Suzuki 2 Strokes

Hi all,

Here's a composite dyno graph showing the relative performance of the engines as they've developed (for anyone that's interested )



Cheers Geoff

Oh, we're interested all right!

Hi AlanH,

I hope you are bearing up in these weird times. The Seeley did go out on a Castle Combe track day a couple of months ago to do a frame check (all sorted) but other than that, zilch

The revised engine ran pretty well, although I think there might a couple of horses to come with some fine tweaking. Next up is a top end refresh on the first 38mm engine and hopefully some dyno time to see how it compares to the (ex 34mm now also using the 38mm) but it has not been dyno'ed with revised pipes.

All trivia to keep me occupied and stirring the brain cells lol

Cheers Geoff

The final dyno run showing both Power & Torque.

66 is a good number. All your hours of toil have certainly paid off.

Hi Paul,

Like always it's the people who have helped and provided services and skills who have done the real work

Lets hope 2021 lets us do some racing (got to find a rider first though)

Cheers Geoff

Nice work there Geoff.

Interesting curve shapes. With that original 34mm motor, the mismatch between components shows up with the twin peaks and that tells us there's more to come when the parts are better matched.

On the latest motor, the graph is way better and the flat top end is interesting. It should be possible to get a taller peak if you knew what was not optimized, but it may well hurt the width of the powerband. The torque curve shows up the 'bend" at around 6500 and no increase in torque after that which suggests that something is optimized for those revs and I'll speculate that it's transfer area but could also be crankcase volume/primary compression. It might just be a long intake tract though.

I wonder how 34mm carbs on the latest configuration would work. All our sims suggest that smaller carbs should lose very little but I suspect that's because the sims don't accurately reflect the inlet volume.

750s usually run the same sized (38mm) carbs and on a motor with a lift plate the intake volume is huge because the port is so tall, and I suspect that becomes more of an issue with small carbs and the sudden change in port area that would theoretically lead to turbulence and low flow velocity and poor filling. With big carbs matched to a large intake, the flow should be less turbulent but still low velocity and that may be what makes the difference.

I am porting a set of TR replica barrels now and the owner wants to use small carbs, so we will see how that works out in real life. I may have to lend him some bigger carbs for a back to back dyno run to see what happens.

Thanks for sharing

Hi tz,

Thanks for the reply. I'll have to study and digest it properly when I'm a bit more awake

The guys at DynoTech retain all previous runs on their archive. Here's a juxtaposition of the two engines performance as they've developed. Still more to come (I know someone who's T500 race engine produces 70 RWHP and 50 lbs/ft torque, and all before 8k rpm). However with increased bhp comes the requirement to be more diligent with the maintenance (more frequent component changes) etc. What I have now will be a really strong engine in it's CRMC 500 Air Cooled class and should also be reliable and consistent in it's performance. It will hopefully last a 6-7 meeting season (if we have one in 2021).

Cheers Geoff

Hi Geoff,

I was just rereading this (great thread!) and wanted to know what you're using for cylinder heads on your bike. I've started building a stock frame based bike for track days and I'd like to optimize things if I get a chance. This bike will have reasonable porting, pipes, 34 mm carbs (possibly bored to 35), electronic ignition possibly incorporating a Zeel. It's great to see these old bikes on the track.

Hi Frank,

Both my race engines sport centre plug/squish heads supplied by Pete Odell of The Motorcycle Works, Peterborough, UK (Google it). I know he has recently had another batch made so should be able to help you out. He can also supply a set of straight cut primaries and a high 1st gear.

Good luck with the build.

Cheers Geoff

Thanks

Well, the 2023 season approaches and we have a re-vamped look in that we have an RG500 Mk1 fairing. Looks pretty good in the raw gel coat black, but it will be getting a silver base coat + graphics.

Fantastic looking bike and tech info. Great work

Pete

Fantastic looking bike and tech info. Great work

Pete

badgereng wrote: ↑Tue Dec 20, 2022 3:26 pm Fantastic looking bike and tech info. Great work

Pete

Thanks Pete

Cheers Geoff