Suffolk Colt - a range of issues!

GOT IT!

The draw bolts go in two the two holes vacated by the screws holding the starter ratchet on  - either side of the rather sorry looking flywheel nut thread - which should be left hand thread. Guess that the nut has been forcibly wound in an anti clockwise direction until the thread gave up. May just be recovererable with a LHT die but will then have to be treated with the utmost care. On the brighter side , there are plenty of used components, short blocks or even complete engines to be had.

You maybe able to see the points through inspection gap in flywheel, I've managed to get a spark from a dead magneto by pinching very fine emery in between points, closing by turning flywheel and pulling emery out, repeat both sides and hopefully will produce a spark, I've also found this didn't work on a few and had to replace whole ignition system so fingers crossed for you. 

Wristpin and Lee - thanks for your suggestions. I've tried them both but, unfortunately, without success. 

I got some emery paper between the points. There was initially some greyish marking on the paper so that they are definitely cleaner than before, but after I'd reassembled it and made sure the plug connector was screwed firmly into the HT lead, I'd didn't get a spark so I went back to trying to remove the flywheel.

I don't understand what's holding it; it feels more than just stuck. I put two large screwdriver heads in the narrow gap between the flywheel and the magneto backplate and gently twisted them( to keep the leverage away from the edges of the backplate which doesn't look particularly stout). The flywheel yields a little but then simply returns to place; it's as though there is an further "lock" somewhere, but I can't see anything in the operating manual exploded diagram.

I made up a stout wooden baton with the two 1/4" screws going through. I pulled it as firmly as I could and then tapped the baton forward with a mallet as firmly as I dared - but with no movement at all. Finally I put the pawl hub (?) loosely back in place with the screws and inserted  a strip of steel between the hub and the threaded end of the crankshaft. I gently, and equally, tightened the screws to see if the flywheel could be drawn forward using the crankshaft as a "fixed point". but I didn't dare take it past pretty tight and there was absolutely no movement.

I don't know what to do next! I wondered whether, when someone previously had tried to undo the LH thread nut so vigorously as to strip the thread, it had somehow pushed the flywheel further onto the crankshaft than it was meant to go and somehow jammed it onto/over the flywheel key. There isn't any "twist" movement although it's difficult to keep the crankshaft in a fixed position.

It even occurred to me that a complete dismantling of the engine to lift out the crankshaft would need access to the screws securing the flywheel backplate - which can't be reached without getting the flywheel out of the way! - there's something of "There's a hole in my bucket, dear 'liza" about this!

t cannot be that these mowers were condemned if someone mistook the thread on one bolt! Please do you have any suggestions for what I do next?

Thank you!

You know that 'stout wooden baton' you used, well replace it with a metal one and you should be able to pull the flywheel off, I would normally advise putting the crankshaft nut back on, but this doesn't seem possible in your case. You will never lever the flywheel off, you will break something first.

Thank you! I've just found an OLMC 2016 thread about this very issue! I'll try this guidance before asking for more help.

- I suppose the nuclear option, if all else fails, would be to FIRST find a correct flywheel and then, second, use a hacksaw to remove the existing one.

Nigel

Unless that last comment was meant as a joke, can I suggest you put the tools down and step away from the engine

If the method with the metal bar and 1/4” screws is unsuccessful (I’m sure it won’t be as it has worked well for me several times), I would try a large two or three leg puller to draw the flywheel off before resorting to cutting it. 

, I would try a large two or three leg puller to draw the flywheel off before resorting to cutting it. 

There is a risk of pulling off the outer ring of the flywheel and leaving the centre still on the crank 

A bit of heat around the centre may help.

Thanks again. The comment about cutting the flywheel off wasn't really a joke! - I honestly couldn't see an alternative if the flywheel just would not move; none of the parts in that area look strong enough to take very much leverage. However, it became a lot clearer to me when I'd read in the previous thread that the crankshaft, at that end, is a taper; I can now understand how the wheel has become "jammed" on, possibly by the retaining bolt being tightened, by mistake, to the point of stripping the thread. I can now visualise what I'm up against and how using bolts and a bar over the end of the shaft should work.

I'm going to get a couple of new 1/4 UNC bolts to use rather than risk damaging the existing ones. I'll have to be very careful about the pressure on the end of the shaft; it's not in great shape after the over tightening and I can't use the bolt for extra support. Unless it comes away easily, I'll try a bit of heat.

Thanks.

I got the flywheel off! - with a couple of new bolts and - very carefully - using the end of the crankshaft as a base. The inside was a bit grubby but I've cleaned it and used Duraglit on the contact surfaces and I've got a spark both from the end of the HT lead and on the plug. The gap on the plug is 0.020 but the "arm" doesn't sit totally directly above the little round pin below it. The arm doesn't yield to reasonable pressure with a pair of pliers but, since it sparks, is it OK to leave it alone?

The gap between the points is about 0.026; this is above the 0.020 called for in the manual but again, if it's working, must it be adjusted.?

