thumper135
Member
- Sep 20, 2009
- 33
- 0
this is how it looks at top..whenfoxforks-ruled said:6 speed straight, or high, low? Nice bike! What is the squish band now? From the edge of the piston to the lowest point of the head chamber?
how do i add pictures? my attachment quota's just 100kb which is used already and linking from places such as photobucket seems not to be allowed?whenfoxforks-ruled said:High compression piston, what, the stock one is flat? Got a pic of the head?
the wrist pin location is the same, the ring land area is somewhat different, also the newer piston uses a thicker 2nd ring.whenfoxforks-ruled said:There is an optimal distance between the top of piston and the edge of the head, the squish band. I do not recall the amount. Your problem is going to be getting the port timing back to where it will run properly. I can not see the if the wrist pin location is the same, but the ring lands are not! You need a professional engine tuner is an understatement. May be that Rich knows a guy??????????
Is there any why you can't get the rigth OEM piston for it?.thumper135 said:the wrist pin location is the same, the ring land area is somewhat different, also the newer piston uses a thicker 2nd ring.
port timing is exactly whats keeping the build progress at the moment.
the ring ends on the piston are exactly where the old piston has its.SHSPVR said:Is there any why you can't get the rigth OEM piston for it?.
Ok you said ring land area is somewhat different but dose both ring keep clear of the timimg ports?.
Base of what you said it look like you need shave and mill the cylinder base and case base at less 1.90mm that will bring your timing back in to stock spec.
Can you post a picture with 2 piston on the Wrist Pin or a picture with the old piston intall in the cylinder like other one.
What about the old piston that what I wanted to seethis is how short the new piston is from deck.
yes the old piston is flat. the old piston is no longer available to compare, it was a 56mm while the new piston is 62mm.SHSPVR said:What about the old piston that what I wanted to see
Look at this screenshot below
Are you saying that the rings are in exactly same place as the old piston has its with the Wrist Pin install for side by side view if that the case then your timing port shouldn't change and don't need shave and mill the cylinder base and case base at all.
Is that old piston a flat top?.
the deck clearance, the new piston was 2mm shorter in height from the deck.helio lucas said:what was the deck clearance with old piston?
simply shave the base to get the same amount and port timing will be the same and you´re done... this answer your question.
now the big question? why does the two pistons look different? old was high performance? not the same model?
are you not able to get one like the old? because later you might need one like the old one.
shaved it has been, 2mm in total has been taken out from the base of the cylinder. that's how short the new piston was from the old.whenfoxforks-ruled said:No professionals yet. My guy figuring says shave the bottom also, the same amount as the difference. Then check the head. The width of the ring lands are the problem though, you can get 1 side to match port timing, but, how to make the other stroke match? Vintage Bob
What he ref to is where ring gap is going when it going up and down in the cylinder bore is should contacting the cylinder wall at all time not near any port passages see below screenshot becuase sometime you have pull old pin out and move it in new place by re-drilling a new hole that holds the ring in place.ring land area, 2nd ring might be a problem?
This will not hurt at all in fact it should give you better fresh fuel/air mix transfersince it uses a thicker ring?
SHSPVR said:What he ref to is where ring gap is going when it going up and down in the cylinder bore is should contacting the cylinder wall at all time not near any port passages see below screenshot becuase sometime you have pull old pin out and move it in new place by re-drilling a new hole that holds the ring in place.
Also it necessary to chamfer the port edges. Rounding of the sharp edge prevents premature wear on the piston and ring assembly. Using a rotary burr to make the initial chamfer, and finishing it out with a sandroll, is a good way to get the proper angle and finish.
Take look here
http://atvconnection.com/Departments/ATV_Tech/Cylinder-Boring.cfm
This will not hurt at all in fact it should give you better fresh fuel/air mix transfer
You need pull that pin and move it and re-drilling a new hole in new place with out it crossing into any port.Now over here if you take a look at the top port passage you will see 1st ring pin crossing in the port. what next?
and leaving it as it is will cause problems? worth a risk?SHSPVR said:You need pull that pin and move by re-drilling a new hole in new place with out it crossing into any port
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