Limited engine turn diagnosis

Previously wrote:

Hi

I have a 500cc Dominator 88 that I have been trying to put back on the road for some months. What I initially thought was a problem in the gearbox is actually an engine issue.

I have never tackled and engine strip and I wanted to ask in here first...

By using a spanner on the stator I am able to turn the engine but never to a full cycle. In fact, I would say it moves freely for 80% of a cycle. Then I need to turn the other way, and I can again go for about 80% of a complete cycle, until there is a hard stop (metal to metal). I have opened timing cover, rocker feed cover, exhausts, manifold and I cannot find anything bent or broken (not that I know too much about how everything should look in there, but valves seem to be straight, I can feel top of pistons moving...). I presume the damage is around the camshaft, but no idea.

Do you recognize this problem? Are they clear signs of a specific failure? Thoughts?

Many thanks as usual!

Isaak

Hello I would Have ago at taking the top end off Then you see want wrong . Your AJD

I would put my money on a valve sticking open and catching the piston near TDC.

As Anna says, you best move is to take the head off and then check all the innards.

The only other alternative cause I can suggest is a broken or stuck camshaft follower.

Hi Izaak, I agree with Anna, and Phil's, comments. I suggest your first move should be to get a Workshop Manual. Try "Mercian Motorcycle Manuals", you will find them on the web. First remove the rocker covers, if a valve is stuck open you should be able to see this (one, or more, of the rockers will have way too much clearance. John.

Look down the plug holes with a torch to see if valve stuck.

I don't understand all this faffing about. Whatever the cause that motor needs taking apart and sorting out. Even if the problem is a stuck valve, servicing just the head could lead to engine failure sooner or later. Without dismantling it, you can have no idea of its condition.

I have always found that "Kim the CD Man" CD versions of manuals and parts books are a good choice. Each CD contains a collection of manuals, parts books, riders' handbooks and other useful stuff in pdf format ready to be printed out. You can try emailing him at kimthecdman@techinfo.com.au. I think some dealers stock his CDs as well.

Bruce Main-Smith also does photocopy versions of out-of-print factory manuals and parts books. Always go for the real factory manual, rather than Clymer or Haynes ones.

Colin.

Previously wrote:

Hi Izaak, I agree with Anna, and Phil's, comments. I suggest your first move should be to get a Workshop Manual. Try "Mercian Motorcycle Manuals", you will find them on the web. First remove the rocker covers, if a valve is stuck open you should be able to see this (one, or more, of the rockers will have way too much clearance. John.

Now you have it apart - if you cannot find anything suspicious and if the valves are not bent or jammed - do the rockers move nicely? If they do - do you have a valve spring compressor (that will fit)? A jammed valve stem is just possible.

If all seems OK, it is also quite possible the previous owner tightened down the head with the rocket ball ends not properly located into one or more of the four push rod top cups. Easy mistake to make - as you will find out when you re-assemble, especially if you did not find out before you took the head off. Take great care. You'll need a torch and some bent wire to pull and prod everything into the right places. Ideally you should employ an octopus to hold the rods in position as you lower the head - without bending a push rod. Then when you turn the engine over, you should find valve clearances on top of all four valve stems (obviously not all at the same time...).

I'm sure others will disagree - but in my view you should not dismantle the engine any more than you have done if is turning over smoothly. You might end up with a basket case - especially if you haven't stripped an engine before. Curiosity is not a good excuse to go tinkering!

As for bits of metal - that's a shame! But since it's above the piston, it cannot have come from the bottom end. Are they bits actually from helicoils - steel - used to repair threads (e.g. plugs)?

Are the "worms" magnetic, i.e. steel or something else.

It is possible I guess that someone tried to sabotage the engine by slipping something in the sparkplug hole.

Have you pulled the valves? Maybe it is a valve seat that has come loose.

Iâm no expert but I read somewhere that some cylinder heads head an alloy ring inserted to fill the gap where the cylinder barrel ridge entered the head. As your cylinder barrel has no ridge the âWormâ youâve found may be the remains of the insert?

Just a guess.

Alan.

Looking at the photobucket cylinder head photo number 11 can you not see an insert in the left combustion chamber, and the right side its missing?

