list of mods

T

tuf720

New Member
hi all iv started to mod my motor so iv plained the head machined a squish band, timed the inlet port bevelled the piston to time the exhaust opened up the transfer ports no base gasket and head gasket opened up the carb just waiting on my 19mm carb with an idle circuit and mixture to its got lots of compreshion now its a little hard to start it locks up the back wheel. its strong through the mid range and bottom end and keeps on winding up, up top and all so made an expansion chamber iv got still got 44 tooth sprocket and got clocked at 70kms or 43.5mph so is there any more i can do i think i need a new bike it runs out of brakes
 
google 'tiny tach' ...have heard good things about them (cheap, reliable)
they work off of the pulse from the plug...you need to get the one for a 2stroke
 
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Using gearratio.exe and allowing for a 26" wheel it would seem you are turning 10,000 rpm at 70km/ph

If its a 27" or 700c wheel then its 9300rpm.

3 or 4 thousand over the designed max.

Not likely or she's about to blow, better get some steel plated undies.
 
i better get some steel plated undies. i just had a car follow me to get the speed i'm a mechanic and can't help my self playing with it i'll double check and find a mini tak and make a vid to show you all the car speedo may be out . iv only got a chinese motor they are cheap worth a go to make it fast as evey one over here just likes to putt around. It was 70km an hour and I converted it to miles (43) as we go by kms not miles.
 
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congrats on the performance you've achived!

Just wondering, what is the rear wheel size and what engine you got? I'm guessing a 26" wheel and a 50cc engine? No way a stock (unbalanced) 66cc could rev to 10K or did u balance the engine too?
 
its a zbox kit its unbalanced its the z80 kit i have no idear what it revs to pritty sure its a 24" rims iv made a custom slide needle to tune it and im just trying a 25/1 mix yes its not susjested but i will be pulling it apart to have a look on whats happening in there and i think openng up the trasfer ports made a diffrence and opening up the inlet and exaust port to wider and and given them a lead in
 
I found this site with a tach for $ 12.00 ENM counting Instruments http://enmco.thomasnet.com/viewitems/enm-counting-instruments/tach-hour-meters-pt16-tachometer?&plpver=1001&bc=100|3001175&forward=1
 
Well if you going 70K's on the Z80 you have been VERY lucky and got a great motor - bit of a lottery with these Chinese engines lol.

Yeah, a custom slide needle is a great upgrade if you have the time/tools to make it. I made one for my Z80 and tapered so that through out the RPM range the bike has a good fuel air mix and no 4 stroking - plus I noticed it revved harder and higher.

Oh, and dont pull apart the crank case - if you engine revs high no need to balance it. However, Id take the head/cylinder off and open up the intake and exhaust (Widen, not tallen the ports). Good luck
 
70kmh! sorry dude 44tooth sprocket on a 24" wheel or even a 26" and 50cc
I have modded my 49cc by lowering inlet and raising exhaust port this did increase the top rpm by about 500-1000rpm so 7,000ish rpm screaming! 59.5kmh is all i could squeeze out on the flats, limmiting factor is the sprocket as stated your talking about 10,000rpm + grenade territory
Get a speedo measure your wheel or get a gps.
 
My top speed is about 65 so I do beleive this claim, there must be some of these motors that were built as was "Herbie". that is what I call mine.
 
we have mesured the rear wheel and removed the spark plug and counted revolutions and came to 18 tdc per one rev of rear wheel. and tryed again and clocked at 65km by a nother older car so im doing 65 to 70 ks. and at 65ks its about 9500rpm and 70 its 10100rpm and runs mint.ITS A CHEEP MOTOR SO IF IT GRANADES I DONT CEAR OK ILL BULD A NOTHER i just want to push the boundres of these little motors and have fun. iv steel in forsed my seat ill tell you how long it lasts.
 
on holaday at the mo they will happen sooon just need to fix the bike came of it and broke a rib need to straten the rear wheel and brace the frame it cant handle the motor lol
 
tuf720 said:
on holaday at the mo they will happen sooon just need to fix the bike came of it and broke a rib need to straten the rear wheel and brace the frame it cant handle the motor lol
Click to expand...

I did some minor mods to my kings motor bushing happytime.
Very nice !

Now I discover that I am afeared to ride it.
Wayy too fast .
I keep snapping the brake mounting bolt off the front and rear.
So far this has not happened to both the front and rear at the same time thank goodness.

I am currently using the hardest bolt I an buy locally.
A set of pads only lasts about a week now.
It is so easy to go too fast I can not seem to control myself and speed along.
 
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