06-25-2010, 08:44 PM #1
What to expect from repitched prop
Hey guys, I really didn't want to start a new thread, but I posted this in another and couldn't get a response. I also did search for it, but couldn't find an answer to my particular question. Some background:
R&D Ride plate
R&D intake grate
R&D Trim Tabs
Solas (I think) 14/20
Wet Wolf adjust-a-thrust cone
Pump Shoe sealed
and 150 psi head
Now my question is that I am planning to have my prop re-pitched to a 13/19. Right now with the 14/20 the max RPM I saw on the tach was 6980 (this was early May temps too, high 60's low 70's). What can I expect from pitching the 14/20 to a 13/19? I know better hole shot, but will I lose some speed or not. I am not sure on the speed because this should put me back into the 7100 range where I should be right? If it does boost my RPM wouldn't my speed stay the same because of gaining RPM? Thanks for any info I get.
06-25-2010, 08:47 PM #2
Important thing is what are your rpm's in the heat? It was 6980 in the cool weather.
Are your carbs rejetted? Didnt see that in your signature.
06-25-2010, 08:58 PM #3
Well I haven't had a chance to ride it this summer yet...it blew up on me a week after I got it, so I am just going by what I saw for the 2 hours of riding time I was able to get out of it before it blew. As far as I know Vern didn't do anything with the jetting, but maybe he will chime in. Wouldn't the RPM's be even lower in heat?
06-25-2010, 09:19 PM #4
What was the problem with the engine in the first place? If it was running bad before it went down then you dont have a good rpm reading to start with. Your rpm is close though with nothing but compression done. Are you running the 85 or 87 nozzle?
06-25-2010, 09:31 PM #5
I really don't know. When I tested it at Verns it seemed to run great, saw 72 on the dream-o...and It was fine when I got it and rode it a couple days. Oh, and its the stock nozzle
06-26-2010, 09:47 AM #6
Stock jetting on carbs, they were rebuilt a few years ago, stock airbox, SS screen still in, just removed the sound suppression/bulb/hose in front of the airbox. Ran this way for 8 years, and Phil is right, rpms were usually 6950 - 7000 on the Tiny Tach.
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