Alan

Previously wrote:

Hi

I have a 500cc Dominator 88 that I have been trying to put back on the road for some months. What I initially thought was a problem in the gearbox is actually an engine issue.

I have never tackled and engine strip and I wanted to ask in here first...

By using a spanner on the stator I am able to turn the engine but never to a full cycle. In fact, I would say it moves freely for 80% of a cycle. Then I need to turn the other way, and I can again go for about 80% of a complete cycle, until there is a hard stop (metal to metal). I have opened timing cover, rocker feed cover, exhausts, manifold and I cannot find anything bent or broken (not that I know too much about how everything should look in there, but valves seem to be straight, I can feel top of pistons moving...). I presume the damage is around the camshaft, but no idea.

Do you recognize this problem? Are they clear signs of a specific failure? Thoughts?

Many thanks as usual!

Isaak

Hello having looked at your very good photos , there are things at to me are not right your engine is a dynamo Model And it should not have 650ss push rods for start and your pistons are high compression ones the crown of the piston is over the top of the Spigots, and it should be level with the spigots .So your pistons are hitting the cylinder head . and from what ,I can see some one as been tamping in the attempt to tune the engine, But they have left you with some work . the valves need removing and a good clean and checking the motor as been sick and not running right you can see all that black carbon . and push rod need replacing there the wrong one for this motor . and the pistons need replacing with the right ones for the correct year .the ones you have are wrong. And this is where your problem lies, You can get the right Pistons from the Club spares scheme ,I hope you now can see what I mean ! , I hope this may help you now! yours Anna J Dixon

What Anna says about the high pistons is the first thing I noticed, but it is really odd as the engine would have never been able to run with the pistons fouling the head. Th epistone clearly HAVE been running - possiblynot in that engine? I'm having trouble with Photobucket crashing so I can't look at the pics in detail. I can't see if the barrel has a protruding spigot. If it does then there would be no ring in the cylinder head face to break. I must admit I hadn't realised these rings were alloy - that sounds definitely dodgy to me! I was considering having the spigots machined off my barrels as one has a split after its last rebore, but I will think twice about it if there's a chance a ring could foul everything up.

Sadly it means that Isaak has opened a can of worms which might well cost him hundreds of pounds! New pistons cost the earth nowadays.

Good luck!

Lionel

Brand new theory. Maybe somebody wanted to remove the cylinder head, and could not do so - probably beause he had left bolt number 10 in place...(you know - the one under the carbs at the â?back)

So in order to try to unstick, he shoved a piece of soft aluminium down the plug hole to kick it over. I've all heard about filling the chamber with string to do the same job (and risk bending the valves). Anyway - no joy - so he put it all back together and sold the bike in disgust.

Maybe if you put it all back together it'll all be OK!

Your bike appears to be a 600cc Model 77. It has the single down tube frame and the pre-downdraft cylinder head. The fat pushrods might possible clash with the sides of the tunnel - but if they aren't marked or bent then they are presumably Ok.

If it were mine I'd check the valves and pushrods are all straight and seats are good, and just put it all back together. Then, hopefully, enjoy it! As Lionel says - it looks like it's been running, and if used pistons had been put in, almost anyone doing so would have at least cleaned their tops first. One of the valves above the 'worm' might be bent...

Brand new theory. Maybe somebody wanted to remove the cylinder head, and could not do so - probably beause he had left bolt number 10 in place...(you know - the one under the carbs at the back)

So in order to try to unstick, he shoved a piece of soft aluminium down the plug hole to kick it over. I've all heard about filling the chamber with string to do the same job (and risk bending the valves). Anyway - no joy - so he put it all back together and sold the bike in disgust.

Maybe if you put it all back together it'll all be OK!

Your bike appears to be a 600cc Model 77. It has the single down tube frame and the pre-downdraft cylinder head. The fat pushrods might possible clash with the sides of the tunnel - but if they aren't marked or bent then they are presumably Ok.

If it were mine I'd check the valves and pushrods are all straight and seats are good, and just put it all back together. Then, hopefully, enjoy it! As Lionel says - it looks like it's been running, and if used pistons had been put in, almost anyone doing so would have at least cleaned their tops first. One of the valves above the 'worm' might be bent...

