ES2 Valve Lifter Problem

If you remove the access plate on the side of the rocker box and look to the front you will see that the shaft of the valve lifter has a flat spot milled on it where it crosses over the exhaust valve rocker. The valve lifter lever arm on the outside of the rocker box ( where the engine end of the valve lifter cable attaches ) has a pinch clamp around the shaft. If you peer inside ( you will likely need a light ) and operate the lifter lever you will see how the flat milled on the shaft acts as a cam to press on the rocker and open the exhaust valve a tiny bit , thus releasing compression. If you back off on the fastener of the pinch clamp on the shaft you can rotate the shaft so the corner formed by the flat on the shaft changes it's proximity to the rocker. Turn the engine over till you see the intake valve open - this way you know the exhaust valve is closed and seated and the exhaust rocker is in it's highest position. Turn the lifter shaft with via the slot on it's outboard end so that the corner on the shaft has a slight clearance between it and the rocker arm , then tighten the pinch clamp . You also have some fine adjustment via the cable adjuster - you may want to set this in a central position before adjusting the the arm/shaft connection so the you can fine tune it either way if necessary .

Hope this helps - Richard

Addendum- I may be stating the obvious here but :

1 - adjust the shaft flat corner / rocker clearance on the advancing side of the shaft - the corner that is rotating downward toward the rocker as the handle bar lever is pulled.

2 - make certain there is some free play in the lever in rest position - just like the clutch lever .

You don't want the shaft corner inadvertently bearing on the rocker causing unwanted . decompression.

Hopefully it's not something as silly as the pinch bolt having worked a bit loose on the lifter shaft?

That was my first thought.......

Pleased to have been able to put something back in after all I've taken out!

George

Not sure about the carb, but the head is Norton, it was fitted to ES2s of the period ( my 55 has one) although Iâm not sure when they were introduced, they were changed again in 57 when the head had integral push rod tubes.

just checked Roy Bacons book, he says the ES2 had a 276 which was changed to a 376 in 1959.

Yes, 389 would be on the big side which might explain your slow running issues. IIRC they start at 1 1/8" whereas the biggest 376 is 1 1/16".

I had the impression that the monobloc was fitted earlier than 1956 but could be wrong. My 1952 should have a 276 but seems to be running quite well with a 376 although I've fitted a 3.5 cutaway slide rather than the specified 4.

Hi Paul.

With the 4 cutaway the carb spat back on opening the throttle unless I was very cautious - the 3.5 seems to have eliminated this although the 3.5 slide is also probably less worn than the 4.

I have a 270 main jet, 106 needle jet, needle in the middle position and 30 pilot jet fitted. I generally prefer to go a little large on the main jet as it only comes into play at wide open throttle which I am unlikely to use with the ES2!

Having said that I have yet to take the bike on the road so all this is with it running on the stand.

Just to add to Dan's comment, I too have a 55 ES2 and it's fitted with a 376 Monobloc, with a No 4 cutaway, 270 main jet, 106 needle jet and the needle in position 3. I think the pilot jet is a 30. Hope this helps.

It hammers along very well and returns around 76 to the gallon which includes a few "blasts".

George

I probably have all the bits to build one up although I've selectively assembled the one on the bike with my "best" parts. Let me know if you're interested and I'm sure we can come to an equitable arrangement.....

A couple of things to ponder:

1. Unless it's much much too small the main jet only comes into operation when nearing full throttle.

2. A 650 twin can't be compared directly with a 500 single as each power stroke on the twin is effectively a 325 single (not exactly I know) so 240 is probably on the small side.

You won't get far comparing a single with a twin, as Ian S has said.

A mid/late '50's Matchless G80 was fitted with a 389, internal bore 1 5/32", around 29mm. Settings; without air filter; main jet 260, 30 pilot, 106 needle jet, 3 1/2 slide cutaway, #3 needle position. Different engines, different manufacturers, different carbs, but at least they are both 500cc singles. I would start with the correct needle, in the central position, and 106 needle jet. I am sure 107 is too large. The TR6 actually had a 106 needle jet, although that is not relevant. I would have a 30 pilot jet to hand, too. It does sound as though the carburettor settings are all over the place.

Hope this helps.

Ian

Oh dear, good luck with it Paul. Let us know what you find.

Ian C.

Hopefully nothing too serious.

Mind you, this thread did start off talking about valve lifters. Yours isn't overadjusted is it?

What Ian Soady said - be certain exhaust valve is closed and seated and re check clearance on valve lifter shaft. Remember there is overlap in valve timing on these engines - exhaust valve will be slightly open as intake valve starts to open. Also be certain you have some free play in valve lifter lever at handlebars when in static position .

Thereâs no need for a gasket on these bikes and the head can be lapped to the barrel. But itâs not unusual to find a gasket fitted.

Itâs easy enough to take the head off, tank off:- carb off, lifter cable off, exhaust off then four sleeve nuts to undo which is easier if you can get the rocker box off but itâs not essential. Assuming my memory is right ! I can do it in 10 mins on my trials bike.

I dont know about a Manx piston but standard replacements are available from RGM, Andover etc, or you can fit a side valve piston which because itâs domed increases compression a little, but you may have to machine valve pockets.

Mike Pemberton is the man to speak to about tuning these engines and worthwhile improvements. I understand that the exhaust valve runs very hot and should be made of autenistic steel (not sure of spelling) if itâs not it might have burned out. You can tell if it is, as autenistic steel is non magnetic.

Hope that helps

dan

Loss of compression could have a number of causes, some easily sorted (loose head nuts, sticking valve or a bit of crud lodged on the seat) others more difficult. My 19S once lost some compression during a long run. Bike was down on power and difficult to start but it did get home. In that case it was a valve guide that had come loose in the head. Not obvious, the loose guide could not be observed until the valves were removed. Solution was to have an oversize guide made up.

