Kymco ZX50

[sidthesloth]

Yeah, funny because last time I decreased the squish it did the same thing, maybe I need to go the other way. Experimentation time.

[zombie]

It just may be the head design... With everything hitting the #'s It has to be somewhere. Just a thought it may be it the cases also. The zx has a very restrictive inlet, and case opening. post what happens w/ the head...(up/down). You just may wind up w/ another project! Opening the cases.    Hey Calo.! I knew you would make me laugh! Got us all pegged do ya? I think you study more than Limey's.    Aussie, Brit, Yank, Reb.......no translation needed here!   PFC

[sidthesloth]

When I checked the spacer on the crankcase the inlets on the case were larger than I thought. I guess you are referring to the other end. If I was going to do that I would prefer to get another crankcase to work on, oh, dear, here comes another obsession.

[Shaka]

The inlet under the reed block is very restrictive.  Matching the case and jug may also help.  That's my next step, once I find some metal for my spacer.  I think I may have found a local supplier.  I'm going to check with them tomorrow.

[zombie]

"The inlet under the reed block is very restrictive. " That's where I was referring to. Also the jug itself has a cut out that may be blocking the flow into the cases. Just thinking outloud. you're gonna get it real close to perfect w/ the finish work you are doing, and when you get it as good as it gets, do you still have a new piston/rings to swap in? That would be the time to investigate the case/jug match.

[sidthesloth]

Well, turn me 'round, kick me arse and send me back to school. Last night coming home from work, long incline, approx. 2 kilometres, 80kmh full throttle bogging down, dying, so this morning I soldered the jet and drilled it out to 1mm, then using tip cleaners reamed it out to somewhere a little below the 120 jet size, took it for a ride, no good, went home and blew out the air cleaner just for the hell of it and was surprised what came out in such a short time of use. Put in the 130 jet and is an improvement, not right but better, must get a spare air cleaner.

[wordslinger]

...filter bites th' ass!!!

 

[sidthesloth]

Yeah, so disapointed with everything else I forgot to check the basics. This is what they call learning I guess.

[wordslinger]

..i know because it's happened to me before...same thing...dirty filter had me all over th' place...


..oh, and keep a check on tire pressures...

..got bit by that gremlin too....

[zombie]

Which cleaner are you using?

[sidthesloth]

A cone shaped cleaner that came with the carb. was premature, bog over half throttle again.

[sidthesloth]

Well, here we go again, I got some 1mm aluminium plate today to make a spacer for the head this time, experimental, when I took the head off I found the spark plug was loose, must be frustration and disappointment coming through. I took out 1 head gasket and that gave a squish of 0.37mm, I checked two points, above the exhaust and left of the rear of cylinder using solder and digital calipers.
Detonation now at it's worst yet so will try the spacer and see what happens, it sort of goes against the rules but whatever work is what we must do!?

[zombie]

Shaka mentioned the combustion chamber in the head. It my all be in the compression ratio that head is creating. We have been assuming the head was a standard 7-9:1 ratio. It may be much higher by design. Therefore decreasing the squish will also reduce the ratio. I think the highest you can run a 2t on pump fuel is 10:1. If you want to get all tecky then it can be measured, but at this point I believe you have it well under control. Sucks tho to get the head shaved, just to put a "wig" on it.

[Shaka]

Sounds like a definite problem with the combustion chamber.  I've heard a good machinist can enlarge the size of the combustion chamber.  I saw a formula for it somewhere.  Otherwise a spacer is probably the easiest fix!  At least we got your ports in the right place!

[sidthesloth]

No need to shave head, hair has been pulled, nah, just kidding, yep, we are getting there, with the one head gasket it did go a bit harder but will cut the spacer tomorrow, rules are made to be broken.