450cc Triple eligible for F3

[jnr]

Hi, I have a query regarding the F3 rules.

Is it possible to take a 600cc bike and remove a piston & rod, spark plug and injector and run it (after tuning it to run on three of course) This will therefore give you a 450cc triple in effect with the fourth cylinder doing nothing.

Your thoughts? Cheers.

[lostinflyz]

i doubt this would really be practical as it would put out of balance the entire engine. it would probably only just run. unless you change out cranks and all and then somehow centrally balance the engine to prevent fatigue on the frame.

but hey i have never heard of it being done so it may be possible. for a shitload of money i imagine.

but seing as you can run a 450 4 cylinder why not a 3.

[scott411]

Hi, I have a query regarding the F3 rules.

Is it possible to take a 600cc bike and remove a piston & rod, spark plug and injector and run it (after tuning it to run on three of course) This will therefore give you a 450cc triple in effect with the fourth cylinder doing nothing.

Your thoughts? Cheers.

yes it is legal, any multi under 450cc is legal,
i know some people have been talking about this,
the other option is to sleeve down, or de stroke a 600 as well,

[jnr]

That is an interesting option to also sleeve it down, would have less drama with the unbalanced 'triple' also...

[Billy]

That is an interesting option to also sleeve it down, would have less drama with the unbalanced 'triple' also...

Nope cant be done without welding up the heads and replacing the valves in a more central position.Someone whom shall remain nameless at this point is turning 600 into a 450 triple as we speak and if this guy cant get it too work then it cant be done.Looking forward to seeing it finished

[jnr]

Hi Billy, thanks for your reply, I guess I'm not the only one thinking outside the square on this one!!

[pete376403]

with regard to sleeving - wouldn't it be easier to take a 400-4 up to 450 as opposed to reduce a 600-4 to 450?

[jnr]

Yeah but looking at it for different reasons, I'll let you guess at what they might be, still under wraps at the moment and don't want to give the game away.

[FilthyLuka]

de stroke a 600

This may well be an option. Shorten the rods and shave metal of the head/block/base.

Would probably rev like a bastard too...

[lostinflyz]

id be impressed if someone got a triple from a four but a shortened 600 sounds easy enough (relatively speaking).

What are the rules in F3 re engines. Does the engine as a whole have to be proddy or just the block???

[roadracingoldfart]

Hi, I have a query regarding the F3 rules.

Is it possible to take a 600cc bike and remove a piston & rod, spark plug and injector and run it (after tuning it to run on three of course) This will therefore give you a 450cc triple in effect with the fourth cylinder doing nothing.

Your thoughts? Cheers.

WHY ??? I cant see an advantage
I love to go outside the square myself but there is a few better more reliable ways to achieve the same result .

[scott411]

WHY ??? I cant see an advantage
I love to go outside the square myself but there is a few better more reliable ways to achieve the same result .


if Burt Munro, John Britten or Kim Newcombe thought that way we would be a boring little island in the middle of no where


this is why F3 is such a cool class and needs to stay, you can do stuff like this still

[Coyote]

I suggest getting 9 RG50 motors and putting them together. More cylinders = more power! :p

5 cylinders up front, 4 rear. RC211V style. It could work. Got to do engineering so I can actually make these silly ideas...

[avgas]

i would not even bother making a triple like that - right now i can feel unbalanced firing order of a 4 - so to completely unbalance it by making it a 3 would be like riding a lambretta without the spare wheel.
What you could do is make the 4th cylinder a balancer cylinder like the old 3 cylinder scoots

[scrivy]

What about cutting up the head to only have 3 cylinders, shortening the cams, cutting one cylinder off the block, shortening the crank, and filling up the crankcase hole where the other cylinder was? :wacko::eek5::blip:

[Taz]

I suggest getting 9 RG50 motors and putting them together. More cylinders = more power! :p

4 cylinders up front, 3 rear. RC211V style. It could work. Got to do engineering so I can actually make these silly ideas...

Your maths needs some work.........

[lostinflyz]

What about cutting up the head to only have 3 cylinders, shortening the cams, cutting one cylinder off the block, shortening the crank, and filling up the crankcase hole where the other cylinder was? :wacko::eek5::blip:

this may be possible but youll run out of money long before you ever get there. You would need to manufacture a whole new crank. then youve got to do the vavlves/cams and all that good stuff. dont even want to think about the trouble of cutting up or shortening heads and blocks. cant just simply shorten the crank as it is timed and balanced for 4 large metal objects being faced about it with some ridiculous force. plus you would end up with a rather long period of no power when one of the cylinders should be firing.

not to mention reorganising the electrics to fire this way.