Previously wrote:

Brand new theory. Maybe somebody wanted to remove the cylinder head, and could not do so - probably beause he had left bolt number 10 in place...(you know - the one under the carbs at the back)

So in order to try to unstick, he shoved a piece of soft aluminium down the plug hole to kick it over. I've heard about filling the chamber with string to do the same job (and risk bending the valves). Anyway - no joy - so he put it all back together and sold the bike in disgust.

Maybe if you put it all back together it'll all be OK!

Your bike appears to be a 600cc Model 77. It has the single down tube frame and the pre-downdraft cylinder head. The fat pushrods might possible clash with the sides of the tunnel - but if they aren't marked or bent then they are presumably Ok.

If it were mine I'd check the valves and pushrods are all straight and seats are good, and just put it all back together. Then, hopefully, enjoy it! As Lionel says - it looks like it's been running, and if used pistons had been put in, almost anyone doing so would have at least cleaned their tops first. One of the valves above the 'worm' might be bent...

And another detail - you should prevent the con rods from becoming scratched where the touch the crack case throat. Polish any nicks out and stuff some cloth in there: a)in case you drop something into all that oil, and b) to make sure they don't pick up fatigue-unducing scratches.

I would reassemble that motor ,tap the valves to check for stuck, test seats with a little petrol in the ports,clean up the cylinder base and case. You will have to use piston ring clamps with some battens or you will break the rings.Space the ring gaps120 degrees from each other,The HC pistons may not be as bad as they look as its a low comp head. The worm may have been jamming the motor. Something dropped into the head for whatever reason.The polished rods say someone did care at some time.Get a Norton man to help!!!.

It seems from the photos that Alan Throssell has the hit the nail on the head

"some cylinder heads head have an alloy ring inserted to fill the gap where the cylinder barrel ridge entered the head. As your cylinder barrel has no ridge the âWormâyou'vefound may be the remains of the insert?

Just a guess."

The photos do show that the insert is missing on one side. I have never seen that befor, wonder why it came out? Too much heat?

Skip Brolund

I wonder if somebody used a piece of aluminium bar to find TDC for ignition timing purposes - then it snapped off when he turned the engine without holding it vertical.

Steve

Norton Dominators of the vintage having generator charging systems and this type of cylinder head did not have rings pressed into the cylinder head recess. The cylinder has a spigot that fits into the recess in the cylinder head.

In the mid-1960s, after AMC had taken over Norton production and at one point eliminated the spigot on the top of the cylinders, they offered rings to the owners of older bikes they could press into their recessed heads so they could use later cylinders that had no spigots.

That being said, at the late date that AMC eliminated the spigots on cylinders, sometime in 1965, they had no generator-style cylinders in their parts books anyway. So pretty much as now, owners of older Dominators had problems finding parts for the older bikes and mechanics have made due with what they could get their hands on.

High compression pistons were an option and available for the Dominator 500 back in the 50s onwards so I don't see why it would be a surprise when they turn up. For 1955 onwards Dommies with alloy heads the owners manual lists two, a standard and high compression. A later cylinder head from a 1960-on slimline Dominator is supposed to give about a 1 point boost in compression without changing pistons.

Since the pushrods on this engine do not appear to have had any interference problems, I would put the engine back together minus the "worm" and see if it turns over and check the compression on each cylinder against each other which would show if the side with debris found in it had damaged valves or seats. If all is good then start it up and ride it.

It was common in the old days to run the bikes with no air cleaner, just an air horn, and just about anything could be put down the carb and find it's way into the engine if one was unlucky....

The rings are very brittle and must stay in the same place ,no usefull reason to touch them, leave the carbon on the area above the rings . valves will be well carboned up ,even the inlets, worth cleaning. Push rods do not easily engage into rockers and need to be checked carefully. Head fixings need to be checked and tightened several times to avoid blown gasket. Good luck.

