Rebuild vs refresh

[Cramer]

The only history I have on the bike is that it was supposedly sitting in a barn for years and the guy I bought it from had had it sitting in his shop for the last few years waiting to fix it up....... Which never happened so he sold it to me.

'79 FXEF 80 in. It's a runner. I've gotten it up to 70+mph, no unusual noise or anything that concerned me, other than the fact that everything is covered in oil when I park it.

My base gaskets leak, my main seal leaks, my rocker boxes leak. (There may be more) I am assuming the gaskets just dried up from sitting. It has dual plug heads and a Compu-Fire HDE-3 Ignition (I called Compu-Fire, but they couldn't give me any date info for that model) so somebody has been into it at some point, but I don't know how long ago. The odometer isn't original to the bike either so mileage unknown.

My question is this: Can I get away with just replacing gaskets and seals? Some guys recommend just completely rebuilding it while it's apart. I am not opposed to doing what is needed, but I also don't want to spend money just for the sake of spending it. What are some things to look for that would signal me to tear it down further? If I do just replace gaskets, any recommendations on metalic vs non, what are the odds I can get away with not having any machine work done?

I know a lot of this is going to depend on what everything looks like once it is opened up, just looking for speculation based on you guys' past experiences. Thanks.

[JBinNC]

On a decent runner that leaks, you need to look at the breather gear and the crankcase breather hose.

If the motor makes decent power, and doesn't smoke or knock, just replacing the gaskets and seals, and maybe a set of rings would be an OK approach. If replacing the rings, have the cylinders honed by someone who knows what he is doing. (I.e., no ball hone or spring hone.)

A compression check, and even better, a leak check before disassembly is a good idea. A decent, cold, shovel motor will leak up to about 12% and still run and perform well. Something like 20% leak would indicate that a full top end rebuild would be the wise choice.

Jim

[Tattooo]

I know a lot of this is going to depend on what everything looks like once it is opened up, just looking for speculation based on you guys' past experiences. Thanks.

That's exactly what I did with this 79 that had been sitting in a barn with a dirt floor for 25 years........... I took it completely apart painted the motor stock colors put it back together and there you go....... No rebuild of the motor was needed...... But it did just have 16,000 miles on ut......

[Cramer]

That's exactly what I did with this 79 that had been sitting in a barn with a dirt floor for 25 years........... I took it completely apart painted the motor stock colors put it back together and there you go....... No rebuild of the motor was needed...... But it did just have 16,000 miles on ut......

Thanks for the replies! I think the case for a rebuild is that conventional oil may corrode some internal components if left sitting for years and years? I have never seen it first hand, just something I was told……myth?

[Dragstews]

A rebuild would net "Peace of Mind"

[JBinNC]

Thanks for the replies! I think the case for a rebuild is that conventional oil may corrode some internal components if left sitting for years and years? I have never seen it first hand, just something I was told……myth?

Detergent oil is somewhat hydroscopic, like brake fluid, and will take up some moisture from the atmosphere. That combined with the acids that are a byproduct of the combustion process could cause some corrosion. Mostly you will see bands of rust in the bores where the rings have sat. Occasionally you will see a rusty valve stem. Otherwise, I have seen very little evidence of damage from a complete motor sitting, even in the very humid South.

It's going to be your call, it's your motor and your pocketbook. A decent full rebuild of a shovel motor will exceed 4 grand, and that price is going up along with everything else.

Jim

[JBinNC]

I will add that synthetic oil is many times worse for corrosion in storage compared to conventional oil.

Jim

[Tattooo]

I have never seen it first hand, just something I was told……myth?

It's not just a myth it's bull shit.............. I've taken apart many many motors that have been sitting for many years with zero rust, Way before modern oils when all there was was detergent oils........... The worst thing was sludge in car motors but I never seen any rust or corrosion in any bike motors..............

[DoomBuggy]

A rebuild would net "Peace of Mind"

And most likely more cubes and horsepower

[Dragstews]

And most likely more cubes and horsepower

Dat ^^ has been known to happen ..

[JBinNC]

And most likely more cubes and horsepower

And so it begins.....

Jim

[Tattooo]

And most likely more cubes and horsepower

LOL Yep, Like all know, I like stock if it's possible.... but that's just me.........

[Dragstews]

Nobody is going to twist your arm to take the Red pill ... !!

[Cramer]

Started stripping the bike down for pulling the motor and found some hacked wiring. Clean up should be fun, I may try and use the factory harness as a backbone and clean up the connections I will keep.

[Cramer]

I am also really seeing how crusty this thing is. At least tearing at all down will make it easier to clean up.

A little scrubbing with a wire brush^^^