Home Forums Tech Talk DIY Leopard Cylinder honing

This topic contains 3 replies, has 2 voices, and was last updated by  Walt Gifford 5 months, 2 weeks ago.

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  • #65425

    Samir Shah
    Participant

    I’m going to try and refresh my pre-09 Leopard’s piston/ring myself, with the help of my (former) 4-cycle engine builder, who has a ton of machinery but has never worked on a 2-cycle engine before. He lives 20 minutes from me, which is a huge advantage over shipping out an engine for refreshing, so if we can do this well, it will make my life a lot easier, besides being cost effective.

    We’re doing just the top end first. We’ll try the bottom end next time.

    We took a look at the engine last night, and read the Parilla repair manual.

    Some questions:

    – What stone grit should we use on the cylinder walls? Any finish pattern? Or brush to follow up with to remove burrs?

    – What is the clearance to use between the cylinder wall and the piston, so we can order the right piston and ring kit.

    – How does one order the right diameter piston pin?

    – Does one need the fancy IAME tool to remove the piston pin circlip?

    – Besides ordering all the gaskets to try out, how does one figure out the thickness of the gasket that needs to be used to get the right engine squish? 0.9mm?

    – What other parts should be replaced at the same time? Rubber o-rings?

    – I have 2 cylinder heads. What will be faster – the smaller diameter, less used one, or the larger diameter cylinder?

    – What other tips can you give us?

    Thanks in advance, Samir.

    #65543

    Walt Gifford
    Participant

    220 grit crosshatch pattern and never use a brush or a ball hone on a two stroke.

    Duckbill pliers to install cir clip.

    FAA certified jet engine and aircraft technician,
    Nicholson Speedway class champion 2001,
    Yamaha KT100 Service Center,
    41 years karting experience

    #67456

    Samir Shah
    Participant

    Follow up: I got an AMMCO portable hone, and used the 220 grit. Under the supervision of my 4-cycle engine guy (John Kurtzman of Kurtzman Racing Engines), did a very careful hone, getting rid of some depressed spots, and measured about 20 times, resulting in a 54.20R piston size, up from a 54.15.

    Reused the old gaskets (since I accidentally ordered MY09 gaskets), and checked the squish – over 1mm, so plenty safe – and very carefully broke it in over a practice day. The engine rocks! My son took pole, and led every lap, winning for the day  yesterday.

    Now to learn how to do the bottom end.

    Thanks again for the responses.

    Samir.

     

    #67660

    Walt Gifford
    Participant

    Ammco hone is great. I use the set with 4 stones, works better than 2 stones and 2 wipers imho.

    FAA certified jet engine and aircraft technician,
    Nicholson Speedway class champion 2001,
    Yamaha KT100 Service Center,
    41 years karting experience

    • This reply was modified 5 months, 2 weeks ago by  Walt Gifford.
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