TZR500 Race bike

[chris]

Whos your dynoguy? I have two bikes i need help with myself.. is he known with twostrokes?

Christer

[ns86]

Just when I thought I'd seen it all another RZ Guru is crowned. Simply inspiring. Just shows the rz500 engine can overcome it's inherent design limits when the upper case is modded. I think this version with the 4dp barrels has the potential to dethrone the gamma once and for all. Personally I need to figure out how to do this with cheaper barrels. The rgv/rs barrel version is good but I prefer to have yamaha barrels if possible. Anyone done any YZ /tzr 125cc barrel research? I just love the factory look of the modded TZ pipes and the overall design of the build. This should make amazing HP on a dyno when sorted!!! Helmers 58's uppercase mod seems slightly different but for those not familiar with this design, check the link http://prometheus-07.com/srd500topcase.htm" onclick="window.open(this.href);return false;

[Helmers58]

Hi

Thanks again for you`re interest in this project. For those of you who are interested in more pictures, I have made a new link with ALL pictures from the project. See below.

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

Wolfgang, regarding HP output, I`m not sure but hopefully it will produce 120-130hp at the rear wheel. I might be dreaming, but I don`t think I have messed to much with the TZ design when making this conversion.

As you can see from the pictures of the engine upper case, I have done a little development myself, by using JB weld or something similar to hopefully increase pumping efficiency. I was inspired by the YZR engine that has an upper case which looks somewhat like this.. I will ofcourse publish the dyno curve after testing.

The rear pistons was also challenging, as I had to modify the ring stopper 180 degrees and make a new window for access to the cylinder boost port. After doing this modification, I thought of the TZ rear cylinder/paralell twin engine, and it might be possible to use these pistons instead..

Christer, the Dyno guys name is Jan Viker. I don`t think he is too familiar with two-strokes, but we`ll see!

I really like the prometheus SRD500 engine upper case design, however, the 4 in-line carb set-up looks better I guess it would be possible to use the SRD upper case design with some minor changes to fit other cylinders as well. If you don`t want to use too much money on stroking the crankshafts, it`s probably worth to stick to cylinders with more or less RD stroke.

Helmers

[begbie]

I think this version with the 4dp barrels has the potential to dethrone the gamma once and for all.

It will have to exceed 156 bhp measured on a Dynapro Dyno, used original RG500 barrels too.

[Helmers58]

Hi! 156 hp at the rear wheel is amazing. That must be app 180hp at the crankshaft, same as the mid ninetees gp500 racers.. Do you have a dyno curve? I guess you are talking amout Mark Dents 570cc bike?

[Ralf]

This is also a nice picture of an engine in this catogory
http://www.prometheus-07.com/srd500i600.htm" onclick="window.open(this.href);return false;

Ralf

[Helmers58]

Wow! I`ve seen the upper case of the srd500, but don`t think I`ve seen this version! Very nice. Does it work well with the injection?

I know Honda was into using injection back in the ninetees, but I belive they where having trouble with the two-strokes continous misfiring behaviour at low and medium rpm, with little power output. It was difficult to detect this and correct the injection. Therefor they kept the carbs. However, two-strokes have made a lot of progress since that time with both snowmobiles, outboards and scooters!

Not to mention this former GP racer with SRT500!

http://www.risingsuncycles.com/400cc+.htm" onclick="window.open(this.href);return false;

Helmers

[oktrg500]

Wow - not many builds of this caliber in Norway.

If any, Viker should be able to sort this out for you. I have him plotted on my list for some visits too. Some time in the future, when I am satisfied with all the parts I want. This time it's is a small Aprilia RS125 road based build. But - certainly, still not cheap. Long scope build.

Congrats very much. I hope it will work as good as it looks. What are your plans for this build? Trackdays? This wouldn't fit within the rules of any current Classic Racing class in Norway, would it?

[ns86]

156 rear wheel hp is amazing. I doubt there are many who would try to beat that number for bragging rights. I do think that these uppercase modded rz engines bring the bike to another level though. The production rg has cult status as the best 2 stroke street bike ever produced. I believe that the rz based hybrids like a costin framed uppercase modded yzr replica is the ultimate road going 2stroke bar none. But that's just my opinion. I will have to settle for a lesser version.

[vma500]

i think around 130hp on backwheel , coz u ve the shorter stroke and u ll have peakier powercurve , i know someone who put some TZ 4DP barrels on his TZR 3XV and he said they weren t magic at all , the newer SPR 3XV50 barrels are much better option he said (more complex valve system)
The RGV barrels are nt so worse to use , they ve good midrange !

[Helmers58]

Hi!

If it reaches 130rwhp, I'm very satisfied I don't have much experience with the tzr cylinders, but I belive it's important to stick with exhaust, carbs, ignition mapping and cylinders which is designed to work together. I've tried to do that as far as possible. However, you have to make some comprimize with regards to what's possible in reality.

For example, the tz cylinders delivers max power at a higher rpm than in the tzr set-up. Carb size, expansion chambers and case volume must also be designed correct for the system to play optimum together. When using different cylinders, especially the case volume or case compression can be a challenge.

On my tzr500, I've also had to make some comprimize here, but hopefully I'm not to far off.

By the way, does anyone know what rpm is safe to run on the rd engine? I've welded and trued the crankshafts at overhaul, but I've heard that the weakest issue with the engine is the crankshafts.

Helmers


Sent from my iPad using Tapatalk

[vma500]

all respect for ur project Henrick , it s just awesome
hopefully the dyno will tell all
most problem will be the clutch not the cranks , but from all 3 the reps , the RD500 kicks the hardest .....there u ll lose power on also .

[hybrid]

I wouldn't rev it much harder than 10,500 although it will be better with the welding.

[Helmers58]

That`s not enough... Pipes are standard TZ250 4dp, which gives max power at almost 12k

[wolfgangh]

we had no issues running RD500s with non-welded cranks with peak power at 11,200 even at 24hrs. endurance races during the 80´s and 90´s, and we finished (mostly).