ESE's works engine tuner

[bucketracer]

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Some handy hints on making cables:- http://www.dansmc.com/solder_cable.htm

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[bucketracer]

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It might be a 12A Rotary exhaust port but there is some interesting ideas about testing and port radiusing applicable to 2-stroke exhaust port shaping. A simple flow bench could be made from a vacuum cleaner and home made manometer like TeeZee used for testing his carburetors. http://www.yawpower.com/Flow%20Testing.html

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[TZ350]

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Next years project.

A RGV250 cylinder fitted to a GP100 crankcase, now do we air cool it or sleeve it back and devcon up the transfers to get the correct port/time/area for a water cooled 100cc with a big carb?

Thomas is also toying with a supercharged 99cc 4-stroke.

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[F5 Dave]

The cleanest best way to power will be as a 100.

The two things working against you is an extra heat inducing sleeve & the positions of the ports as they progress inward if you think about it.

& a 5 speed gearbox. oh dear.

Maybe a 125 would be a better route. But will the RGV produce a wide enough torque curve for the aforementioned 5 speed gearbox esp as compression etc will need to be lower with aircooling?

Only thing is not many cases will take such a large barrel. Your GP still requires quite some welding fabricating to put in studs to hold that down securely, obviously just sitting it there is not even 1/2 the job as I'm sure you're aware.

An RGV250 bottom end would be too big. . . . Maybe. RGV150 bottom end might be ok but the SS150 racers will have scooped up most of them.

[Buckets4Me]

Only thing is not many cases will take such a large barrel. Your GP still requires quite some welding fabricating to put in studs to hold that down securely, obviously just sitting it there is not even 1/2 the job as I'm sure you're aware.

dam you I was thinking that my next hotrod engine was nearly finished
and you go and spoil it like that

dont burst my bubble

I was also wondering what those guys where doing with rotary engines ????
and what cc can they be to run in a bucket ??

[TZ350]

Only thing is not many cases will take such a large barrel. Your GP still requires quite some welding fabricating to put in studs to hold that down securely, obviously just sitting it there is not even 1/2 the job as I'm sure you're aware.

On our setup the barrel requires a 10mm spacer, I have found that I can bolt it down using three of the original GP stud holes and only need to add a fourth. The barrel itself will be held down by studs screwed into the spacer plate.

Marking the plate out was a bit tricky but Thomas managed to get all the holes in the right places. The next trick is to cut a hole for the cylinder spigot and transfer cutouts. The spacer plate is being made out of steel for strength and will be surface ground to thickness to set the final piston/deck height.

Like you say Dave there are pro's and con's between the 100/125 configurations and we are still debating which way to go, thank you for your ideas, it all helps.

As is, I have heard that the RGV cylinder is short on blow down time/area, but this could be a handy thing. Because the transfer ports are so wide their roofs could be devconed down thereby increasing the blow down time/area and still have plenty of transfer port/time/area for making a more tractable engine that runs "phater" at lower revs.

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[F5 Dave]

Spacer plate is a great idea, but you would need to lose some of that height from somewhere, obviously a longer rod would help & it is possible that the RGV barrel matches to a taller bottom end, in which case very lucky.

[TZ350]

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RGV rod is 5mm longer than a GP one and the RGV case crank and piston crown heights are a little different too. The total difference is a little less than 10mm hence the final adjustment of the spacer plate to get an accurate piston/deck height.

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[TZ350]

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I know a carb's size is measured across the throat next to the slide because that is usually the narrowest point of the carbs venture. But.........

Dave is a 32mm carb with a 24mm venture inserted into the rear away from the slide still a 32mm carb or is it a sleeved down big carb that meets the 24mm carb rule for F4 125 2-strokes.????

I see in the posts about the GreyMouth races the fast F4 2-stroke was referred to as having a sleeved down big carb, clever idea as it moves the point of maximum air velocity away from the point of maximum disruption around the slide. And I think bulk air flow could be improved that way.

Its an idea I would like to try myself if its legal, any one know?????

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[bucketracer]

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Using a venture instead of a throttle plate in the carburetor to controle engine speed...........

Venture throttle:- http://www.prvperformance.com/PRV_in...l_overview.pdf

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[speedpro]

venturi, lok it up

[bucketracer]

venturi, lok it up

Using a venture...................venturi

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[Chambers]

Rule 24-2-4 F4 2 stroke engines over 104cc are restricted to carburation equivalent to a single 24mm carburator. Can this mean a big carb with a 24mm restriction??????? Does anyone know, I to would be interested.

[speedpro]

"I" would think that any carb would be OK as long as at some point within it the cross-sectional area was equivalent to a single 24mm diameter orifice.

[speedpro]

I have some bits for an RGV250 here somewhere including alloy rings to fill the space between the standard head gasket and a 100cc bore.