SF750 engine rebuild

[Robin Webster]

I have been slowly working on the SF750 I bought from Grant and the Chassis and engine are back together.

When building up the sides of the engine (in situ) I've got the clutch and primary chain back on but have a problem with the oil pump.

The shaft which enters the oil pump from the outside with two keys and the drive wheel on it appears to be too large a diameter to enter the oil pump cog. I am aware of the keyway in it, and that lines up fine, just the shaft goes in so far then the interference fit is too tight for it to go in the whole way.

The garage is cold, could the engine need warming to expand tolerances?

Robin  ???

 

[phil37]

Hi Robin - If you are saying that the drive shaft is too tight a fit in the pump body - then  heat may help - the pump can be manoeuvred a little to get the best alignment of the body,cogs and shaft - then remove shaft before final tightening - Regards - Phil

 

[Robin Webster]

Thanks Phil, I'll have another look.
Just need to time the 500 then I'm offering it for sale.!

Robin 

 

[piranha-bro2]

Hi Robin - If you are saying that the drive shaft is too tight a fit in the pump body - then  heat may help - the pump can be manoeuvred a little to get the best alignment of the body,cogs and shaft - then remove shaft before final tightening - Regards - Phil

Just to clarify what Phil said, if the pump body is not properly aligned with the bronze-bushed hole in the cases, then it will seem that the shaft is too big - LOOSEN the oil pump screws, then try fitting the shaft (you may need to break the seal between oil pump and body and cases, then start again - only a VERY thin smear of hi-quality sealant required (and you could probably use none at all), fit the screws with very light pressure, align body, shaft and case holes, remove and fully tighten.