ESE's works engine tuner

[kel]

Gigglebutton running 3rd on his F5 RG50 in F4 and going for the Doctor trying to beat all the FXR150's.

Great little vid. Giggles 50 just keeps getting quicker!

[TZ350]

On page 200 there is a simpler 23 rwhp setup using a RG250 chamber modified to RM125 specs.

And on this page, the basic details for 27rwhp from a 1978 Suzuki GP125 Engine and RS125 Expansion Chamber.



Not at all peaky, 3.500 rpm power spread.

Cylinder Deck Height (Squish) 0.8mm.
Exhaust 25.8mm from top of cylinder, and opens 80deg ATDC for 200deg Duration.
Transfers 40.8mm from top of cylinder, and open 116deg ATDC for 128deg Duration.
Inlet port opens 145 BTDC closes 80 ATDC and is 45deg wide and inlet port opened to 30mm equivelent dia with 24mm carb.
Std 1990 Honda RS125 Pipe. The pipe is 40mm and the exhaust port is 36mm, we leave it as is and don't match the Ex port to the pipe.



Opening the rear transfers and flatening the port roof to 5 deg. Main std at 12 deg. Boost std at 55 deg, but all opening together.



Primary transfer pretty much std., secondrys and boost as wide as possible, Exhaust 72% of bore diameter.



A view of the transfers, the copper is to take heat from the exhaust port area and distribute it to the extra copper under cylinder finning we use.



Dimensions of a Honda RS125 Pipe.



Suzuki GP125 engine and RS pipe in a Yamaha FZR 3LN 250 rolling chassis.

And for somethig different, Rick doing the classic deck inspection. http://www.flickr.com/photos/dty1/55...7626304686340/

[ac3_snow]

good thing (or not) that the video didn't last any longer I did a bit of track side gardening about two laps later

[wobbly]

The cylinder pic is a CPI Cheetah Dave, the reed blocks are CR250, the Cub has smaller standard Banshee type reed bolt pattern.
I have just got the worlds first 3 CPI Cheetah cylinders with 66mm bore to run 400cc in the new F3 Superlight class, dead cool with more
power than the 485 will be absolute missiles.

[F5 Dave]

Yeah, looked like a monoblock, but then I edited when I saw the 4 bolt hole reedblock & guessed they were cubs. (The pic I posted is from my 496).

I read in CMM that Stan Stevens was building a 610 & it was supposed to have bigger reedblocks (CR500) but the ones they supplied didn't even fit.

The 400 idea is cool, have you got many takers for engines?

[wobbly]

I am building one into the prototype RS250 Aprilia racebike I have, and am building another complete Aprilia bike for a guy in Wellington.
The other cylinder is for sale - as part of an engine kit, once I have done the R&D, on reeds,pipes,ignition, PV curve etc.

[F5 Dave]

kewl. should shake up F3 a bit, look forward to seeing it in action.


. . . not that I make it to many race meetings these days.

[wobbly]

Sorry - yes the original pic was a Cub, I thought you had reposted the same pic.

[TZ350]

The popped head gasket from last nights dyno runs. I have been experimenting with using a head gasket to thermaly isolate the head from the barrel. With the copper fin and head gasket the head runs about 50-60 deg C while the cylinder is 90-100 after a good session on the dyno.

[Gigglebutton]

Great little vid. Giggles 50 just keeps getting quicker!

Cheer's Kelly. I had forgotten how much fun it is. The racing is way faster now, so it,s taking a while to get up to speed. I am going to pull the motor down and try to get a bit more power out of it before the next meeting and play with handling a bit more. Here's hopping

[wobbly]

I would suggest a couple of easily implemented changes to the 27Hp GP125 setup.
Fill the outer wall of the main transfer duct, to about the same radius as the secondary.
This would about 1/2 the entry area.Fill the case to match this new outer wall angle.
Drop the cylinder 0.5mm.Lift the front transfer and the exhaust back to where they were.
Fill the main transfer roof with epoxy such that there is none at the port exit, but change the roof angle to around 25*.
This would mean you have epoxy on the roof to the end of the outer turn, then epoxy starting to fill the outer wall from the same point at the beginning of the outer turn.
This directs the main port flow up and over the secondary transfers - the slightly reduced area due to the increased angle is more than offset by the better scavenging flow pattern in the "loop".
I would run this setup, then cut the valve to 85* closing.

[TZ350]

Fill the outer wall of the main transfer duct, to about the same radius as the secondary.
This would about 1/2 the entry area.Fill the case to match this new outer wall angle.

Ok.......... this was the 30 rwhp engine until I machined the crank down for more clearance (and more power). I can easily implement the other suggestions and if the idea is to reduce entry area of the main transfers.

Then could I build up the inner wall of the mains instead and make the divider wide like the Aprila RSA.

This would be easier for me than taking the cases apart again and it would mean the other cylinders would still fit the cases.

[wobbly]

I did wonder about the effect of the crank machining on the CCR,its the old story,make a change to affect a particular element in the design and the follow on effects on other elements may have greater impact on the power produced.
But either way you fill the transfer ducts, this will raise the CCR, and the roof angle change ,along with the port stagger,will give much better scavenging efficiency.

[TZ350]

I did wonder about the effect of the crank machining on the CCR....

Yes, I still think the crank has potential. I will try modifying the transfers with a bit of Devcon and see what happens.

If the crank clearance has to be closed up again, I can modify the transfer entrys and glue the cases to suit the smaller flywheels and get even more CC compression.....

[bucketracer]

A quick calculation and machining the cranks looks like it may have added 50-55cc to the crankcase volume, losing 3 or more ponies seems a big effect for just 50 cc's.