Timing

Oldfart1stATV

New Member
Oct 29, 2007
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Well, drank a couple beers and did some measurin'. Ol' vito did some work to make his kit work. He cheats the stroke and timing with a notch on the piston. The porting is pretty cool and should give improved air flow. A good P&P job may make a nice unit out of this, I don't know. What it is in a nut shell is a new sleeve in a stock cyl. with a little bit of new channeling. The timing on this is pretty critical. A few degrees advanced will be nice, but a stroker will impair it's working. By raising the stroke the timing and notch are now off, so she is not going to be happy.

I'd say don't stroke a vito's without a want to do other machining. Which all said and done will get you up to a diff. big bore price range pretty quick.

That said, I think a couple degrees advance timing, a fat exhaust and bigger carb is what this was designed for. When I get it put together i will let you know.

I would not call this a good mod. for a serious rider. If I was racing these for bucks and what not, I'd go another route. You are limited with what you can do to these.

BTW, good fit on all the parts. Bore is German pussy tight, rings are snug and all surfaces are flat as an 8yr old.

I hope she sounds a little deeper!!

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BTW hit 200 posts!!! have I said anything yet??
 
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congrats on the good work!!!,ok for your timing port prob here is a solution thats we doo on my friend vito's 240 with 4mil crank,just order a big bore piston from ct-racing or wiseco you wont have the notch in the piston and it will adress your timing issue, been there done thats trust me!!!
 
Hmmmm?

How do you have the cyl. mounted? Any spacers, or just a gasket? What did you do to the head? How did you trench out the crankcase? How close is the sparkplug?

AND, most of all, how is the performance? I know I can get her to run and more than likely be better than a stock 200 motor, but that notch is leaving power on the table and the bigger the stroke, the more it leaves.

Oh yea, does anyone know if there are any pistons with diff. ring height? I can get a custom set of pistons in any form I want for a V-8. I'm figurin' the same would be true for this...at 1/8th the price!!! I would think that dropping the ring set 1mm and dropping the piston top 2mm and going with a flat top design would be the trick. Save you the head work do what the notch does and get the 10cc from the 4mm stroker. The timing @4 advance should cap it off.

Way too much math, but, if anyone has done it....

Oh yea, do the stock reeds feed this pig? Lot more volume in there, seems like a new cage would be in order.

I dunno, will know more later when I start putting big pieces together.

A
 
How do you have the cyl. mounted? Any spacers, or just a gasket? What did you do to the head? How did you trench out the crankcase? How close is the sparkplug?

AND, most of all, how is the performance? I know I can get her to run and more than likely be better than a stock 200 motor, but that notch is leaving power on the table and the bigger the stroke, the more it leaves.

Oh yea, does anyone know if there are any pistons with diff. ring height? I can get a custom set of pistons in any form I want for a V-8. I'm figurin' the same would be true for this...at 1/8th the price!!! I would think that dropping the ring set 1mm and dropping the piston top 2mm and going with a flat top design would be the trick. Save you the head work do what the notch does and get the 10cc from the 4mm stroker. The timing @4 advance should cap it off.

Way too much math, but, if anyone has done it....

Oh yea, do the stock reeds feed this pig? Lot more volume in there, seems like a new cage would be in order.

I dunno, will know more later when I start putting big pieces together.

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ok we put a 60mm spacer,trench the bottoms of the casing with a die grinder (just where the rod pass)the head is mill 25mm,and the spark plug is 25mm closer than stock,we use a ct-racing (wiseco)big bore piston,pj34mmcarb ,g3 reed and vito's reed spacer,we use a ct pipe right bend pipe,and +4deg timing on the timing plate,and i did raise exaust port 0.10mm,its running on pump gas 93 0ctane plus klotz octane booster so its running about 96to97 octane,at 32to1oil mix ratio the quad iis running for about a year and still running strong,ah and yeah i port match the piston too,its running at 170psi of comp and we did not dyno it but my guess is around 30to35 rwhp and there you go if further info needed you know i will be there for you!!
 
THANKS!!!!!!!!!

How much work on the piston/ports did it take?
"60mm" spacer?
"25mm"?

I'm assuming 6mm and 2.5mm is that correct?

What jet in the PJ?

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How much work on the piston/ports did it take?
"60mm" spacer?
"25mm"?

I'm assuming 6mm and 2.5mm is that correct?

What jet in the PJ?

A
not much work on the piston port , you put the piston in the cylinder and you match the piston port to the cylinder,(just put the piston in and take a marker and trace it on the piston by the intake and remove the piston and remove material take about 20min to do so,and yes 6mm and 2.5mm and jet size is 165
 
Awsome!!!

Thanks a ton!!! I have see which jets i have, now. Now if I can only find the time....


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