Torquing a 750 head

THE COPPER WASHER!

If you decide to re-torque a Breganzie 750 SF Head - This is how you do it.

4657582372_f7b7dfc638_o.jpg


Consider them copper washers are virgin and compressible, smooth and likely to seat. Makes me wonder why the Breganzie bothered to use Cap Nuts. Doesn't mean you can't re-use copper washers a few times as long you file them flat and parallel and not penned beyond compression.

Bee Hive nuts do prevent oxidation and you don't want oil leaking around the head pressure stanchion rods that service oil to the top end.

In other words them copper washers are important, let alone torque spec's and stretch stanchions.
 
Surprised you have enough rear wheel adjustment to tilt the engine that far forward without removing the chain. The axle must be close to the rear end of its adjustment when the engine is back in place.
 
Dellorto: The rear wheel is position standard and ran a Kiwi 530 "O" chain. Breganzie designed it so with a little re-leaf filing clearance in the chain cavity and mount 130 rear rubber.

Really a chain for life as long you keep it clean.

Keep in mind any oil or gas leak over a battery will flame your ass ;o)
 
Laverda SF said:
THE COPPER WASHER!

Doesn't mean you can't re-use copper washers a few times as long you file them flat and parallel and not penned beyond compression.
Click to expand...

Best is to warm them up with a butane torch to anneal them soft again. They become work hardened after they are torqued. Annealling (and as you say filing them flat) brings them back to original specs.
 
Best is to simply use new (correct) washers when refitting the head.

They actually need to be quite hard, not soft.  Soften them and they will spread, often to the point that they need to be removed with a chisel in order to dismantle the head.

If the washers spread under the pressure of the fully-torqued nut, for how long can one expect them to hold up when exposed to even more pressure through heat cycles?

600+ bucks for new slugs, but no 10 bucks for new washers??  Old head washers can be re-cycled for low-stress applications such as the primary chain tensioner...

piet

 
sfcpiet said:
Best is to simply use new (correct) washers when refitting the head.

piet
Click to expand...
Does anyone know if the correct thickness and size ones are a readily available item from generic fastener shops? Or do they have to come from Wolfgang et al? I've recycled mine far too many times!
 
Piranha Brother 2 said:
Does anyone know if the correct thickness and size ones are a readily available item from generic fastener shops? Or do they have to come from Wolfgang et al? I've recycled mine far too many times!
Click to expand...

Probably not Quentin.  Industrial/trade suppliers should have them though.

piet
 
I have seen at least two 750 engines with replacement stainless "domed" (beehive) nuts and the threads had bottomed in the nuts causing leakage and warpage. The original nuts with yellow plastic inserts have been snapped up by rebuilders in the past, does anyone know of a source for new ones?
CLEM
 
CLEMTOG said:
The original nuts with yellow plastic inserts have been snapped up by rebuilders in the past, does anyone know of a source for new ones?
CLEM
Click to expand...

Clem, your mate 'Poxy Coxy' is planning to do a manufacturing run of them :-*
 
I was once asked to rebuild a 750 engine.

Amongst numerous horrors, the head had been skimmed so much, it needed two washers under the head nuts to torque it down.
That was tne last time I did a bike for someone else. Never again.

Paul
 
CLEMTOG said:
I have seen at least two 750 engines with replacement stainless "domed" (beehive) nuts and the threads had bottomed in the nuts causing leakage and warpage. The original nuts with yellow plastic inserts have been snapped up by rebuilders in the past, does anyone know of a source for new ones?
CLEM
Click to expand...

Didn t have the yellow nylocs on early 750s
 
shaun there not really nyloc's in the way of a lock nut , they are a doomed seal nut as the studs are in the oil pump system  if you get my drift and 3 of the 8 yellow ones on the ex Dave Mintons GTL are white don't no why.
regards andy
 
Piranha Brother 2 said:
Does anyone know if the correct thickness and size ones are a readily available item from generic fastener shops? Or do they have to come from Wolfgang et al? I've recycled mine far too many times!
Click to expand...
I got some from the local diesel injector refurbisher, seems he had a use for the thicker ones as required for the Laverda and kept them in stock.
 
You must log in or register to reply here.
Back
Top