Ozzy27 F3 Race bike

[Cleve]

This is a really cool idea. If I was going to race f3 this looks like the bike to go for.
How hard would it be to convert them back to a 600? then you could keep the same bike and step up to f2?

Or the opposite to some extent. It is wonderful option for older 600's when they are no longer 600SP competitive.

Also wondering if someone will be keen to do a Daytona 450 TWIN by knocking out the middle cylinder on a 675...

[Mental Trousers]

Or the opposite to some extent. It is wonderful option for older 600's when they are no longer 600SP competitive.

Also wondering if someone will be keen to do a Daytona 450 TWIN by knocking out the middle cylinder on a 675...

That'd be criminal!!!! The 675 is

[Ocean1]

Somewhere above Ozzy said that if the valves are removed the bike is within the rules. Can't think of how you leave the valves to seal off the cylinder unless you alter the cam shaft so they're never lifted, but that means altering a cam shaft.

Don't know the engine. Presume it's bucket type followers, if the lift is less than the total thickness of the bucket and shim stack, (probably unlikely) you'd just leave the follower out. If it's more you'd need shorter valves, not the end of the world.

[k14]

Yep. To reduce friction loses to an absolute minimum you'd want to get rid of the rings all together though.

But if you removed all the rings you would loose oil out the exhaust port?? The bike would smoke a bit (not too bad) but the more important thing is that it would loose oil so you could risk it running dry??

[Mental Trousers]

But if you removed all the rings you would loose oil out the exhaust port?? The bike would smoke a bit (not too bad) but the more important thing is that it would loose oil so you could risk it running dry??

I think you missed a post.

Not if you seal the entire cylinder off. Block the intake and exhaust ports and sparkplug hole and there's no reason to have a piston that seals the cylinder anymore.

[scracha]

Also wondering if someone will be keen to do a Daytona 450 TWIN by knocking out the middle cylinder on a 675...

If it's a twin you can go to 650 so get the 955 and lop a cylinder off it.

[Ozzy27]

Back to the bike.... its an awesome idea Ozzy and I take my hat off to you for actually DOING it rather than just thinking about it.

You mentioned that the counterbalancing piston is draining about 8.5hp. That leads me to some questions (which will be asked in very non technical terms):
1) on an inline 4 crankshaft, is each piston/rod and crank throw self balancing, or do they work in pairs, with 1 and 2 balancing each other, and 3 and 4 balancing each other?
2) if they are self balancing, is it possible to rebuild the crank so that it just runs straight through- i.e you remove the piston/rod and throw?

I'm picking that if it is possible, it will be bloody expensive...

Hi Tony B,
Each piston and rod is balanced by its owm crank web but in a 180 Deg crank 4 cylinder it is also balanced by both the piston next to it in opposite phase and the piston in the same phase. Ie if you cut the engine in half you get a 180 deg parallel twin which has ok primary balance but a large rocking couple trying to rotate the engine. piston 1 is going up as piston 2 is going down the sum of these 2 forces are added together. where as on the 4 cylinder you have a virtual 2nd engine canceling out the rocking couple force.
Yes you could have a crank made without the crank pin but to stop a rocking couple force you would have to have the crank pins spaced at 120 degs. This would also mean new cams, and a redesign of the electronics. All is very possible but Expensive!!
Cheers
Chris

[steveyb]

Ohh I like it when he talks all teknucle like......

A large rocking couple, that's naughty.....

[Ozzy27]

This is a really cool idea. If I was going to race f3 this looks like the bike to go for.
How hard would it be to convert them back to a 600? then you could keep the same bike and step up to f2?

Hi,
The bike in its current state could be changed back to 600sp rules very easily. To make it a front running f3 bike would require pistons, cams and a ported cylinder head. The pistons and cams could be removed easily but once the head was ported a new head would be needed to meet sp rules but for club racing as a step up no worries.

[Ozzy27]

You guys are on about it being a "cheap way into racing" and the usual "chequebook racer" waffle. I'm sure I heard similar arguments when SV's were first entered in the class....now look at the money that's spent on them. As much as we're proclaiming the virtues of being able to grab cheap not so competitive ex F2 bikes, it's a certainty that a chequebook racer will get a BRAND NEW 600, get it down to 450 and then spend about 25 grand on it.

The 450 is a corker of a bike and a wonderful feat of engineering but if anything it's gonna increase racing costs to similar levels to F2 (more power = more tyres for starters).

