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2003 Yamaha XLT 800 66e Projects

28K views 272 replies 5 participants last post by  neppy5 
#1 ·
It is a build thread, filled with pictures, my random questions, and hopefully some decent answers, tip, recommendations. I am a newbie to the PWC scene but somewhat of a wrench-turner. Purchased 2x 2003 Yamaha XLT 800's to rebuild as a project. I'll be building the thread as I go, just wanted to get it started tonight.

 
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#3 ·
It's a start!

Both were running at time of purchase. Unfortunately I had not done my homework before purchase. Skis both had about 130 hours. I bought them on Saturday and was on the lake Sunday, ski #1 ran great until something broke with the impeller, ski revs but doesn't move. Ski #2 ran ok until it would not start without constant manipulation of the choke. Ski#1 is on the trailer while I work on ski#2 as it was more of a major issue though I plan on rebuilding both engine. I was unaware that both oil pumps had been removed so I plan on reinstalling the pumps with rebuilt lines and going back to stock. The pumps don't fail, its the hoses and zip ties that fail. I don't want the hassle of premix.

Picked up a cherry picker from HF, a sling, and built some ******* rollers for the garage. Couple pics below.

Dave in DE, you are one of the reasons I came to this forum to post. Your knowledge and willingness to help on the Yamaha forum is undeniable. Thank you for posts, past, present, and future.
 

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#4 ·
Thanks for the kind words
The use of wire ties for the oil lines is ok but you must use a wire tie gun to get them tight enough to hold. The pumps are great and are veriable ratio. At Idle it's around 200/1 saving oil and fouled plugs all the way up to 30/1 at full throttle.
I have 2, GP800r's an 01/02 the 800is a very strong motor with a nice power band. I have done my research on them and my Two will carry max load at 56 mph. Stock motor, and blueprinted pump solas impeller.
 
#5 ·
Engine Breakdown

For rebuilding, I am leaning towards Oetiker clamps when replacing the oil lines. I have the motor out of the hull with the head and carbs off. I was posting on a different forum but hadn't received much help. Apparently no one likes discussing the older smaller 2 cyl 800's.
 

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#6 ·
The Oetiker clamps are nice and work well. I've never used them though. The last 2 weeks I've been enjoying my vac lake house in upstate NY. On the finger lakes. Pic is me and my daughter enjoying the afternoon at the park with my cousin and his daughter. This is 02 it has all of 47hrs on it and all original except for impeller.
 

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#9 ·
Nice! That pic looks oddly familiar to a spot here at Old Hickory Lake in Middle Tennessee us locals call Two Foot, names pretty obvious. I am trying to get these skis torn apart and back together before Summer 2020, ha! In all seriousness, before the end of July I hope.
 
#11 ·
Wsm is a good parts supply, there valves and links will be fine. From what I can see in one of your pics at least one of your cyl's appears sleeved.
I looked at your post on the other forum and posted. That forum can be very picky on what they reply to I use it rarely and post if I can help.
Get a plastic dish pan. There about 11"x 15" and 6" deep. use mineral spirits and clean everything up real good. Change the spirits if it gets really dirty. Then use a spray bottle mixed with Dawn dish soap and water. About 1.5 tablespoons of soap to a quart of water. Spray the parts and hose them off. Dry well and coat any machine surfaces with 2stroke oil to ward off rust.
The reads you posted on the other site are bad and more than likely are the cause of your poor compression.
What were your compression numbers on both cyl?
I have any and all specs on the 800 with me so Holler if you need them. Do you have a manual? If not get one asap.

Where did these skis come from local? Have they been in saltwater? The skis look well cared for but motor looks rough like saltwater and not cleaned or flushed?
 
#16 ·
From what I can see in one of your pics at least one of your cyl's appears sleeved.
I'll try to clean up the engine over the weekend and get some more pics.

I looked at your post on the other forum and posted. That forum can be very picky on what they reply to I use it rarely and post if I can help.
Ha, the very reason I came to this forum.


The reads you posted on the other site are bad and more than likely are the cause of your poor compression.
What were your compression numbers on both cyl?
75 in the front, 85 int he back.

I have any and all specs on the 800 with me so Holler if you need them. Do you have a manual? If not get one asap.
Yes, I have a service manual.

