Results 1 to 9 of 9
  1. #1
    I like Boobs. wetwolf's Avatar
    Join Date
    Nov 2005
    Location
    The NSA know's that I'm in Spokane, WA
    Posts
    805
    +1
    106

    Exclamation XL 800 powervalve missing WTF???

    Short story. A friend had somebody else fuel up his xl800. They filled the oil tank with gas, then rode across the lake back to his house. they ended up frying a thrust washer on the pto rod which went thru the top end. So I am going to do a rod kit and the pto bearings, along with a piston and rings. The cyl has a little alum transfer, but nothing that can't be taken out with a little muriatic acid and a hone....

    Anyhoo, heres the wierd part. I went to pull the powervalves out. the pto cyl was full of sludge as normal, but the valve came right out. I noticed that the mag cyl valve didn't look right. When I pulled it out, there was no valve on the stalk. It looks like it broke right off on the end, but it's not in the motor!!!!! the mag cyl is in great shape, you can tell the valve never touched the piston. I'm not really sure how this could happen in the 1st place. It looks to me like the thing was installed that way from the factory. Am I missing something here, or did yami run a different valve on the front cyl that actually had no valve???

    I'll try to get pix tomorrow.

    Any clues?


  2. #2
    TX21's Avatar
    Join Date
    May 2007
    Location
    North Texas
    Posts
    988
    +1
    7
    Quote Originally Posted by wetwolf View Post
    Short story. A friend had somebody else fuel up his xl800. They filled the oil tank with gas, then rode across the lake back to his house. they ended up frying a thrust washer on the pto rod which went thru the top end. So I am going to do a rod kit and the pto bearings, along with a piston and rings. The cyl has a little alum transfer, but nothing that can't be taken out with a little muriatic acid and a hone....

    Anyhoo, heres the wierd part. I went to pull the powervalves out. the pto cyl was full of sludge as normal, but the valve came right out. I noticed that the mag cyl valve didn't look right. When I pulled it out, there was no valve on the stalk. It looks like it broke right off on the end, but it's not in the motor!!!!! the mag cyl is in great shape, you can tell the valve never touched the piston. I'm not really sure how this could happen in the 1st place. It looks to me like the thing was installed that way from the factory. Am I missing something here, or did yami run a different valve on the front cyl that actually had no valve???

    I'll try to get pix tomorrow.

    Any clues?
    Is it in the exhaust?

  3. #3
    I like Boobs. wetwolf's Avatar
    Join Date
    Nov 2005
    Location
    The NSA know's that I'm in Spokane, WA
    Posts
    805
    +1
    106
    It's not in the pipe, I haven't checked the waterbox. Here are a couple pix.

    I'm pretty sure this boat has never been apart, I was undoing the OEM yamabond and loctite the whole time. Any of you GPR guys ever see this?? They are the same valve and cylinder..........
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	2pv.jpg 
Views:	224 
Size:	33.3 KB 
ID:	207298   Click image for larger version. 

Name:	pvstalk.jpg 
Views:	115 
Size:	36.0 KB 
ID:	207299  

  4. #4
    if the piston isn't trashed someone put it back together like that Yami never had a weird setup like that

  5. #5
    I like Boobs. wetwolf's Avatar
    Join Date
    Nov 2005
    Location
    The NSA know's that I'm in Spokane, WA
    Posts
    805
    +1
    106
    This engine has never been apart. My friend bought it new and Ithas never been in the shop for any problems. Like I said, there was still Yamaha loctite on all the bolts. It had to come this way from the factory. Anybody got a used powervalve for sale??

  6. #6
    Thats nuts

  7. #7
    hi all
    I have a xl 800 and had a very similar thing with the power valve on number 1 cylinder
    i had a hesitation at full thottle for a long time and put it down to dirt in the carbs but after a long blast a full throttle the ski cut out when returned to idle when trying to restart
    the motor sounded the way that makes your heart sink and you know that its terminal and
    going to cost you !
    any way after removing the cylinder head and barrels i found no 1 power valve had broken at the stem and was being machined away by the piston when compared to the new one it was a third of the size not as bad as yours but not far off
    so may be your power valve went the same way but you where lucky that it did not smash the piston up in my case may be thats where it went ?
    mark

  8. #8
    I have took my xlt800 apart and found the same thing. The ski was running perfect before I started this project to put wave water clips on. Bore scoped the cylinder everything is great shape good compression. Just wondering if was put together that way? The power valve shaft was seized and black buildup looks like it's been that way along time. Thoughts?

  9. #9

    Join Date
    Aug 2016
    Location
    Panama city
    Posts
    271
    +1
    18
    They are setup to run lean to pass EPA requirments. (So lean, that they need accelerator pumps) If they are leaned out any more (think, greenish pilot jet, need a magnifier glass to see it) they cherry heat and shatter the PV from heat cycles.. .Why pilot jet? Because that is the jet in play when the valves are down in the exhaust stream.(At 1/3 throttle, where I tend to ride) Mine did it twice in 10 hours with a greenish jet (when I got it, PV was missing also, that's 3PVs)...Up pilots to 95s, problem went away. Lucky on the 2nd pv, I found enough of it, to see the cracks had formed over time. (Part of the crack was sooty) ...yes a new 90 jet might of also fixed it, but I added fuel for insurance and it runs great. (At sealevel) Piston wash looks good also.Just my two cents...kevI
    Last edited by Crazypirate; 04-30-2017 at 05:55 PM.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. 2000 xl 800 Missing stuff
    By buckeye4313 in forum Yamaha PWC Performance (2-stroke)
    Replies: 1
    Last Post: 05-23-2012, 03:37 PM
  2. WTB: Intake grate for XL 800.
    By lt1transam in forum Yamaha Classifieds
    Replies: 0
    Last Post: 08-04-2008, 04:39 PM
  3. WTB 800 Powervalve Servo
    By JeffSki in forum Yamaha Classifieds
    Replies: 2
    Last Post: 07-17-2008, 05:11 PM
  4. Xl 800 heat sensor question
    By truairspeed in forum Yamaha PWC Performance (2-stroke)
    Replies: 2
    Last Post: 06-28-2008, 05:51 PM
  5. xl 800 hesitation issue
    By surferdude345 in forum Yamaha Open Discussion
    Replies: 5
    Last Post: 06-11-2008, 07:27 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •