Engine Rebuilt - Help

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
dada
Posts: 99
Joined: Tue Apr 10, 2018 10:43 pm
Location: Malta

Re: Engine Rebuilt - Help

Post by dada »

Thanks will check I found it was tight when going into bush end float.
Mick D
Posts: 2886
Joined: Mon Mar 24, 2014 5:44 pm
Location: Aberdeenshire

Re: Engine Rebuilt - Help

Post by Mick D »

Hi

Have you disturbed the main bearings? a 'cocked' bearing can give your symptoms. It's quite easy for a sliver of case material to be removed during bearing installation - this can then cause the bearing to not sit in it's housing correctly.

Regards Mick
User avatar
Ozmadman
Posts: 2651
Joined: Wed Dec 14, 2011 1:02 am
Location: ESSEX UK

Re: Engine Rebuilt - Help

Post by Ozmadman »

clanger9 wrote: From memory, you need at least 20 thou there (more is fine).
That's correct BUT this is before you fit the crank sprocket and rotor. Once they are fitted and tightened the end float disappears as it pulls the crank across to the left and that 20 thou or so is now a clearance at the other (timing bush) side to allow for expansion when hot.
Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed
dada
Posts: 99
Joined: Tue Apr 10, 2018 10:43 pm
Location: Malta

Re: Engine Rebuilt - Help

Post by dada »

When it was fully tightened it came very tight especially when you turn it in some palces.
User avatar
clanger9
Posts: 1165
Joined: Sat Jun 20, 2015 9:38 am
Location: Chester, UK

Re: Engine Rebuilt - Help

Post by clanger9 »

Ah, so it became tight when you did up the sprocket nut? That is a good clue: it suggests that
- one of the main bearings is skewed (as suggested earlier), or
- there's a gap between the breather rotor and the two bearings (there should be no gap), or
- there's not enough clearance between the drive side flywheel and the left hand crankcase (not sure what would cause that)

I did a diagram to illustrate how it all fits together: http://www.jampot.com/forum/viewtopic.p ... 04#p194020
Maybe helpful?
1989 Moto Morini Dart 350
1993 Ducati 750SS
dada
Posts: 99
Joined: Tue Apr 10, 2018 10:43 pm
Location: Malta

Re: Engine Rebuilt - Help

Post by dada »

Thanks will check it later today
Locked