52 Mk 11 the start

[jasonu]

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Its not that they didn't think of it, I think they were leaving the door open to other carb ideas other than the traditional motorcycle slide carb, so that some could use a kart carb or automotive or make or modify something for themselves.

Tell me how can you specify a measuring method that covers all carb possibilitys, other than the light or turd method......

That's easy, you measure it the SAME WAY as the manufacturer did.

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you could have a 24mm hole and tip the petrol in from a bucket

Yes you could (hillbilly)

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2003 is the oldest rule book I could find and it talks about "carburation equivalent", carburation not carburettor.

So it looks to me they were leaving it open for any kind of fuel/air control system including kart carbs, fuel injection, automotive or even home made or modified carbs.

"carburation equivalent" are the key words...........

You are correct

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The whole debate is over where it's measured. If a larger carb is modified so it now has a piece that has a cross-sectional area equivalent to a 24mm circle then it complies with the rules as written. The 24mm restrictor has to be part of the carb to meet the rules. There is nothing in the rules that says where the measurement is made, unlike karts. The idea of where the measurement was to be made may have been there but was not written in the rules.

That is my entire point. The rule needs to specify WHERE the measurement should be taken and IMO it should be the same place as where the manufacturer takes the measurement it in the venturi where the slide is. As for FI the same goes, where the manufacturer measures it. If you have a home made carb, it will be up to you to prove its legality.

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So that you could run two 17mm carbs if you felt so inclined? 452 mm2 split over both cylinders of a twin to give same area as a 24.

Yes you are correct.

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It was written to stop smart asses using two 24mm carbs. There was buckets round with 2 carbs at the time. I know of one that had a carb on the rotary valve and one on a crankcase reed on the same engine. If we had just said "24mm carb restriction" then you have to use a 24mm carb, but as many as you like.
The rule was a bit unfortunate for the 125 twins but the one I've seen ran just fine with some copper plumbing fittings and a single 24mm carb.

Pete Steadmans Rat motor. Didn't work though. The front faceing carb hole was blocked off when I bought it.

[F5 Dave]

Yeah just hit quote as you did & submit, then do it again on the other post, & copy what you see & hit the back button & edit into your old post & paste it in. etc.

First bucket I was offered (I'm glad I didn't buy) was a YB100 with a scooter barrel on & disc & piston port carbs.

Not really much point in having multiple carbs (beyond trying to slip a loophole restriction). Even if you had short inlet timing & huge amounts of area with two carbs you could replicate the same with one huoge carb. The suction would be reduced by the same amount so would behave as a too large carb would. You'd still need to have the longer inlet duration to get more air in as the engine suction would be constant.


the only exception I can see is if you had a separate carb feeding the boostport, or possibly supplementing the transfers with a direct reed arrangement & only flowing when the pipe is sucking. Actually thinking about it, on a disc valve arrangement this might be worth while, as a reed engine will continue to flow the boost after the reeds have stopped filling the crankcase. So if you had a disc valve 100 with marginally restrictive carb size & a reed trapdoor into the boost port with a small carb feeding it without disrupting the main flow you could benefit. Sounds like a KE/RG100.

cheques to the usual address.

[rwh]

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Yeah just hit quote as you did & submit, then do it again on the other post, & copy what you see & hit the back button & edit into your old post & paste it in. etc.

For quoting multiple posts? The Multi-Quote button (bottom right of each post) is what you want.

Just hit that on each post you want to quote, then hit reply to thread.

Richard

[Buckets4Me]

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I'm not sure what you are trying to say but I'm reading ?

[TZ350]

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Some of us can read brail and my reply is Dr no, no .........

[F5 Dave]

He has edited the other posts, you can delete them too.

Multiquote button! Hey I hadn't seen that

[Rick 52]

Thanks to the guys at ESE I have a better power curve now as well as 20 BHP ..This was by replacing the old standard TF Ignition with a CR 85 set up ..The fly wheel taper was wrong so I drilled the rivits out and bolted in the correct centre with correct taper ..
We increased the ex port timing by raising the ex port height by 1mm (more to go) and cutting 5mm of the rear of the piston skirt increased the inlet port timing ..After all the hard work I am looking forward to trying it out tomorrow but more looking forward to riding it at Tokoroa
as last year I couldn't enjoy the great track because the bike was so hard to ride with the small power band and overall lack of power !

[Rick 52]

Its miles better ! I didn't need to change down then back up through the infield and after going from a 230 to 240 then to a 250 main jet it felt even better..Even had a win for my troubles . Second race my throttle cable snapped of the start ,glad this was this weekend and not next ..
I made the cable and used Silphos to fit the nipple and I think this has made it brittle so will use soft solder next time..

[richban]

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Its miles better ! I didn't need to change down then back up through the infield and after going from a 230 to 240 then to a 250 main jet it felt even better..Even had a win for my troubles . Second race my throttle cable snapped of the start ,glad this was this weekend and not next ..
I made the cable and used Silphos to fit the nipple and I think this has made it brittle so will use soft solder next time..

Will be interesting to see the comparison from the last time we raced. I was surprised how fast it used to exit the corners back then for the power it had. I will have my camera again. Lets try not to crash on tape this time. I was trying to find a really close call from the GP but I have lost a heap of footage. Gutted. Will be good to catch up again.

[Rick 52]

Looking forward to catching up ! Yes no crashing on film this time lol!
I have a spare cam for Wills xl ( xr) should I bring it for your bro to have a peek at ?

[richban]

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Looking forward to catching up ! Yes no crashing on film this time lol!
I have a spare cam for Wills xl ( xr) should I bring it for your bro to have a peek at ?

Yeah good idea. Do you have a spare piston. The bigger the valve pockets the better the cam can will be. I had a quick look for a hi comp piston but didn't see anything.

[Rick 52]

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Yeah good idea. Do you have a spare piston. The bigger the valve pockets the better the cam can will be. I had a quick look for a hi comp piston but didn't see anything.

Just a standard old piston ...But could order a new standard piston !

[richban]

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Just a standard old piston ...But could order a new standard piston !

Ok. Bring standard old piston. Might be able to bodge some valve pockets into it. Would be good for a play.

[speedpro]

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Just a standard old piston ...But could order a new standard piston !

Old piston and run the bandsaw through the middle. Then you can look and see how much metal there is in the pockets. The same treatment of an old head is good for shedding light on where to go with the grinder.

[Henk]

I can drag a seriously abused 1mm over version of the same piston along if it will help.