what gen yx engine is this?

[user 20441]

i have this engine with bend con rod but very low hours engine yx 150.
i measure the kickstartshaft 16mm, does this make it 100% sure gen 3 engine?

i'm looking into buying parts for this engine, maybe make it a 160cc with the longer 57mm cranck.
cheers for the replies,
Hannes.

 

[gottagetacheaperhobby]

That would be a gen3, clutch cover is also tell tale sign. Tb head, hi comp piston and let the good times roll

Sent from my ALCATEL_4034A using Tapatalk

 

[user 20441]

could you tell me if the heads of the previous gen's would fit?
mine's wasted and i know of a gen 1 or 2 that still has a good head and cil...
just fit a 160 cc cranck (does this fit in a 150?) and then the fun will start!

 

[gottagetacheaperhobby]

It should fit, only difference is rod length between the 150 and 160, i would assume the head off older models fit, they mainly upgraded them bottom end over the different models.
Tb head would open your motor up a whole lot more though, stock heads flow pretty poorly

Sent from my SM-T110 using Tapatalk

 

[user 20441]

a Tb head costs as much as the whole new engine :-/
what if stock head would be flowed, squich can be worked out?
just an immense risk not to touch the valve seats ...

it's gonna be too expensive by the time i've upgraded all the rest, suspension front and back and longer swingarm to make it rideable with the increased power...

thinking about the Zs 155/160 motor instead, because i don't think i'll be upgrading the motor later on... seems the Zs is better stock then yx... allso Zs no problems have accured (or did i not rad enough? )
cheers for the quick replies allways (y)
Hannes.

 

[AntNZ]

zs 155/160 engines are good torquey engines stock, add a oko26 carb makes a huge difference in power also..
They do rev to valve float really early though, if I could find HD valve springs to fit the z I would be more than happy with the stock engine...
bottom end is preety good although the shift forks seem to bend quite easy and render 2nd gear useless!!
I do put that down to improper clutch adjustment though and a hydraulic clutch/self adjusting should sort that out.
yx valve springs do fit but the minimal gain in revs is not worth it imho....
T-bolt usa tested xr100 valve springs with good results and gains but the extra pressure on the rockers caused the rocker arm to break so they gave up......
I wish you could buy tbv2 valve springs by themselves......

 

[user 20441]

thanks on the input on the Zs engines.
i heard about putting shims under the valve springs could help some?
i could make a couple on a lathe?
anyone an idea how thinck they need to be?
anyone else had there shift fork bent on these Zs engines?