I've recently had the chance to compare multiple cylinders from different builders, one of which seems to pull taller gears easier than the rest. The hardest pulling motor seemed to have less agressive durrations than the rest. While most of the cylinders seem to be around 187*-188* of exhaust, and 127*-128* on transfers, the hardest running motor degreed out at 121* transfers (which is close to stock), and 187* exhaust.
I degreed a stock cylinder out at 177.5* on exhaust, and 120.5* on transfers
I was always under the impression that the transfers needed to be raised approximatley the same number of degree (maybe a little less)as the exhaust to make the most amount of power? The longer the transferes are open, the longer the cylinder will fill right (or atleast as long as possible without not having the proper amount of blowdown)?
The cylinders with the taller transfers seem to make a little milder hit than the other.
port timmings
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Re: port timmings
I am out..........
Last edited by gammabusa on March 4th, 2011, 3:46 pm, edited 1 time in total.
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Kinda like if a young kid goes to the hot rod shop and buys a huge cam for his stock SBC and it doesn't make as much power as a smaller cam would make!
Bigger isn't always better!!!!
Bigger isn't always better!!!!
00'cr500 trailclimber
93'cr500 beater
92'cr500 hillclimber
08,KTM SR500r hillclimber (conv)
89'cr 500 bent frame
04'crf230(wifeys)
02' cr125(sons)
02,pro jr 50 open exh. hill climber(sons)
02'sx65(sons)
03'xr50(sons)
93'cr500 beater
92'cr500 hillclimber
08,KTM SR500r hillclimber (conv)
89'cr 500 bent frame
04'crf230(wifeys)
02' cr125(sons)
02,pro jr 50 open exh. hill climber(sons)
02'sx65(sons)
03'xr50(sons)
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- Joined: July 4th, 2007, 6:57 pm
high transfers have their place, just as low ones have theirs also. any legitimate literature will explain the how and why and show proof in theory and practice. high ones can let excess charge into the pipe and also have reverse blow back into the tunnels. key word is CAN. depends what the rest of the cylinder is doing.
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- Joined: July 4th, 2007, 6:57 pm
Re: port timmings
have you done a map on all the cylinders ? that could give you some insight why one works better than the others. it goes well beyond just a degree wheel. takes a fair amount of time and requires good math skills.23champ wrote:I've recently had the chance to compare multiple cylinders from different builders, one of which seems to pull taller gears easier than the rest. The hardest pulling motor seemed to have less agressive durrations than the rest. While most of the cylinders seem to be around 187*-188* of exhaust, and 127*-128* on transfers, the hardest running motor degreed out at 121* transfers (which is close to stock), and 187* exhaust.
I degreed a stock cylinder out at 177.5* on exhaust, and 120.5* on transfers
I was always under the impression that the transfers needed to be raised approximatley the same number of degree (maybe a little less)as the exhaust to make the most amount of power? The longer the transferes are open, the longer the cylinder will fill right (or atleast as long as possible without not having the proper amount of blowdown)?
The cylinders with the taller transfers seem to make a little milder hit than the other.
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- Location: Australia