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  1. #11
    Flying Scotsman's Avatar
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    You should realy get a hone on a sunnen honing mach but if your ok with the croshatch then
    Nothing not right about using a used piston if its done right.Boring her out and raising comp would make her faster than stock.If you use a used piston mic it to make sure its good and make sure the locating pins for the rings are tight and use a bore gauge to measure the bore.You want new rings after a hone.Minimum you can do would be get a hone/Sunnen on the 1 bad sleeve and a used piston with new rings.If you already honed the other bores you would want new rings there too.I like a big bore it makes more power thats why I sugested that lol...


  2. #12
    Yamaha artisan Cutlass's Avatar
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    Alright, I can no longer resist the urge to do this the right way. I'm going to bore and hone all three cylinders and install new pistons. Looks like ProX has .25mm, .5mm, .75mm, 1.00mm, 1.5mm, and 2.00mm oversizes. Seems obvious that bigger is better, but is there any reliability or tuning issues I need to be concerned about? Or should I just play it safe and go with like .5mm oversize?
    What kind of cranking compression increase am I gonna see with oversizes?

  3. #13
    Moderator OsideBill's Avatar
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    Important tip when having your cylinders bored on the 65U motor. Make sure they have a backing plate that mounts across the exhaust, or bore it with the exhaust manifold bolted on and torqued to spec.

  4. #14
    20 feet Boy's Avatar
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    I like to use the smallest bore because it gives more life to the cylinder.

    When you bore to a larger size more chance of the sleeve cracking or warping. We had a lot of this happen to our 350 banshee motors in the past. sleeving the motor gets expensive. It is nice that they make so many size piston. Back in the day it seem like you dint have much of a choice. Make sure the crank is good. It would suck to put all that money in it and have it grenade.

  5. #15
    Yamaha artisan Cutlass's Avatar
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    Ok will do. Bore and hone with exhaust manifold torqued down, go with smaller oversize for reliability, and make sure the crank and everything else is in good shape.
    Anything specific to look for on the crank or just make sure the bearings are ok and everything looks normal and in good shape?

  6. #16
    20 feet Boy's Avatar
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    Some time there look like hot spots on the crank. But most of the time if the bearing are good you will be fine. make sure they feel smooth when you roll them. If you have some doubt maybe take to the service department at the local shop and have the mechanic look at it. Most of the time they will look at it for free. But sometime they will just want to sell you something. I have been friendly with mind and a second opinion is alway good.

  7. #17
    Yamaha artisan Cutlass's Avatar
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    ok sounds good.

  8. #18
    Yamaha artisan Cutlass's Avatar
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    1997 GP1200

    If I do the Jetworks mod, this is the fitting I attach it to, correct?


    And this it the fitting I need to plug/block off? How? pipe plug?


    And this is the exhaust gasket I should replace with a Raider 1100 gasket for better cooling?

  9. #19
    20 feet Boy's Avatar
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    I am sorry I am not familiar with your cooling someone should help.

  10. #20

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    You just opened up a whole new can of worms. You are correct on both of those pluggin and attaching for JW valve. HOWEVER, the 97 pipe is 1/4" and the 98-99 pipes are 3/8". It is *easier* to get a 98-99 pipe and use the 3/8" JW valve. I think it only has one barb instead of two as well. That is also the more expensive route. However, the Mid/front section of the pipe on the 97 is also not effeciently cooled and their is a better piece to get. I cant remember if it is the waveraider pipe or 99 pipe section that is improved over stock.

    Also, another route and you may have experience or expertice with this...those hose barbs on the pipe are supposedly pressed in. If you have the knowledge and tools to press them out and press in a new fitting then that is an option. I was going to cut my barbs off tap new 3/8" fittings in but I was told the pipe may crack and become completely useless. Apparently they crack easy. Hope this helps.

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