Hi learned commando owners
My engine has seemed a little noisy lately so while cleaning out the clutch plates I had a look at the alternator rotor, I couldn’t feel any up and down play however I can feel some play as if the crankshaft is moving left to right so time for a look inside the cases I recon however is this the usual way main bearings behave when worn? I would have thought any play would have been up and down on the crank.
Hi a little crankshaft end float (side to side) is a good thing, assuming your engine was built with roller bearings supporting both ends of the crank. Whats the year and model of your bike how many miles has it done since the motor was last looked at. Is there any metal debris in the crankcase filter.
Mines a MK2a, 1974 and coming up to 47,000 miles which with its history is pretty much accurate, I’ve had the bike since October ‘97 and on the advice of Mick Hemmings I run the engine on Castro’s XL40. I was trying to figure how could a bearing being worn cause side play, I haven’t checked the crankshaft in the timing side yet to see if everything’s ok that end, and maybe I should remove the alternator stator which would give me better access to any movement on the end of the crank, what do you think Katherine?
Oh, and there’s no debris in the crankcase filter or in the oil I drained out but there was a small amount of aluminium swarf in the primary case , no great lumps, just flecks of it.......Ady
The factory did not shim for control of endfloat, unless the endfloat has increased then it tells you nothing about the condition of the main bearings. A mk2a will have the super blend main bearings so normally bullet proof. Have you checked the free play on the timing chain.
No not had the timing cover off yet John however there is an automatic tensioner on it , doesn’t mean it hasn’t failed in some way though, will investigate at the weekend
Aluminium flecks are probably off Alternator stator mounting. Doesn't take much slack in the primary chain for this to occur.
Wouldn't worry too much about the end float, this will probably be much the same as when the engine was assembled, give or take.
One of the auto tensioners over tensions and eventually fails. I use a pre tensioned chain (already run in) which is a simplex Iwis of the same chain used in duplex form on Mercedes engines. You do not need to re tension after 500 miles as there is no bedding in and the chain hardly wears. Fit and virtually forget.
Put a three phase on the bike about 18 months ago, it was one stamped Wassel and required some fettling to make it fit proper, I do recall some end float then, did look like the primary chain was on the loose side too Chas however, I need to find what the measurement is to determine how much it has stretched it’s been on there for 30,000ish miles according to my notes
many thanks...... Ady
I will check over the weekend, where did you get your timing chain? I did speak to The Chainman who recommends a merc chain for the primary, me norton gives me a lot of satisfaction for very little cost so she deserves the best when needed ,
Minimum of 0.005" to 0.015" tops if you go by the book plenty of bikes out there banging along nicely with far more. For the some reason the MK3 is allowed to float up to 0.024" possibly because of the extra length added to the crank for the electric start ;0)
+ 1 on the Merc primary chain from Jason (the chain man) I have had one on the MK3 for a while just bought another for the conversion on my t160.
Time and family have conspired to look further, will measure the end float and check the timing chain however it does run a treat , I’m away at the end of the month so in all honesty it will be after that , how do you get on with your T160? that was the other machine that interested me before the norton came along.
End float, usually looks worse than it is, if you measure it then you will know exactly what it is. Even at the top end of manual's limit I would not be concerned.
I'm new to this merc primary chain so forgive me, do I have to do any modification to my 72 commando primary chain side to fit this Merc chain? any info on the part numbers or chain size would be appreciated.
This is really interesting for me haven't heard of this before, looking forward to any advice. Thanking you in advance.
From the Chain Man, the Merc or Ducati chain is duplex IWIS not triplex 92 link 3/8 x 1/4