ES2 usually has an aluminium head gasket. You can dispense with this and lap the joint as per ohc heads but you need to pay attention to the height of the barrel spigot wrt the head recess. The spigot should be 0.001" taller than the depth of the recess so that the gas seal is acheived on top of the spigot rather than on the broader surrounding area. See George Cohen sketch attached. You may have to skim the head to reduce the depth of the recess. Small o-ring pockets can be machined in the top surface of the barrel to cure oil leaks around the valve oil drains.

If you are seriously considering alternative pistons then compare the weights of the original and new pistons. If any more than just a few grams difference you may have to rebalance the crank. I once fitted a Big 4 piston to the 19S (domed top instead of dished) without considering the weight difference (almost 60g heavier). I later calculated that the balance factor had dropped from 51% to 47%. The vibration was horrendous, the oil tank sprung a leak and I couldn't see properly!

Cheers, Ian McD

Yep the new pistons are definitely heavier than the heptolite ones, but as mine is a trials bike I donât notice! Ianâs post reminds me that my valve guide fell out when I took out the exhaust valve, but fear not oversize guides are available! I had mike fit the later valve springs while he was in there that gives more room for the rockers which can clatter against the rocker box if the valve and seat wears too much.

If the head over oils which it can easily do, then much oil will travel down the valve guide and it may well gum up.

Dan

The 'Wellworthy Alfin' refers to a casting process, and was a proprietary technology of the Wellworthy compnay. Alfin meant 'aluminium fins' cast onto an iron cylinder liner. The liner had shallow ribs machined into the outer surface. It was heated, then dipped in molten pure aluminium, and then the fins were cast in aluminium alloy onto the prepared liner. It was a way of making a very strong bond between liner and fins for good heat transfer. Wellworthy made the alloy barrels for Internationals, Manx and 500T, and also supplied alloy cylinder heads castings.

The Manx piston is much higher compression, and standard bore is 79.6mm. A standard ES2, or an International, is 79.0mm. So a standard Manx piston is 0.6 x 0.040" = 0.024" oversize. If you want a stronger piston than the ES2, consider an International, they are a race piston with a nearly flat top, so will not have a major effect on compression ratio. And be cheaper than Manx.......

With the carburettor, take a look at the stamping on the right side of the mounting flange. That will have a number 389/.xxx - this will enable you to look up the exact bore size and tell you what bike the carb was originally fitted to. Go here:

http://archives.jampot.dk/technical/carburation/amal_monobloc__numbers_type_and_use.pdf

Alternatively you can put a ruler or (better) a vernier across the carb bore. The smallest 389 is 1 1/16", or 27.0mm. It's the same size as the largest 376, rarely fitted as it cost more than a 376, but if found it's a catch, because they have more bearing surface so wear less. The next size up from 1 1/16" is 1 1/8", or 28.6mm. That is a VERY mild increase in bore size, and hardly makes a race-tune.

Don't do anything rash, go through the carburettor tuning stages progressively. Set the idle mixture, make sure the bike doesn't spit or stumble just off idle. This could be due to too much cut-away, or a blocked pilot compensator hole. This is an important check, DO NOT OMIT THIS. There is a very small drilling above the pilot jet into the inlet tract, just on the engine-side of the spray tube. Blow it out with an air line, or carefully poke a fine wire into it. Carefully.

These checks should be done before you experiment with the needle and its jet. Yes, the needle jet operates over most of the throttle range, but the idle and cut-away affect the mixture from the needle. So build from a good foundation. THEN go experimenting with the needle. And only when that is right can you bother with the main jet. Unless it is seriously undersized, it makes little difference until you are at or near peak revs on WOT

Paul

That does look nasty.

Hi Paul,

The Manx piston can be made to fit but is not a straight swap. The pre 1939 type are 79mm and this was changedfor 1939 to 79.62mm. Both sizes were made from forged aluminium-alloy and have a raised crown and weigh quite a bit more than the cast alloy ES2 piston so you will need to bore the fly-wheels to compensate. The small endwidth is 0.25" narrower on the Manx so you will need to remove 0.125" from each side of the con-rod. The piston height from the centre of the gudgeon pin to the top of the ring land area is 0.125" lower on the Manx than the ES2, which as you say will be around 8-ish to 1. The Inter piston is the same dimensions except the bore size which remained 79mm and a flat top which will only give you a 6 to 1 compression ratio. The Inter is cast alloy and a similar weight to the ES2. You can shorten the barrel but it seems a shame to modify a rare Alfin barrel. If you want a bit more go the easiest and cheapest piston will be a pre 1948 16H (same as WD). You will need to shorten the skirt and make two small valve cut-aways but no more than 2mm deep and put a 1.5mm spacer under the barrel. This will give you about 8.5 to 1 but will be heavier than the ES2 unless you can lose some more material.

Regards, Richard.

Itâs difficult to see from the pics but it looks a bit like a seize to me, trapping the rings will certainly remove much compression, is there definite evidence of something big scoring the piston? I can see something at the top of the bore but itâs a bit blurry! Is the top of the piston white in places?

Iâm no expert being a short term owner of an ES2 but it looks like a seize to me, what was happening before it happened?

We're a bit "off topic" but I agree with Dan. It's happened to me years ago (on an ES2) and looked very similar.

George

Pistons and bores are subject to more wear on these faces because they are the thrust faces . After TDC on the power stroke the resistance offered by the crank forces the piston against the cylinder wall opposite the crankpin. After BDC as the piston is on its way back up on the exhaust stroke the opposite wall is also effected to a lesser degree

75mph on a 64 yr old bike with a top speed (when new) of around 82 could be said to be pushing it - unless you're very confident of the innards!

George