Where did these skis come from local? Have they been in saltwater? The skis look well cared for but motor looks rough like saltwater and not cleaned or flushed?
Skis were purchased from North Alabama. He mentioned he owned them for 2 years and bought them from Florida, about all the history I have on them unfortunately.
 
#14 · (Edited by Moderator)
Have you ever rebuilt a carb?
For your carbs get MIKUNI kits ONLY. Go one at a time. Carb 1 and carb 2 are different. So one at a time mark and then slowly turn in both your high and low screws. Record how many turns on each. It may be 1/2, or 5/8 of a turn. Or could be 1.5. I mark the carb body on the edge of the screw hole with a small sharp chisel and very lite tap of hammer. Then disassemble with camera Pics for reference. And let soak in the carb cleaner.(a gallon can pre purchased from auto parts store) I know Napa carries carb cleaner in cans. I'm sure most the others do to. Soak it over night works best agitation once in a while helps but not to hard. Then rinse with hose and blow dry with air if you have it. Then use carb cleaner spray to spray through every office you see. Then follow the drilled return mod under "how to's" and clean again with spray cleaner and reassemble. Reuse your old needle/seat spring.
Items needed:
2) mikuni kits
2) 1.2mm needle and seat
1) Gallon can of carb cleaner
2 or 3 cans of spray carb cleaner
1) 87.5 mikuni main jet for mod.
1) 5mm tap for mod. "Local hardware"
Mikuni kits and jet from: watcon.com for kits and needle and seat and jet.
Sbt for excelerator pump diaphragm, needle and seat, kits. "No jets"
 
#24 ·
Carbs? CARBS!!!



Short answer, No. I did just rebuild a carb on a Ryobi blower but no where near as complicated as this set. I picked up two Mikuni carb kits from Bay Area Powersports. I had to return the aftermarket set to them and just exchanged for this SET that includes genuine Mikuni kits, needles and seat.
 
#15 ·
Going good, staying busy with 2 both jobs, and up keep of mine and the in laws properties. lol
Finally got the 1100 on the water last weekend for a couple of hours until the lower pivot bolt on the steering nozzle came out some how. Luckily had another one from the project ski. Not real happy with how it ran, but it ran. lol For some reason I had the slow speed screws out like 1 3/4 (way off lol). Also found out the temp sensor was severely restricted. Just a small stream at speed. Had to disassemble it to clean the crud out. Looked like pipe thread compound.
Either want to get a late model Complete ZXI minus engine, or a Gp. Gp's probably don't porpoise as bad as the ZXI's, but never been on a GP, so don't know. Just not real fond of power valves at all.
 
#23 ·
It was a brand new gauge, I may not have held the throttle wide open when testing though. If I get some spare time tonight, I'll compression check the other ski just for another set of numbers. I'll do it the way I did the first ski and I will test with the throttle wide open.

My garage is too small for both ski's so unfortunately it is one ski at a time. The second ski is on the trailer outside. I was planning on tearing it down regardless so both ski's are identical in service requirements and timeline.

I hope to have requested pictures to you this evening. Do I need to separate the cylinders from the crankcase for best view? I guess they will need to be removed at some point even if I just have them honed.
 
#29 ·
Cylinders and Power Valves

Finally got some work in and was able to break down the cylinders and power valves. It appears the installed power valves have already been updated. I have all screws undone, do the valves lift up out of the slot to the cylinder? I cannot get mine to budge. I have attached cylinder pictures to determine if I am sleeved or not. Thanks for the help.
 

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#31 ·
I marked the tell tails of being sleeved in red on the left cyl in pic. Note the parting line just in from edge.
Just for info. look at the sides on your connecting rods. See if they says "SBT" on it? Someones been in this motor before. No biggy just need to make sure all is there and correct as you go. unlike an original that you know everything is as it should be.
 

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#32 ·
This is where I am a bit confused. So the factory nikasil coating has been removed (bored) and sleeves have been installed due to damage to the cylinder walls that could not be repaired. How many times can a sleeve be bored and honed? Do I need to return my +1mm kit and get a standard bore kit or can the sleeves be bored out to accommodate the larger pistons?

You are correct Dave, can confirm rods say SBT.
 

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