Scooterotica

Right following on from the rt/gt thread
I have a gt 186 kit ready to put on my series 2

What I am looking for is info on how different crank and pipe combinations, will affect performance.

My other scoot is a series 3 li 125 with gori race 200 kit with anchalotti exhaust, 22mm jetex, 58mm cranck with 107 rod
And 17/46 gearing.
Still running in but very happy with it nice and smooth and should top out at 65 + once run in.

So far for the gt 186 I have the following,

1. The gt 186 kit with head and 30mm reed manifold.
2. Gt chain guide
3. Li 150 gear box.
4. Electronic ignition with 2kg flywheel

So what crank and exhaust would you recommend and what results do they have on engine characteristics ?

I want the scoot to be quicker of the mark than the gori but don't want it to be revving its nuts off all the time.
Suppose I want a fast touring set up!
Cheers mike

I would suggest a Franspeed race or supertourer with a 16/46 primary drive and 82 link chain (pull down). You did not say if your 30mm manifold is L/H or R/H. If you're on a budget go for a PHBH30, if you've got funds spare go for a VHSH30. Lift the exhaust by 0.8mm with a dremmel and buy a good crank PM or MEC with 107 rod, if you have a bit more budget go for a 110 rod with 60 stroke. On the GT/RT post I have listed the port timings so you can see the combinations of Rod/stroke and timings. This set up should give you 21bhp around 7.5k rpm and around 12-14bhp around 5.5k rpm

What's happening with your cranks Rich?

Rich, I'd like to go for a longer conrod for my GT186. I have a 25 dellorto ,16-46 primary drive, BGM bigbox V2 exhaust. Would the 60 stroke 110 conrod mean any improvement on the kit? Does the use of a 60 stroke 115 conrod with 8mm packer mean a big loss in primary compression?
Thanx!

Thanks for the reply Rich.
Looks like I have a L/H manifold, what are the advantages of a VHSH30 over a PHBH30?
Looks like a franspeed pipe will be the way to go, so will add one to my shopping list.
Just getting the parts together over the next few months, so just wanted to make sure I am getting the right parts that will compliment the kit and give me the end result I have in mind.
So thanks again for taking the time to reply.
I will post the results on here in the coming months
Cheers mike

drunkmunkey6969 wrote:What's happening with your cranks Rich?

The factory are making some pre-production samples. It is a way off though, its a big cost.

Pepot wrote:Rich, I'd like to go for a longer conrod for my GT186. I have a 25 dellorto ,16-46 primary drive, BGM bigbox V2 exhaust. Would the 60 stroke 110 conrod mean any improvement on the kit? Does the use of a 60 stroke 115 conrod with 8mm packer mean a big loss in primary compression?
Thanx!

with the 60/110 combination you gain a bit of capacity and slightly longer durations. Theoretically, you are supposed to gain power too as the crank - con rod angle is increased so more of the piston pressure is transferred to the crank pin rather than the cylinder wall but I'd be surprised if that were really quantifiable. I think the easy back to back wins are slightly extended durations and capacity.

Some people go on about low primary compression but personally I'm not that convinced. I know its been done and run but I don't have experience of this rod in a GT kit so I can't confirm either way.

On the other post I did list out the timings for different rod and stroke combinations, you might want to look through that.

Best regards

Rich T

Many thanks for your answer Rich.

Im interested too in what advantage a VHSH has over a PHBH as I already have a PHBH on my current setup and originally planned to use that and a chiselspeed ADS3 but this threads making me think franspeed now.

So VHSH vs PHBH? Is it just a case that the VHSH is flatside?

Donnie wrote:So VHSH vs PHBH? Is it just a case that the VHSH is flatside?

VHSH is flat slide with an air governed idle circuit. In practice I got a bit more power from a VHSH30 than from a PHBH30 (about 2-3bhp during initial testing, open no filters) but in general terms I did not think the performance difference justified the price difference (nearly double). Additionally the parts are a lot more expensive compared to PHBH and little things like the cable termination into the slide is a pain so if you have to service a broken throttle cable on a rally its going to be trouble unless you're prepared. Just my thoughts though