The rehabilitation of Sir Gustave Sabastian (‘Gus’)

Discussion in 'New Zealand' started by Box'a'bits, Aug 22, 2010.

  1. advNZer?

    advNZer? Long timer

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    :evil both events?
  2. Box'a'bits

    Box'a'bits In need of repair

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    Starting to make progress with Gus. I realised that the timing marks on the flywheel are different between early '78 (12/77 production date) & '91 flywheels. I actually knew this, but hadn't really thought about it when I put the heavy flywheel on. Consequently I've been running '78 timing. The later bikes ran with 'S' marks 6 degrees further towards TDC (about 12.5mm movement in marks). By using an existing mark above the 'S' mark, I get things about right for idle, but exactly on the 'F' dot on the flywheel at full advance. That may mean the advance unit has some wear on it, or it may mean I need to research further. Need to think on it.

    The jettings getting closer (mixture 1 & 3/4 out, needle jet 266, needle 3rd clip down), BUT I've still got that stumble on load at 100 Kms. What the..? :huh

    The 25mm increase in front travel seems good. I can hit speed humps at speed, & it takes it in its stride. It hasn't slowed steering too much. We'll see how things go, but at the moment we have a qualified success. :D.

    The fork seals are not leaking. Unqualified success!!!!. :wings For future reference Honda Part no 41490-MEN-A31. Includes one dust seal & one fork seal.

    Priced up new fork bushes. $95 for 2 sets of All Balls, $78 for one side of Yamaha OEM. Gone with the OEM to see if there is a significant difference (especially given the experience with the All Balls / Honda OEM seals). Eventually got the Yamaha Bushes. 5XE-23171-LO & 5XE-23125-LO. While on that topic, Prutser had this to say on bushes for the KTMs. Basically tapering the teflon on the bushes & also using feeler gauge material to bush out the bushes for a tighter sliding fit. On my forks this makes sense - I can feel movement if the seals aren't in, therefore this has to wear them out faster.

    Need to find a new place for the horn, now that the crash bars are gone. The horn had been shifted onto them after I relocated the oil cooler off the right crash bar.

    Yes, those events. GuzziTony has suggested a pre-event trip through the Karapoti as well. That is fairly weather dependent from my perspective. If its pissing down all week (or its been snowing, as the weather forecast suggests), well....dunno...probably

    Don't know about the Sunday Airhead event. We'll look at the detail Saturday.

    Padmei, you could fly up, & I'm sure we could help you out here. Otherwise I'll take lots of photos for you.
  3. advNZer?

    advNZer? Long timer

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    the event(s) i speak of were mentioned to me by MD??.Do you want to have a look at my bike re timing and jets?
  4. Box'a'bits

    Box'a'bits In need of repair

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    Yes

    Happy to help with timing. It's easy. Jetting - not so much...
  5. Padmei

    Padmei enamoured

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    You didn't do a timing chain writeup cos the girl took the camera for the day:cry
  6. Box'a'bits

    Box'a'bits In need of repair

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    Yes but I talked about it - almost the same thing isn't it? :lol3. Actually there are a few photos there
  7. Padmei

    Padmei enamoured

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    Ahhhh. I puched in timing chain not cam chain into the search box.
    Thanks for that - very informative as I was wondering about what to put on the end of the crankshaft & how to heat the bearing etc.
    I did mean the sprocket when I was asking about the matching marks.

    Well done sir!
  8. advNZer?

    advNZer? Long timer

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    no,i meant you can look at my bike for the purposes of getting yours right if you want
  9. Box'a'bits

    Box'a'bits In need of repair

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    Spent a bit of time working on the rear brakes. A while ago I posted over on the Olds Cool Forum, querying whether the Paralever rear brakes could be improved. Generally the Forums response was unhelpful, but Travelling Sam was able to put me in touch with Simon from ‘Sore Bums Across Asia’, who had modified the brake lever to achieve a better cable pull.

    The theory is that the lever in its stock configuration doesn’t have a straight pull on the cable. The eye is about 70 degree to the pivot, so some of the movement is upwards, rather than forward. The recommendation was to cut the eyelet off, turn it around, & re-weld to achieve a pull that is more at 90 degrees to the pivot.

    I’d seen a write up on this modification before, but had almost forgotten about it. The posts with the mod had lost their photos, so Simon’s email & pictures were very helpful

    The modification is not universally adored in the States. The gurus are of the opinion that brake components should not be welded. My view on this is more pragmatic. I don’t really have a useable rear brake as it stands. At least this mod gives me the capacity to enjoy some braking. I have spent 2 years relying on engine braking and front braking, which in the dirt can be exciting at times.

    I did the modification last night. Here’s a photo just before I buttoned everything back up.

    [​IMG]

    I also discovered that the rear brake light can be adjusted. That’s very helpful. The brake light had sometimes stuck on previously. Finally I’ve also adjusted the brake upwards a little, so that I can actuate it when I’m standing. I’m sure this will need some fine tuning.

    The Mod was a complete success. I can lock the rear brake now, which was impossible previously.

    Tuning Out The Stumble At 100kms:

    The exhaust valve on the right pot had become noisy. On checking the clearance was wider than it should be. Unfortunately I didn’t measure it. I’m now wondering if I should pull the head. I’ll watch it over the next few rides.

