ESE's works engine tuner

[husaberg]

That's a TZ125 4JT frame not an Aprilia. Have used the 14 X19 small end in a kart motor that lived at 14,000 only one to fail was when we were forced to run a bearing for the extra meeting when the supplier was out of stock. With the width of the bearing according to my crank bloke( a clever Kiwi as well ) there was a certain year TZ that switched to a wider bearing, with the rollers poking out the sides of the rod, that solved lots of small end drama's on the previous model.

Well i bow my head in shame. nah not really i just thought it looked to right to be a Y.A.M.A.hoo.
Does explain why it is striped done though as it probably blew up trying to keep up with a Honda or Aprilia

I thought this was interesting.
The R0.5 Minimono (half an R1 - geddit??) came together after a deal was brokered with Yamaha Europe to supply a YZ426 engine - the Japanese giant’s Euro-HQ in Amsterdam is full of people interested in Supermono racing, and the chance to see how the firm’s new generation of ground-breaking off-road four-strokes would perform on tarmac, has been an unanswered question many of them were eager to resolve. Dave Pearce initially planned to match this motor up with a TZ125 chassis sourced from his fomer race mechanic Katsuaki Umemoto, who today runs Tigcraft Japan - but opted instead to design his own Tigcraft tubular steel frame for the bike while retaining the Yamaha suspension, because of the vibration and extra stresses which a heavier, torquier fourstroke engine would impose on the 125 GP bike’s aluminium Deltabox chassis, typified by the fact that it broke the TZ125 cushdrive the first time they tried to bumpstart it!


Chassis geometry is the same as the TZ125 which inspired the bike, with a 22-degree head angle and just 82mm of trail from the 35mm Kayaba upside down forks, which retain the same springs as on the GP bike they’re sourced from, with only slightly stiffer damping settings. The GP racer’s aluminium swingarm is also retained, pivoting in the vertically-split engine cases and working a Dutch-made TechnoFlex shock via the stock TZ125 rising-rate link. "The shock is exactly as supplied for a 125 GP road racer, but with 25% more rebound damping, which we’ve found seems to suit big-pistoned singles better," says Dave Pearce. Fitted with RS125 Honda polycarb bodywork, but a special aluminium Tigcraft fuel tank reflecting the greater bulk of the four-stroke engine, the R0.5 Minimono weighs in at just 88 kg. with oil and water, but no fuel - a figure achieved without the use of any titanium, says Pearce, apart from the bolts securing the single 300mm front Braking petal disc, and its 185mm rear counterpart. "It’s important to stress that this is a very low-budget bike," says Dave. "We effectively have no carbon-fibre or titanium in it at all, and it’s been designed to readily accept the running gear from any Honda RS125R or Yamaha TZ125. It’s hard to over-emphasise how completely different the Minimono is to ride compared to the Gallina or another of the big 700cc-plus singles - though ironically it does share quite a lot in common in terms of technique and riding style with a Ducati Supermono. That’s because the key to redressing La Ducatina’s horsepower and weight disadvantages compared to the maxi-singles has always been to exploit its sweet handling and extreme 54/46% frontal weight bias (thanks to the horizontal cylinder’s heavy desmo head) to maintain corner speed and keep up momentum. The R0.5 has the same weight distribution, and asks you to ride it the same way, making the guff about the danger posed by conflicting lines through corners from little and large,
http://www.designdatamanager.com/sco.../mainbody.html

[RAW]

Hello all, great forum, great to see a bunch of enthusiest sharing ideas, knowledge & encourigement

My question, can anyone assist with the direction to the page where Frits Overmars mentioned, fuel pump type / site link, pressure ect upon the Aprillia

Cheers all, keep up the great sharing of a common interest, Without competers we all LOOSE

[kel]

That's a TZ125 4JT frame not an Aprilia.

Would make a great bucket. There's a TZ125 chassis on Yahoo Japan for approximately $280NZ

Shame they don't offer overseas shipping

[husaberg]

Would make a great bucket. There's a TZ125 chassis on Yahoo Japan for approximately $280NZ

Shame they don't offer overseas shipping

We do have a Japan based contributor remember, where is he has been a bit quiet lately. Maybe he is bored and ........

