OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Chainsaws and Concrete Cutters McCulloch Chainsaws Mc Culloch SE 2000

Hi i am having trouble with a little McCulloch Silver Eagle SE2000 sreies. Heres what i have done, cleaned coil& flywheel and reset them, cleaned out carby all gaskets and diaphragms are good, cleaned spark plug bit black but plenty of spark. Has approx 110psi compression, so everything from what i can see is good. Now the fun part, it will run, bout without side cover and chain and bar on. Put them back on and try to pull start it all it will do is kick over no attemp at starting, even tried a tiny bit of areostart but still no go. Any help or advice will be appriciated. Paul.

The first question is whether the chain clutch is disengaging, Paul. If one of the springs in the centrifugal clutch is broken, you'd get about what you've got. Usually you can't pull it fast enough to start, and it won't idle anyway, if the clutch is locked in the engaged position. Also, if the bar nose sprocket is seized, it may have burned up the clutch so it stays locked in, with the same result.

Hi Grumpy have checked both, they are free with no sign of resistence. I was thinking it could be when i put it all together i have done it to tight, not that i over tighten them, but tried it a number of times with the same outcome so it cant be that. Will check the chain brake, just incase, and get back to you.

So, let's talk about how it runs with the chain removed then. Does it jump like a chainsaw should when you touch the throttle, and does it idle steadily for a good while? The reason I ask, is that you can get the carburetor right but have a loose cylinder base leaking air, or a leak between the crankcase halves, which results in weak crankcase compression. This causes very poor running especially at low speed and light throttle. One of the signs I've found that point toward leakage, is needing to use the choke to restart the engine when it has only been stopped for a couple of minutes.

Hi Grumpy, did check the chain brake just in case it wasnt coming off in the off position, all good. Runs perfectly without chain/bar on, will rev up instantly and idles no problems. Was having a look this morning and found the bar had a slight bend in it right were it bolts on, thought maybe its touching the clutch ( knew it wasnt, theres to much room) but straightened bar back out and decided to put it back together just to see what would happen. Kicked over straight away, let it run for a little bit, turned it off. Sat down at work bench and could hear a fiant noise coming from saw, listened hard and it sounded like air being sucked into fuel tank. Maybe it wasnt running for long not getting enough fuel due to vacum. Took it all apart thinking it might be the air nipple on fuel tank is blocked,wasnt, put it all back together, wouldnt start so i let it sit for awhile. Kicked over again first go, was running for about 1 minute done a wicked backfire and chewed flywheel key in half. Big lesson learnt, come and read what you suggest first. Will now go check what you suggest, basically chainsaw will run until it hits a certian tempreture then stop due to expansion which will cause loss of compression, yes??

In this case, the symptoms don't seem to clearly point in a single direction yet Paul - I'm not predicting a leak between the crankcase halves, which would be pretty unlikely unless it had been dismantled. However the cylinder can come loose, and needs to be checked. I've found your symptoms a bit mystifying, so far. Were the chain and bar fitted when it did its strange kick-back that sheared the key? I suggest you leave them off until we achieve some certainty that it runs properly without them. My experience with tiny 2 strokes using diaphragm carburetors is that they are tricky enough to begin with, without adding in extraneous factors like a load that may or may not be applied at any given moment. Essentially, your mystery crash-and-burn could have been just the chain seizing in its track for a moment, which would be unsurprising when we don't know how good the chain lubrication is, and we know the bar was bent.

I'm not yet sure that the fuel tank is behaving properly. However, chainsaw designs vary: some of them pressurise the fuel tank rather than using a fuel pump, or to assist a fuel pump. Can we get access to at least an owner manual?

Let's see if we can sort out the bare engine first, and then worry about the bar and chain.

Hi Grumpy, am having trouble getting the clutch off at moment, but have been able to locate the four screws that hold the crank case and the cyclinder together and they are that tight i am not able to tighten anymore, without going silly on them. Yes the chain and bar were on when it had a hissy fit, most certianly will be leaving them off till i know everything is good. Chain lubrication is good, plenty of oil. Will keep trying to get this clutch off.

I suggest you don't focus on crankcase leakage at this point, Paul, until you gather more data on the engine. It needs to be run enough to understand what it is doing, with the field cleared of irrelevancies like whether the external bits (clutch, chain, chain lubrication and lubricant distribution, bar nose sprocket, chain brake, and so forth) are in trouble. Once we have a bare engine, either it gives a problem that should fit into a pattern, or it works like a charm and we know the problem lies in the bolt-on bits.

Hi Grumpy, i seem to be going backwards somewhere. Spoke to friend who owns the saw and apparently 2 other people have had a play with it some time ago, but doesnt know what they have or have not done. Have done what you suggest, taken off all external parts and had a play with it that way. I am thinking it is more internal as last night and again this morning i gave it a quick run approx 1 min with a light rev then idle ,repeat, both times it started no problems, but both times i switched saw off and went to start it again the flywheel key had been broken, these times without the motor even missing a beat. Starting to think it might be possesed. Could it have something to do with the crank.

How are the main bearings? If they are broken up, and catching occasionally, the flywheel key could shear, but the engine would make noises. The same is true for piston rings catching on a modified port.

1. Is there a loud main bearing rumble?
2. Does it kick back on the starter?
3. Any sign of damage to the flywheel, or damage to the keyway in either part (flywheel or crankshaft)?

