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Discussion Starter #1
I have finally got a chance to try my summer project out. Keep in mind that it is a fresh motor but I expected to see an increase in rpm. Last year It was stock engine with a BMP pipe, cudney clutch kit. This year I added new piston and rings, cudney head 13:1, porting, ceramic coated the pipe, and what I think is the proper jets, 20 pilots, shimed the needle,410 mains. The sled has improved but I have not seen 8000 on the tach yet. With this set up I have been told to clutch for 8100 or so and probably add a little weight. I left it where it was from last year and expected to see rpms too high but thats not the case.
 

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journeyman sled/motorhead
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is it jetted right? plug and wash ok? assuming it is making more hp they (rpm's) should be higher now as it is easier to spin. secondary up shifting to fast for the powerband now, maybe? you could have narrowed the power band even more with the port job. did you change the port timing? moving the peak hp up higher in rpm.
 

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Discussion Starter #3
Yes the peak HP has been brought up 300 rpm or so. Port timing, not sure but they told me it would make more power in mid to high, so probably. The jetting, I started out where Cudney told me to. ( A starting point) . I havent had a chance to check the plugs and as far as piston wash, dont know. I guess I have to start there.
 

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journeyman sled/motorhead
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Yes the peak HP has been brought up 300 rpm or so. Port timing, not sure but they told me it would make more power in mid to high, so probably. The jetting, I started out where Cudney told me to. ( A starting point) . I havent had a chance to check the plugs and as far as piston wash, dont know. I guess I have to start there.[/b]
that is where I would start. you need it running right to get the clutching right.
 

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Discussion Starter #5
I put 150 km on today and I feel that the jetting is very good and the motor is pretty close to be broken in. The sled revs maby 1 or 200 rpms more now but seems to be where it was before the mods. Do you think I have to take pin weight out to get it up to the 8000-8100 mark where its suppose too make the most HP? I was expecting the sled to need pin weight added?? The clutch kit is a Cudney.
 

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Discussion Starter #6
I had a chance to play a little. I added more weight and it pulls harder but revs are the same. On a long haul it will almost hit 8000. The sled is running strong but Its recomended to run at 8100-8200. Maby I need a diff. spring? :confused:
 

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journeyman sled/motorhead
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4,440 Posts
I had a chance to play a little. I added more weight and it pulls harder but revs are the same. On a long haul it will almost hit 8000. The sled is running strong but Its recomended to run at 8100-8200. Maby I need a diff. spring? :confused:[/b]
heavier spring will bring the rpm's up.
 
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