Munro/Britten/Newcombe ect thought outside the box. true. but they stayed close to reality. Basic physics didn't make thier ideas excessivly difficult.

That being said it is cool to think of the possibilities

[koba]

plus you would end up with a rather long period of no power when one of the cylinders should be firing.


That is a good thing.
Ever heard of big bang motors?
It is why singles make good dirtbike motors that gap is good for traction.

I Think it is a great idea.
The balancing wouldn't be all that bad- Remember It doesn't have to meet the same standards of refinement as a road motor either....

[koba]

You could leave the guts of the cylinder that isn't running in there and cut holes in the piston to stop it compressing.
The piston could be re weighted and then act like a supermono type balance shaft.
This way it could also be air/oil tight with a plug in the spark plug hole.
Ring drag could also be minimised, maybe just run the oil ring?
It would work well to start with and could be developed to work very well, maybe with a rocker type locator on the rod if you were getting serious.

I would do it myself if I had the money and less other things already on the go!

[svr]

This has been discussed previously.
Balance shouldnt be an issue if you leave the 4th piston in (just take out the inlet valves). In theory you'll get 3/4 of the power of a decent 600 (say 90 - 95) so a good advantage over the 3 or 4 national level sv's out there (and maybe even Andy Bolwells old zxr 450?) Like any race bike it'd be cheap enough to get going but you'd start to spend on chassis, quickshifter, wheels, more power etc and end up with a 30k `investment'.
Jason Eastons svx 550 in 125 gp chassis should in theory still be the bike to beat in F3 this season. Should be interesting though.

[malcy25]

This may well be an option. Shorten the rods and shave metal of the head/block/base.

Would probably rev like a bastard too...

Would still be a 600 too....Rod length is not stroke. Capacity is defined by bore & stroke

You could have a con rod 10 feet long or 6 inches long, but if the stroke is the same for both the capacity is the same for both.

[koba]

Jason Eastons svx 550 in 125 gp chassis should in theory still be the bike to beat in F3 this season. Should be interesting though.

Nice! Pleased to hear someone is going to try that, should be great to see how it goes :yes:

[svr]

Would still be a 600 too....Rod length is not stroke. Capacity is defined by bore & stroke

You could have a con rod 10 feet long or 6 inches long, but if the stroke is the same for both the capacity is the same for both.

You'd need a `de-stroker' crank - can't imagine there's a big demand for those or anyones tooled up to make them!
Detuning goes against a lot of deap-seated beliefs that racers hold dear.

[scott411]

Jason Eastons svx 550 in 125 gp chassis should in theory still be the bike to beat in F3 this season. Should be interesting though.

i would have thought he would only be able to go to 500cc, that is the twin limit unless it comes under the exemption with the production parts (ie SV650's)
sounds really fucken cool tho, even with the SVX450 motor

[Hoon]

This has been discussed previously.
Balance shouldnt be an issue if you leave the 4th piston in (just take out the inlet valves). In theory you'll get 3/4 of the power of a decent 600 (say 90 - 95) so a good advantage over the 3 or 4 national level sv's out there (and maybe even Andy Bolwells old zxr 450?).

I'd estimate more like 1/2-2/3rds of a decent 600. There is an overhead cost involved with each cylinder that is usually covered by the net output of that cylinder (i.e. drag of piston going up and down the cylinder, valve train, effort on the compression stroke, etc).
Say a 600 puts out 120hp, each cylinder might produce 40 hp but lose 10 hp to drag/overhead. You remove the power of one cylinder but are still left with the 10hp bill.

Thats just that cylinder. The gap in the firing order will cost the next cylinder hp as well as it will catch the engine on deceleration instead of picking up where the last cylinder usually left off. This will result in that next cylinder not reaching the peak output it usually delivers either and having to work harder than the other 2.

Intake and airboxes will be affected. The reflected pulse of the intake stroke which is used to assist drawing in the next charge will be screwed. Can't see how you can tune for that while keeping the other 3 optimal.

Likewise with exhaust tuning and scavenging.

But hey I'm no engine expert and you may have all this already covered and more (assuming you've put much thought into this and not just a "brilliant" idea you had over a couple beers). Probably way easier ways to achieve the same result but I'd be glad to be proven wrong.

