E series engines

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mercenary223
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Post by mercenary223 »

Why do these power valves break I've never had any powervalves break on me I've owned quadracers. 1 tecate with kips and a 01 yz250 and this 91 kdx200 which has never been apart and has been ridden quite a bit but the valves work what's the deal and how do they do this. Thanks for your time with all my questions :razz:
BobbyZ
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Post by BobbyZ »

I know this is a old thread but my 93 e series was done by FRP years ago.The biggest issue with a overbore is the cyl wall thickness in front of the center valve.It's been years and I'm just putting the old girl back together but you can go bigger on the bore on a e series.It's been a while but I think mine is around a 212cc at its max,back in the day we did toss around the idea of going bigger with some creative welding but after running it we decided not too as it wasnt in the budget.I'll mic my old race jug if you'd like.
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Julien D
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Post by Julien D »

Doesn't matter. The main reason I considered a big bore was to eliminate the valves. I did my last rebuild with a different cylinder, which I had repaired and re-plated, and fashioned an aluminum plate which secures the collar for the main rod much more securely. Haven't had them break again yet. When they do go, I'm probably shopping for an H series.
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BobbyZ
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Post by BobbyZ »

do you have any pics of the plate?I'd be interested to see how it was done.I rode a few h series bikes and to be honest I preferred my E series engines power and delivery.
On your bike have you had all the problems with just one jug or with different cylinders?I know you used a different one this time but I dont recall if all the problems where with the same jug.Years ago I had one cylinder that ate a few valves similar to your issue..It was a used one I bought to have Jeff port and bore,To go bigger with the porting he had to clearance the center valve some so when I had valve issues I blamed it on FRP's work at the time.It got to the point where I was about to drive out there and toss it through his window :blink: because i swore it was something he caused,but in the end he found me another jug and took very good care of me on the work the second time around.I must now have had that same jug replated 4-5 times and had no real issues other then maintenance.
In hindsight and with some info found on the web I wonder if Kawasaki maybe had some problems with a batch of cylinders?
Personally I'd like to go bigger on the bore and keep the valves,Maybe just loose the center valve as thats the one that affects how big you can go on the bore due to wall thickness........It also imo(may be wrong on this) has the least affect of all the valves because it just opens up the main exhaust port a tad more.where if I understand it right the side valves are the ones that affect the port timing and such that coincides with the timing changes in the ignition box.If I'm right bottom end power losses would be minimal if at all due to the increased bore while the gains might be enough for me to hurt some new 450 riders feelings ;)

anyways good luck and I'd like to see what you came up with as my old Race E series motor is going to wind up in a newer 125 frame in the near future.
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Julien D
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Post by Julien D »

When I got the bike, the guy gave me a spare cylinder that was gouged up. I assume it was the original cylinder for the bike, and lost a circlip or something. All the problems were with the cylinder installed on the bike when I got it. When I did my last top end, I sent the gouged cylinder off for repair/re-plate.

I think the valve failure is a combination of issues. The collar on the RH side is poorly secured with one set screw, and the aluminum sub valves wear against the aluminum journals in the cylinder creating slop there. Things get bound up and something snaps.

Your thinking seems sound on the center valve, I would like to see how that works out keeping the subvalves and losing the center....

I'll snap a pic of that plate for you, it was pretty simple, really.


J.
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