Zenoah head and piston fit Rovan 32cc ??

[Seandonato73]

Yeah 1191 not 97, for some reason I can never remember the model off the top of my head.

 

[szaki75]

This thing is WAY faster with tons more torque and top end , different motor now !!!!

curious of how much exhaust, transfer and intake port duration the esp topend has at 0,022” clearance.
with my ported rovan, i got 180, 128/119 and 155deg respectively with 0,021” squishband clearance

 

[buzzkill]

curious of how much exhaust, transfer and intake port duration the esp topend has at 0,022” clearance.
with my ported rovan, i got 180, 128/119 and 155deg respectively with 0,021” squishband clearance

I have NO IDEA ???? total loss , would have to ask Doug @ ESP

 

[szaki75]

his business.. wont even ask
i have my own port duration numbers... just would be good to compare them with what professionals are using.
when my rovan top-end dies, i'll replace with zenoah. have the genuine set already

 

[buzzkill]

his business.. wont even ask
i have my own port duration numbers... just would be good to compare them with what professionals are using.
when my rovan top-end dies, i'll replace with zenoah. have the genuine set already
View attachment 66130View attachment 66131

Have you ported a Rovan head yet ?? any good ? just curious , I noticed I had a bunch of blowby on my ring at the slot so it was to small , I think if you re ringed and ported it might be ok ??

I don't know if you were watching the low cost DYNO thread but Im designing a small engine dyno for low cost , might be interesting to see.

 

[szaki75]

yes. i ported the rovan head. i did not want to invest too much into my first porting work hence i went with rovan, not zenoah. i’ve just rebuilt it after 18-20 liters, replaced all bearings, both oil seals and the ring (with zenoah), refined the porting and put it together.
i saw signs of blowby at the flywheel side, but thought it was the semi-syntetic oil made it. (...and hell a lot of carbon deposits too)
i’ll check the diy dyno thread...

 

[buzzkill]

yes. i ported the rovan head. i did not want to invest too much into my first porting work hence i went with rovan, not zenoah. i’ve just rebuilt it after 18-20 liters, replaced all bearings, both oil seals and the ring (with zenoah), refined the porting and put it together.
i saw signs of blowby at the flywheel side, but thought it was the semi-syntetic oil made it. (...and hell a lot of carbon deposits too)
i’ll check the diy dyno thread...

WTH that looks like crap man ! what oil are you using it looks burnt to me , did you check the ring end gap ?

 

[szaki75]

?
https://www.motorex.com/en-us/moto-line/motor-oil/scooter-2t/

believe it or not, this one fulfilled the oil requirement recommended by zenoah.
rovan ring gap after 20 liters was 0,5mm and 0,3mm with the new zenoah ring... in the used rovan cylinder.
i think the flywheel side just cannot get enough cooling because the ignition coil is masking the air flow. also, my killswitch cable with silicone tube goes around the coil and exits just by the exhaust... so it needs to be rerouted to the front

oil seal at clutch side was wrecked too, hence the engine couldn’t start. wt990 doesn’t have choke so i removed the plug put a few drop of pertol on the piston and it started after 2-3 pulls.

 

[Seandonato73]

That seal has been going out for a wile, I would suspect it was a small air leak as well. Whatever oil your running is garbage. I haven't seen build up like that in a properly tuned engine in years.

 

[szaki75]

i have replaced the seals and applied thin CA glue outside where they sit in the crank case. changed oil to full syntetic and will use 1:28 mix instead. just for an experiment, drilled 2mm oiling holes between the seals and crank bearings...
will see how it holds
and i’m happy to provide a case you haven’t seen before ??

 

[buzzkill]

That seal has been going out for a wile, I would suspect it was a small air leak as well. Whatever oil your running is garbage. I haven't seen build up like that in a properly tuned engine in years.

That looks like a motor that was sitting outside for 20 yrs !

 

[szaki75]

yes... certainly w/o leaking it doesn’t get the oil mud
when starting, the ascending piston pulls air not only through the intake track, but through the broken seal too... imo
making the starting difficult

 

[buzzkill]

yes... certainly w/o leaking it doesn’t get the oil mud
when starting, the ascending piston pulls air not only through the intake track, but through the broken seal too... imo
making the starting difficult

And leaning it out at the same time

 

[szaki75]

And leaning it out at the same time

also
anyways... it’s been sorted and ready to beat the rovan head for one more season. then the zenoah head comes with all my experience gained on this poop knockoff.

transfer port plates for comparison (with zenoah)

rovan ones were not used for a minute, just the ported (for flow) zenoah ones

 

[Seandonato73]

Dry for them to the cylinder and see how they match up to the ports. You may have to do a but more grinding on the port or cover to make them blend into each other.

 

[szaki75]

i’m done with it. these sharpened ones run this season for about 20 liters. i had to grind them for a decent match to the port window. one side i had to file the window roof too for symetry with the other side.

 

[buzzkill]

BTW this thing KICKS AZZ NOW way different motor