Now I don't like failures or giving, especially when I know there's an actual solution to the problem. As such it seriously annoyed me that I didn't find a way to have the old TM38-86s run nicely on my TR1. So I bought another set.
Additionally I bought (per carb):
- 2x M3x10
- 2x M4x16
- 4x M5x20
Plus a 40 degree throttle-cable bend and a 2in1 throttle cable 51-6506.
I started with unscrewing the splitter and then GENTLY clamping the cables in the vice using the splitter as a funnel to oil both sets of cables.
Then hooked up the cable and replaced all the hardware for stainless allen bolts with plenty of copperslip on the threads. Also a bit of grease goes a VERY long way on the paper gasket of the carb top and prevents it from sticking to the carb body and subsequently tearing apart.
The stock jetting of #22.5, #230, 1.5 turns on the airscrew is probably a good starting point, if you run huge velocity stacks or something like that, but for me a more modest #17.5, #185 and 2.0 turns stopped the smoke and yielded some rather respectable performance on the way home from the workshop. (Mind you my exhaust is far from stock...)
Out with the old VM38-9s ...
... and in with the fresh TM38-86.
The difference between 1.5 turns fluctuating between 11.0 and 11.6, because it wouldn't run cleanly.
And 2.5 turns out, running a stable 12.2 to 12.4:1 at idle.
On the way home I noticed that the idle had crept up considerably and now with some slight detonations on a very hot engine, probably around 2.0 turns out would be more the right ball-park for the setup.
But even with quite some room for improvements this is where we're at at the moment:
Addendum: Air-screw 2.0 turns out from a soft seat and idle set to roughly 1400rpm, when hot did the trick. Bike runs better than ever and I can't hear any detonation or notice any stumbling or hesitation in the rev-range. I also went ahead and sync'ed the carbs once more and shot a little video of it, especially for those, who keep telling me they can just "eyeball" it. (I can't - at least not to this degree.)
So the next step will be to find out how good or bad the fuel consumption is. 😏