A10 timing side bush

[baza57]

I recently had an engine seizure at 35mph locking back wheel, on stripping engine found that the 2 piece timing side bush had seized to the crank. All other components ok ie big ends/rings/bore/drive side bearing/ oil pump all good, so what caused it? It was fitted with a anti wet sump valve which i removed stripped it, but it seemed ok, (have not refitted it) the two piece timing bush had turned snapping the retaining peg causing oil way to block, but could this have happened when it seized?....Anyway i took the crank assembly to an engine builder who fitted a new solid bronze bush and line reamed it also set end float.
I assembled engine and it seems much too tight, have a job to depress kickstart and engine will start up for 1 second before stopping because its tight.....help.
baza 57.

[RDfella]

Could be a whole load of things. Let's go one at a time, otherwise we all get confused and the advice becomes counter-productive.
So, when you assembled the engine (just crank / cases) did it turn fairly freely by hand? If so, did it still turn by hand when the timing gears etc were fitted?
 

[baza57]

no could not turn by hand with just crank had to use a  big spanner, its a large journal crank, even with all ancilleries fitted still had to use a big spanner.

[berger]

a properly set up line bored and shimmed crank should freely fall from tdc with or without the rods on in bare crankcases. you shouldn't have to use any spanners to turn it.

[RDfella]

no could not turn by hand with just crank had to use a  big spanner, its a large journal crank, even with all ancilleries fitted still had to use a big spanner.

In that case you need to strip it down again and start from the beginning. As it didn't turn by hand you should have stopped there to find out why.

[baza57]

got it stripped down to crank rods and cases, will take it to engine builder for him to check, its very tight, rods and big ends free, just crank tight.

[Richard Hinton]

Maybe you have already taken to builders, but if not I would pull the cases apart myself. when turning crank can you feel or hear grinding. when split look for scratch marks on crank that may give you a clue as to where or what is creating the friction. Also check all the bolts that have access to the crank cavity are they too long? ie oil pump, clutch cover these have 3 large screws that can reach into the crank.
It maybe over shimmed ask what size the shims are.

I have to rebuild my engine soon, something I have changed is the drive bearing back to ball bearing type and not roller. I noticed some some marks on the crank. although shimmed a roller bearing will allow axial floating where as a ball cage bearing will restrict this.

Any way good luck.

[bikerboy]

I would have a lot of questions for that engine builder for sure

[sean]

I recently had an engine seizure at 35mph locking back wheel, on stripping engine found that the 2 piece timing side bush had seized to the crank. All other components ok ie big ends/rings/bore/drive side bearing/ oil pump all good, so what caused it? It was fitted with a anti wet sump valve which i removed stripped it, but it seemed ok, (have not refitted it) the two piece timing bush had turned snapping the retaining peg causing oil way to block, but could this have happened when it seized?....Anyway i took the crank assembly to an engine builder who fitted a new solid bronze bush and line reamed it also set end float.
I assembled engine and it seems much too tight, have a job to depress kickstart and engine will start up for 1 second before stopping because its tight.....help.
baza 57.

did you check crank end play when you got the engine back from the ??builder ?
ask the builder how he checked crank end play ?
did he assemble with all the bolts in the cases and torque comp spring nut ?
I think I would be looking for a new builder .....if you assembled the rest of the engine why not do the crank build yourself ....any questions you have doing it would be answered here many generations of knowledge on this forum .
Good Luck on the rebuild

[RDfella]

That new bronze bush may need a shade more clearance, or perhaps the radius needs easing where it mates with the crank web. Of course this all assumes it was reamed in line with the other main bearing.