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Post by 2strokd on Mar 23, 2010 7:44:59 GMT -5
Looks like your on the right track bud! Love the regular "car size" wheel!
Makes our motors look even smaller. And easy to read! 190,s got all the good tricks!
70% is what Bell says is 'safe', read about others going to%75
but who knows whats true and whats not?
Thats allot of grinding for sure but i think the Polini is the
better choice for your needs also.
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Post by 90GTVert on Mar 23, 2010 13:28:27 GMT -5
I had double checked before the mark. Triple checking was making sure that degree lined up with that mark. I had more time than I thought this morning. I managed to get it done, just didn't have time to take pics and upload 'em then. I raised the cylinder and widened it about 1mm each side. I tried to keep the same basic shape to the best of my ability. I also opened the exhaust port up from 22-23mm to just over 25mm and smoothed everything out a little.   |
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Post by 2strokd on Mar 23, 2010 13:55:28 GMT -5
A little HELL! Thats a mirror finish  ! GREAT JOB Brent, looks very pro! |
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Post by drawkward on Mar 23, 2010 14:05:01 GMT -5
Man I can't wait to hear how it does! Very good work! It really does look legit man.
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Post by 90GTVert on Mar 23, 2010 14:16:03 GMT -5
Thanks guys. I hope it runs legit. lol
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Post by 190mech on Mar 23, 2010 16:18:53 GMT -5
Beautiful job!!What is the exhaust port diameter at the flange
now?Read recently that the port should taper(1.6 degrees+/-)
from the cyl to the flange to aid in exhaust extraction.I never
paid attention to this little detail before....
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Post by shiftless on Mar 23, 2010 17:17:50 GMT -5
Killer work most inspiring  |
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Post by stepthrutuner on Mar 23, 2010 19:37:50 GMT -5
138 still is a bit high on the transfers,how much of the piston will be 'showing' if you pull some shims to get 130-132?We could trench the head,then raise the exhaust port to get around 192. Remember piston speed is a factor on a stroked motor,they always have a lower rev limit with increased stroke... Bell concerning piston speed: You can not arbitrarily say, for example, that all single cylinder 125s can be safely run at 12,000rpm. As a starting point, run the engine initially at a speed equivalent to a mean piston speed of 3800 feet per minute and work up from there to a maximum of about 4500 feet per minute. The mean piston speed is calculated using the formula: Mean piston speed (ft/min) = S x 0.00654xrpm S = stroke in mm |
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Post by stepthrutuner on Mar 23, 2010 20:47:35 GMT -5
If those lil' exhaust molecules don't decide to stop and primp and preen in front of that mirror finish this thing ought to run like a scalded dog. |
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Post by 90GTVert on Mar 23, 2010 21:10:54 GMT -5
Beautiful job!!What is the exhaust port diameter at the flange now?Read recently that the port should taper(1.6 degrees+/-) from the cyl to the flange to aid in exhaust extraction.I never paid attention to this little detail before.... It's just over 25mm at the flange. I say just over instead of a specific number because it's damn hard to port a hole round enough for a uniform measurement.... or at least it is for me. I have no idea what the taper is. |
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Post by 90GTVert on Mar 23, 2010 21:14:00 GMT -5
138 still is a bit high on the transfers,how much of the piston will be 'showing' if you pull some shims to get 130-132?We could trench the head,then raise the exhaust port to get around 192. Remember piston speed is a factor on a stroked motor,they always have a lower rev limit with increased stroke... Bell concerning piston speed: You can not arbitrarily say, for example, that all single cylinder 125s can be safely run at 12,000rpm. As a starting point, run the engine initially at a speed equivalent to a mean piston speed of 3800 feet per minute and work up from there to a maximum of about 4500 feet per minute. The mean piston speed is calculated using the formula: Mean piston speed (ft/min) = S x 0.00654xrpm S = stroke in mm Using that, my mean piston speed would be 3800ft/min @ roughly 13,000RPM. |
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Post by 90GTVert on Mar 23, 2010 21:16:21 GMT -5
Just to update everyone, I sent a package off to 190mech earlier today. He's going to lighten 2 more flywheels for me and cut my cylinder head so I won't be smashing the piston into it. ;D Very cool!
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Post by 2strokd on Mar 23, 2010 21:25:01 GMT -5
Good idea!
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Post by 90GTVert on Mar 23, 2010 21:29:07 GMT -5
lol Yeah. I figured the clack clack clack would get old after a bit.
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Post by 190mech on Mar 24, 2010 4:35:25 GMT -5
Dont like that diesel sound?13000 is just a wonderful piston
speed limit!!!
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! GREAT JOB Brent, looks very pro!
