Broken stud....

[robint]

No not me.....but one that holds the rocker block in place.

Having re-built the Sport it seemed like a good idea to take her for a ride so as Les Skinner & Co had arranged an autumnal jaunt round Leicestershire and Rutland it seemed sensible to do join them. Fortunately Phil (I think) had some spare engine bolts - note to self use Loctite on S/steel bolts - and then no problems until Uppingham and a misfire.

Seemed fine after fuel (and a stop for food) but returned about 15 miles later. Stopped for 10 minutes, and off we went again to have same problem recur after about another 20 miles (and not too far from home). Limped on and made it home.

Stripped off rocker covers - front seemed fine, plug a little dark but valve clearances fine. Front carb air screw was a lot further out than the rear so could have been a bit rich I suppose. At the rear found that one rocker block nut was missing (and sitting neatly in the head) and the stud sheared. Could relate to misfire as valve clearance was nil and maybe on cooling allowed some clearance??

Anyway - how to extract stud - presume head off and large vice, certainly mole grips made no impression. And do NLM have spares - these are questions to be pondered on a Sunday night over a glass of something alcoholic.

Thanks to Les and all those on the ride for help and suggestions and waiting for me - promise to have her sorted before the next trip!!

[3potjohn]

I hope this is not a common fault on Morini's. What length of stud is there to play with?
The bodges of the ex British bike owner follow.....
The worst is when they break off level with or below a casting. You could try cutting down to allow a flat blade screwdriver in but it sounds as though it is very tight if molegrips won't turn it. Or cut some thread on it ,add 2 nuts counter tighten them ( even loctite!)and then try and turn the lower one.
I have had to drill into similar with a view to trying an "easy-out". Some trepidation as I know that these can also break off and being hard may cause more of a problem.I also don't have a pillar drill so drilling anything like this is risky as it's difficult not to go off centre. I did buy new cobalt drill bits however which cut through the metal very easily and in fact the stud in my case came loose as it was being drilled.

[3potjohn]

I forgot to mention "reverse drill bits" which may loosen the stud as you drill it.

[EVguru]

Is it an early 6mm stud, or a later 7mm? Whatever the outcome, I'd upgrade to the later.

The stud shouldn't have corroded into the head, so if it's difficult to remove someone may have used threadlocking compound. Heat will break down the bond and even if compound hasn't been used, it's going to be easier to remove the stud if you heat the head.

[robint]

Plenty of stud left visible so having failed with the mole grips it was head off, clamp stud in vice, turn head and no problem. Stud is 7mm, so quick trip to NLM. Not sure why it would have sheared - my muscles (and spanners!) are not that good!!

As there was a bit of smoke on that cylinder at times I suspect a quick look at the valve guides will be in order - NLM or local engine specialists?? Still some of the latter around Nuneaton and usually cheap and friendly.

[robint]

New stud and nut from NLM (expensive at just under £6) and head etc on, twiddle with carbs and Miss M now back and running. Check timing in the morning, try to balance carbs and then worry about smoke (probably rings having looked at valves properly and worse underload than overrun), tank respray and the funds over the winter.

Still seems odd for the stud to shear in use rather than when tightening - hope my fettling helps rather than hinders!

[robint]

Having looked further at Miss M and got the timing light out from its dusty corner it looks as if the vibration could be something to do with the timing belt being one tooth out ....... Been that way for some time as I cannot recall when I last changed/fiddled with the belt. Surprising thing I suppose is that it runs at all with around 16deg retarded (I think) timing!!

So find puller (NLM again???) and put things right and see how she runs!! Hopefully a bit better.........

[EVguru]

Check the cam timing with a degree wheel rather than relying on the timing marks.

[robint]

Got the puller and a new belt while everything in bits, along with shares in NLM or so it seems at the price of the belt.....

Anyway fitted it and now have timing in the right place as far as I can tell and does seem to start easier. Rear cylinder doesn't seem to want to fire on its timing mark - front though is spot on - thought new pick ups were supposed to deal with this ?? More chat to NLM.....

Went for a quick blast and still some vibration but very flat in 5th and 6th - no pull at all - but would pull max revs in 4th OK (about 70mph ish) - felt overgeared.

So next try balancing carbs - and start a new thread with a relevant heading.....

[EVguru]

Do you still have original transducers?

The timing is affected by both the pickup and the transducers.

When the transducers were new, they were built with +/-10% tollerance components and would have been reasonably well matched. They may however have aged differently. I built my first pair of replacement transducers because my 250 2C developed a mid-range missfire, but only when the ambient air temperature was high enough.

Try swapping your transducers over and see what happens to the timing. Uneven timing between the two cylinders is one possible source of vibration.

[neil]

There is a simple mod to even out the timing between the cylinders which involves fitting a resistor in one of the red leads to the transducers. The details are on the dutch morini riders club website in the technical info section about the ignition system under tip number 1 "efficient method". Tried this myself when I found the rear cylinder timing was a long way out, have now got both cylinders much closer to the timing mark although still not spot on.
Neil.

[TonyH]

Hello everyone, this may sound a daft question but how are you timing your rear cylinders with a strobe? My early 350 only has a timing mark for the front cylinder, do later ones have two marks? or am i missing something obvious here?

Many thanks, Tony

[robint]

No marks (orginally) on mine but degree disc (or tape and careful measuring) allows an 'ANT2' mark with beautiful assitants' nail varnish.....

Still further to my on going saga - got timing to about the right place - with pick up as far advanced in its slots as possible - not sure that there isn't something else not right though (how many negatives can you put in a sentence??). Cannot see any advance (at the flywheel with the strobe) as I rev the engine from about 2000 to 6000 rpm - should I?

Had to meet a friend in Llangollen (100 miles each way) today so got brave (and took RAC number...) and set off. Clearly having the correct(ish) timing makes a big difference - pulled well in all gears but still some (a lot really) vibration - have some new throttle cables, will get some new return springs and adjusters, clean and check the carbs (again) and have another go at balancing which so far I have been unable to do properly. Bike did the 200 mile trip without too much problem (loose exhaust port due to missing gasket!) and ran up to naughty speeds readily - progress!!

Have lost the instructions to my mercury filled carbtune - vacuum is such that the columns are too high up the scale and disappear - how do I reduce the level - anyone with the info out there - though I'm sure that Morgan will still have someone there who can tell me in the morning!

[EVguru]

It's easy to make a timing mark for the rear cylinder.

Wrap a strip of paper round the flywheel and make marks for the front cylinder TDC and timing. Place the paper TDC mark on the rear cylinder TDC mark and then transfer the paper timing mark to the flywheel.

[robint]

Still fiddling - swapped carbs (and slides) from one side to the other no difference in which carb was pulling most vacuum so clearly 'cylinder' or ignition related. Will hold buying new carb bits!!

Managed to almost balance the carbs, starts easier and runs better but still some vibration. Need to look further at ignition when time permits.

First of all get flange (washer!) welded back to the end of the front exhaust pipe since it came loose - will slightly modify design to strengthen. Note to self - if adding gasket to exhaust port then adjustment needed to silencer mounting bolts rather than just tighten everything up!!