85 Marathon 244cc Engine Rebuild

[Dabble Inn]

Problems already, The crank bearings in this kit are junk. 2 out of the 3 had a flat ball or something, Very rough and a few kink spots. So I'm returning them and bought SKF brand locally.........

And as always with me the plot thickens and need advice, The original crank measures 2.240" distance between the machined bearing mating surfaces and had 3 shims on the clutch side. The shims are .008" each equaling .024" for a total distance of 2.264".....

The new crank measures 2.250", (.010" more)..

If I use 1 shim it'll be under original by .006" at 2.258", 2 shims will be over by .002" at 2.266"...

I gotta think 1 shim to be under is the way to go, Being over sounds like trouble even though it's only by .002". It might not let the cases mate and/or put unnecessary lateral pressure on both the cases and the bearings??...Help and Thanks

[Dabble Inn]

Scratch the numbers above as they have changed LOL, The new bearings are .001" thinner than original... I have them installed and dry fit the halves together, Now the distance between bearings for the crank is 2.255". The crank bearing mating surfaces are 2.250" without any shims.....

Anyone know the lateral tolerance? I assume the case anaerobic sealer will greater the distance a tiny bit, So I'll have at least .005" clearance. I don't think I dare use one of the .008" shims.

Am I being too picky? .005" clearance sounds pretty good to me especially since everything is pressed together

[Dabble Inn]

Progress!! Wish I knew how to edit out my posts above from yesterday, I went into panic mode for a bit . It's all ok today, Bottom line is I put it together without the old crank shims resulting in .005" lateral end play.

Here's some pics of assembly

[Dabble Inn]

More

[Dabble Inn]

And finally a before and after, It's pretty much ready to drop in as soon as I get the buggy back from the paint shop. I can't wait to take a compression reading, And of course to see how it runs..... Thanks everyone for the help

[Dabble Inn]

I went ahead and installed the starter/gen and clutch, Now it's complete and ready to drop in. Pretty ain't it? Huh? Huh? LOL........

Probably won't get the buggy back for another week or so, I'm sooo curious to get a compression reading I can't hardly stand it. Think I might hook jumper cables to it and spin it over for a few seconds on the bench just to see what it gets, It may not be a real true reading as it's got a lot of oil in it from assembly. So it better be really high

[Alex Faught]

Compression won't be super high until it is broken in. How does it feel by hand? If it is to low to start the engine initially, you can put a little 30 weight in the plug hole. This creates a temporary seal for the rings until they wear in.

[Alex Faught]

Looks good by the way!!!

[Dabble Inn]

Thanks, And yeah I hope it runs as good as it looks LOL......

I can roll it over by 'hands on the clutch' buts it's hard on the compression stroke so I know it's pretty good, In fact I tried to get a compression reading by that method but I'm not tough enough to get it past the second stroke with any speed lol. It read about 45lbs at that point, But I'm using a compression tester with about an 18" hose. So really I don't know anything yet....

I should be getting the buggy back from paint within a week so I'll just drop the engine in and fire it up, run it for a while then do a compression test. Or maybe do one first just for the fun of it and see how it changes after the break in, I'm thinking the 2 cycle oil I used during assembly has probably ran off the bearings and cylinder wall by now. So I would have to at least add some more to the cylinder like you say

[Dabble Inn]

Update;

Got it back from paint, Purdy huh??

Got the engine in and it runs great, Checked the compression on the bench at only 120. Thought it'd be higher but I'll check it again after the first tank....

Have only been around the block a few times but top speed is 22 by gps, That's good enough for me. Seems a lot quieter now too, Spent the last two days on finer details of the body. Repainted the undercarriage, inner fender wells and front end all gloss black.

Next is cut the rubber floor, install the rear fender caps, all the rubber trim, the new wood grain dashboard and onto the roof... I'm going to strip and repaint the roof supports gloss black too.....

Oh, The painter dude bondo'd up the holes for the front roof/windshield support so I'll need to find the holes and drill them out..Ugghh!!

Think I need about 2 more days to get it all together.......