improving oil flow

[StephenG80]

If the oil pump is worn, is it normally the housing that wears (so that'll be engine out and sleeved???) or the plunger that is worn (in which case an easy fix i.e. replace it!)

[Andy51]

Hi Stephen, never heard of the oil pump wearing to the extent that the flow is noticeably reduced, but there's a first time for everything. There could be scoring to the alloy tunnel in the crankcase, or the Guide pin operating in the cam slot in the pump plunger could be badly worn, causing lost motion and reduced flow. Check guide pin and replace if necessary as this is a relatively easy and cheap job. Is there wet dumping? This would indicate scored bore and/or worn plunger. I have a spare plunger somewhere; if I can find it, I will mike it and let you know diameter so you can compare with yours. If you can find someone who will sleeve the pump bore, let me know! I have spoken to a couple of engineering shops and they say setting up the job would require extensive jig/tooling and would cost a fortune. If wet dumping is a problem, drain the dump before starting (or run it daily as they were intended to be all those years ago). My G80 wet sumps a bit (worn tunnel) but I can live with it - after all, the twin owners do! Cheers, Andy

[StephenG80]

Hi Andy - my flow seems to have returned to a steady beat. I thought maybe things were array as I got no oil through at all after draining and renewing the oil for a few minutes so lost faith (before I lost the big end!)switched her off. had another go just now and normal service has returned. Its very unnerving seeing nothing come out of the return spout for a few minutes so glad she is now pumping well. She does sump but I have fitted a anti sumping valve so hopefully that will sort that.

The only thing left to sort now is an annoying vibration band from about 50 to 55 - its pretty bad. Don't know if it is timing issue (she is manual) or carb (which is knackered so getting the metering right is difficult) Anyhow I have new carb to fit next. Any other ideas what might cause the vibes? - she is lovely and smooth at 45mph.

Stephen

[Andy51]

I have also had a worryingly long wait for the return oil flow to settle down, but it does eventually! I have 2 500 singles, one standard, one tuned. There is a vibration patch on both around 50 - 55, nothing serious, then they go smooth till 65 plus, when vibration settles in all the way to max speed. Have you checked the head steady and frame bolts for tightness? My G80 has standard frame studs/bolts, but my 18S has bespoke ones I made myself with full diameter non threaded engagement in the frames - the standard studs often have threaded portion engaged in frame plates. These hammer down and get loose. The AJ handles better and feels taughter. Andy

[StephenG80]

Hi Andy - the vibration is pretty white knuckle stuff. I'll check all the bolts though