I work at Asaka, ( actually it s asakadai , next station up ) and I can vouch for that article ,
Stephen

We import thousand's of second hand cars per year into new Zealand imagine how many frames someone (say Stephen) could stuff in a say a Second hand Hiace van.
I also think Bert may have a contact in Japan as well.

Tigercraft from Grumph as well

[Frits Overmars]

Improving the handling by moving the engine forward to put more weight on the front wheel.
Its hard to see what can be done. There is already quite a distance between the front sprocket and swing arm pivot, and it doesnt look wise to increase it.

I agree. But how much is your wheelbase? Bringing the front wheel back towards the engine might be an option. Riding against a brick wall is the quickest solution, but it is rather difficult to bend both fork tubes exactly the same amount. Dropping the head stock is a better idea. Maybe you can shorten the lower fork legs so you can get the tire closer to the lower yoke. And / or you can revert that lower yoke which will give you more room to move the fork tubes up in the yokes before the lower fork legs hit that yoke.

On the dyno under power this bike has a definit squat, is that good or bad? does it unload the front wheel in a corner? this bike does suffer from front end chatter when pushed hard.

Squat does not unload the front wheel; it drops the center of gravity so your rate of acceleration is less limited by wheelie-tendencies (which may not be all that important for a bucketracer). Chatter can come from anywhere: tires, damping, frame flexing; just ask poor Valentino Rossi.

Maybe shortening the frame rails to bring the front wheel back to the engine is a possibility

If you do that, you may want to steepen the fork angle as well. You can go well below 20°, provided you watch the trail; it should be about 85 to 95 mm for your kind of bike and tires, and you can control it with yoke offset. Optimum would be yoke offset zero, as this would bring the masses of forks and wheel closer to the steering axis. That reduces steering inertia; it leaves more wheel feedback to reach the handlebars which will give the rider a better impression of the available grip and a lot more confidence in the bike.

Yes, improving the handling is something we are very interested in.

That is very good, but by now you may have gathered it is a rather complicated matter; not something I can explain on a saturday morning.

[F5 Dave]

. Have used the 14 X19 small end in a kart motor that lived at 14,000 only one to fail was when we were forced to run a bearing for the extra meeting when the supplier was out of stock. With the width of the bearing according to my crank bloke( a clever Kiwi as well ) there was a certain year TZ that switched to a wider bearing, with the rollers poking out the sides of the rod, that solved lots of small end drama's on the previous model.

Thanks for the input.

Ideas anyone on clearance. is 2.2 total waay too much?

[TZ350]

Yes, improving the handling is something we are very interested in.

I agree. But how much is your wheelbase? Bringing the front wheel back towards the engine might be an option, but by now you may have gathered it is a rather complicated matter; not something I can explain on a saturday morning.

From memory, the wheel base is 140mm longer than the Honda RS and I can realistically cut about 100mm out of the frame rails and maybe get the rest by steepening the forks.

I am grateful for your input, I will make a start with what you have told me already and post my progress as I go, any tips or suggestions along the way will be welcome.

[TZ350]

... yoke offset. Optimum would be yoke offset zereo, as this would bring the masses of forks and wheel closer to the steering axis. That reduces steering inertia; it leaves more wheel feedback to reach the handlebars which will give the rider a better impression of the available grip and a lot more confidence in the bike.

Thanks for the insight ...

Maybe you can shorten the lower fork legs so you can get the tire closer to the lower yoke. And / or you can revert that lower yoke which will give you more room to move the fork tubes up in the yokes before the lower fork legs hit

Inverting the bottom yoke for clearance, good idea, I will look into it ...

... you may want to steepen the fork angle as well. You can go well below 20°, provided you watch the trail; it should be about 85 to 95 mm for your kind of bike and tires, and you can control it with yoke offset.

My bike is 22.5 deg and the RS is 21 as best as I can tell. How much below 20 is sensible?

