05-27-2011, 08:04 PM #1
Possible problem or just need repitched???
Last year when I just had the intake, grate, 83mm nozzle, and free mods I had you repitch my 15/22 with a setback and I was right around 8100 all summer with 74-75mph.
Now I added the wedge, waterbox, intercooler relocation kit, and BO's. At 3/4 throttle I'm hitting the rev limiter and my speed is down to 71mph or lower. Also have lots of cavitation from a start and in tight turns. I thought that my wear ring was bad but i checked the clearance and it was well within spec of what the manual said is allowed.
Is this normal of how drastic the mods make the prop pitch or should I check some other things out?
05-27-2011, 08:16 PM #2
Yeah repitching would most likely be your problem there if you haven't neglected any maintenance or winterizing, etc. You're talking mods that, theoretically, should add 3-4 mph...though this is a stretch. But if you were near the limiter before you should absolutely be on the limiter now I would assume. Look up repitching in the how to section its's very simple, just need an impeller removal tool, preferably the long one for repitching...
05-28-2011, 10:04 AM #3
Alright thanks. I just wanted to make sure I'm not missing something.
05-28-2011, 10:54 AM #4
I don't see any mods that you added that should yield RPM gains. The cooler temperatures are probably giving you 200+ RPMs. Try a 80mm nozzle ring before you go crazy. Dinging up the prop in any way by hitting a rock etc. can easily cause a gain in RPM and a loss in speed. Don't ask me how I know
05-30-2011, 08:32 AM #5
Lets think about this.......wedge lifts front of hull for less water friction on the hull, & the waterbox added a couple of HP. This alone will add some rpm/speed. Combine that with excellent weather conditions and suddenly you're over the rev limiter......in summer heat your ski was previously at 8100 rpm and now in cooler temps its over the rpm limiter.
Add more pitch to the impeller......but have it pitched for the summer heat. Keep a weather log of every ride and document performance changes of mods added.
05-30-2011, 09:14 AM #6
05-30-2011, 09:58 AM #7
I think the adjustable venturi is better because you can fine tune RPMs for different barometric pressures from day to day, or even on the same day. Each ring is worth about 40-50 rpm.
Users Browsing this Thread
There are currently 1 users browsing this thread. (0 members and 1 guests)
By XLT Chad in forum Yamaha ClassifiedsReplies: 4Last Post: 05-07-2011, 01:48 PM
By Rampage in forum Yamaha PWC Performance (2-stroke)Replies: 5Last Post: 06-26-2010, 09:47 AM
By SHOBiz in forum Yamaha PWC Performance (4-stroke)Replies: 6Last Post: 03-23-2009, 11:45 PM
By Pinoy in forum 4-Tec PerformanceReplies: 23Last Post: 03-08-2008, 08:33 PM
By dongee in forum Yamaha How To & FAQsReplies: 1Last Post: 07-16-2007, 07:04 PM