cranks and crank parts

[Rick Lance]

I'll chime in on this. The quality of Gus' cranks was in my opinion the same as factory. I'm sure the new parts will be as well. The power valve linkage is adjustable and will not be bothered by a total cylinder height change of 2 mm or less (keep in mind that the stock squish clearance is more than half a mil loose and can be addressed with the spacer plate, possibly allowing for a less than 2 mm height increase). The carb spacing will only be moving on the rear cylinder bank and could be compensated for (if needed) by a thicker gasket on the front reed block. The fairing mount is easily reshaped or rotated for the slight change in position of the head. The pipes will not notice the change. No one will be doing this performance mod with the use of stock pipes and any performance pipe does not hold to fit tolerances of 2 mm anyway. Spigots with springs are very forgiving. The rear pipes won't be affected by the slight raising of the port since the length of the assembly isn't affected, only the angle (imperceptibly). The lowers may need a slight slotting of the rear mount but I doubt it. The water manifold for the front cylinders seals with O-rings and may not require the bolt holes where it attaches to the cylinder to be slotted. Time will tell. The stock stroke of 50 mm brought the rod pin too close to the O.D. of the crank center pin to allow for its removal, hence the one piece inner flywheel / rod pin design used on the RZ5 and the Gamma. With the stroke moving the rod pin out to RZ350 territory, a pressed in pin makes sense. One issue of concern will be the use of cylinders that have already been modified with substantially taller ports. An aggressive exhaust port timing will be exasperated by the raising of the cylinder and the timing change from the stroke increase. Perhaps the best results with the stroker motor would be had with stock cylinders. The increased piston speed brought on by the longer stroke would suggest the observance of the stock 10k redline.

Good luck with the project, Gus!

[guss]

I have a head that can have the piston 2mm up into the head and won't do a 4 mil without a 2 mil offset pin forged piston

[WVWRZ500N]

Not to be the bearer of bad news but as soon as you introduce a spacer plate you render the OEM YPVS linkage useless. All that must then be recreated. In addition, use of OEM carbs will no longer be an option, and the waterpump piping connected to the lower cylinders will have to be completely revamped. Of coarse the fairing mounts on the lower cylinder head is now in the incorrect position and all 4 exhaust mounting points will no longer align. Sure all can be worked through but it is not going to be a kit, a bolt on or anything of the sort.

I'm glad to see your considering new cranks again Gus. But want everyone to understand the huge implications a few mms can cause.

Regards,
Bill Wilson
Wilson Performance
Lee's Summit, MO
http://www.wilsonperformance.net" onclick="window.open(this.href);return false;
Member RZ500 Owners Group #573
816-377-3185
WVWRZ500N@aol.com

Interesting information Bill - thanks for the insight into problems that may be encountered with a spacer - would the powervalve problem be sorted with longer actuating arms - or would the operating arms and whole mechanism need to be spaced higher to compensate as well ?

Cheers
Paul

Paul,

I really don't know. I completely disagree with Rick's assumption that nothing will have to be done.

It's all doable on a custom build for sure. But kitting it is likely not an option especially if individual parts have to be singly modified to make fit. I personally wouldn't want to slot the holes on the lower cylinder water log per Rick's solution. I'm of the opinion that there need not be any coolant flow issues to begin with and certainly none with a modified engine. Shifting the coolant pipe would create a flow path that was not true.

Regards,
Bill Wilson
Wilson Performance
Lee's Summit, MO
http://www.wilsonperformance.net" onclick="window.open(this.href);return false;
Member RZ500 Owners Group #573
816-377-3185
WVWRZ500N@aol.com

[rd84]

Thanks Rick and Bill - lot's to consider if I go for a stroked crank RZ500 engine - doesn't sound too bad for a RZ500 special - but perhaps a bit painful for a standard bike - but not impossible.

Cheers
Paul

[WVWRZ500N]

I'll chime in on this. The quality of Gus' cranks was in my opinion the same as factory. I'm sure the new parts will be as well. The power valve linkage is adjustable and will not be bothered by a total cylinder height change of 2 mm or less (keep in mind that the stock squish clearance is more than half a mil loose and can be addressed with the spacer plate, possibly allowing for a less than 2 mm height increase). The carb spacing will only be moving on the rear cylinder bank and could be compensated for (if needed) by a thicker gasket on the front reed block. The fairing mount is easily reshaped or rotated for the slight change in position of the head. The pipes will not notice the change. No one will be doing this performance mod with the use of stock pipes and any performance pipe does not hold to fit tolerances of 2 mm anyway. Spigots with springs are very forgiving. The rear pipes won't be affected by the slight raising of the port since the length of the assembly isn't affected, only the angle (imperceptibly). The lowers may need a slight slotting of the rear mount but I doubt it. The water manifold for the front cylinders seals with O-rings and may not require the bolt holes where it attaches to the cylinder to be slotted. Time will tell. The stock stroke of 50 mm brought the rod pin too close to the O.D. of the crank center pin to allow for its removal, hence the one piece inner flywheel / rod pin design used on the RZ5 and the Gamma. With the stroke moving the rod pin out to RZ350 territory, a pressed in pin makes sense. One issue of concern will be the use of cylinders that have already been modified with substantially taller ports. An aggressive exhaust port timing will be exasperated by the raising of the cylinder and the timing change from the stroke increase. Perhaps the best results with the stroker motor would be had with stock cylinders. The increased piston speed brought on by the longer stroke would suggest the observance of the stock 10k redline.