The problem now is the carburettor; fuel drips quiet freely out from the tube at the back of the carb which the air goes up. I've cleaned it out and can see no dirt or blockages; the stem from the base of the brass, cylindrical float is free in the little hole in the base and the tickler is not stuck. The needle is a bit stained but, under a magnifying glass, it looks straight and comes to a fine point without any obvious distortions, but my problem is that I haven't seen one of these before and have no comparison in mind!

However, if the needle is faulty or worn out, can I get a replacement? The carb type is a Zenith 13TC and the float is brass and cylindrical.

I have tried to start it a few times, without success, although it does occasionally splutter out some exhaust on a pull but it doesn't catch 

I'd be very grateful for some guidance.

I would first check the float carefully for holes or splits. You could submerse it in liquid and look for bubbles. Check that the needle hasn't come free from the float i.e. it should be fixed in position in the float. I would also check where the needle seats, top and bottom in the carburettor body to make sure that there is no dirt or debris stopping the needle from seating correctly.

Thanks for the advice, Ransomes-Suffolk. The float is sound but I cleaned the carb again with a piece of thread through the needle hole and it's done the trick! No more leaking!

I then closed the points to 0.020 and got a much perkier spark. Frankly, I don't know why I asked the question; if they say 0.020, they don't mean 0.027. Apologies. 

- and then it started first pull!

Tomorrow, I'll see if the engine actually makes the blades go round! - I don't know what the neighbours are going to think of this; it must be audible 1/4 mile away!

Thanks again.

Things are moving on. I've got the engine starting easily and there's no petrol leaking from the carb or the fuel tap any longer. It runs comfortably enough but there doesn't seem to be as much difference between idling and full throttle as I would have expected.

Although both clutches seem to work (I've had the blades spinning and the roller turning) it's a bit 'hit and miss' and there isn't any strength or "commitment" there; the clutch will be spinning fast but, having slowed it quite easily by hand and then engaged the blades, it takes a bit of encouragement to start them spinning and very little to stop them!

I used a very helpful thread, started by Steveb on 25/5/15, and checked the clutch plates. Both were moving freely but I loosened the small screws to make them easier to open out. (This clutch is the model Wristpin described as "a scaled down iron version used in the Colt" in the thread)

I re-started the mower but, although the blades spun very well (they are set just clear of contact with the fixed blade), there still wasn't any "strength". BUT when I turned the engine off, because I'm not going to be "at it" again for a couple of days, I did so by shutting the fuel tap and I was very surprised to hear the engine suddenly run much faster and smoother than it has before!

Could it be that the problem is actually with the carb? I'd be grateful for some guidance on what to adjust; thank you.

The easy bit; it’s not unusual for an engine to speed up as the mixture weakens just before it stops, especially if the running mixture is set a bit on the rich side.  

Difficult to remotely comment on your other issues ; sounds as though either the clutch is slipping or that some component that is supposed to be locked to a shaft is slipping on the shaft and only partially transmitting the drive.

Wristpin - thanks for the advice. I've thoroughly cleaned the clutch and set the little screws to their least resistance (I was interested to see how they work, which explains why they have a limit on their range; I don't think the last person to try them knew this by the look of the damage to one of the screw slots! I can't see anything elsewhere in the line-up which is loose.

- but rain stopped play so the test drive will be tomorrow; I'll report back.

The fact that you have clutch shoes with the adjuster screws says that they are from an early production machine and could be well worn. In addition those linings tended to harden and glaze .  An image of the drive line will be of assistance, but the early design of centrifugal clutch suggests that your machine may also  have the push / pull dog clutch to disengage the drive to the top sprocket. There's an outside chance that this  may be disengaged and that its just "residual" friction that may be turning the top sprocket. 

Thanks for that, wristpin. I've attached a few pictures of the clutch and the shoes and I have to say that your words "..harden and glaze" fit exactly with what these linings seem to be. (One was slightly loose but I gave the rivets a tap with a punch and it's tight now.) I have to say, I did wonder why two surfaces that are supposed to grip firmly enough to drive a machine are so smooth and hard but, as is a frequent problem for me in this area, I don't have a background knowledge of what a good one ought to look like! The depth of the shoes and the linings combined is 48/100" and the depth of the rivet heads below the lining surface was 2/100" on three and 4/100" on one; this might make their degree of wear more apparent if you've got a decent one for comparison!

b

c

These are pictures of the dog clutch you described. It seems to work; the only point I'd make is that the hole in the shaft, opposite the sprung-loaded ball securing the clutch when it's moved into position, is vacant. I don't know whether there was supposed to be a second ball there but, if there is, there ain't.

DDD

rrr

I'll be very grateful for your verdict.

I think there is something missing on outside of clutch housing. Angus, is there supposed to be another dog that engages drive. I'll try and find a photo. 

Thanks Lee - it's "the drum for the centrifugal clutch" according to the manual. I do have it, and it's in good shape, but I left it off for the photo op to give a better picture of the clutch linings.

A useful set of images . It all looks fine  and only one ball detent to locate the dog clutch is correct.  Obviously it’s not possible to judge the friction coefficient of the clutch linings but so long as there’s a bit above the rivet head they should be ok. You could try roughing them up a bit but the usual warning about asbestos dust applies. 

