Race chassis

[Bert]

I'm assuming Scott won't want to try another KTM ?

Wonder if the local Mahindra importers would come to the party...

Scotty didn't have much involvement with the KTM (IMD) other than frame. It has been a little unlucky project (but luck relates to preparation in my books). Apparently you can buy one (IMD) for 15+K (did you know that Scotty - man your going to be busy with all the orders)...

Mahindra, hadn't thought about that.
Maybe GPR needs to do a proposal to them.

[Grumph]

Scotty didn't have much involvement with the KTM (IMD) other than frame. It has been a little unlucky project (but luck relates to preparation in my books). Apparently you can buy one (IMD) for 15+K (did you know that Scotty - man your going to be busy with all the orders)...

Mahindra, hadn't thought about that.
Maybe GPR needs to do a proposal to them.

I was vaguely aware Scott was involved with the IMD but thought he'd done a KTM bucket motor too ?
I remember some posts on it but didn't it break ?

Mahindra are trying to get exposure in the NZ market - I'd say well worth an approach.

[Bert]

I was vaguely aware Scott was involved with the IMD but thought he'd done a KTM bucket motor too ?
I remember some posts on it but didn't it break ?

Mahindra are trying to get exposure in the NZ market - I'd say well worth an approach.

Wires crossed, my bad. Yes there is a KTM super bucket.

[chrisc]

Hoping Frits sees this to continue the conversation on Freetech 50 chassis:

There must have been something wrong with the timing of that AM6's balance shaft then. The AM6 can be quite civilized, vibration-wise.
I don't know all the engines that could be considered, but Derbi seems to be the most-chosen engine, preferably pimped with a KTM 50SX cylinder or an Emot cylinder.

Did I? My intention has rather been to comment on the inappropriateness of an RS125 chassis, or any other 125 cc chassis for that matter.
They are simply too heavy for a decent 50 cc racer. Anyway, see you there: http://www.kiwibiker.co.nz/forums/sh...chassis/page43

When I said "appropriateness of using a RS125 chassis for a freetech 50 bike", I was really alluding to you had saying they were too heavy. What's a more reasonable wet weight for a 50? Presumably the weight reduction would come from using smaller components everywhere (wheels, brakes, forks, swing arm, etc) to suit the lower power rather than one significant change (i.e. JUST the main frame)?

I think I recall you saying they have too much tyre too?
Would using a Dunlop 95/75R17 slick (front tyre) on both the front and rear of a Freetech 50 bike be more appropriate than the 95/75r17 and 115/75R17? The bike might have an odd feeling having the same sized front and rear tyres but I'd imagine a proper race 50 would always feel pretty odd compared to a larger conventional bike anyway.

[Grumph]

I'll be interested in his answer too. I've been saying to the bucket boys here that pushing RS125 size tyres on big circuits with around 20HP is a tad self defeating....

[mr bucketracer]

I was vaguely aware Scott was involved with the IMD but thought he'd done a KTM bucket motor too ?
I remember some posts on it but didn't it break ?

Mahindra are trying to get exposure in the NZ market - I'd say well worth an approach.

just another bike that made me angery , bigend to small , one peice crank , weld , make a new one , or cut and spark new hole and lap ..

[diesel pig]

Would using a Dunlop 95/75R17 slick (front tyre) on both the front and rear of a Freetech 50 bike be more appropriate than the 95/75r17 and 115/75R17? The bike might have an odd feeling having the same sized front and rear tyres but I'd imagine a proper race 50 would always feel pretty odd compared to a larger conventional bike anyway.

It does not feel odd at all, the first two buckets I converted to 17" slicks over 15 years ago using old XL250 rear rims laced onto the original CB125 and H100 hubs were only 2.15" wide and could only really take the 90/70R17 slicks that were around second hand at the time and they handled fine given the limitations of the original frames.

[chrisc]

Two interesting bikes I found trawling for freetech and classic 50 information

[husaberg]

Two interesting bikes I found trawling for freetech and classic 50 information

last time I posted that same frame (bottom)everyone was all over the welding.
http://www.hermanmeijer.nl/hemeyla/ftame.html
http://www.hermanmeijer.nl/hemeyla/frame-2.html
that bike also has as a ubber special self made gearbox and selector. (along with the rest of the bike)

http://www.hermanmeijer.nl/hemeyla/afstelen.html
http://www.hermanmeijer.nl/hemeyla/waretkoeling.html
Check out the yokes.

[Frits Overmars]

Hoping Frits sees this to continue the conversation on Freetech 50 chassis:
When I said "appropriateness of using a RS125 chassis for a freetech 50 bike", I was really alluding to you had saying they were too heavy. What's a more reasonable wet weight for a 50? Presumably the weight reduction would come from using smaller components everywhere (wheels, brakes, forks, swing arm, etc) to suit the lower power rather than one significant change (i.e. JUST the main frame)? I think I recall you saying they have too much tyre too?
Would using a Dunlop 95/75R17 slick (front tyre) on both the front and rear of a Freetech 50 bike be more appropriate than the 95/75r17 and 115/75R17? The bike might have an odd feeling having the same sized front and rear tyres but I'd imagine a proper race 50 would always feel pretty odd compared to a larger conventional bike anyway.

The Freetech minimum weights are 55 kg for the bike and 120 kg for bike + rider, so you would want to get as close as possible to those 55 kg.
When you start with a Honda RS125 chassis it will be difficult to even get below 70 kg.
What's more, for racing on kart tracks the RS125 wheelbase is too long. And I'm talking about the 1220 mm NX4 now.
The old Honda NF4 with its 1280 mm wheelbase was too long even for 125 cc Grand Prix racing; Honda didn't change it without a reason.
Being a big rider is no argument for a long wheelbase. A german friend of mine is big. I don't know quite how big, but judge for yourself: he's on the left, yours truly (1,76 m) is center (and on the right is hollands brightest young tuner, Harm van Gaalen, hvg-engineering.com).

