my zx50 issues

[art]

Hey bat thats what im working on for my next build with a machinest the first thing we did was set the squish,instant gain on stock barral,went from 85 main to a 105 and about + 4mph the next step is the exhaust port(supposed to be done today!)the delay has been he had to make a jig to get the angle set right (This guy is very precise).This is a bit over my head,whats this magic book you speak of?Sounds like there is some matching in my future    Good luck.I'll let you know how it turns out.

[thebatman]

het art... you are huh? cooooool!!  yeah, i believe this is going to be MY issue, not having a spare scoot(almost had one but was sold before i got there).. id be ok if one of my ladies would stay for a few days, instead of a night...lmao....   you had to rejet, AGAIN??? OH HELL, HERE WE GO!!!! what scoot you building?? assume its not a zx... so what was your squish? did you measure like shaka spoke of or did they do it all???      its jennings' 2t tuner handbook. there is a link in this thread sumwhere...lmao..  what, he just opening the exhaust port to match pipe??

[art]

I'm working on another peoples 50,this was on a stock jug don't panic yet!I had the machinest do it,but was there to watch same method.He took 40thousants off and said I could run without the head gasket.The exhaust on the other hand is where it gets over my head.something like setting the angle and opening to the piston to allow free flow to pipe,all i know is it = more air out 

[thebatman]

ok, heres an update.. went out to measure squish as per shakas way. if i measured correctly, MY squish right now is .050in./1.27mm.  and if .035in./.90mm is ideal then i m thinking i need to reduce it .015in. to get this .90mm, correct?!?! and if its only .015in. , i know the base gasket is thicker than this....

[thebatman]

just had a brainfart...idk what thickness the base gasket is. providing it isnt usable, why couldnt i make a gasket out of rubber, which is like .033, but once i tighten her up again, squish SHOULD be at .90mm???   see there, imma thinking!!! (watch out)..

[sidthesloth]

Don't use rubber for a base gasket, use paper. By adjusting the thickness of the base gasket you will be changing your squisg, compression, and also your port timing. Last week I took out 1 gasket which was 0.4mm. It has increased my compression but has also brought back that dreaded preignition which gives me more work to do.

[zombie]

You can mill the .015 directly off the head. I shaved .5mm off mine, and it worked out great. I used a band saw table as a base, and ran the head over 600 grit emory paper. It took about 20 minutes of careful circles to get .5mm. Changing the base gasket will as sid pointed out change everything. If you really want to blueprint the engine make a port map to inspect the timings then you will know if there are any changes needed that will affect the squish. 

[thebatman]

well zombie, im getting nervous again...you said myself?? table, 600 grit paper, circles??        how did you make sure you didnt actually "warp" it??.   did you measure the whole head (bottom 2 top of fin) to get your measurements??.. i only have this one head also btw....so the idea i spoke of(w/50% actually being covered, a plate over piston)), isnt right then??           oh no, what do you mean change everything?? id have to start all over again??      is this where i WILL HAVE to know these formulas??   god i hope not... wonder if #s in the manual could be used( if i can figure the formula)        i assume the matching, port map, math, etc. is gonna take a day or so

[art]

Hey bat I took my head to the machinest and after b.s.ing with him for awhile he did the shave for free!I broke the motor down for him of coarse,but he quoted a price of $40 for the exhaust.I figured what the hell at those prices!He normaly charges $150 to $200 for port and polish,When i told him I could get a whole kit at that price he decided to work with me a bit to see what we could do since not to many are doing these mods on scooters at this time.He seen my interest and it peaked his too!Anyway he did the head shave in about 2 min.once he figured the squish.The exhaust is still not done yet 

[Shaka]

If your squish is 1.27mm then the easiest way to only change the squish is use a thinner head gasket.  You will need to measure your head gasket then you will know what you are working with.  I know that both my head and base gaskets for my Airsal kit are 0.5mm thick.  I actually ended up making an aluminum base gasket that was 1.6 mm thick then removing my head gasket to get optimum squish while also raising my ports timings and duration.  I read the part about the exhaust, but don't really want to go there.

[zombie]

Bat has the stock head/jug, and the only gasket available is the stamped steel one. Like art said you can get someone to shave it for a few bucks or as I did use a known flat surface, and work it slowly on oiled Emory cloth. I measured from the squish band inside the head, as this part is machined, and true. the cooling fins are all off square. Even if you forget the rest of the porting/timming for now doing the squish will pay off w/ more pep, and quicker response

[Shaka]

Bat has the stock head/jug, and the only gasket available is the stamped steel one.

But you can always fabricate your own gaskets, I did!    The hardest part is finding the correct thickness material!

[zombie]

Oddly enough for us scooter'ers Beer cans make excellent gaskets. Two of my nc/50 engines have them. The oem gasket is going for 24.00

[thebatman]

i dont even have a clue as to my head  gasket.. it is alum??,idk, pretty thin i remember.. well i wws waiting on a call, trying to see if i can haveit done before i try it myself(squish band). i thought of this tho...is the .90mm squish gonna be ideal for all scoots, or for the bbks?  id hate to take .015in. off and it mess me up.. this is one of my issues with my scoot, i cant afford much down time with her since i dont have a spare...oops..lmao. figure the squish band, then try to match cyl,. maybe i wouldnt have much down time....            oh yeah, since my cvt changed with carb adjustments, guess its gonna change again with squish and/or matching??....

[art]

Mine has changed so much i'm almost back to stock weights