I suppose that one should ask whether the engine is running fast enough, but I can’t recollect seeing a figure for the top no load governed speed . I’d guess between 2500 and 3000. 

It's been one step forward, one step back since yesterday! I had the mower out at the front, mainly to give the neighbours at the back a rest from its rather lusty exhaust, when a friend who runs a small car/ag.machinery garage happened to pass. He said the engine sounded good but "is that as fast as it goes?". The result was that - at a two meter distance - he reduced the fuel intake and adjusted the idle speed; it now sounds much livelier.

So, this morning, and encouraged by wristpin's advice that there was life in the clutch linings, I set about adjusting the spring pressure on the clutch shoes so that they didn't engage on 'idle'.

BUT, from an odd sound/feeling from the starter pulley, I found that the nut securing the magneto flywheel onto the driveshaft had come off. This was an early problem, where someone had stripped a large part of the LH thread on the shift and in the bolt. I'd thought there was enough left to secure the flywheel, and there had been at the low revs., but a proper speed was too much for it.

Fortunately, there's no apparent damage but I've taken it to the friend's garage where there's a chap with much experience of mowers, who's going to see what can be done to restore this joint. 

So that's it for a week!

Two forward; one back(?). I reached a milestone yesterday when it actually cut grass! - blades and roller both flying round and quite happy at rest on a low tickover. So at least the goal is achievable!

However, the solution to the stripped threads securing the magneto flywheel isn't the best. My friend with the garage said that there was nothing of the original LH thread on the shaft capable of repair (the pictures I put up earlier show what was left) so tapping a new thread of reduced dimension was the way. Unfortunately, and this is entirely my responsibility, he considered that the cost of a LH thread tap and nut was too much so he used a correct type RH thread tap and secured the bolt with Loctite. 

If I had been there, I think I would have born the cost of the LH tap but I wasn't and, believe me, if I were in the middle of the Atlantic or the Gobi with a 4-stroke problem between me and death! - he's the man I'd want there! 

And his solution seems to work; we had to release the flywheel for another adjustment and, with a gentle heat, the bolt came off and went on again. 

Maybe, now I know that it actually cuts grass, I'll treat myself to a proper solution some time - at least I know I wasn't responsible for the original sin!

Three further questions, please:

I'm adjusting the small screws of the clutch shoes so that they engage at the least increase in revs. Is there a way of ensuring that both shoes are at the same pressure/tension? I've used a spring balance but I wonder if there's a more accurate way.

While exploring the carburettor to get the mix/revs better, I find that the the idler needle ends in a "flat" rather than a point. The manual shows both needles as being pointed; but the engine starts and runs as it is. Does it need replacement and is a replacement available?

A friend told me that a pad of wire wool in or over the exhaust would dampen the sound. Is this possible/safe? 

Thanks

Wire wool will burn quite easily  - sparks from an angle grinder or Ray Mears with a pair of jump leads !

Clutch shoes; only after you’ve had the flywheel and crank dynamically balanced - don’t bother.

Thanks for that, wristpin.

The right hand thread on the flywheel, although secured in place is a bit worrying. 

The right hand thread on the flywheel, although secured in place is a bit worrying.

Short of fitting a replacement crank, you are stuck with it .  The flywheel is keyed to the crank so should be fairly resistant to undoing itself,  so having ensured that the points etc are as good as you can get them I would just reassemble with a drop of a fairly strong grade of Loctite on right hand  threads or even just a new self locking nut.

Thanks for the thoughts. I had wondered about a carefully made split-pin through the shaft, just as a safety stop, but there's no spare length on the shaft and very little room around the nut once the pulley is back on. As part of the repair, an extra washer has been put between the nut and the flywheel (there was - and still is - a thin washer with a little tag on it in place). I'll see if there's room for a self locking nut if I remove the "new" washer.

In the meantime, I have actually cut the back garden grass! It looks pretty good - nice lines! - but there's obviously a knack in doing the about turns under power! By the end, I was performing quite a neat little arabesque at each turn but I need more practice - not a subject for the Technical Forum!

It’s quite easy to turn a standard self locking nut into a “ thin”  nut by carefully sawing a thin slice off the non locking end..

You mention the tab washer, possibly without realising that there should be two tabs; one to engage into the hole in the flywheel and the other to lock the nut. Over the course of time the nut one often disappears . 

That's an interesting point about the two tabs. In this mower's case, it confirms for me that the washer is not the original; apart from having only one tab, it is square shaped and, I think, a homemade replacement. When I started work on the flywheel/pulley arrangement, I noticed that the inner part of the pulley wasn't lying quite flat against the flywheel. I found that the "washer" was slightly too long for the space for the nut at the back of the pulley; I cut a little bit off and it fits neatly now. 

Just out of interest, how did the second (missing) tab engage with the nut if the first tab was fixed to the flywheel or have I missed the point?

Thanks again.

Just bent up against one of the flats. A common arrangement in other critical areas such as big end bolts.