Good luck with the project, Gus!

Rick,

I'm curious how the powervalve linkage is 'adjustable'. The linkage arms are fixed length. The distance on the centerline of the attachment points for the arms will be effected at a minimum of 1mm and more likely to 1.5mm. I'm curious as to where you see getting this extra length?

I guess you have never worked on anything older than 1984 as with ALL Yamaha's since the very beginning the rod pins were individual pressed pieces. The centerline of the crank has nothing to do with whether or not the pin was machined on the flyweight. The fact that a flyweight could be precisely manufactured and assembled faster was the reason for this change. This fact holds true with the example you gave, the RZ350 and Banshee cranks, which could easily have a pressed pin all come with machined pins instead.

I'm also curious where you come up with the idea that the piston speed is now so dramatic that the OEM RPM of 10K should be observed? Are you aware that a modified Banshee routinely lives at 10,500RPM? Or that highly modified bigbore engines of the same routinely turn +11,000RPM? Our own Pike's Peak engines saw sustained RPMs of 11,300RPM for over 8-9 second intervals of the race coarse! That's an engine with a bore of 68mm and stroke of 58mm! And if you're not familiar with the Pike's Peak International Hill Climb, it's a race up the mountain road to the top of the peak. It's 12.42 miles with 156 corners with a starting elevation of 9,390' ending at 14,110'. Just during practice the engine will endure over 65 miles of high RPM beating divided into 3 sections of the race coarse. Then on raceday the complete coarse.

The engine that this longer stroke will produce will be around 57mm bore and 54mm stroke. Closer to a square bore than OEM and easily capable of higher sustained RPMs than the OEM platform.

Regards,
Bill Wilson
Wilson Performance
Lee's Summit, MO
http://www.wilsonperformance.net" onclick="window.open(this.href);return false;
Member RZ500 Owners Group #573
816-377-3185
WVWRZ500N@aol.com

[Rick Lance]

My further comments as requested by Bill Wilson.


> Rick,

> I'm curious how the powervalve linkage is 'adjustable'. The linkage arms are fixed length. The distance on the centerline of the attachment points for the arms will be effected at a minimum of 1mm and more likely to 1.5mm. I'm curious as to where you see getting this extra length?

You are not familiar with the adjustment screws located on the PV wheel that are for altering the distance between the two PV's? Now I find that curious. As for the effect on distance from the linkage pivot points from the 2 mm increase in cylinder height, note from the picture that the linkage rods approach the PV from a relatively flat angle and nowhere near parallel to the bore axis. Because of this angled approach, the distance between the pivots will not change perceptibly. Perhaps SpeedFreak would like to draw this up in CAD for you and get exact measurements. I would predict the combined length change for both rods would total less than 0.3 mm and be easily accommodated by the PV adjustment on the wheel.



> I guess you have never worked on anything older than 1984 as with ALL Yamaha's since the very beginning the rod pins were individual pressed pieces. The centerline of the crank has nothing to do with whether or not the pin was machined on the flyweight. The fact that a flyweight could be precisely manufactured and assembled faster was the reason for this change. This fact holds true with the example you gave, the RZ350 and Banshee cranks, which could easily have a pressed pin all come with machined pins instead.

Nope. I have chosen to specialize in RG500 and RZ500 motors exclusively for the last 27 years. That doesn't make me ignorant of other crank designs, just disinterested. I commissioned a 750cc version (66x54) of the RG500 motor some 23 years ago with Racer's Edge in Riverside, CA. Dan Lamey is a respected and accomplished motor development specialist who was under contract with Factory Yamaha to design watercraft motors and competition ski's. Dan pointed out the fact that with the pin diameters of the RG (same as the RZ5) that the rod pin was forged one piece with the flywheel because (with the 50.4 mm stroke) a pressed pin would leave too little material between the pins to allow for a stable press fit for both pins. However, with the 54 mm stroker crank we had in mind, the additional offset would be suitable for a pressed rod pin. As shown in the photo of the RZ5 crank flywheel, the material available between the pin diameters (25 mm center pin and 22 mm rod pin and 50 mm stroke) is approx. 1.5 mm's and would cause stretch in the adjacent hole when the rod pin was installed as a press fit. Some cranks for the 350 Yamaha were made both ways (again with 54 mm stroke and more room allowing for 3.5 mm's between pins). The relatively low tech RD350 used pressed pins and the high performance power valve equipped RZ350 had a more robust (and stiffer) forged pin.



