ESE's works engine tuner

[Muhr]

I need help with this. I know that wind across the bell mouth causes issues. Does this windshield look Ok or does it look like it might be causing me problems? What would a good windshield look like?

Advice from anyone who has experience with a rotary valve carburetor running around naked out in the breeze would be very welcome.

Thinks that a low pressure area can potentially build up behind the shield which in the worst case can start to fluctuate. Based on that, an opening in the direction of travel is a more stable environment.

[wobbly]

Having an extended length of carb bell mouth hugely affects the intake tuned wave response. You are way better to have a simple airbox with a forward facing intake that has the enclosures flat face no less than 20mm
from the carb bell end. This you can model in EngMod easily.
I have tested the effects on Hines World Champ winning 250 Superkart , when the engine was on the right and thus the carbs all but touched the seats flat side .
And at 20mm away it has no effect on the carbs fuel standoff and thus power , at full noise.

[Muhr]

Having an extended length of carb bell mouth hugely affects the intake tuned wave response. You are way better to have a simple airbox with a forward facing intake that has the enclosures flat face no less than 20mm
from the carb bell end. This you can model in EngMod easily.
I have tested the effects on Hines World Champ winning 250 Superkart , when the engine was on the right and thus the carbs all but touched the seats flat side .
And at 20mm away it has no effect on the carbs fuel standoff and thus power , at full noise.

Could not help but not include such an option!

[F5 Dave]

Has to have some benefit if you put it in the kitty litter too. Bolted to sidecover holes could have crash resistance plus the inlet out of the dirt. .

[pete376403]

The carb shield on Harry Klemms 350 Bighorn (R/V) racebike

[wobbly]

In EngMod you can vary the volume and the intake tube length/intrusion/size to explore Helmholtz effects.

[TZ350]

After a lot of dyno time and a days abuse at Hampton Downs the piston looks remarkably good. None of the deto damage or seizure marks that I was expecting.



At 80% bore width, the exhaust port looks Ok too.



A fly in the ointment looks to be that the ring ends are gouging the cylinder as the exhaust port top edge pushes them back into the grove.

What I need is a single ring piston with the ring gap at 6 o clock. The piston I am using now has two rings with the gaps at 5 and 7 o clock.



When I got the rotary valve going I just plugged the carb inlet rubber and transferred the original cylinder complete over from the piston port case reed engine.

Now in the interests of science I am going to remove the reed block and block up the inlet tract and inlet port with epoxy. It will be interesting to see what the extra case volume does.

[TZ350]

20:1 compression ratio and supercharged, what could go wrong? nothing apparently. https://youtu.be/lyDOWiSprtE

[DoldGuy]

After a lot of dyno time and a days abuse at Hampton Downs the piston looks remarkably good. None of the deto damage or seizure marks that I was expecting.



At 80% bore width, the exhaust port looks Ok too.



A fly in the ointment looks to be that the ring ends are gouging the cylinder as the exhaust port top edge pushes them back into the grove.

What I need is a single ring piston with the ring gap at 6 o clock. The piston I am using now has two rings with the gaps at 5 and 7 o clock.



When I got the rotary valve going I just plugged the carb inlet rubber and transferred the original cylinder complete over from the piston port case reed engine.

Now in the interests of science I am going to remove the reed block and block up the inlet tract and inlet port with epoxy. It will be interesting to see what the extra case volume does.

TZ, from the pictures posted, how is the Intake Side / C Port being feed? I’m sure to be missing something as it appears to only use the A/B transfers.

[Condyn]

Tz, I am in the same boat as you. I use a 75% chordal exhaust port, and only have trauma on the rear wall at ring end gap at timing edge height. Oddly, I have found that switching to the cheaper cast version piston which also uses an L-ring, has almost entirely eliminated this issue.

[F5 Dave]

TZ, from the pictures posted, how is the Intake Side / C Port being feed? I’m sure to be missing something as it appears to only use the A/B transfers.

Have a look at an 80s RM or PE engine, it will become clear.

[DoldGuy]

Have a look at an 80s RM or PE engine, it will become clear.

F5, I’ve had the early RM’s & PE’s and fairly familiar with the Piston Port / Case Reed design, but I thought he was running a Rotary with Carb mounted at the Disc, is it a dual carb setup?

[andreas]

80% exhaust width, it will come at a cost. I had it working with a L-ring ( if this, or ring material helped, not known). Just changing the ring gap location , I don't think will do much, furthermore it will present a big risk of ring/cylinder havoc, as the C port divider, I think, is too small to support the gap.
The induction system on these suzukis I'm convinced is very good, the only drawback being that wonky C-port feed from the B-ducts. So if the rotary thing is permanent, then it would be a good idea to give it a proper C-duct.

[F5 Dave]

F5, I’ve had the early RM’s & PE’s and fairly familiar with the Piston Port / Case Reed design, but I thought he was running a Rotary with Carb mounted at the Disc, is it a dual carb setup?

Reread the very post you quoted for TZ350.

[DoldGuy]

The induction system on these suzukis I'm convinced is very good, the only drawback being that wonky C-port feed from the B-ducts. So if the rotary thing is permanent, then it would be a good idea to give it a proper C-duct.

Thanks for clarifying as this answered my question.