Stock exhaust performance

[jumjum01]

I ordered a Koso Dual EGT kit to make sure I dont need to buy pistons in the near future. Hopefully it will arrive tomorrow.
Here is a video on the exhaust sound..
https://youtu.be/7BjbNIl9Xkk

[(F5)]

Pretty sure I said that virtually exactly in comment 10.

[JanBros]

Frits Overmars has published a rule of thumb to get that diameter:
https://4.bp.blogspot.com/-MgZiKNYsFws/ ... s_ex10.gif

that is an older version, here is an updated one from 2017 :

https://www.dropbox.com/s/z0l77u5pe9tm4 ... 7.png?dl=0

[jumjum01]

I had a couple of runs with the modifyed exhausts. Even though it can rev over 9000rpm now, it feels like the power starts to drop at around 8000-8500rpm. Mabye thats just the way they perform by design. Looking at stock bike dyno charts w/1UA exhausts, max HP is between 8K-9K rpm. The cigar exhausts make max HP at 9200rpm on my bike.
The sound is awesome so I will definitely keep them.
Interesting facts about the YPVS. I have a manual switch to control the YPVS valve with 3 settings -full open-, -full closed-, -automatic-. With YPVS fully open the bike pulls like crap below 6K rpm, as expected. At fully closed the bike runs great up to 8K rpm and mabye looses at tiny amount of power on the top. I was expecting it the choke the bike at high rpm, but not the case.
Also I am impressed with the dual EGT meter. It works well and the temps on Left and right cylinder are within 10 deg. most of the time. I tried switching from BR9ES spark plugs on both cylinders to BR9ES on LH and BR8ES on RH cylinder, expecting to see a diference. But there was absolutly no difference in the EGT

[kpke]

I know I said it before but that is a beautiful bike.

That is interesting to hear about the power valves. Someday maybe I will pull the fuse on mine when it goes open and go for a ride and do some butt dyno testing.

Do you have KOSO EGT's on there?

[jumjum01]

Thanks Yes I have the Koso Dual EGT and Koso RX2 speedometer. You guys that run EGT, what is a safe max temp. to avoid metdown

[MK]

You guys that run EGT, what is a safe max temp. to avoid metdown

Easy answer. It's that temp reading that didn't melt the piston.

Or in a more extended version: Depending on the type of sensor, the state of that sensor, the connection cables and the electronics at the very end, you can basically get a pretty wide range of readings for the same temperature.
I have compared stuff by putting it into the same propane flame and easily found 100 deg C difference. Not even speaking of the dynamics (i.e. how long it takes the gauge to show the equilibrium temperature)

So if anyone tells you to aim a certain temperature, don't interpret that as an absolute value. You have to find them for your own setup and then use tem as your individual target.
(i.e. the Koso does not automatically show where the optimum is, but it shows if something is wrong)

[JanBros]

I tried switching from BR9ES spark plugs on both cylinders to BR9ES on LH and BR8ES on RH cylinder, expecting to see a diference. But there was absolutly no difference in the EGT

why would you expect to see a difference ? a spark is a spark.
if you had measured the temp of the spark plugs themselves, you probably would have seen a difference, depending on how much you open the throttle.

[jumjum01]

Because I read this article and misunderstood it... https://www.gsparkplug.com/shop/spark-plug-heat-range

"the difference from one heat range to the next is the ability to remove 70°C to 100°C from the combustion chamber"

[JanBros]

don't believe everything that is on the internet...

if that was true, we wouldn't need any sort of engine cooling, just pick the right spark plug. run your RD without water and use a BR1ES, it will draw another 700° C of heat from the combustion chamber

[kenny]

Please read this for info on egt
http://www.rzrd500.com/phpBB3/viewtopic ... 21&t=12202

[hondaror]

A bit of food for thought. You might want to do a chemical dip on your exhaust for more power. The 1UA bikes came to Canada jetted way too rich, just like all the other RZs. They will more than likely be very plugged up with oil and crud. Most owners did not jet the bikes to local conditions. You’d be surprised what lurks in these old pipes. Have them flushed out. The 1UA pipes work really well on the 31Ks.

[RZtuner]

You can use an Oxy-acetylene torch to clean out the pipes. Start at the flange, heat until the end turns red hot and the crud starts to form a burning ring, then turn the acetylene off and feed pure oxygen through the pipe . You will see a red ring travel slowly down the whole length as it burns out all the crud. It will smoke a LOT and your neighbors will be calling the fire brigade, (so do it while they are at work) Once all the glow is gone, you're done. Pipes will be whistle clean inside.

[Pedec]

IMG_4899.jpeg (135.01 KiB) Viewed 997 times

download/file.php?mode=view&id=5233

[Pedec]

I bought a rz 350 in boxes and it came with these pipes are they any good. Says Micron on the side and there in not bad shape? The bike is 89 rz350. I used a cordless drill with cable with ends of cab unwound and got nothing out carbon or oily crap. I also changed packing and it was like dried straw not really oily at all. The pipes have marks on them and have been used just weird so dry.