HI Grumpy, the main bearing seem okay to me ,does not kick back on starter and yes there is some light scoring on flywheel were it sits over crank. Having a really good look and doing some pushing and pulling the crank itself has movement in it, though only a coulpe of thou ( will get correct measurment today ) would that be enough to be causing all of these/ some problems.

If the flywheel is loose on the taper (or parallel if it doesn't have a taper), the key will be chewed and broken quite quickly - that is a chainsaw, not a whipper snipper, it is a fairly high performance engine. Is it a taper or a parallel shaft, and how tightly does it fit/how tightly are you doing up the nut/what is the condition of the bearing area like? Is the key too tall for the space between the bottom of the shaft and flywheel keyways? In my experience the most common cause of sheared keys on shafts which have had amateur repairs, is that too tall a key has been fitted. Of course that prevents the bore fitting properly on the shaft: it is distorted in the region around the key, reducing the bearing area and introducing the potential for slippage.

I do not think a small amount of crankshaft end-float is likely to be the problem here.

Hi Grumpy, the chainsaw has a tapered shaft. I checked out all you have suggested and found, the flywheel is the wrong one or been rounded out due to loose fitting. I thought i was getting it on tight enough and it was fitting properly but last night was checking it out and there is actual movement once fitted on shaft, why i never picked it up earlier i dont know. I found this out as i have 3 of the same chainsaws myself,1 going and 2 for spares, and thought why dont i try a spare flywheel compared to original of saw. No movement using my flywheel, even if not screwed on, it fits very snugly. Should i give it a go using my flywheel , no i'll wait for you to get back to me first.

If your flywheel is literally the same, and the taper on the crankshaft has not been damaged, that should be a perfect and permanent solution Paul. However watch out for minor differences, such as the two flywheels not having the magnet in the same place. Stranger things have happened: if you don't have a parts list, they'll catch you every time. Just have a good look, and if possible, put some blue on the taper and see what the markings look like when you put it on firmly but don't tighten up. Then watch when you put it together that nothing hits the new flywheel due to a dimensional difference you hadn't notices. It should all work out: the only likely problem, is that the crankshaft taper had become a bit beaten-up and the two parts will have to be lapped together.

I'm glad you found it. That is a good illustration of why you watch out for things the previous tenant has "been at" himself. It's way better to work on things that have just stopped working, and the tenant has left it at that.

Hi Grumpy, sorry i havent gotten back earlier bit busy. Did check out both flywheels as suggested and the only difference was the size of the centre hole taper end that is closest motor, other then that magnet was same size same spot, virtually identical flywheels. I made up some black pva glue and spread around taper on crank put on flywheel with a medium amount of pressure, took off again and all of taper and centre hole on flywheel were clean, except for minor nicks that come from years of use. I started small first by attaching oil pump and starting, ran perfectly. Repeated 3 times just to be sure. Put on chain, bar and side cover and with my toes crossed started it up , idled perfectly, gave it a quick squirt, back to idle, repeated, repeated turned it off. Checked everything, all okay, repeated reving, idling a number of times, all is good.Could i please ask you to explain what was actually happening here, can kind of understand but not seeing the full picture.. Thanks heaps Grumpy.

The engine can't run without the flywheel: the crankshaft alone doesn't have enough rotational inertia to get it through the compression stroke. As the engine runs, there has to be quite a substantial amount of torque transmitted back and forth between the crankshaft and flywheel, several times during every revolution. For that to happen, the attachment of the flywheel to the crankshaft has to be very strong, and very rigid. The key is not capable of transmitting anywhere near enough torque to enable the engine to run - it is only there to control the timing between the flywheel and crankshaft, so that the ignition occurs at the right point in the compression cycle. The rather large, very rapidly repeating, torque required to be transferred between flywheel and crankshaft has to be transmitted by a very good, very tight fit between the two. If there is any garbage or burring in between the two parts, or damage to the mating surfaces, the torque can't be transmitted by friction, and the key tries to do the job instead. Of course it fails, immediately.

For one reason or another - probably running loose, due to poor assembly by one of the previous tenants - your old flywheel had become damaged so its internal taper was not a perfect fit on the external taper on the crankshaft. Whenever the engine ran, the flywheel became a sort of rotating slide-hammer, moving rapidly back and forth across the key. The sudden rise in cylinder pressure after ignition during every revolution, caused the crankshaft to twist very violently in the flywheel, and the loose fit between the two allowed movement, fatiguing and shearing the key in perhaps a few hundred repetitions of this violent movement. A few hundred revolutions of a chainsaw engine only takes a very short time, and that is how long your key lasted each time you started the engine.

Hi Grumpy, thanks for that explination, can now fully understand what was happening and why it continued to happen. You wont believe it but went to run the chainsaw today, 5 pulls and it wouldnt start, well what now. Had a look, stupid me forgot to turn kill switch to on, can you believe it. Anyways ran the chainsaw a couple of times today, started, idled and reved all without fail. Thanks heaps for your help Grumpy, its much appriciated.

You're welcome, Paul. About a week ago I finally bought a starter that had been missing from a whipper snipper I've had for nearly a year, and tried to start it. No action. Checked for spark: there wasn't any. Scratched head: there was when I turned it over with an electric drill, a year ago. Tried a different spark plug: same result. Then I turned off the kill switch, and it started first pull, in a big cloud of smoke due to all the choking I'd been doing. So, you aren't alone in missing that particular detail at times.

I'll close this thread.