jc2

How about some pics of your bike? Here's a couple I found on the net.

Just curious about that bike to the right of the TES in the 1st pic in SM museum. Is it the prototype D18 Bantam? Or a Mickmar?

Many thanks Sparks. Fantastic result for him & the little Suzuki. Am I right in thinking it was his 1st Scottish?

Thanks Steve. The model 221 from '78 was the only one I was aware of too, until re-reading Morley's book on Spanish Trials Bikes where he says, "the resulting 175cc Sherpa mini-trialer was rushed out during September 1968", but I think he got mixed up with the '78 one. Its a great book, but I've found numerous errors in it.

That'd be great thanks. Apart from the diff triples already noted, the one of westyfield's seems to have a much steeper backbone tube where it rises from the swingarm pivot & much steeper steering head than other Cheetahs. Wheelbase also looks shorter. Gorgeous looking bike

That's a very nice bike Westyfield. Can you tell me tho if it's a later model Cheetah frame? There are similarities to the other Cheetah frames I've seen but there's some distinct differences too. I'm now wondering if there was an early model & a later one.

Thanks Guys. I understood he finished in 69 on the Gaunt-Suz & placed well - something like 5th. Can anyone confirm his '69 result? Big John, I saw somewhere on the forum that you have some info/pics on the Alta-Suzukis. Any chance you could PM it to me please? Thanks

Woody, I'm fairly sure the original MAR porting was the same as the Pioneer, which I always tho't was a little radical for trials, but I never rode an MAR. It was probably tamed by the heavy flywheel. As I understand it the smaller inlet port/tract does increase the inlet charge velocity & may well give better crankcase filling at low RPM which probably would make it a little sharper response. 5mm higher on the bottom of the inlet (which controls inlet timing) is quite a bit. It amounts to about 20deg less inlet duration which you would think would knock a bit off the top end (both rpm & HP) but it also means less blow-back at very low RPM (the port closes 10deg earlier), making it smoother down low & (again) a crisper response.

Hi Guys, Can anyone tell me what year it was in the late 60s that Martin Lampkin finished in the top 10 at the Scottish on the little Suzuki? And what was his actual placing? thanks

Nice find. I recently rode one of that very model & loved it. Inspired a fair bit of confidence quickly to this 'rusty' rider. Lovely bike for a clubman it seems to me. I think you'll find that if there's a T2 or T3 on the VIN plate &/or S2 or S3 prefix to engine # that indicates 250 or 350 respectively. Just don't let the kickstart lever crash into the footpeg when starting or it WILL break the shaft & they're unobtainable. Enjoy

Does anybody have a pic (or two) of the Ossa Pennines modified by Colin Moram of Windsor in about 1970? I think Bill Wilkinson may have ridden one in the SSDT

Many thanks. Trialonline listed just what I needed. Does anyone know a site that lists results & placings for British Championships, '65 to '68. (I know SHM won, but I want top 5 placings if possible)

Hi, I'm doing a bit of research & I need results for some of the major trials events of the mid-late 60s. I've found the winners of these events easily enough on the net, but I'm looking for placings 2nd to 5th if possible, or at least 2nd & 3rd. I'll start with the European championship of 65, 67 & 69 (or its fore-runner the Henry Grouters Trophy). Can anyone please help me with who filled the placings & what they rode? Or direct me to a website that would tell me? Thanks for any help

Looks to me very much like its an RT2 or RT3 barrell, head & piston on a TY250 bottom end. It'd be a lot of work to adapt it as the stud spacing is different, as is the stroke (70mm vs 64mm). Probably uses the std 64mm stroke giving 321cc actual capacity, as Matty suggested.

Is that a Mick Mills (or replica) frame?

If my memory is correct, I think they require diff spacers tho don't they ??

Hi Guys, Can anyone tell me how much a bare Bantam frame & swingarm weigh please? cheers

Trying to find that issue in Australia - can you tell me whats on the cover please. cheers

I'm a bit of a skeptic about the value of larger airboxes on Ty175s too. I've often wondered if its any more than placebo effect. So long as the airfilter area & inlet pipe (carb mouth to airbox) are sufficient to flow freely at max rpm, its difficult to see how airbox volume would have much effect unless the airbox lid/inlet is quite restricted Patrik, you haven't accounted for volumetric efficiency in yr calcs, which is way below 100% in a 2T, especially one set up for trials with a small carb, small ports & little/no suction pulse from the exhaust. And its even lower at part load, part throttle opening & below peak torque rpm (or above it for that matter). So airspeed will be much lower than you calculate Also, I'm not convinced of the relevance of air speed at the carb throat/venturi anyway, even if you could calculate it accurately. I'd have tho't it more relevant in the inlet pipe, which has cross-sectional area 3.7 times that of carb venturi, or at the bottom plate/restrictor in the airbox which has cross section about 2.7 times that of the venturi. Air speed is much reduced at those points compared to carb throat (since its inversely proportional to area). And as I understand it resonance effects come more from the inlet system volume on the other side of the carb mouth - ie crankcase volume + inlet tract volume (to the carb inlet/mouth). I'd have tho't the main pressure drop (& hence performance loss) in the inlet system upstream of the throttle (carb slide) is normally the air-filter element. In the TY175 that bottom plate in the airbox may also contibute, so some slight advantage may be gained from improving those 2 areas, tho I suspect it'd mostly be at hi rpm. If there was any improvement in throttle response at low rpm, you'd nearly have to be Magic Mick to notice it.

Would it be worth trying with the drive side flywheel removed?

Can anyone tell me if a 250 Italjet top-end will bolt straight onto a 350 Italjet bottom-end, or is there diff stud spacing, diff little end dia etc?

It's difficult to tell what hub it is from that pic but looks to me like YZ or RM. Fairly sure its not pursang. Probably YZ.

David, I'm of that theory too, tho expressed as a percentage rather than ratio. I read years ago (in twinshock era) that footpeg-to-rear-axle should be 29% of wheelbase. Thats what I work on as a starting point. (Tho the modern trend I'd imagine would be different.)

Many thanks Nick

Has anybody got a Fantic 200 cylinder on the bench who could help me out & measure up the port heights for me please? I want to compare specs of a standard cylinder (which I don't have) against another