My german friend is not really light either; he tips the scales at 103 kg in his shorts; that's 116 kg with full riding gear.
He develops Simson tuning parts for a living (www.langtuning.de) and he races them as well. But can you believe him winning multiple championships on aircooled 50s?
He is a talented rider and his engines are the best but he would not stand a chance without his homebuilt frames: light, stiff, straight mild steel tubes (no fancy chro-moly), 1200 mm wheelbase, weight concentrated on the front wheel.
And notice his rear tire width. It doesn't last forever but it gives unrivaled steering precision. (while you're at it, notice the cooling fins on the clutch cover).

[chrisc]

What a legend. Man those bikes look like they've had a tonne of development. Thanks for pointing those minimum weights out Frits.
I know all about big riders overcoming their clear mass disadvantages. In this years 125GP national series, Ashley Weller (106kg, literally works as a lumber jack) made a fool of me on a number of occasions (60kg, spreadsheet jockey) due to better race craft and strong consistency. Tip of the hat to him, deserved every result. He's also very tall but with a longer seat subframe, foot peg hangers, handle bar mounts, and a big A-kit honda front fairing, he was able to fit 'better' on the tiny RS125.

Interested to see more of that bike he's riding. Looks like it might have an Aprilia RS125 front end and a home made swing arm.

EDIT:
Been thinking about what would be suitable wheels for a freetech 50 with 95/75r17s front and rear slicks. The Honda NS-1 came out with 17x2.15 and 17x2.75 wheels to take a 90 front tyre and 100 rear tyre. They're really cheap, probably fairly light given their size and readily available in Japan. They're the same design as the Honda NF4 RS125 too which I think look pretty cool. Thoughts?

[dark art]

EDIT:
Been thinking about what would be suitable wheels for a freetech 50 with 95/75r17s front and rear slicks. The Honda NS-1 came out with 17x2.15 and 17x2.75 wheels to take a 90 front tyre and 100 rear tyre. They're really cheap, probably fairly light given their size and readily available in Japan. They're the same design as the Honda NF4 RS125 too which I think look pretty cool. Thoughts?

I have the same ns1 as the picture. They are freely available in Portugal and Spain since the exact same model came out with both the 75cc engine (ns-1) and the 50cc engine(nsr50), they share the same chassis and most parts except engine related. Can give you any specs or wheigts of the bike.

[husaberg]

What a legend. Man those bikes look like they've had a tonne of development. Thanks for pointing those minimum weights out Frits.
I know all about big riders overcoming their clear mass disadvantages. In this years 125GP national series, Ashley Weller (106kg, literally works as a lumber jack) made a fool of me on a number of occasions (60kg, spreadsheet jockey) due to better race craft and strong consistency. Tip of the hat to him, deserved every result. He's also very tall but with a longer seat subframe, foot peg hangers, handle bar mounts, and a big A-kit honda front fairing, he was able to fit 'better' on the tiny RS125.

Interested to see more of that bike he's riding. Looks like it might have an Aprilia RS125 front end and a home made swing arm.

EDIT:
Been thinking about what would be suitable wheels for a freetech 50 with 95/75r17s front and rear slicks. The Honda NS-1 came out with 17x2.15 and 17x2.75 wheels to take a 90 front tyre and 100 rear tyre. They're really cheap, probably fairly light given their size and readily available in Japan. They're the same design as the Honda NF4 RS125 too which I think look pretty cool. Thoughts?

Moriwaki did a race bike version of the NS1.
MH80R
http://www.moriwaki.co.jp/global/product/md250_08.php

MORIWAKI used to produce “MH80R”, GP80 road racer with HONDA NS-1 chassis and CR80 MX engine.
There were 2 major concepts in MH80R.
1. It must have a reasonable price so more people can experience the machine, and 2. It must be a good tool to improve riding skill.
MORIWAKI chose a standard street bike frame and 80cc 2-stroke engine to achieve low cost. HONDA genuine parts are also intentionally used instead of special made racing parts.
It was because of its cost but also to restrict its performance. The “restricted performance” machine requires riders to understand the machine behavior and engine characteristics to run fast. When riders think while they ride and try to improve, they will be able to build up riding skill inevitably.
Many riders would be confused at their first experience with MH80R and thinking why this bike doesn’t stop, grip or turn. But soon they will realize importance of its strange characteristic as they continue riding it. Riders need to control the bike certainly… in other words, “It’s a great tool to correct bad riding habit and improve riding style.”
It is easy to see importance of having such motorcycle by counting numbers of riders in the history of WGP and WSB who once trained with MH80R, and the bike is still used for that purpose in recent years.

I'm pretty sure they use them in Aussie.
Don't be fooled by the frame, its Ferous painted to look Al

[Pumba]

The “restricted performance” machine requires riders to understand the machine behavior and engine characteristics to run fast. When riders think while they ride and try to improve, they will be able to build up riding skill inevitably.
Many riders would be confused at their first experience with MH80R and thinking why this bike doesn’t stop, grip or turn. But soon they will realize importance of its strange characteristic as they continue riding it. Riders need to control the bike certainly… in other words, “It’s a great tool to correct bad riding habit and improve riding style.”

Is that the PC way of saying "the bike is underpowered and handles like poo, but if you figure it out, ride the wheels off it, and not crash you are going to be a pretty sharp rider"?

[husaberg]

Is that the PC way of saying "the bike is underpowered and handles like poo, but if you figure it out, ride the wheels off it, and not crash you are going to be a pretty sharp rider"?

I think it a polite Japanese way of suggesting that it rewards a smooth riding style with high momentum and not point and squirt.