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Grumpy225
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Mon Aug 17, 2015 7:50 pm

dutch wrote:update to previous, on rich taylors advise i change the gearing to 17/46 and it is much better at high speed ie not revving so high and so not getting so hot.

I have a garvin gps speedo and have had it at 67 mph and still not revving very high, i have just put a bgm clubman on as i think it will let it rev a bit more and should reach 70mph with ease and still not revving the nuts off it.

I know a lot of people will say they go faster but this is with a gps speedo not a lammy one so more accurate. 65mph is the speed i like to sit at on motorways so more than happy.

if it's getting too hot then there is a jetting/ignition/cooling issue that needs to be corrected.

Also some of the replacement RD pistons have been known to drop ring pegs. It's a common problem. Last I researched this issue it looks like ProX pistons are the good ones and the Wiseco were the ones having problems but that was about 5 years ago.

dutch
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Tue Aug 18, 2015 7:48 pm

if it's getting too hot then there is a jetting/ignition/cooling issue that needs to be corrected.

Also some of the replacement RD pistons have been known to drop ring pegs. It's a common problem. Last I researched this issue it looks like ProX pistons are the good ones and the Wiseco were the ones having problems but that was about 5 years ago.[/quote]


the reason it was getting too hot was cos it was revving too high but with the change of gearing is much better, i was worried about the piston but think it will be ok now running cooler.

psychedelicropcircle
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Tue Aug 18, 2015 8:12 pm

Thread swerve.....does anyone know the temp gauge you use in the porcupine head it's a K type thermocouple unsure of mm size for the screw in ? Link recommendations welcome.

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Rich_T
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Tue Aug 18, 2015 8:41 pm

it is a 1/8th NTP thread with is pretty standard on all EGT gauges or K type thermocouples.

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Yanker
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Tue Aug 18, 2015 9:29 pm

dutch wrote:if it's getting too hot then there is a jetting/ignition/cooling issue that needs to be corrected.

Also some of the replacement RD pistons have been known to drop ring pegs. It's a common problem. Last I researched this issue it looks like ProX pistons are the good ones and the Wiseco were the ones having problems but that was about 5 years ago.

the reason it was getting too hot was cos it was revving too high but with the change of gearing is much better, i was worried about the piston but think it will be ok now running cooler.[/quote]

Sorry but that is complete b@11@x: RD350 pistons should be able to handle 10 - 12k rpm and NOT fail at 6 - 7K

That gearing will give you 4:8 final ratio with the completely s**t 3rd to 4th ratio change of the GP150 box and be a ballache to ride. 16/47 would be my choice....

dutch
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Wed Aug 19, 2015 5:55 am

Sorry but that is complete b@11@x: RD350 pistons should be able to handle 10 - 12k rpm and NOT fail at 6 - 7K

That gearing will give you 4:8 final ratio with the completely s**t 3rd to 4th ratio change of the GP150 box and be a ballache to ride. 16/47 would be my choice....[/quote]


it rides fine and 3rd to 4th bit of a gap but still no problem as the gt has the power to pull it so the proof is in the pudding , as for the rd piston, in an rd at those revs would not reach the heat of a lambretta engine and rd would be lc, you cant compare an rd to a lambretta engine.

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