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  1. #1
    Tony's Avatar
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    I'm back in the saddle again

    I finished rebuilding the fuel system and top end of my 780 today. She fired right up, after I figured out that I had the Mag line and the inlet line crossed on the new Mikuni pump.

    I ran it on the trailer 3 different times...5 minutes, cool down, 5 minutes, cool down, 10 minutes, and then shut it down for the night. It seems to be running great... smooth idle @ 3000 rpms, good throttle response, no strange noises.

    I'm headed for the lake in the morning. I'm running 32:1 and going to vary speed and keep it under 3/4 throttle. Any other advise for the combination shakedown/break in cruise?

    BTW I've decided to name her "Nickle & Dime" as in "Nickle and dimed me to death"


  2. #2
    ph2ocraft's Avatar
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    Tony, it sounds like you're on the right track. Be sure to do some plug chops and make sure she's safe.

    Fingers and toes crossed.

  3. #3
    Tony's Avatar
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    Quote Originally Posted by ph2ocraft View Post
    Tony, it sounds like you're on the right track. Be sure to do some plug chops and make sure she's safe.

    Fingers and toes crossed.
    I'm running my lows at 1 3/8 (spec) and the highs between 1/8 and 1/4 fat just to be on the safe side. I figured I'd keep an eye on the plugs and developing piston wash and tune after a break in period.

    I thought chops were done 100 yrds @ WOT. Shouldn't I wait a while before any WOT runs?

  4. #4
    ph2ocraft's Avatar
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    That has always been a point of debate.
    I ALWAYS used to break it in and make sure everything was just perfect BUT if things aren't right (say way to lean) you can actually burn her down before you ever finsih breaking it in.
    What happens is at roughly 3/4 throttle you have more timing advance and load on the engine, which of course is pretty tough on a new engine IF things arent right.
    I will now go through probably 1/4 tank varying speeds and temperature. Then I'll perform a couple quick WOT runs and perform my plug chops, it's worked better for me.
    I really don't think there is a right or wrong way anymore but more an understaning the engine should go through cycles. Hot/Cold, varying speeds.

  5. #5
    Tony's Avatar
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    Quote Originally Posted by ph2ocraft View Post
    That has always been a point of debate.......
    I will now go through probably 1/4 tank varying speeds and temperature. Then I'll perform a couple quick WOT runs and perform my plug chops, ......
    ..... the engine should go through cycles. Hot/Cold, varying speeds.
    Thanks for the tips.

    I tried to get the cycles started tonight. I had planned on putting around tomorrow 10-20 minutes at a time and letting it cool down, checking the plugs and pistons during cool down times. I've gone through the entire fuel system and don't anticipate running lean <knock on wood> but I'm still going to keep a constant check on things. I guess I'll follow your direction and do some chops after 4-5 gallons of fuel.

    I'll post my results when I get back from the lake.

  6. #6
    ph2ocraft's Avatar
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  7. #7
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Have you pressure checked the cases since the rebuild? Just making sure you aren't sucking air before you start.

  8. #8
    Tony's Avatar
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    Quote Originally Posted by xlint89 View Post
    Have you pressure checked the cases since the rebuild? Just making sure you aren't sucking air before you start.
    I pulled 10" of vacuum...15 minutes later I had 7 3/4".

    Just got back from the lake, I'll post pictures and report later.

  9. #9
    Tony's Avatar
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    Pictures...still a little lean

    Ok, we hit the lake for about 6 hours today. For the first 1 1/2 hours I'd stop every 20 minutes and check plugs. They started takeing on a nice milk chocolate look pretty early. But, they're darker on the intake side and lighter on the exhaust side.

    Holeshot and throttle response were awesome. At 2000 rpms I'd hit it for about 50 feet and this school girl don't blubber on a quart of beer...no hesitation either...just get up and go.

    After about 3 1/2 hours I did some plug chops. They looked ok but I was a little disappointed in the performance, 47.8 gps and about 6560-6570 rpms. The rpms would peak at 6610 and drop off a little. Thinking this was lean I opened up the low screws 1/8 and I opened up the highs as far as the limiter would allow. I took the limiter of the Mag and went an extra 1/8 for good measure.

    Pictures tell the story...Mag looks good, center and pto are lean.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  10. #10
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Interesting, usually the MAG is the one that requires more fuel than the others. At least you know what to look for. Good job, not fatten them boys up a little.

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