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Drag Racing 1978 Suzuki TS185 Nostalgia Bike

Discussion in 'Motorcycle Racing and Track Days' started by Frankster, Mar 22, 2020.

  1. ruckusman

    ruckusman Well-Known Member Premium Member Dirty Wheel Club

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    Last time I visited @kiffsta we were chatting and he mentioned that he knew someone that spent a lot of time isolating vibrations from an RZ350 engine they'd put into another frame - he may be able to chime in here and advise what the solution was - beats re-inventing the wheel

    Actually wondering if some weight, a KG for instance mounted down near the lower front edge of the engine, onto the frame might change a potential resonance with the frame
     
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  2. Frankster

    Frankster See the World before you leave it Staff Member Premium Member Ride and Events Crew

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    Actually wondering if some weight, a KG for instance mounted down near the lower front edge of the engine, onto the frame might change a potential resonance with the frame

    Yes, I was thinking the same thing when I was discussing adding a square piece in that part of the frame. A bit like a stone guard welded into both frame rails. I'm guessing there must have been one on this frame at some stage, but only @Murdo can confirm that. There is a cross-brace there now, but again, not sure if that's standard or an "addon"

    Brace TS185.jpg Brace.jpg
     
  3. Frankster

    Frankster See the World before you leave it Staff Member Premium Member Ride and Events Crew

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    Last time I visited @kiffsta we were chatting and he mentioned that he knew someone that spent a lot of time isolating vibrations from an RZ350 engine they'd put into another frame - he may be able to chime in here and advise what the solution was - beats re-inventing the wheel

    Chris and I spoke about this too. He was the one who suggested rubberizing all the mounts.
     
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  4. ruckusman

    ruckusman Well-Known Member Premium Member Dirty Wheel Club

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    I'd definitely go that route then as I don't think there's enough ballast weight in that frame and bike to damp the vibrations from that engine
     
  5. Frankster

    Frankster See the World before you leave it Staff Member Premium Member Ride and Events Crew

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    Yep, I had planned to do this after testing the new tyres on the bike. Murdo used the DT250 engine to brace the two front frame rails by adding custom engine mounts, but I'm not sure that is enough. As I said somewhere else on this thread, adding extra bracing can't hurt and a bit more low down weight seems okay. We're only talking about 1kg at most and the extra bracing should help.
     
  6. ruckusman

    ruckusman Well-Known Member Premium Member Dirty Wheel Club

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    If you can get some of those little power walking hand weights, they're usually rubber coated and 1KG, strap one or two to really tight with cable ties and gaffer tape to those frame rails near the front to see if it makes a difference - then you might be able to get some really thick wall tube and tack weld it in place if that works - at the least, if there is a resonance it will lower it's frequency so it will smooth out as revs rise

    Or if you can get that brace/bash plate a lead slug in there and you know I got that idea from Burt Monro c/o The Worlds Fastest Indian
     
  7. Frankster

    Frankster See the World before you leave it Staff Member Premium Member Ride and Events Crew

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    Last edited: Mar 25, 2020 at 2:16 PM
  8. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    They should come out same way as removing a motorcycle wheel bearing , there's a spacer tube in between the left and right bush's
    Try putting some rod down through one bush and the spacer, as you get close to coming out through the other bush, push down on the rod and try to feel for the lip of the second bush.
    Tap the rod through and the bush should come out
     
  9. Murdo

    Murdo The Good Doctor Staff Member Premium Member Ride and Events Crew Contributing Member

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    Pretty sure the original bash plate would have bolted on, and would have only been a thin sheetmetal pressing. The crossbrace was my add in as the suzuki engine had mounts on either side and a long bolt through, using the engine case as the brace.
    Stick a long bolt through the rubber bushing and see just how much movement you can get. If the holes in the frame are worn (unknown to me) then maybe the vibes are just the engine moving around and could be stopped with some machined bushes in oversized holes.
    If your going to weld in some plate, make it at least 6mm thick, maybe thicker if you want weight there.
     
  10. ruckusman

    ruckusman Well-Known Member Premium Member Dirty Wheel Club

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  11. ShaneP

    ShaneP Well-Known Member

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    2 strokes are notorious for vibration, but it sounds like you need to balance the crank. There are 2 parts to this process. First is making sure the crank is aligned properly. They are a 3-piece crank, so the 2 shafts need to be aligned on the output and flywheel sides. Specifications are usually a bit generous, so try to get them closer, but be aware that the end of the flywheel shaft is not a good test point as it may no longer be true. Nor might the webs, so test a few points. The second factor is weight balance. There are 2 weight factors: crank with the big-end (rotational weight) and weight with the whole rod and piston (reciprocating weight that comes into effect at the top and bottom of the stroke). I don't have the specs on me and I won't be able to explain it as well as some others, so I won't confuse you by trying. But ask a good 2 stroke engine builder, or we could do it up here. Changing the piston may have altered the weight distribution.

    I missed a bit of the thread, did you get the running issue sorted? Again, changing pistons can be an issue as some have cut outs to match postings, which can disrupt flow when mismatched. I did see that you were onto the exhaust turning, which can also influence intake turning. Not sure what you are allowed as far as porting, either. Lots of fun stuff (I mean that positively) about 2 strokes.
     
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