First thing I'd do is put the 600 on a dyno with one of the plugs off. This will give you a starting point and indication of how much work you'll need to do.

[Coyote]

Your maths needs some work.........
It was the morning, that's my excuse :rolleyes:

Course, how smart can I be when I'm thinking of making a 9 cylinder 450...

[quallman1234]

It was the morning, that's my excuse :rolleyes:

Course, how smart can I be when I'm thinking of making a 9 cylinder 450...

Don't think a 9 Cylinder 450 2 Stroke would be eligible for F3

How about a 4 cylinder 250 2 stroke? Get an RG500 and sleeve it down, put it in a nice frame and have massif chambers coming out all directions and use 250GP fairings. Done and Done.

[Coyote]

Don't think a 9 Cylinder 450 2 Stroke would be eligible for F3

Fuck fuck fuck, getting everything wrong today, maybe I should call a quits and go to bed early.

What's a fairly decent performing 50cc 4 stroke anyway? Don't know why I was thinking an RG50 was one... Never even tried pot...

[quallman1234]

Fuck fuck fuck, getting everything wrong today, maybe I should call a quits and go to bed early.

What's a fairly decent performing 50cc 4 stroke anyway? Don't know why I was thinking an RG50 was one... Never even tried pot...

How's the mighty GP100 going?

[svr]

I'd estimate more like 1/2-2/3rds of a decent 600. There is an overhead cost involved with each cylinder that is usually covered by the net output of that cylinder (i.e. drag of piston going up and down the cylinder, valve train, effort on the compression stroke, etc).
Say a 600 puts out 120hp, each cylinder might produce 40 hp but lose 10 hp to drag/overhead. You remove the power of one cylinder but are still left with the 10hp bill.

Thats just that cylinder. The gap in the firing order will cost the next cylinder hp as well as it will catch the engine on deceleration instead of picking up where the last cylinder usually left off. This will result in that next cylinder not reaching the peak output it usually delivers either and having to work harder than the other 2.

Intake and airboxes will be affected. The reflected pulse of the intake stroke which is used to assist drawing in the next charge will be screwed. Can't see how you can tune for that while keeping the other 3 optimal.

Likewise with exhaust tuning and scavenging.

But hey I'm no engine expert and you may have all this already covered and more (assuming you've put much thought into this and not just a "brilliant" idea you had over a couple beers). Probably way easier ways to achieve the same result but I'd be glad to be proven wrong.

First thing I'd do is put the 600 on a dyno with one of the plugs off. This will give you a starting point and indication of how much work you'll need to do.

I had thought about pumping and friction losses, but really know nothing about them and would be just guessing the numbers - anyone know what they'd be? assuming no compression, no compression ring, no cam drag and little intake or exhaust flow resistance - 10hp from one cylinder sounds high (some 150cc 4 stroke singles dont even make that). Intake and exhaust resonance issues are more problematic to decifer. Probably a `suck it and see' for the guy doin it (who knows his stuff - which points to these problems being surmountable)

[svr]

i would have thought he would only be able to go to 500cc, that is the twin limit unless it comes under the exemption with the production parts (ie SV650's)
sounds really fucken cool tho, even with the SVX450 motor

With a standard intake up to 650 twins are eligible (my reading)

[FROSTY]

of course there are people in this world that rather than talking about it are busy out there doin it.
-The advantage of taking a 600 and "loosing a lung" has to be pretty odvious to anyone thats granaded a 450 or who has tried to get a commuter bike to handle like a racebike or has payed moonbeams for a bike.
if it works shit theres gonna be a ready market for 3 year old 600's

[scott411]

With a standard intake up to 650 twins are eligible (my reading)

rule that covers it reads,

over 500cc three or more valves per cylinder, are restricted to 650cc and fuel above, additionally these machines must retain oem air box, air filter element and carburettor,

i would say the airbox would be the biggest problem, it depends on weather you count the airbox being modified to fit into a new frame as a difference,

in my opinion i think it would, (again only my opinion)

but you are allowed up to 500cc 4 valve per head twins with the only restriction being fuel,

be an interesting day when that gets brought up, man its fun to be a steward some days

[CHOPPA]

or you could keep the 600 and race f2....

[koba]

Don't think a 9 Cylinder 450 2 Stroke would be eligible for F3

How about a 4 cylinder 250 2 stroke? Get an RG500 and sleeve it down, put it in a nice frame and have massif chambers coming out all directions and use 250GP fairings. Done and Done.

