500 Two-Stroke Tech

No,,, in this case it doesn't suggest the piston is to tight? If the piston was to tight you would see "many" piston marks up and down the piston. If you look carefully at the piston marks and then try to match them with the cylinder marks you can see they dont look the same. Good chart to look at showing all types of things. Many time with our TZ 250 race bikes we good run the 56mm TZ pistons forever. Top would hardly ever sink. The 56mm TZ pistons are very stong. I think i would also bring up the squish a little more to .80 .85? .65/.70 i think is maybe a little close for an RZ500 bike. Reason i say this is many aftermarket pipes and even the stock pipes use 19mm stinger tube? That will make it deto real easy with that tight of squish. Now if the stinger was 22mm then you would be fine.

Tube in stingers have an internal diameter off app 25mm, so I guess I'm on the safe side there. However, rear pistons are TZ 86/87 1RK, with modified top. Std are domed, but I have shaved off a bit to make them flat like the 4DP. Material thickness in top of piston is therefor somewhat thinner.. Had to use these since they don't have a skirt cut-out, and I could make it myself. Pistons are also rotated 180 degrees to have the wrist pin offset against power stroke side, and the ring lock pin has been removed and re-positioned against the inlet side.


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After looking over the pictures of the piston and cylinder I am now of the opinion that Mr. Lance was in deed correct with no seizure left in the cylinder. Since the engine has run only a short time AND without high revs, I gather from everything Henrick has eluded too, that the coolant system was over pressurized to the point that coolant then reversed into the cylinder and the ring 'washed' the oil from the cylinder wall and left true metal on metal ring to nikasil wall thus polishing markings as shown in the photos.

I've blown a fair amount of head gaskets and not had this occur, however all mine were on engines that were running hard right out of the gate. The coolant system would always over pressurize and spill out the coolant over flow as well the temp gauge would begin to climb, climb, climb. Since Henrick never built high cylinder pressures forcing a continual over pressurization of the coolant system it final reached a plateau and reversed into the cylinder causing the issue.

Publicly I'm sorry for going off on you Rick and calling into question your diagnosis and hope that you can see some humility in my retraction and request for forgiveness.

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

Hi Bill! Thanks for you're comment. This forum has for sure helped me a lot finding the reason for the strange wear marks and understanding of how this all works. Thank you all for you're input with a high degree of know-how on the two-stroke engines. As soon as I've done some more testing, I'll let you know how the engine performs.

I'm also working on a Bimota 500 V-due engine, converted to take snowmobile cylinders, and for sure I need some comments on squish, expansion chamber design, crankcase compression ratio, port dimentions etc. As you might have understood, I'm very facinated of these engines and there performance

Best regards Henrik


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Just uploaded a start up video of the bike Dyno test will be done soon!

https://onedrive.live.com/redir?resid=4 ... der%2c.AVI" onclick="window.open(this.href);return false;

http://youtu.be/cWMZXxq9oZI" onclick="window.open(this.href);return false;


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Helmers58 wrote: I'm also working on a Bimota 500 V-due engine, converted to take snowmobile cylinders,...

That is definitely something worth sharing on here!

Hi guys!

Finally did a dyno run yesterday. Engine runs fine, but went out of smaller main jets. The engine is therefor running very rich, and max power is only at 10.300 rpm. Got plug fouling on last run as well.

I believe it will rev higher, hence producing more power when smaller jets have been installed. (Just ordered)

For now, 111hp at rear wheel and app 76Nm torque.




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Is it going to see the track? That is some horsepower and what was the weight? Congrats and be safe.

Thanks! Yes, it's a track bike only. 145kg dry. Hoping to reach some more power with new main jets. New dyno results to come


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Lucky you. It appears you have ridden two stroke quite a bit. The power band looks pretty peaky. As they say slow in fast out but this bike will be different. Have norm throttle or quick turn. With a bike like yours longer throttle could be a good thing or just a switch. Off or oh crap.

Hi Henrik

Perhaps a little late since you already have dynode it. I have Dellorto VHSB 38 on my 250 roadracer.
Ill send you a PM with the jetting.

Racer

Hi all of you two stroke lovers! Thought it was time to give you an update regarding my RD500 build with TZ barrels.

I have not been on the lazy side with projects and machining, but have had some issues with my spine and also been working on a RG500 project. I know, it's a suzuki

To make a long story short, I found a water leak in one of the cylinders after 4 dyno runs, which has been present all the time, and getting worse with the tests. At first, I thought it was a jetting issue, so know I have spent a whole lot of money on atomizers, jets, floats etc.

At the last run, water was also coming out of the engine, so I had to take it apart. I have used some kind of JB weld on the spacers which came loose...

I desided to make new, improved adapter plates and also install longer rods, 110mm, to increase crankcase volume. After reading almost 200 loong web pages from the RSA Pit-lane forum buy Jan Thiel and Frits Overmars, I was convinced to install longer rods

I'm still working on the engine, and I will try to post some pictures during the re-build.

See attached pictures of engine.










Helmers58

that is a nice project

What kind of power did you make?