Hello the pistons should not be above the top of the barrel and if I were you I would fit the cylinder head on with out putting the push-rods in ,just to see if its hitting inside the cylinder head , Then I would find out if you have flat cam follower fitted if you have there no need to replace the push-rods as they been working OK before now , its the pistons at look to me to be not the right ones, But we will see if you check to see if there hitting inside first before final re-assembly hope this helps yours Anna J Dixon

They pretty much have to be Norton twin pistons because the valve pockets are handed LH and RH. I don't know of any inferior makes like that. The compression ration must have been very high, and if you need to keep those pistons you could put a 2mm copper plate (cut the same shape as the cylinder base gasket) under the cylinders, to get the ratio back to normal. That would obviously help with any clearance issues too. Just check that all of the tappet adjusters have another 3 turns of adjustment first.

I think that as you have been riding it for years and know its recent history, it must have been running with very little valve/piston clearance until that foreign body got inside it.

I would definitely replace the inlet and exhaust valves which were hitting the worm.

Steve

The allegedly tall pistons don't look odd to me - they look just like mine in fact. And my comp ratio is only about 8 to 1

Since you have single down tube frame and 500cc engine, you seem to have a rarity. According to another web site you have one of the approximately 50 Norton Nomads that were built with 500cc engines. Not mentioned in most of my books...

So maybe one of the other 49 decided to get you off the road by sticking a bar down the plug hole!

p.s. I'm not joking about the need for an octupus. Clever use of a few rubber bands might assist instead.

Hi David, I tooenjoyedthe octopus comment!

The pics show the duplex featherbed frame rails:

http://s1263.photobucket.com/albums/ii632/theguanche/Dommie/

Skip

You do not have to be an octopus!

Mike Taglieri wrote the following way back in 1997. Why it is hidden in the depths of 'Commando Hints and Tips' is beyond me as it should be much more prominently placed, but it really works and makes head removal and installation an easyone person job.

George.

Mike Wrote:

Techniques for easier removal of cylinder heads

This problem of installing Norton heads arises because Nortons have their pushrod tunnels permanently cast into the cylinder barrels rather than using the vast array of little tin tubes, rubber washers, etc., found leaking onto older engine designs (the names of which modesty prevents me from mentioning). The Norton design was a major improvement in oil-tightness, but it makes getting the head off and on with the engine in the frame very tricky indeed if you do it the way the book says; because you're supposed to lift all four pushrods as high as possible into the head and hold them there while you lift the head out of the frame, or you won't have enough clearance to get it out. Six hands are the practical minimum for this job, and most Brit-bikers have only two. The answer is to use a pair of nylon tie wraps (the kind used on electrical harnesses, etc.) As soon as the head is lifted free from the gasket, put one tie wrap around each pair of pushrods, fastening it so the long end of the tie wrap points out away from the barrel. Snug them up tight enough so that it's a bit difficult to move them up and down on the pushrods. Now, as you remove the head, push the tie wrap down all the way on each pair of pushrods, then put a finger from each hand under the tie wrap on the pushrods to hold it up (and its pair of pushrods) as you're lifting the head free of the engine. Holding each pair of pushrods this way leaves you eight fingers to lift the head out of the frame. it will be easy to keep the pushrods snug against the head and you'll clear the frame with no danger of bending a pushrod, and no extra hands needed. After the head is off, keep the tie wraps on the pushrods (unless you need to service them, of course), so you can tell the left pair from the right pair by the direction that the end of the tie wrap is pointing. To reinstall the head, just hold the pushrods high up in the head with a finger on the tie wrap as you did before while lifting the head loosely onto the barrel. Once the head is past the frame and over the barrel, with the pushrods in their tunnels, you don't need the tie wraps anymore, so snip each one off while holding the long end, to be sure no nylon bit falls into the engine. Note that the only purpose of this trick is to keep the pushrods out of harm's way during removal and installation of the head. During installation, you still have to follow the book and be sure the pushrods are properly located on their rocker-arms before tightening down the head bolts, or a pushrod could be bent. If, like the writer, you've already taken the head off by the traditional blood and chaos method, you can still put it back on with the tie-wrap method; firstly making sure the pushrods damaged during removal have been replaced and all skin lacerations have stopped oozing, which could cause rust. You simply have to put a tie wrap on each pair of pushrods, aiming the end of the tie wrap toward the outside of each pair so you'll be able to tell the left from right. If you've mixed them up already, you'll survive, but it's better practice not to interchange pairs. I invented this trick many years ago, and used it last October on my ring-job with no problem, even though I was out of practice. Easier head installation is probably the only good thing that can be said about separate pushrod tubes of the earlier engine designs - this trick makes Norton head removal and installation almost as easy, without giving up the oil-tightness and durability of cast-in pushrod tunnels.