[speedpro]

I have a similar 3LN FZR chassis with emulators in the front forks and the suspension setup exactly as Robert Taylor said but with one turn extra on the emulator adjustors. I've slid the triple clamps down the forks about 20mm and with no springs, fully compressed the forks "just" touch the bottom of the triple clamp. I was looking at the chassis tonight trying to see where it could be shortened and it isn't obvious yet. One thing I am considering is moving the motor forward, maybe 100mm or so, but as mentioned the sprocket ends up a long way from the swingarm pivot. I'm thinking maybe a cambelt tensioner mounted on the 10mm adaptor plate with a small sprocket on the outside, set back close to the pivot. My thoughts were to fully compress the rear suspension and mount the motor low enough so that the chain just runs on the roller. The cam belt tensioner has an eccentric mounting system to allow adjustment which might be useful as well. I was actually looking at doing this engine relocation with a view to achieving something else. I also just thought that I could turn the unused top part of the alloy lower fork legs off allowing the triple clamps to be slid down a bit more. It's nice and stable so can be made a bit steeper yet.

[F5 Dave]

Thanks for the insight ...



Inverting the bottom yoke for clearance, good idea, I will look into it ...



My bike is 22.5 deg and the RS is 21 as best as I can tell. How much below 20 is sensible?

When I measured my RS it was 23 fairly cranked up. my gauge is a 3' long tube on a pivot drilled in a reasonable decent size of ply that can be flat on the ground & with lines scribed from a large protractor. The long tube means easier to line up with the fork tube in a few places.

You'll know when you've gone too far, the bike will self steer when leaned over & its bloody 'orrible.

[husaberg]

When I measured my RS it was 23 fairly cranked up. my gauge is a 3' long tube on a pivot drilled in a reasonable decent size of ply that can be flat on the ground & with lines scribed from a large protractor. The long tube means easier to line up with the fork tube in a few places.

You'll know when you've gone too far, the bike will self steer when leaned over & its bloody 'orrible.

I had saved this stuff from a while back this his how the RS125 Honda frames seem to stack up STD.


Year: 1991
Make: HONDA
Model: RS125R

Item Specification
Dimensions Overall length 1,830 mm
Overall width 560 mm
Overall height 985 mm (38.8 in)
Wheelbase 1,260 mm
Ground clearance 110 mm (4.3 in)
Dry Weight 68 kg
Half dry weight 71 kg (156 lbs)
Frame Caster angle 25 °
Trail length 95 mm
Tire pressure-Front 1.8kg/cm2
Tire pressure-Rear 2.0kg/cm2
Tire size-Front 2.65 x 3.25-17
Tire size-Rear 2.85 x 4.00-17
Front brake Single disc / 296 mm
Rear brake Single disc / 186 mm
Suspension-Front Telescopic 90 mm
Suspension-Rear Swingarm 110 mm
Frame type Twin tube
Fork oil capacity 210 cc
Fuel system Fuel capacity 12 liter
Mixing ratio 30:1


1997 Honda RS125 Specifications
Item Specification
Dimensions Overall length 1,800 mm (70.9 in)
Overall width 570 mm (22.4 in)
Overall height 985 mm (38.8 in)
Wheelbase 1,215 mm (47.8 in)
Ground clearance 110 mm (4.3 in)
Seat height 700 mm (27.6 in)
Half dry weight 71 kg (156 lbs)
Frame Type Aluminum twin tube
Front suspension Telescopic, inverted type
Rear suspension Swingarm, Pro-link
Front brake Single disc / 4 piston caliper
Rear brake Single disc / 1 piston caliper
Fuel capacity 13.0 liter (3.4 US gal)
Caster angle 23 ° 30'
Trail length 84mm (3.3 in)
http://www.fatbaq.com/mainpage.phtml...rs125_timeline
The next candidates for the wind tunnel test were the 1990 and 1996 Honda RS125 GP bikes. To look at the bikes, you'd expect the more current model to have the more slippery shape. The older RS has a blunter nose and a sharply cut-off tailsection, which don't "look" aerodynamic. But the wind tunnel proved otherwise

[richban]

I had saved this stuff from a while back this his how the RS125 Honda frames seem to stack up STD.


