china bike 122cc dohc 4 valve project

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I'm pretty sure that the engine has to match what the plate says not that it's going to stop anyone...

Hans, Yamoto make a cheaper one for less than $2,000 (they pop up on eBay sometimes for $1,500). It's good for nothing other than the roadworthy part but you could swap everything with your own components i.e: suspension, rims, tyres, etc.

And back on topic... loving your work tormentandglory! Good to see someone doing things a little differently.
 
Cam chains! Does anybody else have trouble breaking those? The china chains are sooo crap. I think they're made from a mix of cheese and rubber bands. Swapping the chain for a kitaco, or even just a D.I.D heavy duty aftermarket is a very good idea.
 
tormentandglory said:
Cam chains! Does anybody else have trouble breaking those? The china chains are sooo crap. I think they're made from a mix of cheese and rubber bands. Swapping the chain for a kitaco, or even just a D.I.D heavy duty aftermarket is a very good idea.
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Soo right...thats the first what had to go when I alterate an engine ...and bytheway a kitacochain cost not that much ..so better be sure than sorry:p
 
Got my cylinder head back today, but rams couldn't machine it :( Anyone know a good machine shop that can deal with 4mm valve stems and a 16.5mm valve?
I got my cylinder and piston back today to. The piston has been coated by HPC. Ceramic on top and teflon on the skirts. Looks super trick.
I haven't made any progress in the last 2 weeks, hopefully get the external oil lines and the cam chain covers made up in the next few days.
 
Theres a couple of pics of the piston. Its a modified yx140 piston with a ceramic coated crown and teflon skirts.
 
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better heat resistence??...is the teflon on the skirts equal to molybden nitrate??...got a piston from akunar and never used him...but its black not blue
 
The teflon anti friction coating performs much the same as the black stuff does. The blue coating is a bit thicker though. The ceramic coating on the top prevents heat loss through the piston. In theory it should help keep the oil temperature down because the underside of the piston will be cooler. The rings and ring lands will also be cooler, so they should last longer. More heat is retained in the chamber so (in theory) it should make more power.
I'm not really convinced though, trapping excessive heat in the chamber and preventing its disipation is just as likely to cause detonation. Especially in a high compression air cooled motor. Hard to say really, unless you tried a coated and uncoated piston in the same engine. I got it done for nothing so I'll run it and see how it goes.
 
hey how much did it cost to get the piston coated?
and how thick is the teflon coating?
great project
if you go on planetminis.com theres a guy on there making a few custom 4v heads sohc and dohc, might be a good idea to talk to him
 
redheadracer said:
hey how much did it cost to get the piston coated?
and how thick is the teflon coating?
great project
if you go on planetminis.com theres a guy on there making a few custom 4v heads sohc and dohc, might be a good idea to talk to him
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The teflon is about 0.002" to 0.003" thick. They also do a different coating which is about 0.001" thick, so either way your barrel will most likely need to be honed a bit before you assemble your motor. I think its about $30 per piston, but I'm not sure, I didn't pay for mine. Google "HPC coatings". They shouldn't be that hard to find.

You run a 56mm bore x 49.5mm stroke in your motard? How does it perform? Thats the same spec as my twincam. I'm expecting it to be a much nicer motor than the long stroke china's.

I got my head back today! Yey! The valve seats have been machined and it looks pretty good. A big thankyou to Hans for putting me onto Lada! :) I should be up and running in a week or so I hope... Watch this space.
 
Pics of the chamber. Still needs a bit of a kiss from the die grinder but its basically finished.
 
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Thats good to hear mate...glad it all worked out for you..im sure you lada would have looked after you...im hangin to see this little monster of an engine running...nice work
 
tormentandglory said:
The teflon is about 0.002" to 0.003" thick. They also do a different coating which is about 0.001" thick, so either way your barrel will most likely need to be honed a bit before you assemble your motor. I think its about $30 per piston, but I'm not sure, I didn't pay for mine. Google "HPC coatings". They shouldn't be that hard to find.

You run a 56mm bore x 49.5mm stroke in your motard? How does it perform? Thats the same spec as my twincam. I'm expecting it to be a much nicer motor than the long stroke china's.

I got my head back today! Yey! The valve seats have been machined and it looks pretty good. A big thankyou to Hans for putting me onto Lada! :) I should be up and running in a week or so I hope... Watch this space.
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ok cool, i was thinking of getting one of the 57mm ceramic kits, coating the piston and honing the barrel, becase from what i have hurd the barrels are a littel out of round... so that seams like a good option.

my 56x49.5 motard screams, revs higher then the 52.5x55.5 with the same setup and has a lot more punch mid to top, and the bottom is pretty good too. i love it.
 
I haven't seen a chinese ceramic barrel first-hand, but I would think that they're not honable. The ceramic coating used in other engines is very thin. Very hard too.
 
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Its nearly finished! All the machining is done. Start assembling on the weekend.
 
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Yeah, its bigger than a stock 3valve head. That pic makes it look a bit funny. I'll put another one up. And for the person who wanted to see the camchain set-up, check out the link. Its a vid of the camchain operation :)

http://www.youtube.com/v/vscfWNN3J1M
 

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