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View Full Version : ZENOAH 36mm cylinder advisory!



TMRperformance
05-26-2010, 04:45 AM
got some useful info on your beloved zenoah engines once again!

so far i can name several builders that have had these cylinders fail, whether or not it was a cold seize on the piston in the transfer area, or a lean seize on the exhaust, or even a cracked base of a cylinder.. when the zen heads first came out a friend of mine had tipped me off and told me to watch the plating, if it looked spotted send it back! well till now i had not encountered that issue, but like i said until now.... well the cylinder i just ran was not ported, and did not appear to be blemished, and after a few pulls on the dyno my paranoia(lol) about these failing kicked in. i took the top end off to find my cylinder looking like a spotted leopard! there are tiny grey-ish spots everywhere!

needless to say i am not pleased with zenoah again!

i know im going to get crap for this but.... the cy 290's have gotten a bad rap for a while now but zen has cy beat in the failed cylinder department now! you say how is that?????? well lets think about this, the cy 290 came out how long ago??????????? and how many thousands were sold????????
and with all that time out you only here of one failing from time to time right??? well zen 36mm kits havent been here 6 months yet and i myself have had 2 junks! not to mention all of the other people that i know of that have had them fail! to count off the top of my head i can name a total of 6 failed 36mm zens! thats not good odds for the time they have been available!

CLIFF NOTES: if u purchase a 36mm zen make sure you inspect it before installing it! you still may have a failure however if u spot something early you can possibly avoid having to make another top end purchase...

mynameismud76
05-26-2010, 10:31 AM
Thanks very much for the heads up (sorry, bad pun). Shall have a look at mine today.

My zen 4 bolt has been through about 4 litres so far. Fingers crossed it will be ok.

Thanks again Al =)

Clubin
05-26-2010, 12:37 PM
I have a ESP ported 28.5 4 bolt to build when my stuffed +1mm crank comes in. I will check it out and see if anything looks strange. Thanks for the info.

mooman007uk
05-26-2010, 04:13 PM
think I'll stick with the full mod 27.2's then

mynameismud76
05-26-2010, 11:57 PM
I'm pooping it a little =(

Freeprawn
05-27-2010, 01:55 AM
Ahh it'll be fine, maybe stick to 25:1 though, might help it out a bit.

Nige

mradlin
05-27-2010, 02:19 AM
Perhaps they're just having problems with the intial batches? :damn:

Clubin
05-27-2010, 02:33 AM
I checked mine out today, it looks perfect. Time will tell, I will be bashing it soon.

mynameismud76
05-27-2010, 07:27 AM
Yup, running 25:1. =)

Hopefully it's just initial batches.

highwaystar
05-27-2010, 01:57 PM
The 36mm Zen I have is still going strong with no marks at all. However I was awair of this issue when I got my headkit and was able to go to LSRC and hand pick my headkit.

Thanks for the tip TMR.

The motor you did for me is running great.

TMRperformance
05-28-2010, 04:48 AM
just so u guys know, 25:1- 16:1- 8:1 isnt going to help the issues ive been encountering or hearing about..

mynameismud76
05-28-2010, 07:31 AM
Do any of these pics show those spots you've mentioned?

http://teammodellinc.forum-motion.net/general-petrol-f7/mcd-esp-head-kit-death-t407.htm

If not, do you have any pictures of those spots?

Clubin
05-29-2010, 01:19 AM
just so u guys know, 25:1- 16:1- 8:1 isnt going to help the issues ive been encountering or hearing about..
Should I run mine, or send it back. It is a ESP ported 28.5, and I paid a few bucks for it. It is still in the box, I was going to build up the engine this weekend. +1 stroke.

Any pictures of the ones that had bad plating? Or the ones you fubared?

TMRperformance
05-29-2010, 04:11 AM
Should I run mine, or send it back. It is a ESP ported 28.5, and I paid a few bucks for it. It is still in the box, I was going to build up the engine this weekend. +1 stroke.

Any pictures of the ones that had bad plating? Or the ones you fubared?

ahhh screw it, keep it and run it! DDM is aware of this so if u do have a prob they should take care of ya' here is some info and pics that i have posted on some other sites....enjoy

here are some pics of a 36mm zen before i ported it, yes thats right i ported it anyway! if it fails i will take the hit and do another one for my customer, what other choice do i have right????? ohhh btw this leopard looking cylinder helped me make 7.04hp and 2.76tq!!!!!
now that you have seen those #'s do you really think i want zenoah to fail and be having any issues????? this dyno secession was backed up multiple times and every low # pull i made was at around 6.7hp! i can even kick it up a notch and make more power with that cylinder , there is room for even more improvement!
those #'s were using a 1mm stroker, so it was a 29.5cc.. here is a link to the pics!

http://img375.imageshack.us/g/36mmzenoah001.jpg/

Clubin
05-29-2010, 11:20 AM
WOW. Is that ever spotty. mine doesn't look like that.

PM sent.