w1nd6urfa

My Feedback: (4)

A wing broke off my Hangar 9 warbird mid-flight, and in the ensuing nose-first crash the engine broke in many places - you can see what's left of it in the pics below. []

So initially i thought I would buy a new engine and keep the salvaged spares out of this one, but after calculating the Tower Hobbies discounts and the historical lows of the dollar vs. euro, I ended up ordering 130 $ worth of replacement parts (crankcase, rear cover plate, rocker cover, pushrod covers and ball bearing).

If anybody has attempted such major repairs, are there any tips you can give me? I have taken the obvious measures: I have marked the rear of the piston sleeve and rod while disassembling, and the salvaged parts are cleaned and lubricated. I also anticipate valve gap adjustment and a mini run-in process.

Will the result be comparable to the original engine or will it be a pita to run reliably?

Texastbird

well as long as the crankshaft isn't bent, it should be good to go with the new parts.

wcmorrison

My Feedback: (2)

As you remove the piston note the orientation of the ring gap. Better yet when you get the piston out, do not move the ring so that it will go back as it came out. I assume you will keep the piston sleeve and reuse it. Not sure why you are changing the bearings, they may be okay. But they are inexpensive, so it is not a big deal.

You will have to fish out the cam bearings. Otherwise it is pretty simple, put it back together in reverse of disassembly. Align the dot on the cam with the push rod tubes when the piston is at top dead center. You can do that before replacing the head assembly.

Cheers,

Chip

w8ye

My Feedback: (16)

It is easier to just put in new cam bearings


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gkamysz

My Feedback: (19)

Are you sure the rod isn't bent?

I personally don't think ring or sleeve orientation is important in four stroke engines. The cylinder wall temperatures are more equal around the perimeter as compared to a two stroke. The sleeve is going into a new crankcase which will have an effect on roundness anyhow. The ring is free to rotate, but it seems they tend to stay put. Rod orientation is OS engines is obvious because there is a chamfer on the big end that faces the crank. I do make sure to put the piston in the same way as the wear pattern is not symmetric.

I just cleaned up an FS-91SII crankcase that will be used to assemble an engine from various parts I have laying around.

w8ye

My Feedback: (16)

I made up a couple surpass II's from various parts at different times. They worked out very well.

w1nd6urfa

My Feedback: (4)

Thank you for the feedback. I will replace the rear ball bearing because there were specs of rust on it after 1 year of operation. I think i will add 1% castor oil to the fuel from now on (I use Cool power 15% on my 4-strokes).

Will post results in a week, when the parts arrive.

w8ye

My Feedback: (16)

Castor oil will be good