Nope, Has got to be a twin.
And limited even further to keep GP parts out.

Rules. (http://www.motorcyclingnz.co.nz/download/Appendix_B_Formula_Three_Championship_Regulations. pdf)

[gimpy]

Nope cant be done without welding up the heads and replacing the valves in a more central position.Someone whom shall remain nameless at this point is turning 600 into a 450 triple as we speak and if this guy cant get it too work then it cant be done.Looking forward to seeing it finished

Yeah should be interesting whether he can do it cost effectively,it will help the class if you can buy a 3-4 year old 600 and built it as cheap as a sv and be a front running bike.

[gimpy]

rule that covers it reads,

over 500cc three or more valves per cylinder, are restricted to 650cc and fuel above, additionally these machines must retain oem air box, air filter element and carburettor,

i would say the airbox would be the biggest problem, it depends on weather you count the airbox being modified to fit into a new frame as a difference,

in my opinion i think it would, (again only my opinion)

but you are allowed up to 500cc 4 valve per head twins with the only restriction being fuel,

be an interesting day when that gets brought up, man its fun to be a steward some days

shit its lucky I modified the frame to fit the oem airbox,can't wait till the first round.

[Ivan]

Yeah should be interesting whether he can do it cost effectively,it will help the class if you can buy a 3-4 year old 600 and built it as cheap as a sv and be a front running bike.

When will we be seeing your beast on track your last one was wicked

[Coyote]

How's the mighty GP100 going?
It's going great. Been teaching my girlfriend how to ride on it. Her second lesson will be tomorrow if the weather is ok. Haven't sorted out the front brakes yet though... Luckily I have a hill down my street to get it going :p

Can't be sure when I'll be taking it racing. Still at Weltec and doing unpaid work experience so funds are short and mainly borrowed.

[gimpy]

When will we be seeing your beast on track your last one was wicked

Hopefully maybe the last round of the vic club after some testing but probably the friday test day of the first round of nationals

[k14]

Hopefully maybe the last round of the vic club after some testing but probably the friday test day of the first round of nationals
Nah, give it a blast on boxing day :whistle:

[svr]

shit its lucky I modified the frame to fit the oem airbox,can't wait till the first round.

Jeez, didnt you read the rules before you started building?!
Gonna be a wicked bike tho - do ya think that little 125 rear tyre will be up to it? Betchya theres a few sv national hopefuls praying for reliability `issues'...

[steve74]

a bit off topic but while we are talking F3, am i correct in my interpretation of the rules that you cannot get a standard 450cc mx bike and fit a road bike front end and shock (as per Roland sands 450 super singles concept) as the motocross derived frame is a no go. But there is no reason why you couldnt say put an RMZ450 or KTM525 in a rs125/nsr/rgv or even homebuilt chassis like jason eastons machine?

http://www.motorcycle.com/products/450-super-single-project-68605.html

[scott411]

you can put any size single cylinder motor into any frame, as long as the handlebars are under 900mm off the ground, you are fine,

so if you can get your 450 MXers handlebars under 900mm, by any means my interpretation is that it will be legal

the super singles are fine

[k14]

a bit off topic but while we are talking F3, am i correct in my interpretation of the rules that you cannot get a standard 450cc mx bike and fit a road bike front end and shock (as per Roland sands 450 super singles concept) as the motocross derived frame is a no go. But there is no reason why you couldnt say put an RMZ450 or KTM525 in a rs125/nsr/rgv or even homebuilt chassis like jason eastons machine?

http://www.motorcycle.com/products/450-super-single-project-68605.html
A guy up north (saw him race at manfeild) had a CRF450 motor in a RS125 frame. Seemed to go alright, he had major issues with rear tyres though. Even the hardest compound 125 tyre he would chew right out.

[koba]

a bit off topic but while we are talking F3, am i correct in my interpretation of the rules that you cannot get a standard 450cc mx bike and fit a road bike front end and shock (as per Roland sands 450 super singles concept) as the motocross derived frame is a no go. But there is no reason why you couldnt say put an RMZ450 or KTM525 in a rs125/nsr/rgv or even homebuilt chassis like jason eastons machine?

http://www.motorcycle.com/products/450-super-single-project-68605.html

There has been one at the Vic club rounds this year.
Seems to go alright.

A guy a a track day had an RS125 with an older aircooled big single in it (XR500 I think) that was a beutifull piece of work with lots of work put into re-engineering the frame to work with the vibrations of the big single.
Dunno how well it went tho.

