Engine locks up

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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Engine locks up

Postby cbranni » Fri Jul 15, 2011 7:04 pm

Hi all, just rebuilding a 62 G2 engine on the bench, and when I tighten the rotor nut tight the engine locks up solid, I didnt split the cases because everything looked and felt ok. Externally everything looks ok, you have spacer against axle bearing inner race, then the sprocket, then a washer and then the nut, as the manual shows, only thing that gives me concern is the rotor and stator of the breather, its the unmodified one...............any thoughts guys?
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Engine locks up

Postby itma » Fri Jul 15, 2011 8:09 pm

have you got the barrel on?
is it a new piston?
if so its probably too long
sounds daft, but its happened to me.
you need to take about 1/4 inch or more off the bottom if this is the case

[if not ignore all above]

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Engine locks up

Postby cbranni » Fri Jul 15, 2011 8:41 pm

Ken, thanks for the reply, engine fully built up with gearbox as well, and had it to run for 10 secs, sounds good, its just when I tighten the nut with impact wrench the engine locks, if I spanner tighten it, its ok, maybe I'm over doing it with impact wrench, but whats locking it up?
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Engine locks up

Postby itma » Sat Jul 16, 2011 11:14 am

impact wrench is a no no for me, 40- 50 ft lbs should be enough.
either its well over tightened or you have left something out
I suspect the former

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Engine locks up

Postby Janet » Sat Jul 16, 2011 12:20 pm

quote:
if I spanner tighten it, its ok, maybe I'm over doing it with impact wrench, but whats locking it up?
Friction. Tighten parts together too much and they stop moving.

Remember when tightening something up that, one day, you may need to undo it again. What seems quite loose when you fasten it can be stuck solid in a few years' time.
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Engine locks up

Postby cbranni » Sat Jul 16, 2011 8:23 pm

Thanks both for the comments, I have done as Ken said 50lbs, I did add a dab of loctite just to satisfy myself.
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Engine locks up

Postby wilko » Sat Jul 16, 2011 10:48 pm

Shouldn't matter how hard you torque it up.I would investigate further, remember the crank and bearings should all lock up as one. Somethings amiss?

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Engine locks up

Postby 1608 » Sat Jul 16, 2011 11:28 pm

If you have an incorrect spacer fitted which is touching on the outer instead of the inner main bearing race this will lock the crank. Sounds obvious I know, but check that nothing is contacting the outer race of bearing. That is all I can imagine is causing your problem.

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Engine locks up

Postby cbranni » Sun Jul 17, 2011 9:01 am

Thanks both for latest comments, tightening up should make no difference at all because its all one axle, everything gets compressed ,alt rotor, sprocket, spacer, inner race of outer bearing, breather rotor, inner race of inner bearing against shoulder of flywheel.
Would the length of the breather stator have an effect, if it is longer than the breather rotor?
Is there anything on the timing side that would lock up when drive side is tightened?
only dead fish go with the flow

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