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  1. #1

    Join Date
    Jul 2010
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    yamaha xl800 engine rebuild?

    First let me say that I have read hours of threads on this site related to this.
    OK, Got in a hurry and Picked up a 2001 xl800 couple months ago without proper testing. My bad. Got 5 weekends out of it before it gave up. Lost comp. on pto cyl. Pulled head. Top ring on pto cyl. is scatered around, ie pieces stuck in head and top of piston. PV is still there but the side of the piston close to the valve is messed up like something is hitting it. There seems to be clearance between piston and valve. The motor had a tap at idle but would go away off idle. The guy I got it from said it was normal for this engine. (I'm thinking not) The mag cyl. looks good but has a lot of piston to wall clearance and by the way, the pv is missing. Looks like it broke off the stem.( I here thats common) The mag cyl. looks stock nicacle (probably spelled wrong) but the pto cyl is sleeved. The pto pv has a non stock clip that holds the very loose pin from sliding out of the stem. The mag cyl has the stock clip. Did I mention that there is a sticker on the head with SBT on it. I have rebuilt 4 wave runner engines over the past 10 years all are still going good, but this one has me nervous. There are nicks inside the crank case like bits of rings visited there. I called SBT with number on head and was told that it was done in 2006. I am afraid to rebuild it not knowing what caused the problem. Maybe it just wore out. The carbs are like new inside, filter screens perfectly clear. My question is, Where is a good place to send this to get rebuilt.
    My older yamahas have been the most reliable skis that I've owned. Thanks for any input. Ralph


  2. #2
    If its a full SBT rebuild then both cylinders are steel sleeves. And both PVs would have the updated levers that contain the pins. Take it completely apart. Have a machine shop confirm the damage on the pto cylinder can be bored out to the next piston size. Then have the mag nikasel cylinder sleeved and bored to match the pto piston size. Order WSM pistons and gaskets also new power valves. You can find all that at Atlanticjetsport.com. Check crank. Order new SBT crank if needed. You can do this for around $1,000.

  3. #3
    Mighty Mouse's Avatar
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    Feb 2011
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    $1200 or less for rebuilt. I'd go that route. Too many uncertain issues.

  4. #4
    SBT piston to cylinder clearance to loose. SBT piston and ring design allows the ring to rotate under the locator pin after cylinder and piston get some hours and use. If you can get your hands on a wsm piston/ring (maybe other brands as well) and sbt piston/ring you can see the difference. Also don't like the SBT wrist pin snap ring. Prone to backing out.

  5. #5

    Join Date
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    va
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    Quote Originally Posted by FlMike View Post
    Stay away from the WSM junk.
    What about wisco?

  6. #6
    For recreational riding I think most pistons are ok but the weakness is in the rings, locator pins and wrist pin clips. I have been using WSM pistons and they have lasted longer than SBTs.

  7. #7

    Join Date
    Aug 2006
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    Indiana
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    The trick with circlip/snap ring pin retainers is you have to get the sharp side of the clip to face out, so it digs into the edge of the groove. If you have the slightly rounded side of the clip facing out it is easier for it to ride itself out of the groove.

    Quote Originally Posted by wavedude View Post
    SBT piston to cylinder clearance to loose. SBT piston and ring design allows the ring to rotate under the locator pin after cylinder and piston get some hours and use. If you can get your hands on a wsm piston/ring (maybe other brands as well) and sbt piston/ring you can see the difference. Also don't like the SBT wrist pin snap ring. Prone to backing out.

  8. #8
    I know that and you know that. I don't think SBT knew that when they put together one of the 800 rebuilts I bought from them.

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