Water cooling and unlimited carbs for 125s

[bucketracer]

Actually Skunk while you're getting the carb ruling changed can you get the Fuel ruling changed so we can run Methanol in single cam, two valve four strokes

Nitro for two strokes and is there anything in the rules that prohibits Nitrusoxide.

While working on my 12500rpm GP100 engine I have found that if I take the std 22mm GP100 carb and offset it in the lathe, with two pases it can be bored out in an elongated shape 25.5mm wide by 27mm high. This leaves very little disruption on the sides from the slide cutouts and I also tossed away the idle screw that pokes into the air streem. Not quite a 28mm flat slide but getting closer.

28mm carb for 125 2/strokes. Good idea, anyone know how to get the rule changed.

[speedpro]

so we can run Methanol

I've tried to get Methanol allowed in another class. There is/was a real opposition to it within the MNZ old guard based on the death of that guy who was running it in his 2-stroke at Pukekohe. Never mind that his bike seized because a bit of bog fell out of the hole they had made in the transfer ports allowing air in. He was running Methanol, he died, Methanol is bad. They might have a bit more common sense now, that was a while ago.

[speedpro]

At Ohakea some years ago there was a XL125S engine in a sidecar that ran a good dose of nitro. It had a real bark to it and went well. They were trying it out as they were entered in the sidecar class at Wanganui on the bucket sidecar. There was a couple of bucket sidecars entered that year. They made the "real" sidecars look pretty stupid going through the kink and a few other places. Unfortunately the nitro motor blew up whilst testing a few days before Wanganui so they used a normal motor. The other guys turned up with a KX500 engine in their sidecar in the end. It was tied in knots every time they gave it some gas and the frame had to be welded after every race. Fun to watch though, from a safe distance!!!

[speedpro]

I don't recall clearly but I think before bucket racing became official that 100cc 4-strokes in open could run "fuel" or forced induction.

[TZ350]

I ran methanol in my air cooled Suzuki TR250 late 70's it made all the difference. Pulled out of corners better, ran stronger down the straights and made good power all day.

But I did find that the latent heat of evaporation of straight methanol made the motor run to cold. Cold motor, fuel does not evaporate, runs lean, more fuel colder motor, leaner still, round and round untill raw fuel is dribbling out the exhausts.

The trick is to blend the methanol with something else to get a balance between refrigeration from the latent heat of evaporation of the fuel and a good working temperature for the motor. I settled on a 50/50 mix of methanol and acetone at 20/1 oil ratio.

For those who want to know. If you can run your 4/stroke at 14:1 on methanol you can then run it at 18:1 on acetone but you cant effectively increase the compression ratio on a 2/stroke running alcohol.

Alcohol for two stroke, yes please, one rule for all.

[Kickaha]

I've tried to get Methanol allowed in another class. There is/was a real opposition to it within the MNZ old guard based on the death of that guy who was running it in his 2-stroke at Pukekohe. Never mind that his bike seized because a bit of bog fell out of the hole they had made in the transfer ports allowing air in. He was running Methanol, he died, Methanol is bad. They might have a bit more common sense now, that was a while ago.

Cal Raybon at Puke on the ex Geoff Perry TZ

Post classic can still run it in four strokes so I don't see why we cant

[k14]

Cal Raybon at Puke on the ex Geoff Perry TZ

Post classic can still run it in four strokes so I don't see why we cant

Anyone got some lying around? I can try it out next weekend at ruapuna in the cb

[TZ350]

Cal Raybon at Puke on the ex Geoff Perry TZ

Post classic can still run it in four strokes so I don't see why we cant

It was Cal but on a Suzuki TR500 from Colman's Wanganui as I remember it, quite possibly Geoff's old bike. Joe Lett was the tuner and was spannering it on the day. The moral is, that if you can't get your own Harley racer out of customs in time, be wary of loners. Joe was absolutely devastated, although thats racing, I don't think he ever rarely got over it.

[speedpro]

My mate runs methanol in his race car. Funny stuff to tune when you start getting close to the limits and "stand back" if you cross the limit. He's torched the end of an alloy head once. You could pretty well get your hand inside the cylinder through the hole. Mind you at 11+:1 and 40psi shit happens. He's also scorched all the hi temp HPC coating off one header and melted the pyro.

[TZ350]

Cal Raybon at Puke on the ex Geoff Perry TZ

Post classic can still run it in four strokes so I don't see why we cant

Post Classic pre 72 can run Alcohol in 2 & 4 strokes. So the very bike that bit Cal can still be run on dope.

Pre 82 4 strokes can but 2 strokes not, I expect this is to help mechanically preserve the TZ's and level the playing field for the 4 strokes in pre 82.

I once setup a TZ350 on Alcohol and Nitrus Oxide for fun but never found a straight longenough to push the button. I bottled out, probably the smartest thing I have ever done.

[Kickaha]

It was Cal but on a Suzuki TR500 from Colman's Wanganui as I remember it, quite possibly Geoff's old bike.

Yeah sorry I knew it was a T something or other and it was supposedly Geoffs bike

Alcohol for two stroke, yes please, one rule for all.

Nope four stroke only to even the performance up, level playing field and all that bullshit

[F5 Dave]

. . .
While working on my 12500rpm GP100 engine . . .

My brain skipped over this & it popped back in focus.

So this is the peak revs it will ever reach, or peak power & say 750 over-rev?

You will need to do some quite fancy re-engineering to get it to stay together at these revs if you really expect it to survive over 13,000.The old TS’s would never do these revs, the cranks were not capable & I suspect the GPs are similar.

For a bit of a laugh the stock TS flywheels were so heavy that at race tuned revs they would shear off & break cover, shooting off like a ball bearing spun by a airline trick, except a bit more dangerous.

I know someone who made a crazily over-square GP by destroking it so he could run modern 125 piston & spin it crazy. Never really worked.

Or are you going off the tacho, which will be about 2000 rpm optimistic?

[speedpro]

25.5mm wide by 27mm high.

This is going on to a 100cc 2-stroke, right? I wrote the rule deliberately with the wording "carburation equivalent to a single 24mm carb" to stop racers doing this sort of thing, or using a couple of 24mm carbs, etc.

[speedpro]

Dave is right. The Suzuki cranks are crap. Even rebuilding with all new rod and bearings for some reason the big ends don't seem to last, on the TS100/125s anyway. That was only turning them at about 11,000rpm though as the pistons didn't look favourably on going much faster in the TS barrells with the reduced support at the back once all ported. GP motors may be better in that regard. The Honda cranks are definitely best being good for up to 14,000rpm.

[F5 Dave]

. . .The Honda cranks are definitely best being good for up to 14,000rpm.

You must have had a 'lucky' one in the sidecar.