Ozzy..still wondering if a trumpy 900 could be cut down to 2 cylinders and a similar trick employed

Hi,
I'm sure it could be done to a 955 but with larger pistons you would have a higher HP drain from the balancer cylinder 15+hp at a guess which might make it har to get the hp needed and they are a quite heavy bike aren't they?
As for Cheque book racing. This is motorsport!! it is expensive!! I have still not seem a rules structure that doesn't give the guy with the most money an advantage.
It could be fresher engines, more tyres, a spare bike, more testing, Better people in the pits. But at leats with bikes the guy on top of it makes a huge difference as opposed to cars. Which is why I love bike racing!

[Ozzy27]

Was wondering that myself.

When ballancing a crank you clamp weights to the journal, not the full mass of the rod/piston but a corrected mass calculated to have the same effect.

So why couldn't you do the same here? Less friction, slightly less rotational innertia... can't see it affecting ballance vertical moments, and I don't think it'd affect rocking moments...

Cool idea btw. As a matter of interest which is the dead cyl?

Yes this the ideal. The amount of space around the crank pin is nothing! The big end journal wont even clear the cases unless the bolts are pointing down.
This mean the only way to get enough mass is to have it going up the bore and then you have to have some way of keeping it centralised. EG Ducati supermono or as has been suggested in following posts a centralising piston.
No. 2 has been removed which is what I thought would be the best 2 years ago when I first thought of this. But in hindsight I don't think is really matters. The bike came with 2 engines that had dropped valves on No.2 so the decision was easy.

[Ocean1]

Yes this the ideal. The amount of space around the crank pin is nothing! The big end journal wont even clear the cases unless the bolts are pointing down.
This mean the only way to get enough mass is to have it going up the bore and then you have to have some way of keeping it centralised. EG Ducati supermono or as has been suggested in following posts a centralising piston.
No. 2 has been removed which is what I thought would be the best 2 years ago when I first thought of this. But in hindsight I don't think is really matters. The bike came with 2 engines that had dropped valves on No.2 so the decision was easy.

Bugger. Still, a lead "bearing" shell inside a steel retainer migh come close... and you could always drill and lead plug the crank. Can't bear the thought of that 8hp just sitting there.

[Ozzy27]

Yup, removing the crank add a bit to costs, not much though.

And with that in mind, to take your idea a tad further... why not just leave the valves in place, (minus the followers?) remove the rings and make a hole in the piston?

Edit: because you'd pump too much oil up top?



... unless you replace the valves?

How many rings do these have? You could just go to 1 or 2 rings on the piston, reduce friction slightly for minimal effort??

Somewhere above Ozzy said that if the valves are removed the bike is within the rules. Can't think of how you leave the valves to seal off the cylinder unless you alter the cam shaft so they're never lifted, but that means altering a cam shaft.



Yep. To reduce friction loses to an absolute minimum you'd want to get rid of the rings all together though.

Don't know the engine. Presume it's bucket type followers, if the lift is less than the total thickness of the bucket and shim stack, (probably unlikely) you'd just leave the follower out. If it's more you'd need shorter valves, not the end of the world.

But if you removed all the rings you would loose oil out the exhaust port?? The bike would smoke a bit (not too bad) but the more important thing is that it would loose oil so you could risk it running dry??

Hi,
To Answer most of above, Yes a dummy piston with the cylinder resealed off might work you would have to ensure what ever was made to take the place of the piston it could handle 16000rpm and at that speed it wasn't still pressurising the crank case too much as it still would have a mass the would displace air.
The current set up still has oil rings and the 2nd compression ring to stop it turning into a big oil pump!(I would guess without rings it would empty the sump in 1-2 laps) and the comp ring also helps to keep the piston central in the bore and dampens out piston chatter that I suspect would happen with no rings as these pistons have a very short skirt.
As for blocking off the ports I thought about cutting threads into some old valves and holding them in place with a pair of nuts locking against each other and to the valve guide. If you cut off the valve stem just above the nuts there would be enough clearance for the cam to pass over.
I have thought about having teflon(or similar) rings made for piston.
I had a target of 90Hp when I started this project and I think this can be achived just with cam and high comp pistons so the expense of making a new type of balancer aren't justified.

[Ozzy27]

Bugger. Still, a lead "bearing" shell inside a steel retainer migh come close... and you could always drill and lead plug the crank. Can't bear the thought of that 8hp just sitting there.

The piston and rod weigh 470 grams so you are going to need 235 grams about which is a bit to try and fit within about 8-10mm of the crank pin. I know what you are saying but as with almost all engineering problems it is a cost vs return equation and for now cams and pistons are a more viable option.

[Ocean1]

The piston and rod weigh 470 grams so you are going to need 235 grams about which is a bit to try and fit within about 8-10mm of the crank pin. I know what you are saying but as with almost all engineering problems it is a cost vs return equation and for now cams and pistons are a more viable option.

Remove 235 grams from the other side of the crank?

And yeah, I know you want to actually ride it.

Gets more beer.