    Another suspect was the new fuel cap I put on pre the MMMM. I wondered if it was breathing properly. I replaced it with the chrome temp cap, to see if this would make a difference. Nup.

    I have a bunch of spare jets from the RS to try. Standard main jets are 150. I've gone up to 160 to see how it runs. No difference with the stumble, but the pops & bangs are reduced.

    Might try the fuel filters next.

    Fork Bushes:

    I am disappointed that TSS Red Baron has not been able to supply the Yamaha fork bushes in a timely fashion. These should have been here Thurs morning. I’m told that Yamaha NZ have supplied to Red Baron’s Akld headquarters, but that that RB are looking to bulk up the shipment prior to sending this on to Lower Hutt.

    Remind me again why I used these guys? :huh
  10. Eddieb

    Eddieb www.AdventureRidingNZ.co.nz

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    I used to have to adjust my brakelight every WOF as either it wouldn't go on or off

    I'm always surprised your experience with TSS is so different to mine.
  11. Box'a'bits

    Box'a'bits In need of repair

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    Spend the day trying to Gus to run properly. I have run through the following:
    • Pulled the ICU & redid the heat sink paste;
    • Pulled the bean can, & replaced this with a spare. I had thought maybe there was an issue in the advance unit. Re-timed;
    • Pulled the coil to check this. Redid the sparkplug lead connections;
    • Put on new fuel filters. The two on Gus were meant for a much smaller bike. The new ones are of a similar style but a little bigger;
    • Pulled the carb / head rubbers. I noted a difference between the left & right spark plug (right side richer, left side very lean. It appeared that the left side had pinched up under one of the clamps, & was (possibly) allowing an air leak. Actually I was certain when I saw this that this was the issue, & that this might resolve things. I borrowed a rubber off the RS. Nup. Didn’t fix it;
    • Pulled the carb to bits, checked all of the passages & cleaned if practical, reassembled with new carb diaphrams;
    • Tried a 160 main jet. Certainly made the plugs appear richer, & allowed the bike to run on more, but didn’t fix the stumble.
    The confusing thing has been the issues I experienced when I switched back to the standard exhaust. However I have come to the conclusion that this is a jetting issue. I am going to run a spread sheet & just work this thing through.

    Eventually I ran out of time to resolve things, & just buttoned things back up. I figured that as long as I could run up to 4k RPM & 100kms I was okay.

    Arrived late at the Airheads function (at 5.30), & not far ahead of the rain. There were a lot of Airheads there, but unfortunately I didn’t get to photograph them. Of the regulars here, saw Igormortis (on his R80RS), Boxer Odyssey, & Pampera (car).

    Anyway, the launch of these were ostensibly the reasons for the function. Pretty cool huh. :nod. Apologies for the crap photos. I was running out of daylight & it was just about to rain.

    [​IMG]

    [​IMG]
  12. Steve in NZ

    Steve in NZ scared/cheap

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  13. Box'a'bits

    Box'a'bits In need of repair

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  14. Padmei

    Padmei enamoured

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    WTF? Did you post a correct link there SteveNZ?

    Nutso.
    I hope you get the problem sorted. Diaphrams I take it are good? Slide working as it should?

    Got any more info on those bikes?
  15. Box'a'bits

    Box'a'bits In need of repair

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    Yup. Replaced the diaphrams today as well (had spares, couldnt see anything wrong, but thought that that would definitely rule that out). Slides do what they should.
    Not a lot. The Bopper is made out of an R80 mono. The tank is from a Keyway cruiser. The battery is under the gearbox. I'm guessing Boxer Odyssey did the casting for the airbox cover. The ISDT is pretty much all BMW parts. Damien from Cycleworks did both bikes exhausts
  16. advNZer?

    advNZer? Long timer

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    there is a wee bit of fire wood there!
  17. innathyzit

    innathyzit AKA Woodman

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    Thinking out loud here, but reading that one of the exhaust valves had excess clearance made me think that maybe you are looking at a cam lobe issue. Have you checked that the valve lift is correct on that valve? Symptom could be that the cylinder is not scavenging enough at 4000rpm-ish but ok under that?

    Do both exhaust valves share the same lobe on airheads? If so then ignore my theory.

    Good luck
  18. Padmei

    Padmei enamoured

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    Which ISDT is that one based on?
  19. msmckeon

    msmckeon Just ahead of the sweeps

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    As you can see Wellington is the "airhead" (as in 2 valve BMW flat twin motorcycle - not limited brain power) capital of New Zealand, not Nelson. Time to visit the centre of the action?

    Actually, flew back from work in Brisbane on Thursday and got a good look down into a cloudless Golden Bay and all the places I rode by BMW a year (nearly exactly) ago. Belay that, time for us to head South...............

    Michael
  20. Padmei

    Padmei enamoured

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    Well yes I can agree that airheadedness is strong in Wellywood.
    I had cautiously suggested to my wife that I go up at labour weekend to catch up with you guys & support Voltaire in the pits at the Barry Sheene classic event however did you know that hampton Downs is actually just out of Auckland & not Wellington?

    When I get Schmidt running I will definitely book a ferry & have a wander over there.

    How far is it to that Highway to nowhere place with the pub that sounds like whangananamoanga? I hear that is a cool ride. How long should I expect to be away if I visit it?

    ps. having an extremely productive weekend in the workshop. These really shitty weekends have some good points.