Gt-125 (x-4)

**nudemetalz** · 21st April 2009, 13:33

Has anyone ever successfully tuned one of these in buckets to be competitive?
What's the carby ruling with them since you can't really do a 2 x 12mm carb to equal 24mm.

I know AJ did a standard one and we all know about Pete Sales T-90 back in the late 80's-early 90's back when all 2-strokes were 100cc maximum.

**Skunk** · 21st April 2009, 13:37

With the right size wallet anything can be competitive. Look at the Long-chins...

The rule is 24mm equivalent. Figure out what that means to you and you're away.

**quallman1234** · 21st April 2009, 14:04

Aj's one, goes well in a straight line. And i think he said it was just over the 24mm limit, standard.

**Buckets4Me** · 21st April 2009, 15:42

y section inlet and fuel injection

single 24mm throtte body
dosent need all that much money just someone that knows or is willing to learn the how to of it

then again hase someone ever done fuel injection on a 2 stroke ?????

and would it have to be a 24 mm thottle body as you could put the 24 mm carb under the seat and use a 30 mm or
twin throttle bodies

you are still only using 1x24mm carbie to run the bike

**F5 Dave** · 21st April 2009, 18:12

The rule is quite clear area of 24mm carb. Search on Ivan's thread we worked it out, but pretty easy math. But likely a Y tube idea would be best, or make a reed block that could feed both cylinders. If you think about it it can be pretty clever (someone else (builder of the Kawi I had for a while) pointed it out he was thinking about it & I guessed his idea, he never progressed due to gearbox). Biggest issue is the 5 speed gearbox & width/size of engine.

Someone made a 100cc twin based on a destroked GT125 (or 185?) using 2 watercooled MB50 barrels. Was pretty fast but not sure why never made much ground. Could tell you where it is, I'm sure they still have it.

**nudemetalz** · 21st April 2009, 18:59

It's all just curiousity than anything else. I'm quite happy racing the "diesel" at the moment

Just love the sound of 2-stroke twins with chambers, be great to hear one or two around the track.

**dangerous** · 21st April 2009, 19:07

Originally Posted by Buckets4Me

then again hase someone ever done fuel injection on a 2 stroke ?????

Yeah... Bimoto V Due,

Originally Posted by nudemetalz

Has anyone ever successfully tuned one of these in buckets to be competitive?
What's the carby ruling with them since you can't really do a 2 x 12mm carb to equal 24mm.

yeah so the toatle size of the GT125's are to large so what?
The GT is an awesome wee beast, let em race as they are, should some one start hotting one up then carb restriction would need looking at, cricky if any one is worried put a restricter in the carbs, same as DC has done on his MB125.

**Yow Ling** · 21st April 2009, 19:52

Originally Posted by nudemetalz

Has anyone ever successfully tuned one of these in buckets to be competitive?
What's the carby ruling with them since you can't really do a 2 x 12mm carb to equal 24mm.

I know AJ did a standard one and we all know about Pete Sales T-90 back in the late 80's-early 90's back when all 2-strokes were 100cc maximum.

This carb equivelent thing isnt well understood. a 12mm carb has 113mm2

of inlet area a 24 mm carb has 452mm2 to apply the 24mm rule to GT125 you could have 2 x 17mm carbs @ aprox 226mm2 each

MVX250 has 3 x 17mm flatslides wot you waiting for ?

**TZ350** · 21st April 2009, 19:58

Originally Posted by F5 Dave

Someone made a 100cc twin based on a destroked GT125 (or 185?) using 2 watercooled MB50 barrels. Was pretty fast but not sure why never made much ground. Could tell you where it is, I'm sure they still have it.

I would be interested in that. Please let me know.

.

**diesel pig** · 21st April 2009, 20:02

MVX250 have 3 x 20mm carbs

**Yow Ling** · 21st April 2009, 20:24

Originally Posted by diesel pig

MVX250 have 3 x 20mm carbs

mmm ok 17 rounds up to 20 ,

you are just messing with my delusion

**dangerous** · 21st April 2009, 20:43

Originally Posted by Yow Ling

This carb equivelent thing isnt well understood. a 12mm carb has 113mm2

of inlet area a 24 mm carb has 452mm2 to apply the 24mm rule to GT125 you could have 2 x 17mm carbs @ aprox 226mm2 each

Very interesting, I did not know that.

**nudemetalz** · 21st April 2009, 20:48

I may have mentioned this before, but a friend of mine machined up a crankcase from a T90 (these are a horizontal twin 90cc) so that one barrel remained horizontal and the other was vertical (well 90 degrees from the other), very similar to an RGV250. He had it sorted to use RG50 barrels.
Now that would have been quite weapon had it been sorted as the T-90's have a got a nice close ratio gearbox despite being a 5 speed.
Pity he never completed it, but I may be able to talk him into it........

I had 2 T125's and a T90 many years ago. Awesome machines.

**F5 Dave** · 22nd April 2009, 09:40

Stop it Nudi you're making Yowling sweat.

A friend has done the same thing to an RG500 making it a 500 V4 using YZ barrels. But the vtwin with 2 RG barrels is inspired, . . . if only they weren't so enormous & 5 speed.

D & Nudi. If you weren't so busy looking at the girlies at school or forming a protection racket trading lunch-money & chocolate biscuits you'd remember area = 2 pi r squared

or the easier derivative, times the bore together to itself, then times 3.14 & divide by 3 (pi D squared over 4, - hard to load symbols here).

hence 17mm carb x 17=289, then x 3.14 = 907, which divided by 4 gives you the area of a 17mm carb at 226. if you had 2 you get 453.7mm. well it's slightly over but so close it's not funny.

The std (18m carbs I believe) are well over. No one complained about AJ's GT but if say Luke had started seriously running it there would have been words.

Rob I'll PM you Dave's number.