06-14-2010, 11:26 PM #1
What do you all think?? 93 SJ modded...
I am new to this forum but my father (LT1GMC) is not. He bought our first Yamahas (and since then ONLY Yamahas) in 1993 when I was 13....I am now 30.
I have a 1993 SuperJet, mods listed in my signature, with the addition of a Solas Concord 13/19 impeller, trued pump and veins, and running 32:1 premix
This is a 760 big bore off 701 cylinders, ported intake/exhaust, dual 38s, welded crankshaft, etc.) All in all, when it's all said and done it's probably making 115HP...
My question to all of you is this. When the engine was new (2007) the ski ran 59 MPH on the GPS....
Now, It's lucky to get 55 or so.....
Is that just wear on the engine? Is it my 20 pounds of weight gain since 2007? (got married, used to weigh 190, now 210)...Or is something else amiss that I could fix....
Keep in mind I ran both these top speeds on my knees...Yes, that's right, knees, b/c I have been pitched off that beast too many times going 50+ to do a top speed run standing up. When I get above 50 or so it likes to start start tilting, and it's enough to overcome my balance control. Even on my knees I have been pitched off when the hull starts wandering... I think it needs sponsons to correct this; as the WORX rideplate I installed already has skegs/fins (thanks to Dad who machined and installed the stainless steel fins)
So in total:
1st question-why the loss in speed? Maybe pump leakage? Need a new nozzle? (still running stock one) engine wear?
2nd question-why does is want to throw me off at 50+ MPH? Speed exceeding hull (I doubt since I remember SJs doing those speeds in the racing days), need sponsons?
Thanks for any help!
Users Browsing this Thread
There are currently 1 users browsing this thread. (0 members and 1 guests)
By konabiker47 in forum 4-Tec PerformanceReplies: 11Last Post: 06-07-2007, 01:04 AM
By ABBOTT in forum Yamaha PWC Performance (2-stroke)Replies: 20Last Post: 07-26-2006, 07:17 PM
By Pistonwash in forum Yamaha PWC Performance (2-stroke)Replies: 8Last Post: 03-17-2006, 06:16 PM
By sbogi in forum Yamaha Open DiscussionReplies: 3Last Post: 11-29-2005, 05:40 PM
By seadoo02xp in forum 4-Tec PerformanceReplies: 11Last Post: 07-27-2005, 05:08 PM