04-27-2013, 09:11 AM #1
2000 Yamaha XL 800 looking for some advice
This seems like the most honest group of folks on the web...I'm expecting some brutal honesty here! I'll caveat and say that this is the family waverunner and we will frequently have inexperienced riders using it, so I'm not looking to put much cash into it beyond what it takes to keep it working right.
I've got a 2000 Yamaha XL 800 with about 200 hours on it. I rebuilt the top end but did not have the cylinders replated or sleeved, and after the rebuild have compression of 120 in the front and 115 in the back. In addition, I had the carbs rebuilt, installed, and set by the dealer. I also replaced the power valve servo motor and cleaned the valves and installed the waveeater clips while I had the engine apart. Replaced plugs, etc. Dealer inspected the exhaust from the manifold all the way back and found no obstructions. Runs great and takes off reasonably well, minimal cavitation for a waverunner this big and relatively underpowered for its weight.
My question is...the ski is revving up close to 7000 no problem, but my top speed is about 40 mph, whereas I gather this ski should break 50 pretty easily. The only odd thing I notice is that as I hold the throttle, it seems that the waverunner doesn't respond any different from 3/4 throttle to full throttle. I would think this means that the throttle cable is adjusted too tight, but I'd appreciate some thoughts as to how to check if the throttle is in fact opening all the way.
Attached are pics of my jet pump and impeller. The impeller has a few dings but very little on the trailing edges, and the clearance looks very tight. I can get little more than a business card between the impeller and the wear ring. I wouldn't think the pics attached suggest the unit should be running 10 mph slow on the top end.
So I guess what I'm asking...if everything is working properly, what kind of top speed should this unit produce with 250# of weight and the compression numbers above? Maybe everything is fine? If not, does the jet pump look ok? I inherited a R&D Intake Grate with the purchase that I haven't installed as from what I've read it seems like that benefit is mostly produced when matched with a different pitched impeller. Should I install it without a new impeller? If I do, is it installing a pump shoe filler kit if I'm not doing any other mods?
Thanks in advance...I know you guys want to talk performance, but in my other hobbies I've found the performance oriented guys also are in the best position to say what works and what doesn't.
04-27-2013, 09:45 AM #2
My buddy had one, 2001, but same ski, he put in a Solas impeller that made a huge difference, his speed was 53-54 GPS, rider weight around 180lbs. I would think you should be able to hit 50+. When you did the work on the motor did you replace the oil lines and check flow? His blew up 3 times..1st from water getting in the gas tank from a small crack in the seal, 2nd-not too sure on cause but think it was the oil line or not letting the pistons heat up-Wiesco--(never replaced oil lines but rebuilt again) and 3rd time blew lack of oil. They fixed it one more time and traded it in! Impeller looks a little banged up from the rear like something went through it, not sure how the leading edges are get up under it and take some pics from the front area. Tolerances look tight.
04-27-2013, 05:43 PM #3
04-27-2013, 07:46 PM #4
I think I'll go ahead and pull the intake this week and take some pics from the other side as you suggest. But assuming the leading edges are ok, would a dinged up impeller cost 10 mph, or is this just a 120 psi motor giving all it can?
04-27-2013, 07:50 PM #5
04-27-2013, 08:47 PM #6
Feel both cylinders after a ride. Maybe you're losing spark in 1 cylinder?
04-27-2013, 08:54 PM #7
It won't do much over 50 stock... I had one and it did high 40's... The 1200 does about 50+
04-27-2013, 10:31 PM #8
04-27-2013, 10:33 PM #9
04-28-2013, 08:12 AM #10
Look under the ski for things that could cause drag as it glides through the water. Is the pump shoe/intake grate hanging down low or the ride plate shimmed or hanging down? or maybe you need a pump plug kit. just throwing some thoughts out there
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