Flatslides on Twinshocks

[sherpa]

Hi I hope these photos help clear up any confusion

[Joe Henderson]

I have an OKO flatslide on my Fantic.

If I grind off the OKO logo and identifying numbers, paint it black (You devil!) and smear silicon over all the adjustment screws ("Just to stop them backing out, you understand officer"), will this satisfy the 'Little grey men in brown coats, clutching the MOMS and muttering about changed components' who seem to be proliferating in our beautiful sport ( A little bit of a phrase-pinch from Brian Clough there)

I note that the reference in the MOMS to major components apears only under the Classic heading. (Pre-65 or 'Not a Spanish bike, but as new and as re- manufactured as I can get a way with and still paint it black and gold and call it British.) Or am I reading the MOMS wrong?

The new Air-Cooled Mono class seems to be blessedly light on restrictions, Thank god!! Post classic seems to be creeping towards ever more serious picking over the regs and finding things to question. A pity.

One of the main attractions to trials for me when I was scratching about in the early seventies in the Southern Centre, was that you could never know what Sammy Miller was going to turn up on, a prototype Bultaco/Honda/SWM/Beta/ Miller. All of them worth about a years wages and all wonderful. Nobody complained then.

I am in danger of repeating my thoughts in another thread, but I, as a pimply-faced sixteen year old youth, could have turned up on a 500 cc Hog Snort Horror that takes seventeen stone Cyril from the workshop half an hour to start, or a two thousand quid special with nitrogen filled frame and a Wal Phillips fuel injector, and I would have been welcomed with open arms.

Trials have never been about the bike - value, configuration, colour, weight etc..

All of us NSW Post Classic riders (about six at the last count) know that Toby Coleman can beat us soundly on one of Gristy's rigid rear end nails.

The rider is what matters. You try beating Mal Chapman, Frank Hull and Geoff King if you think otherwise. (I am not sure I ever have!)

Lets leave the eligibility questions to classic motocross and road racing. You know, the branches where money talks!

Yours in simplicity and a spirit of acceptance,

Joe Henderson.

[armstrong]

I agree with Joe the enjoyment of old twin shock bikes is being able to fiddle with them to make them run better. There are not enough riders in the class now without trying to eliminate riders by having rules that make little difference other than add cost & parts difficulty. I used to run a square float amal carb on my rotax powered twin shock & there is no better carb to tune but they wear out & require regular parts. Kehins don't I have had one on for at least 10 years it starts & runs properly every time I drag the bike out of the shed probably every 6 months. The TLR Honda is a far greater advantage than any carb can make to the older twinshocks.

[Scorps]

Howdy Y'all,

Yes those early 250 moto-xer's did have Keihin flatslides - 38mm Keihin PJ Carbs I believe.

The Carbs we use are 28mm Keihin PWK's. The PWK wasn't available until 1989 - as I said before, it is not eligible.

The Mikuni VM28 was available in early RM80's, and as such are eligible. I don't think any one has successfully got these running well on a t/s bike.

Whether or not this should even by an issue is another topic all together, but I still say the Keihin PWK28, and any OKO derivatives are currently not eligible. (And yes, my favourite Kawi runs an OKO, but I don't ride MA, so I don't really care)

Cheers,
Your friendly Neighbourhood KawiMan,
Scorps

[armstrong]

sherpa has posted documented evidence that flatslide carbs were used in the MA rules period, the rules do not comment on carb size PJ & PWK carbs are very difficult externally to tell the difference they use the same jets, the rules imply period looks which rule 23.5.0.4 states below as such there is no grounds to exclude PWK flatslides.




23.5.0.4 Major components that were manufactured
outside the period, but which are visually
indistinguishable from period components
shall be eligible for that period.

[Scorps]

Howdy Y'all,

PJ & PWK carbs are very difficult externally to tell the difference

I think it is quite easy, the PJ has a round screw on slide cap, and the PWK28 has a rectangular cap with two retaining screws. Refer attached diagrams.

Since the statement "visually indistinguishable" is being used here, the PWK28 is clearly not "visually indistinguishable" from a PJ. Therefore, the availability of the PJ carb is not sufficient to make a PWK28 eligible.

I have also attached diagram of the larger PWK carb (33mm and over). As you can see, this carb may be "visually indistinguishable" to the PJ. This is great news if you want to run a PWK33 or larger.

I still stand by my statement that a PWK28, and any OKO derivative, is not allowed in twinshock competition under the current rules.

Cheers,
Your friendly Neighbourhood KawiMan,
Scorps

[David Lahey]

Why not get a rule put into the 2012 MA MOMs covering flat slide carbies in Twinshock class?

This is the time of year to make submissions for next years MA MOMs (rulebook). I think there is a couple of more weeks before the time window closes. Individuals can make submissions or you can go throught your MA club or through your state trials sub-committee.

I would like to see a suitable rule in the MOMs on this issue because what we have now is often interpreted in different ways.

I'm thinking of making a submission but want to be sure that it covers what the riders who compete in twinshock class want. I realise there are pros and cons for allowing modern flat slide carbies on twinshocks but what would be the best overall for the class (in Australia)?

The options I have thought of are:
Only round slide carbies made before the date cut-off or visually indistinguishable from after that date
Any type of carby made before the cut-off date or visually indistinguishable from after that date
Only round slide carbies but can be any age and can look modern (ie an OKO round slide)
Any type of carby and can be any age
Mechanical fuel injection made before the date cut-off or visually indistinguishable from after that date
Any form of fuel injection allowed

Opinions please

[brt650]

Hello David,
I like "Any type of carby and can be any age" . That way there is no error to be made.
Thanks
Brian

[Scorps]

Howdy Y'all,

David, I vote for this one:

Only round slide carbies but can be any age and can look modern (ie an OKO round slide)

Unless someone can convince me a pre 86 twinshock bike came standard with a flatslide, it should stay this way. I am not convinced that pre-86, people were putting flatslides on their bikes as a normal mod.

Cheers,
Your friendly Neighbourhood KawiMan,
Scorps

[brt650]

Hello ,
Now where in the rules does it say the Carb has to come from a trials bike,the following information was from

www.motorcyclespecs.co.za/model/suzu/suzuki_rg500.htm

Make Model Suzuki RG 500 Gamma
Year 1985
Engine Liquid cooled, two stroke, square four cylinder, rotary valve with exhaust port valves,
Capacity 498
Bore x Stroke 56 X 50.6 mm
Compression Ratio 7.0-1
Induction 4x 28mm Mikuni VM28SH Flatslide carbs
Ignition / Starting Magnetically Triggered / kick

Cheers
brt650