Mike Taglieri (miketync@)juno.com on NOC-L 3rd. Jun 1997

You do not have to be an octopus!

Mike Taglieri wrote the following way back in 1997. Why it is hidden in the depths of 'Commando Hints and Tips' is beyond me as it should be much more prominently placed, but it really works and makes head removal and installation an easyone person job.

George.

Mike Wrote:

Techniques for easier removal of cylinder heads

This problem of installing Norton heads arises because Nortons have their pushrod tunnels permanently cast into the cylinder barrels rather than using the vast array of little tin tubes, rubber washers, etc., found leaking onto older engine designs (the names of which modesty prevents me from mentioning). The Norton design was a major improvement in oil-tightness, but it makes getting the head off and on with the engine in the frame very tricky indeed if you do it the way the book says; because you're supposed to lift all four pushrods as high as possible into the head and hold them there while you lift the head out of the frame, or you won't have enough clearance to get it out. Six hands are the practical minimum for this job, and most Brit-bikers have only two. The answer is to use a pair of nylon tie wraps (the kind used on electrical harnesses, etc.) As soon as the head is lifted free from the gasket, put one tie wrap around each pair of pushrods, fastening it so the long end of the tie wrap points out away from the barrel. Snug them up tight enough so that it's a bit difficult to move them up and down on the pushrods. Now, as you remove the head, push the tie wrap down all the way on each pair of pushrods, then put a finger from each hand under the tie wrap on the pushrods to hold it up (and its pair of pushrods) as you're lifting the head free of the engine. Holding each pair of pushrods this way leaves you eight fingers to lift the head out of the frame. it will be easy to keep the pushrods snug against the head and you'll clear the frame with no danger of bending a pushrod, and no extra hands needed. After the head is off, keep the tie wraps on the pushrods (unless you need to service them, of course), so you can tell the left pair from the right pair by the direction that the end of the tie wrap is pointing. To reinstall the head, just hold the pushrods high up in the head with a finger on the tie wrap as you did before while lifting the head loosely onto the barrel. Once the head is past the frame and over the barrel, with the pushrods in their tunnels, you don't need the tie wraps anymore, so snip each one off while holding the long end, to be sure no nylon bit falls into the engine. Note that the only purpose of this trick is to keep the pushrods out of harm's way during removal and installation of the head. During installation, you still have to follow the book and be sure the pushrods are properly located on their rocker-arms before tightening down the head bolts, or a pushrod could be bent. If, like the writer, you've already taken the head off by the traditional blood and chaos method, you can still put it back on with the tie-wrap method; firstly making sure the pushrods damaged during removal have been replaced and all skin lacerations have stopped oozing, which could cause rust. You simply have to put a tie wrap on each pair of pushrods, aiming the end of the tie wrap toward the outside of each pair so you'll be able to tell the left from right. If you've mixed them up already, you'll survive, but it's better practice not to interchange pairs. I invented this trick many years ago, and used it last October on my ring-job with no problem, even though I was out of practice. Easier head installation is probably the only good thing that can be said about separate pushrod tubes of the earlier engine designs - this trick makes Norton head removal and installation almost as easy, without giving up the oil-tightness and durability of cast-in pushrod tunnels.

Mike Taglieri (miketync@)juno.com on NOC-L 3rd. Jun 1997

You do not have to be an octopus!

Mike Taglieri wrote the following way back in 1997. Why it is hidden in the depths of 'Commando Hints and Tips' is beyond me as it should be much more prominently placed, but it really works and makes head removal and installation an easyone person job.

George.

