[mrunderhill1975a]

Does anyone have any good suggestions for the removal of a difficult cylinder head?  The PO put on an aluminum cylinder, and the head wants to stick.  The cylinder itself is free from the case but stuck to the head. 

[Bilgemaster]

Still no tips, huh? Well, I've not yet had to pull the head off my Enfield, but the issue has come up before on this forum. So you're not alone in your woes.

That "Indian Rope Trick" described earlier sounds both clever AND poetically appropriate given the eastern provenance of our rides. If you're "at the end of your rope" and need some, then the 3/16 in. x 50 ft. Fluorescent Polypropylene Rope or the thinner but longer 1/4 in. x 100 ft. Glow in the Dark Polypropylene Rope from "Harbor Fright" should do the trick and later serve you well for camping and whatnot. Get a freebie tarp and you've always got a quickee rain shelter to glare manfully out of with your Beenie Weenie. Coupons are always found here.

Whichever method you choose, it seems likely you'll need to temporarily re-attach the cylinder to get some real purchase on the head.

You do have ALL the headbolts removed, right? 'Cause otherwise...

[ace.cafe]

Tap a thin flat paint scraper into the head joint all the way around the head. It will destroy the head gasket so that it lets go of its hold.

[mrunderhill1975a]

Yes, I have all the head nuts removed. If all the head nuts are removed (6 I believe) there would only be one nut(just above the tappet door) holding the cylinder to the case, is that correct or am I missing one?

[Stanley]

That's correct. When I used the rope trick on mine, I forgot the single tappet area nut and luckily didn't damage anything.
That's a cleaner method than filling the cylinder with oil and kicking it off.

[mrunderhill1975a]

Ok, thanks everyone that worked. I got the head and cylinder off.  Now I need some help interpreting the marks on the piston. To review, I picked up this 2004 e-start bullet 500 last February.  The PO said it had an Alloy barrel and piston put in but could not get the bike to run. Following the advice of Kevin Mahoney, I cleaned the battery ground behind the battery and the bike immediately started up and ran well.  I spent about four months breaking in the cylinder and piston and put on about 1500 miles or so.  Ran great up until  a hot August day (95 degrees F). I was on a 30 minute ride and was cruising at about 50 mph when it lost power and seized. Pulled the clutch and coasted to a stop.  I waited about 20 minutes and it restarted and made it slowly back home. From then on it ran ok but used 1 quart of oil between fill-ups.
See the attached photo of the alloy piston. There are two major scuff marks on the intake side of the piston and one narrow scuff on the exhaust side of piston.  The major scuff marks look like alloy melted.
The cylinder itself shows very little sign of scuffing, the cylinder scuff can only be seen when the light is just right.  I can still see the cross hatching on the cylinder wall.
My question is "what is the next step in evaluating failure"?  There are no "maker's mark on the piston, so presumably it was the cheapest piston the PO could get. I'm not sure how to evaluate the barrel, is it out of round?

[ace.cafe]

Looks like an OEM piston to me.

I wouldn't put it back in.

Take the barrel to a good automotive machine shop and have them use a bore micrometer at the top and bottom of the swept area of the bore.
Then you can determine if you need to bore to the next oversize.
Look for a better quality piston and rings once you know the bore size.

[Tarnand]

Ran great up until  a hot August day (95 degrees F).

That should not happen even on a hot day.  My guess is that there was insufficient clearance between piston and cylinder.   And yes, it may also be out of round so accurate measuring, and not only at the top and bottom, would definitely be recommended.  The alloy barrels are made in India and only those from Hitchcock are guaranteed to be properly bored.

[Bilgemaster]

Just out of curiosity, and for my own and other newcomers' future reference, are there Forum members who can do a good job sorting this kind of precision engineering out for Enfields in the USA? Stuff like rebores, camshaft grinds, that sort of thing?

I've had mixed results in the past with just walking in with my cylinder off the street. I'd just as soon keep it "in the family," as it were, and give the work to someone already familiar with all the little foibles of the breed, like what is and isn't a good piston. 

[ace.cafe]

Just out of curiosity, and for my own and other newcomers' future reference, are there Forum members who can do a good job sorting this kind of precision engineering out for Enfields in the USA? Stuff like rebores, camshaft grinds, that sort of thing?

