Drag Racing 1978 Suzuki TS185 Nostalgia Bike

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

 

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

 

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

 

Try getting a small blade screwdriver in one edge and squirt a little Inox in there and then work the small blade screwdriver around - the final step will be the push from the other side as suggested by @my67xr

 

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.

 

That's a shame. Now you can be! Especially with covid19, there are heaps of online learning courses...

2-strokes are a magical world of scientific wizardry.

 

Did you check the squish band and port timing? Spark timing? Varying the ratio of conrod length to stroke can alter the port timing, opening size and squish band. That can affect performance, too.

 

Is it off a 2-stroke cruise liner?