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  1. #1

    Ultra 150 top end - PTO cylinder running hot

    Just finished up a top end on a Kawi Ultra 150. I was running it on the hose for a few minutes and noticed the PTO cylinder was heating up while the other two were staying cool.

    I shut it down, and checked out the water log (there was a small hole that had corroded through.) replaced it with another. Also pulled the pisser hose from the PTO cylinder and blew it out, blew out the 90 degree fitting.

    Ran it again, had good flow coming out of the pisser (didn't check before I blew it out.) Same story, PTO cylinder heating up (almost too hot to keep your hand on, while the other cylindes and pipe stayed cool. Shut down again, I didn't want it to get too hot.

    During the rebuild, I had all the jugs off, cleaned out all the water jackets, same thing on the exhaust pipe and manifold.

    Also, had all three carbs off and rebuilt them, cleaned out out the CV valves, all three are moving free and clear. Primed the oil lines, plus I'm running 40:1 premix for break in. Cylinders were bored .05 over, I believe I will need to remove the tamper caps and open up the high speed needles a turn or two, but I don't think that would be creating a lean condition in just one cylinder, right?

    Not sure what could be causing the PTO cylinder to run hotter that the other 2. Am I being too sensitive / worried? I don't really feel like toasting a new piston...

    Any help appreciated!


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  3. #3
    steve45's Avatar
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    Just a guess, there are restrictions in the head gaskets and the exhaust gaskets. Perhaps you have one that's installed upside down or something.

  4. #4
    This is how I run a jetski shop in the desert nmpeter's Avatar
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    I recall that running on a hose does not provide full cooling. To simulate real conditions you need to feed the water via the jetpump inlet, not the flush fitting

    I'd certainly want to have a laser temp gauge so you can confirm temp rises before things get too hot.

    if it continues, the bite the bullet and pull the head and exhaust to check for a restriction

  5. #5
    So - sorted out the hot cylinder issue. I had pulled the carbs and rebuilt them, but did't realize when i ordered the kits that they did not come with the packing gasket under the jet covers. I put them back together loosely and ordered the packings while I was finishing up the top end over the next weekend, but never remebered to open them back up and install. Pretty sure the PTO cylinder was running lean becuase of it. Once I acutally put the carbs back together correctly, all three jugs seemed to heat up evenly (warm to the touch, but not too hot.) Luckily I was checking the temps carefully on the hose before getting out on the water for break-in. It would have sucked to blow up a new piston...

    I now have a new issue - she'll run at WOT for 3-5 seconds, but then bog down to around 4500RPM. Let off the throttle and she'll idle fine, and will open back up to around 7000RPM for a few seconds, then drop back down. Seems like it's either not getting enough fuel flow, or running lean? I bought the ski not-running and did the top end, so Idon't know if this is a new issue or an old one.

    The cylinder walls were scored, so I had my machine shop bore them to .05mm over and put oversized pistons in when I did the top end. Do the stock CV carbs need to be adjusted to account for the larger displacment? I belive there is a high-speed adjustment, but it's burried under a tamper cap (like the stock 50mm Mikuni's on the Yam GPR's.) Can't seemt to find anything on the forums about people adjusting the CV carbs. Anyone know of a good thread?

    The other thing I'm thinking is fuel supply. I installed a new inline filter when I put it back together and blew out both the reserve and the main fuel pick-ups. Is there a screen or a filter in the tank that could be clogged? Any other common problems with fuel restrictions on these skis? Also, it was frustrating that I couldn find a diaphram kit for the Klheihn fuel pump. Anyway to check that the pump is putting out?

    Other suggestions?

  6. #6
    steve45's Avatar
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    You need a service manual. There is no hi-speed adjustment screw buried under a tamper resistant cap, you change the jet inside.

    I'm guessing that your shop bored 0.5 mm oversize, not .05 mm. This means that they went through the Nikasil coating if the cylinders are original. Otherwise, you must have aftermarket sleeved cylinders. (neither is good).

    There is a filter on the pickup inside the tank, but at this point, it's warped so badly due to age that it doesn't filter anything anyway. I'd suggest you order a replacement fuel level sender--while you can still get one! ($329!!!)

    Did you inspect/replace your oil lines when you had it apart? How about the oil pump cable?

    As I said, you NEED a service manual.

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