Year: 1991
Make: HONDA
Model: RS125R

Item Specification
Dimensions Overall length 1,830 mm
Overall width 560 mm
Overall height 985 mm (38.8 in)
Wheelbase 1,260 mm
Ground clearance 110 mm (4.3 in)
Dry Weight 68 kg
Half dry weight 71 kg (156 lbs)
Frame Caster angle 25 °
Trail length 95 mm
Tire pressure-Front 1.8kg/cm2
Tire pressure-Rear 2.0kg/cm2
Tire size-Front 2.65 x 3.25-17
Tire size-Rear 2.85 x 4.00-17
Front brake Single disc / 296 mm
Rear brake Single disc / 186 mm
Suspension-Front Telescopic 90 mm
Suspension-Rear Swingarm 110 mm
Frame type Twin tube
Fork oil capacity 210 cc
Fuel system Fuel capacity 12 liter
Mixing ratio 30:1


1997 Honda RS125 Specifications
Item Specification
Dimensions Overall length 1,800 mm (70.9 in)
Overall width 570 mm (22.4 in)
Overall height 985 mm (38.8 in)
Wheelbase 1,215 mm (47.8 in)
Ground clearance 110 mm (4.3 in)
Seat height 700 mm (27.6 in)
Half dry weight 71 kg (156 lbs)
Frame Type Aluminum twin tube
Front suspension Telescopic, inverted type
Rear suspension Swingarm, Pro-link
Front brake Single disc / 4 piston caliper
Rear brake Single disc / 1 piston caliper
Fuel capacity 13.0 liter (3.4 US gal)
Caster angle 23 ° 30'
Trail length 84mm (3.3 in)
http://www.fatbaq.com/mainpage.phtml...rs125_timeline
The next candidates for the wind tunnel test were the 1990 and 1996 Honda RS125 GP bikes. To look at the bikes, you'd expect the more current model to have the more slippery shape. The older RS has a blunter nose and a sharply cut-off tailsection, which don't "look" aerodynamic. But the wind tunnel proved otherwise

FXR 150
Caster: 24 degrees
Trail: 85 mm

Mine is jacked 10mm in the rear must measure it. Handles fab. Just a heap of flex. Hey but what you don't know won't hurt you. Must ride some more bikes.

[Ocean1]

One thing I am considering is moving the motor forward, maybe 100mm or so, but as mentioned the sprocket ends up a long way from the swingarm pivot. I'm thinking maybe a cambelt tensioner mounted on the 10mm adaptor plate with a small sprocket on the outside, set back close to the pivot. My thoughts were to fully compress the rear suspension and mount the motor low enough so that the chain just runs on the roller.

Looong time ago my old man built a frame from scratch, the countershaft drive went to a sprocket on the swingarm pivot, another from there to the rear axle. It's almost certainly been done elsewhere too.

Doubt you've got room for twin sprockets on the pivot, but if you can manage it you get to put your motor wherever you like. You also get to reduce unsprung weight by making the rear sprocket much smaller.

[Brian d marge]

We do have a Japan based contributor remember, where is he has been a bit quiet lately. Maybe he is bored and ........


We import thousand's of second hand cars per year into new Zealand imagine how many frames someone (say Stephen) could stuff in a say a Second hand Hiace van.
I also think Bert may have a contact in Japan as well.

Tigercraft from Grumph as well

One of the biggest problems is the shipping back to NZ , I have just wrapped a frame up , and it will get there but its not very efficient .

if someone can show me a way I dont mind ( time is tight but ,,, )

Stephen

[casal-fan]

Squat does not unload the front wheel; it drops the center of gravity so your rate of acceleration is less limited by wheelie-tendencies

Isn`t a wheelie the outermost sublime manifestation of unloading the front wheel?
The back squating, appears to be a manifestation of center of gravity shifting backwards, thus removing weight from the front wheel...???
Sorry, I´m not getting it.