro, but I'd love to find one with lots of adjustment.

    I think I might also look around for a 32/10 mono fd.
    #17
  18. CanadaBiker

    CanadaBiker Been here awhile

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    I might have to put the K70s back on the list. I like that they have a nice 3.25 / 4.00 combo. I think they also make a 3.5 19" as well.

    I've been looking at the Mefo. They have lots of size options, front and rear, including a 100/90 - 19. They get good reviews, but are not as cheap as say, Shinko.

    [​IMG]

    The Heidenau K60 might be an option as well.

    [​IMG]

    I'm kind of fixated on not using a front tire larger than a 100/90, but maybe I should reconsider.
    #18
  19. Jim K in PA

    Jim K in PA Long timer

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    I run the 3.5x19 on the front of my '79, which is probably equivalent to the 110. Fits fine with the stock brace pushed up to the max position the bolts will allow. It is actually too close to the fender for my taste, as even little rocks get semi-trapped between the tire and fender. I would go with the 3.25 if I were to do it again.

    Cheap is relative. The K70 is cheap, but the rear is wearing pretty fast on my '79 and will require replacement much sooner than the front. I think the Shinkos wear fast also from what I have read, but I have no personal experience with them.

    I keep hearing how sketchy the K60 Scout is on the front in the wet on tarmac. Otherwise it seems to perform well?

    10mm is not that much of a difference in cross section, but pay attention to actual overall height to make sure it will clear your fork brace and fender.

    What Henry says! Lots of choices for sources, thankfully. I went to Works Performance for the replacement shocks on my '79 at the suggestion of Chris Canterbury (Boxermetal). No regrets, and they were great to deal with. They will ask for the key dimensions and load/riding intent and put together a unit that will be appropriate for your use.

    Just be prepared to pay for the appropriate solution! :cry
    #19
  20. CanadaBiker

    CanadaBiker Been here awhile

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    Thanks again for the continued input from all.

    So... I got busy. Removing things is great fun. Almost therapeutic. It will make up for the times of stress when reassembling.
    #20