> I'm also curious where you come up with the idea that the piston speed is now so dramatic that the OEM RPM of 10K should be observed? Are you aware that a modified Banshee routinely lives at 10,500RPM? Or that highly modified bigbore engines of the same routinely turn +11,000RPM? Our own Pike's Peak engines saw sustained RPMs of 11,300RPM for over 8-9 second intervals of the race coarse! That's an engine with a bore of 68mm and stroke of 58mm! And if you're not familiar with the Pike's Peak International Hill Climb, it's a race up the mountain road to the top of the peak. It's 12.42 miles with 156 corners with a starting elevation of 9,390' ending at 14,110'. Just during practice the engine will endure over 65 miles of high RPM beating divided into 3 sections of the race coarse. Then on raceday the complete coarse.
>
> The engine that this longer stroke will produce will be around 57mm bore and 54mm stroke. Closer to a square bore than OEM and easily capable of higher sustained RPMs than the OEM platform.

With faster piston speed comes higher stress and more frequent service intervals. For those who worry about exceeding the 10k stock redline, be aware that the 4 mm increased stroke accelerates the piston at redline to speeds (and stresses) that would require an additional 800+ rpm with the stock stroke. There is also a greater rocking motion and side load stress with additional stroke. Any increase in piston weight compounds these issues and should be avoided if possible or taken into account. Minor details but all make more sense with a goal of mid-range gains and lower revs overall.

[WVWRZ500N]

My further comments as requested by Bill Wilson.


> Rick,

> I'm curious how the powervalve linkage is 'adjustable'. The linkage arms are fixed length. The distance on the centerline of the attachment points for the arms will be effected at a minimum of 1mm and more likely to 1.5mm. I'm curious as to where you see getting this extra length?

You are not familiar with the adjustment screws located on the PV wheel that are for altering the distance between the two PV's? Now I find that curious. As for the effect on distance from the linkage pivot points from the 2 mm increase in cylinder height, note from the picture that the linkage rods approach the PV from a relatively flat angle and nowhere near parallel to the bore axis. Because of this angled approach, the distance between the pivots will not change perceptibly. Perhaps SpeedFreak would like to draw this up in CAD for you and get exact measurements. I would predict the combined length change for both rods would total less than 0.3 mm and be easily accommodated by the PV adjustment on the wheel.

Rick, I keep forgetting that you don't work in the tight tolerances I do. Sure you can rotate the powervalve wheel back into adjustment and get the valves themselves to line up per the manual with the 8mm hole above the exhaust port. But, in changing the actual geometry and amount of throw for the entire system to travel you will now effect the actual opening and closing of the valve alignment within the port. The slotted wheel allows for the syrconized timing of each valve so that each valve is in the exact same location when the cable is attached. However, by changing the position of the cylinder you then effect the rotational geometry of the valve in relation to the cables movement thus causing a mis-alignment of the valve in the port. How much? I have no idea without completely mocking up a spacered engine with working powervalve system attached and trying it. But one thing is for certain on a port that has been highly modified where the powervalve is completely smooth to the port any mis-alignment is detrimental to the performance.



> I guess you have never worked on anything older than 1984 as with ALL Yamaha's since the very beginning the rod pins were individual pressed pieces. The centerline of the crank has nothing to do with whether or not the pin was machined on the flyweight. The fact that a flyweight could be precisely manufactured and assembled faster was the reason for this change. This fact holds true with the example you gave, the RZ350 and Banshee cranks, which could easily have a pressed pin all come with machined pins instead.

Nope. I have chosen to specialize in RG500 and RZ500 motors exclusively for the last 27 years. That doesn't make me ignorant of other crank designs, just disinterested. I commissioned a 750cc version (66x54) of the RG500 motor some 23 years ago with Racer's Edge in Riverside, CA. Dan Lamey is a respected and accomplished motor development specialist who was under contract with Factory Yamaha to design watercraft motors and competition ski's. Dan pointed out the fact that with the pin diameters of the RG (same as the RZ5) that the rod pin was forged one piece with the flywheel because (with the 50.4 mm stroke) a pressed pin would leave too little material between the pins to allow for a stable press fit for both pins. However, with the 54 mm stroker crank we had in mind, the additional offset would be suitable for a pressed rod pin. As shown in the photo of the RZ5 crank flywheel, the material available between the pin diameters (25 mm center pin and 22 mm rod pin and 50 mm stroke) is approx. 1.5 mm's and would cause stretch in the adjacent hole when the rod pin was installed as a press fit. Some cranks for the 350 Yamaha were made both ways (again with 54 mm stroke and more room allowing for 3.5 mm's between pins). The relatively low tech RD350 used pressed pins and the high performance power valve equipped RZ350 had a more robust (and stiffer) forged pin.

