yx 4 valve heads?

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GTS221

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been having abit of a look on google images and found a 4 valve head to suit a yx engine are they worth buying im planning on putting the biggest piston i can in my yx160 so its like 180 upwards would this head be worth it over a ported 2 valve?
 
no , i would stick to a Trail bikes v2 head . much easier to get pistons to suit as well.

and there havnt been much feedback about the 4 valve heads .. noone is keen to try them out , and people have said they make around the same or less then the V2 head . so its not really worth it.
 
i've got a 4v head and the matching 62mm piston/cylinder kit for sale. I would recommend porting for best performance. V2 heads aren't ported stock.
 
Hmm would be interesting on the smaller bores but i dont think you could get the port area for the bigger bores?

tormented?
 
I bought this kit to run on my bike, but cash is running low and I'm gonna have to re-sell it :( The stock ports are quite conservative. I'd be opening it up a lot if I was gonna run it on my bike. But I do that with every head I run on my bike, including the V2 thats on my z50j. I haven't done any maths to calculate flow area. It looks pretty good, and with the nice shallow chamber and central plug I reckon it'll run pretty hard.

inlet valve 21.5mm, exhaust valve 19mm
 
Hey boys, I got that head, it's on the engine bench here.
I am onto AKUNAR, about a crank, cylinder, and piston for it.
The head came assembeled with a 7 mm lift cam, so that will remain unchanged. When measuring the valve lift noticed that it would not turn over fully, the exhaust lobe on the cam is crashing somwhere inside the head ?!, Trap for young players .
Intake port is 26 mm, exhaust port is 23.
Porting would (will) consist of mainly reducing valve guide prourusion diameter and general clean up, with only minor port expansion. Some work on the valves will also take place.
I intend putting the finished engine on the dyno, and publishing my build notes on this thread, if anyone is interested.
TO ALL of you 2 V diehards, 4 VALVES ARE BETTER THAN 2.....
 
if you ignore the rattle and how out of tune it is, it sound f#@king sweet to me
 
I'm very interested to see how this performs, I would still like to have a go at building one myself. I just bought a milling machine, so I won't be spending to much money on mini's until the bank balance recovers!
 
tormentandglory said:
I'm very interested to see how this performs, I would still like to have a go at building one myself. I just bought a milling machine, so I won't be spending to much money on mini's until the bank balance recovers!
Click to expand...

did you end up selling your 4 valve kit??
 
tormentandglory said:
I'm very interested to see how this performs, I would still like to have a go at building one myself. I just bought a milling machine, so I won't be spending to much money on mini's until the bank balance recovers!
Click to expand...

milling machine...awesome...
iv been looking at getting one but its hard to find one thats at a decent price unless you settle for a china one, but apparently they have a fair bit of play in them.

what mill did you get and where from if you dont mind me asking...

im looking for 1 to setup and do case boring, piston fly cuts, seat cutting, deck machining and boring...
as well as other things...
 
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