Mike Wrote:

Techniques for easier removal of cylinder heads

This problem of installing Norton heads arises because Nortons have their pushrod tunnels permanently cast into the cylinder barrels rather than using the vast array of little tin tubes, rubber washers, etc., found leaking onto older engine designs (the names of which modesty prevents me from mentioning). The Norton design was a major improvement in oil-tightness, but it makes getting the head off and on with the engine in the frame very tricky indeed if you do it the way the book says; because you're supposed to lift all four pushrods as high as possible into the head and hold them there while you lift the head out of the frame, or you won't have enough clearance to get it out. Six hands are the practical minimum for this job, and most Brit-bikers have only two. The answer is to use a pair of nylon tie wraps (the kind used on electrical harnesses, etc.) As soon as the head is lifted free from the gasket, put one tie wrap around each pair of pushrods, fastening it so the long end of the tie wrap points out away from the barrel. Snug them up tight enough so that it's a bit difficult to move them up and down on the pushrods. Now, as you remove the head, push the tie wrap down all the way on each pair of pushrods, then put a finger from each hand under the tie wrap on the pushrods to hold it up (and its pair of pushrods) as you're lifting the head free of the engine. Holding each pair of pushrods this way leaves you eight fingers to lift the head out of the frame. it will be easy to keep the pushrods snug against the head and you'll clear the frame with no danger of bending a pushrod, and no extra hands needed. After the head is off, keep the tie wraps on the pushrods (unless you need to service them, of course), so you can tell the left pair from the right pair by the direction that the end of the tie wrap is pointing. To reinstall the head, just hold the pushrods high up in the head with a finger on the tie wrap as you did before while lifting the head loosely onto the barrel. Once the head is past the frame and over the barrel, with the pushrods in their tunnels, you don't need the tie wraps anymore, so snip each one off while holding the long end, to be sure no nylon bit falls into the engine. Note that the only purpose of this trick is to keep the pushrods out of harm's way during removal and installation of the head. During installation, you still have to follow the book and be sure the pushrods are properly located on their rocker-arms before tightening down the head bolts, or a pushrod could be bent. If, like the writer, you've already taken the head off by the traditional blood and chaos method, you can still put it back on with the tie-wrap method; firstly making sure the pushrods damaged during removal have been replaced and all skin lacerations have stopped oozing, which could cause rust. You simply have to put a tie wrap on each pair of pushrods, aiming the end of the tie wrap toward the outside of each pair so you'll be able to tell the left from right. If you've mixed them up already, you'll survive, but it's better practice not to interchange pairs. I invented this trick many years ago, and used it last October on my ring-job with no problem, even though I was out of practice. Easier head installation is probably the only good thing that can be said about separate pushrod tubes of the earlier engine designs - this trick makes Norton head removal and installation almost as easy, without giving up the oil-tightness and durability of cast-in pushrod tunnels.

Mike Taglieri (miketync@)juno.com on NOC-L 3rd. Jun 1997

"In response to a previous comment, the "faffing" was justified, and requested by me because if it was 100% clear that the failure was known and it was going to involve many hundreds of pounds, I would have probably taken radical solutions like buying a new machine or selling this one, etc. But since there is no consensus I decided to go ahead and hope to be lucky."

I stand by my "faffing about" comment and I am pleased that you took the motor apart. Having got so far, you should finish the job. Split the cases, check the crank, replace the bearings etc. Someone has done some work on those rods. You could secure some bubble wrap around them to stop them bashing the cases. You don't want to put a nick in them. There is nothing wrong with the type of piston as far as I can see from the photos. They look just like the ones I ran in my 88. Have you measured the cylinders? If they are clapped out, get them rebored. Check the valves, particularly the one that looks like it has been hammering the "worm". Courage, Nortons are not that difficult to work on if you think about what you are doing. Be discriminating when you read the posts on here.

Cheers

Alan

Despite what is often said, these rings are not essential. The annulus that is left if you leave than out will in time fill with carbon. That's what happened when I fitted spigotless barrels with an earlier head (designed for a spigotted barrel) and it worked just fine. Better than having one come loose with the attendant problems. Pragmatism wins every time as far as I am concerned.

Isaak

Good to see a definitive answer. I couldn't really believe that anything that big could get past the carbs and inlet valve without getting mashed into pieces and bending the valve big time.

The only solvent I have found which is aggressive enough to soften carbon is aerosol gasket remover. It is very nasty stuff to use, only use it outdoors, and simply dissolves protection such as thin surgical plastic gloves (then your skin). Those heavy rubber construction gloves are probably better.

Please ignore my earlier comment about the pistons, I am used to 99 pistons which are much flatter. I was wrong.

Steve