We all know how you follow Mr. Lamey. But repeating his opinion is irrelevant as is the assumption that there isn't enough support. Both are pressed fit and 1.5+mm is as good as 10mm when it comes to a pressed fit of this type. It all comes down to production. The manufacturer can mass produce the ones with pins and then have a person assembling them faster with less hassle in truing. It's a bit interesting that you blow off the older RD350 cranks which are brother to the TZs as well. The TR3 and TZ350 engines peak HP is above 10,500RPM and routinely live over 11,500RPM. For such a weak designed crank it worked pretty well for almost 10 years! Further the OEM crankshafts in the RZ500 and the RZ350 are not forged units. They are cast. I have personally broken tabs and ends off each. A forged crank won't break like a file.



> I'm also curious where you come up with the idea that the piston speed is now so dramatic that the OEM RPM of 10K should be observed? Are you aware that a modified Banshee routinely lives at 10,500RPM? Or that highly modified bigbore engines of the same routinely turn +11,000RPM? Our own Pike's Peak engines saw sustained RPMs of 11,300RPM for over 8-9 second intervals of the race coarse! That's an engine with a bore of 68mm and stroke of 58mm! And if you're not familiar with the Pike's Peak International Hill Climb, it's a race up the mountain road to the top of the peak. It's 12.42 miles with 156 corners with a starting elevation of 9,390' ending at 14,110'. Just during practice the engine will endure over 65 miles of high RPM beating divided into 3 sections of the race coarse. Then on raceday the complete coarse.
>
> The engine that this longer stroke will produce will be around 57mm bore and 54mm stroke. Closer to a square bore than OEM and easily capable of higher sustained RPMs than the OEM platform.

With faster piston speed comes higher stress and more frequent service intervals. For those who worry about exceeding the 10k stock redline, be aware that the 4 mm increased stroke accelerates the piston at redline to speeds (and stresses) that would require an additional 800+ rpm with the stock stroke. There is also a greater rocking motion and side load stress with additional stroke. Any increase in piston weight compounds these issues and should be avoided if possible or taken into account. Minor details but all make more sense with a goal of mid-range gains and lower revs overall.

I'm curious if you sell or recommend aftermarket exhaust for the RZ500? I believe Mr. Crawford no longer manufactures pipes if I'm correct so I'm curious who you, if at all, recommend for aftermarket pipes? Other than original Toomey's I know of no aftermarket pipe that makes peak HP less than 10,500RPM. Jolly Moto's peak at 10,600 and overrev to 11,200 while Lomas add around 200RPM to the Jolly figures. Nikons are the same. So given these figures the piston speeds have to be so high that the service life is now in hours and not years of use right? I suppose anyone building one of these would likely discuss these things with the prospective builder or have some idea that engine life is directly attributed to how hard the engine is turned in the first place. The entire piston speed topic is completely mute.

Regards,
Bill Wilson
Wilson Performance
Lee's Summit, MO
http://www.wilsonperformance.net" onclick="window.open(this.href);return false;
Member RZ500 Owners Group #573
816-377-3185
WVWRZ500N@aol.com

[Speed Freak]

Why CAD?



calculating the angle on the right side:
alpha = tan-1(2/100) = 1,1457°
Reverse calculating the length of the "new rod":
X = 2/sin(1,1457) = 100,025

=> Length difference ~0,025mm

I think the length tolerance of the rod itself in production is ~+-0,2mm

[Ronnie]

Why CAD?



calculating the angle on the right side:
alpha = tan-1(2/100) = 1,1457°
Reverse calculating the length of the "new rod":
X = 2/sin(1,1457) = 100,025

=> Length difference ~0,025mm

I think the length tolerance of the rod itself in production is ~+-0,2mm

I need to go back to school!

[guss]

There will be pistons and heads that will leave the cylinders in the stock position, anyone that spaces up the cylinder would I believe be able to make all the necessary adjustments, I will get anything that's needed to make this a simple project, biggest hurdle in my mind is pipes.

[Rick Lance]

Perhaps heads with replaceable domes? That would be a boon for these motors. The stroke change should benefit from an optimized pipe design. Tough to get it right within the stock bodywork. Good luck, Gus!

[guss]

I have billitt heads with removable domes, oring inner and outer.

[guss]

Got an email today that all the bearing info has been lost! may have to take a trip

[Rick Lance]

Got an email today that all the bearing info has been lost! may have to take a trip

I envy you! I would love to go to Taiwan and meet some talented folks there. The possibilities seem endless....

Anyone making expansion chambers there?

[gpaddict]

You're a saint Gus! Also, good to see you back.