[quallman1234]

Nope, Has got to be a twin.
And limited even further to keep GP parts out.

Rules. (http://www.motorcyclingnz.co.nz/download/Appendix_B_Formula_Three_Championship_Regulations. pdf)

I was actually talking about f3. Multicylinder 2 strokes up to 250cc are allowed.

[koba]

I was actually talking about f3. Multicylinder 2 strokes up to 250cc are allowed.

Ok but rule 5 (5-1 to 5-6-4) basicically excludes anything extreme being done with a multi-cylider two stroke.

[gimpy]

A guy up north (saw him race at manfeild) had a CRF450 motor in a RS125 frame. Seemed to go alright, he had major issues with rear tyres though. Even the hardest compound 125 tyre he would chew right out.

The bike you are thinking of is properly brent symes bike, he made a great job of builting it,it was pretty quick too we had a line up at manfeild and our bikes were on par for top speed , the tyre issue is only a setup thing, I run b compound tyres on my bike most of the time and never had an issue ,it was better on tyres then my 125, it definitly pays to invest in good suspension with backup like Rob cross dresser Taylor can give you when builting shit thats abit different.

[Ivan]

The bike you are thinking of is properly brent symes bike, he made a great job of builting it,it was pretty quick too we had a line up at manfeild and our bikes were on par for top speed , the tyre issue is only a setup thing, I run b compound tyres on my bike most of the time and never had an issue ,it was better on tyres then my 125, it definitly pays to invest in good suspension with backup like Rob cross dresser Taylor can give you when builting shit thats abit different.

Your tires were good worked well on my 125 until I upgraded to the SV and the other setarestill on my brothers bike haha

[FROSTY]

Hmm the 08/09 nats are gonna be interesting this year.

[slofox]

That is an interesting option to also sleeve it down, would have less drama with the unbalanced 'triple' also...

Years ago I raced a stroked down MAC velocette - from 350cc to 250cc.....worst bloody bike I ever rode...vibration paralysed your arms and dropped out your fillings.....but it CAN be done!

[k14]

The bike you are thinking of is properly brent symes bike, he made a great job of builting it,it was pretty quick too we had a line up at manfeild and our bikes were on par for top speed , the tyre issue is only a setup thing, I run b compound tyres on my bike most of the time and never had an issue ,it was better on tyres then my 125, it definitly pays to invest in good suspension with backup like Rob cross dresser Taylor can give you when builting shit thats abit different.
Yeah thats the guy, wonder what's happened to him? His bike was pretty cool.

You should have come back to the 125 class again, or did all the young'ns scare you off :buggerd:

[gimpy]

Yeah thats the guy, wonder what's happened to him? His bike was pretty cool.

You should have come back to the 125 class again, or did all the young'ns scare you off :buggerd:

Haha,i dont think it will be the young'ns scaring me off but being called the old fella in the class ,it wasn't that long ago I was calling steve ward that, must admit did have fun this year having a play with the young'ns and giving abit of advice.

[k14]

Haha,i dont think it will be the young'ns scaring me off but being called the old fella in the class ,it wasn't that long ago I was calling steve ward that, must admit did have fun this year having a play with the young'ns and giving abit of advice.
Yeah I was laughing at the commentary about you on the tv coverage, those guys weren't letting up on you eh. Good luck with the f3 bike.

[svr]

Yeah thats the guy, wonder what's happened to him? His bike was pretty cool.

You should have come back to the 125 class again, or did all the young'ns scare you off :buggerd:

Brent high-sided onto the front straight at Taupo in the 1st round of the last pmc series and broke his leg - about 15 minutes after complaining about getting a 125 tyre to work on the bike.
Lyndon Perry is the guy thats built the crf450 based bike.

[Ivan]

I Think like Jason said it was etup as I had the ex Tigcraft tires and they were still mint they wernt chewing up and what I saw of that bike it was cleaning up:wacko:

[gav]

So anyway, whats the go with this 450 triple then?

[roadracingoldfart]

It takes along time to get through a block with a hacksaw . :laugh:

Hes busy assembling specialised tools like , bog spreaders and an electric hot glue gun.

Its a concept a bit like some of the ideas i have had , :blink: worrysome.

Ahhh hell , its only money $$$$$$$$$$$.

[Shaun]

Hmm the 08/09 nats are gonna be interesting this year.




They sure are dude