RZ/RD 350 & Misc. 2-Stroke Tech BBS

On the RD350 tach and speedo that resting position is a few mm behind the pin.
Something between 2 and 5 mm should be in the ballpark.

It can be calibrated later with your smartphone and a GPS speedo app.
For the rpm calibration you could get a cheap tach from Alibaba and hook that up.

That gap will easily weld up.
Don't worry and get the torch out.

Slightly bend the needle over the resting pin. Then mark the equilibrium position.
This is where you put the needle back on after repairs/resto.

I guess that's a problem of all old fashioned "Forums" where I'm active.
It's an old man's thing that has moved on to FB groups.
Younger folk prefers other platforms like Tiktok , Instagram , ...

I'd throw in using Koso RX1 / 2 units as they come close to what you're after: https://www.caferacerwebshop.com/de/rx2nr-snelheidsmeter-toerenteller-en-schakel-alarm.html They come with a manual and you can get several additional sensors like CHT https://www.caferacerwebshop.com/de/10mm-cilinderkop-...

Here's an example on how you determine the optimal open/close rpm. Simulate or dyno with PV closed, then with PV open. Usually you'd pick the point where performance starts to drop with PV closed and have it fully open a few 100 rpm before top performance. Voila, that's your transition rpms to start...

FYI: If you have such a device, try curve 14 (6000-8550) for stock'ish engines. That's been confirmed by quite a lot people to be the best compromise. For higher revving engines (modified+pipes) , something like 6k - 9-9 5 k was more appropriate. If you want to do this on your own, here's the how-to...

I'd have them laser cut from foam plate with the right thickness. Check out for maker projects around your place. In our town they'd offer such services here: https://makerspace-bs.de/lasercutter/ As an alternative there's always professional laser cutting services like these guys: https://www.cutwo...

Thanks mate, glad you like it :-) I wouldn't call that racing, it's only track days with like-minded people. In some cases even two-stroke meetings. Unfortunately age is already striking. In the last years I lost some seconds on my favorite Kart track If you haven't already found it, check out some ...

The dip at 8.5k could be cured a bit by more ignition advance in that range.
And fiddling a bit with the PV fully open rpm. Try 9 - 9.25 k.

It turned out to be a super fun ride. Especially indoors during winter time. I do track days on a monthly base then. For outdoors I upgraded the engine to a 4 valve 155cc Daytona but it's still kinda small breasted. https://i.postimg.cc/9FPRt5D5/IMG-6210.jpg https://i.postimg.cc/rsNVWTQf/IMG-2827.jpg

I've been busy with other important things in live, so the 2016 version would be still available, if it weren't for my printing shop closing down a month ago. Honestly I was too lazy to source another one, yet. The 500 manual is available for download here: https://www.rd350lc.de/downloads/MK-Dokume...

I went the easiest path and simple had the head machined some 0.5-1 mm bigger than the bore size.
That saved dowel pins but still avoided piston to head collision.

- Enlange exhaust port down -2mm to match piston top at BDC (very small gains, might not be worth it) - Keep transfer ports as they are (I cant find any good gains modifying them) I once ran engmod sims that showed around 1.5-2 HP gains when matching the lower transfer port edges to the new piston ...

Try something like 16-18 deg @ 9000 and fully open PV @ 8k