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  1. #1

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    no pulse pressure on gp1200r

    had a cylinder burn up, replaced it with good oem. Carbs are clean and built to osidebills recipe. My cylinder that burned up doesn't want to fire. Has spark. Pulled the reeds, they are good and sealed. Noticed on cranking that the cylinder doesn't seem to have any pulse coming out of the port unlike the other two cylinders. Compression came in at 125 for that cylinder. What am I missing? This is the forward cylinder having the issue.


  2. #2

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    anyone? I am thinking seal between magneto housing must be leaking....

  3. #3

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    well, found the problem, if anyone has this problem in the future, my seal between magneto and crankcase was completely wiped out making all the bottom pressure go out the magneto housing.

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  5. #4
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    This is why any time there is a lean burndown I do a full engine teardown with all new gaskets and seals. I just finished an XLT800 on Friday that burnt up the front piston. Stator and mag looked vey similar to yours except the whole front crank bearing had come apart. It was SBT crap made of chinesium.

  6. #5

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    Quote Originally Posted by Myself View Post
    This is why any time there is a lean burndown I do a full engine teardown with all new gaskets and seals. I just finished an XLT800 on Friday that burnt up the front piston. Stator and mag looked vey similar to yours except the whole front crank bearing had come apart. It was SBT crap made of chinesium.
    you're right, we blamed it on the carbs instead of looking further. Luckily we never took it out with the new cylinder since it didn't sound right and was bogging on the hose.

  7. #6
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    Thank goodness.....intuition saved the day!

  8. #7

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    I’m having a runaway condition with ours after going pre-mix. Myself suggested the same issue you have, with the bad crank seal. As bummed as my son is, we are planning on going to a 1300 with some head work. So, I guess this could be looked at as a blessing in disguise. We already have a call into Chris Newmiller. We just have to nail down some particulars.

  9. #8

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    Quote Originally Posted by Jonesyfxr View Post
    I’m having a runaway condition with ours after going pre-mix. Myself suggested the same issue you have, with the bad crank seal. As bummed as my son is, we are planning on going to a 1300 with some head work. So, I guess this could be looked at as a blessing in disguise. We already have a call into Chris Newmiller. We just have to nail down some particulars.

    yeah, don't ride it until you sort it out. I am installing new seals tonight then hopefully as will be good

  10. #9

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    We found it at the dock while adjusting our holeshot kit. I thought maybe we got some crud in the carbs after installing dual feed fuel lines, my son left the dock and it stalled and he cane right back in, no power and wouldn’t even get on plane. Compression is decent but not perfect, gonna check the block off nipples and if. nothing changes the engine is coming out.

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