I own a 1994 FXDWG with a stock Evo engine that has about 66,000 miles on it. I use it for cruising, performance doesn't really matter much to me.

My problem is I have a base gasket on the forward cylinder jug that has been leaking for years. The bike's usually a mess because of it, when I park it in the garage it always has a couple good size pieces of cardboard beneath it. So this winter, I'm going to take care of the problem but I need some guidance as to how serious to get about it. I have the mechanical skills to do the job.

Does it make any sense NOT to install new rings? If I install new rings must I have the cylinder honed? Is it possible to hone a cylinder without having to installl oversize pistons?

My engine is still stock, internally. Should I keep the same stock cam? This is a California bike so I understand the cam is really wimpy, but then I'm not a real performance guy and I kinds like the MPG I get. Is there a compelling reason to upgrade?

Should I use the same pushrods?

So the basic question is while I'm in there, what ELSE should I do besides replace the base gaskets? Given that I would replace all gaskets and O-rings that I encounter on the way in.

Thanks guys,

 

Replace the base gaskets with stockers, I used James Gaskets and they are really thick in comparison (lowers compression).
If the bike is a good runner with good compression and uses no oil, then just slap it back together.
If you really want to re ring it, deglaze the cylinders with a hone, clean them really well and install new rings of the same size you took out.
If replacing the rings, you really should have the heads redone. Now, you have a bike with a fresh top end.

 

I just did the same thing this past spring. My bike had half the miles yours did and I had the cylinders bored .010 over. My engine guy said "hone or bore is the same price" but of course new pistons and rings cost money.

After doing some reading, I went the rebore route. It will true up the bore, and gives you a brand new start. Your in there, so go all the way and be done with it.

Rebore, new pistons, rings, pins, new lifters, new cam bearing (this is a must), valve job, new gaskets, and this is a great opportunity to put in a more efficient bolt in cam and cam bearing. Consider new valve springs also. Regardless of what you end up doing, the cam bearing and lifters (if original) NEED to be replaced.

Cometic MLS gaskets are good to seal up that base gasket, and you can even get a thinner head gasket to give you a little better squish/quench for more efficient burn. Yes to getting a valve job also. You are in there,so get it all done right. Make the engine like MoCo should have....An aftermarket bolt in cam will not hurt your mileage. Enjoying your new found power with a bolt in cam might...

You will find that getting your old base gaskets off will be a nightmare, so have the machine shop true up the cylinder bases. This will give you a better, nice and flat sealing surface and will remove the old gasket material at the same time. Also carbon build up will be on the pistons, valves, inside the cylinder heads, etc, So having the machine shop do a valve job will get everything nice clean and sealing well.

Original valve seals and umbrella valves are old, years of carbon build up, questionable cam bearing, lifters that probably have over 30K on them (moco says change them every 30K), and 66K on the rings and bore...IMO, I would do a complete and thorough top end. I don't like spending money unless I have to, but your gonna be in there so do it so you don't have to worry about it for a loooong time to come. YD

 

The OEM HD Evo cylinder bases were NOT machined from HD.
We machine them true to the cylinder C/L.
A quick hone and re-ring would be prudent also at that point, as long as piston/wall specs fall in place.
Cam?
An Andrews EV13, for example, would be a nice increase, still using your existing pushrods.
Be aware that HD suggested to inspect and/or replace the lifters at 25K.
Scott

 

I've forgotten how many HD top ends I've taken off and not done anything to the rings or cylinder wall. Just realign the rings and proceed.

Personally, given your riding characteristics, I'd pressure wash the gunk off, then just do a gasket swap (base and rocker box/pushrod tubes).

 

We do not have the machine shop necessary to machine the cylinders at my shop so we use these (https://www.haydensm6.com/tof_single.htm) a lot and have not had leaks after installing them on a number of EVO engines...As mentioned by Scott, a hone and re-ring would be a good idea with the mileage on your bike and since you are there anyway!

 

No one mentioned this so I'll throw it in ... EVO's love a little bit of warmth ( heat ) in them before taking off ... This can aid in the longevity of the base gaskets

 

JUST the time you do not re-ring/hone, you can end up with an issue.
Scott

 

.005" over pistons - cylinders are seasoned - will be a great set to bore.
New cam and bearing
I would replace EVO lifters without blinking an eye at that age and mileage
Trock EVO lapping ring to true up bottom of EVO cylinders - you're going to need someone to do that for you unless you buy it for a one time use.
Have the valves/seats cleaned up - it doesn't make sense not to with all the labor.
Pig tail inserts for cylinders (not necessary but would prevent returning oil from ever hitting the gasket again.)

 

When the cylinder base is actually machined, the bases are dead-***** perpendicular to the bore C/L.
Then, if boring is needed, the cylinder base is dead-true, and is used as the locating surface.
Scuffing them an a lapping plate, in no way will establish that.
It will create a flat surface, yes, but will not correct out-of-square condition, that is witnessed when performing this simple operation.
Scott