I've had mixed results in the past with just walking in with my cylinder off the street. I'd just as soon keep it "in the family," as it were, and give the work to someone already familiar with all the little foibles of the breed, like what is and isn't a good piston.

Well, I used to do it.
But, the work dried up a few years ago and it became so sparse that I couldn't keep operating. I make a few UCE parts now, and that's about it. I had to get a local retail job to make ends meet.

[Stanley]

That looks like an OEM piston that has this weakness.

[mrunderhill1975a]

I pulled the cylinder and made some measurements. See the attached data sheet. I measured with a bore gauge in four diameters at the top of the cylinder and four near the bottom of the stroke. "A" was measured where the large scuff appears, "B" was measured perpendicular to the push rod tunnels, "C" was measured in an un-scuffed area about 70 degrees from A, and D was measured in the narrow scuff area.

I measured each 4 times then averaged the result, then subtracted the largest from the smallest. The top of cylinder maximum difference between "B" - "D" is 3.317 - 3.302 " or 0.015"

The bottom cylinder stroke maximum difference between "B" -"C" is 3.322 - 3.2995" or 0.0225"

The bottom of the cylinder appears to be approx. 0.0075 narrower than the top. (0.0225 - 0.015 = 0.0075").

What should the proper tolerances be?

[ace.cafe]

It really needs to be round to within about a thousandth.

The reason that the bottom is tighter than the top is because it was bored too fast, or had no heat sink on the bare liner section. The finned section dissipates heat better, and the bare liner doesn't. So the bottom liner expands during the machining process more then the upper finned area. When the cylinder cools back down after machining, the lower portion bore diameter is smaller than the upper portion, even though the boring bar was set to the same diameter on the whole cylinder.
We discovered this early on, and we used alloy torque plates and slow boring processes allowing cooling between passes. It is common to get seizures when the cylinder gets bored with a tighter diameter at the lower portion like that.

Pick the largest diameter that you measured, and bore it round and true to the next larger oversize bigger than that. Probably the easiest size and piston to find will be 87mm or nominal 3.425".
Get the piston, and bore/hone the cylinder to fit that exact piston with the diametrical skirt clearance needed for that piston.

[Bilgemaster]

Well, I used to do it.
But, the work dried up a few years ago and it became so sparse that I couldn't keep operating. I make a few UCE parts now, and that's about it. I had to get a local retail job to make ends meet.

Actually, I was in fact thinking of you in particular, but didn't wish to presume. Any guy that can engineer his own high performance heads from doodly-squat is the guy I'd want messing around with my own ride's guts. Not Goober from Mayberry.

With a bit of luck, the next couple of years may find the new Twins, Himis, and whatever all else they hammer out in Chennai making real inroads into the American market, or at least enough to support a healthy aftermarket performance sector, if that's what you'd prefer to be doing. Once you can roll up to a Home Depot on an Enfield and not have EVERY person you talk to say, "What the hell is that?", would be the time to sign the lease on a shop, and not a moment  before. And let's face it, Bullet singles and their Continental spawn have never really been about PERFORMANCE writ large, right?

[ace.cafe]

Actually, I was in fact thinking of you in particular, but didn't wish to presume. Any guy that can engineer his own high performance heads from doodly-squat is the guy I'd want messing around with my own ride's guts. Not Goober from Mayberry.

With a bit of luck, the next couple of years may find the new Twins, Himis, and whatever all else they hammer out in Chennai making real inroads into the American market, or at least enough to support a healthy aftermarket performance sector, if that's what you'd prefer to be doing. Once you can roll up to a Home Depot on an Enfield and not have EVERY person you talk to say, "What the hell is that?", would be the time to sign the lease on a shop, and not a moment  before. And let's face it, Bullet singles and their Continental spawn have never really been about PERFORMANCE writ large, right?

Things have really come along lately for performance Bullets.
The record fastest lap for a single cylinder 500 at the Isle of Man is currently held by a Bullet. Not a Manx or a G50, but a Bullet!
There are other Bullet accolades out there, including a Bullet with our Ace head work on it winning the British Historic Racing Season  Championship in the post-1962 500cc class in 2015.
The Bullet seems to be a late bloomer, but it is showing its stuff now.