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So Kainzinger's bikes don't exist b/c no one here knows an owner ? And the conversions he sells on his website are bogus ? Wasn't one of his SP2's in an sbk shootout ?
 

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RC51 only 4stroke I liked
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168 Posts
Stroke +

The stroke enlargement is a single order dimension increase, so if you were to add 2mm on the journal axis it would be 4mm increase of stroke, ~7% increase in displacement.
The problem here is if this crank fits in the crank case, you need clearance between piston skirt and crank. So you may need a longer rod by at least 2mm to have the same clearance as before, while pistons don't have that much to begin with. You already had the piston with stock rod going 2mm higher, and if your new rods are an other 2mm longer, the piston now travels 4mm higher.
Since this engine's cylinders do not separate from case (in those cylinders you just add a spacer on the bottom of them and raise them, which you can not also do to the valve train on the RC) your piston rings are running out of cylinder, so you need pistons with smaller distance from crown to rod pin/bearings. I say those were borderline already.

Without a longer stroke this engine is already oversquare, just adding bore size will not help it much.

But let's say you did all this and got 1150 out of it, will the transmission/cases hold the extra torque?

I say that piston shapes, valves, head, cams, have some room to worth playing with in an effort to get more rpms/hp.
It is not going to be a Honda when you mess with the engine so much so it might as well be a ducati. How about shoe horning an 1198 engine in the RC frame?
 

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RC51 only 4stroke I liked
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168 Posts
From a reply to an older thread

This chicken fight has gone on elsewhere last year I'd take the 1120 is the highest possible overbore one can do.

Turbo, Port/polish and bore? - Page 4 - Honda RC51 Forum : RC51 Motorcycle Forums

That gives 105.9mm or 2.95mm scraped of the bore and head dome.
The question I have is how well does an engine behave at 106x63.6 ?
I'd rather have an engine with 100x70 dimensions giving 1100, which in this case it would take a ton of money to do, if possible.

To me it makes no sense going through that expense when you can pick an 1198 up for a quarter of the money, unless you are about to cheat club racers for an under the table bet.

Quote:
Originally Posted by SubSailor
Kainzinger in Germany not only mods up stock engines, he also has two project bikes with larger sizes.
One is an 1120 with stock stroke and 106mm bore that develops 170 HP and 90 ft/lbs of torque.
The other is a 1315cc engine with 106mm bore and 74.6mm stroke that develops 190 HP and 106 ft/lbs of torque.
Both of these engines are not even streetable as they have 13:1 compression.
The 1315cc engine can't even be turned over by a 12v system and uses a 24v system. They both rev to 11.5K RPM.
However his streetable RC51 bikes make around 150 HP.
 

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You setting up a group buy wingnutt? :D

The stroke enlargement is a single order dimension increase, so if you were to add 2mm on the journal axis it would be 4mm increase of stroke, ~7% increase in displacement.
The problem here is if this crank fits in the crank case, you need clearance between piston skirt and crank. So you may need a longer rod by at least 2mm to have the same clearance as before, while pistons don't have that much to begin with. You already had the piston with stock rod going 2mm higher, and if your new rods are an other 2mm longer, the piston now travels 4mm higher.
Since this engine's cylinders do not separate from case (in those cylinders you just add a spacer on the bottom of them and raise them, which you can not also do to the valve train on the RC) your piston rings are running out of cylinder, so you need pistons with smaller distance from crown to rod pin/bearings. I say those were borderline already.

Without a longer stroke this engine is already oversquare, just adding bore size will not help it much.

But let's say you did all this and got 1150 out of it, will the transmission/cases hold the extra torque?

I say that piston shapes, valves, head, cams, have some room to worth playing with in an effort to get more rpms/hp.
It is not going to be a Honda when you mess with the engine so much so it might as well be a ducati. How about shoe horning an 1198 engine in the RC frame?
Check out this little nugget in the pics of the kainzinger bike:



Sure looks like a shim on the oil pan to me. Who knows what he's done inside the cases.

More bike porn here: Google Translate
 

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WSMC #51, CVRA #51
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696 Posts
I stopped posting here because I just got tired of all the nonsense. From time to time I check my photobucket account and see may of the photo views are still coming from this site so I stop in now and then to read whats going on.

I did stroke my crank up 2mm to 65.6mm and had custom 103mm pistons made (comes out to 1093cc). We moved the wrist pin up 1mm rather than change the rod length. 1mm of extra throw should have no problem inside the crank case and the clearance to the piston skirt should be fine. The nice thing about +3mm on the pistons and +2mm on the crank the stoke/bore ratio stays the same (1.5725 vs 1.5723). The pistons are done, the crank is done, the case is off to be bored and sleeved now.

Im using Ti rods, custom C350 lightweight wrist pins and fully CNC under head milled pistons to keep the reciprocating mass low. Im also keeping the rev limiter very near stock. The extra stress on the crank will be at TDC exhaust stroke where the extra peak piston decel will try to pull the crank and rod apart. The lighter the reciprocating mass the easier it will be on the crank and rod but it still have to have enough strength to resist flex. It can be done but it gets very expensive.

I have already sunk so much in to it I have to finish it. Many times I wish I didn't start this project as Its taken far longer and cost far more then I care to admit. Once its done it there is no way to tell how long it will live, how much power it will make or how ridable it will be. We have a good idea on several of those aspects but only time, the dyno and the track will tell for sure.

Is it worth it? Hell no. I could have bought several other nice track bikes instead and been out riding. That said, I sure will be glad to hear it run again.

Mike is usually 100% correct in his sarcastic wisdom but I'm that one in a thousand fool that actually did it.
 

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I stopped posting here because I just got tired of all the nonsense. From time to time I check my photobucket account and see may of the photo views are still coming from this site so I stop in now and then to read whats going on.

I did stroke my crank up 2mm to 65.6mm and had custom 103mm pistons made (comes out to 1093cc). We moved the wrist pin up 1mm rather than change the rod length. 1mm of extra throw should have no problem inside the crank case and the clearance to the piston skirt should be fine. The nice thing about +3mm on the pistons and +2mm on the crank the stoke/bore ratio stays the same (1.5725 vs 1.5723). The pistons are done, the crank is done, the case is off to be bored and sleeved now.

Im using Ti rods, custom C350 lightweight wrist pins and fully CNC under head milled pistons to keep the reciprocating mass low. Im also keeping the rev limiter very near stock. The extra stress on the crank will be at TDC exhaust stroke where the extra peak piston decel will try to pull the crank and rod apart. The lighter the reciprocating mass the easier it will be on the crank and rod but it still have to have enough strength to resist flex. It can be done but it gets very expensive.

I have already sunk so much in to it I have to finish it. Many times I wish I didn't start this project as Its taken far longer and cost far more then I care to admit. Once its done it there is no way to tell how long it will live, how much power it will make or how ridable it will be. We have a good idea on several of those aspects but only time, the dyno and the track will tell for sure.

Is it worth it? Hell no. I could have bought several other nice track bikes instead and been out riding. That said, I sure will be glad to hear it run again.

Mike is usually 100% correct in his sarcastic wisdom but I'm that one in a thousand fool that actually did it.
I subscribed to your thread, I can only imagine what that bike will feel like when done. Very nice.
 
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