Oil pump

[vibrac]

Getting back to the main track of this thread.Ive sat and pondered even looked at some worn pumps (I must have 6 or so) but I cannot see how trevs mod works -to clarify Im sure it does work and I certainly put a few pumps together but I must admit defeat I am sure I am not the only one - am I?

 

[clevtrev]

Getting back to the main track of this thread.Ive sat and pondered even looked at some worn pumps (I must have 6 or so) but I cannot see how trevs mod works -to clarify Im sure it does work and I certainly put a few pumps together but I must admit defeat I am sure I am not the only one - am I?

The object was to ensure that the pointed corner of the worm, does not contact the runout of the cut rack, at the full extent of the pumping stroke. That`s what has caused the premature wear of both the worm and rack, from the very first revolution of the pump.

 

[bmetcalf]

Is there a sharp edge on the rack that the worm will rub on or is it polished over?

 

[clevtrev]

Is there a sharp edge on the rack that the worm will rub on or is it polished over?

Sorry Bruce, don`t quite understand what you are asking.

 

[greg brillus]

I think what Trev is saying is that if the longitudinal grooves (teeth) cut into the plunger where longer......that is towards the scavenge end of the plunger, then this would fix the issue. So on Trev's one ....he has machined a groove around the area where this machining has finnished, so that the worm teeth clear any possible tight spot that would occure when the plunger is at full travel towards the front of the engine. This is something the average Joe Bear would never pick up on.....very clever.....Trevor..........Greg.

 

[Ducvelo]

Interesting. So will the spares company machine us some plungers with the ClevTrev undercut(s) on them for us then?

 

[timetraveller]

Look at my posting No. 5 above where I mention that there was at least one batch of plungers where the teeth were machined out with a cutter that had too large a radius. That meant that the run out at the end of the cut was too long and too shallow. Hence the premature wear. This was ten(ish) years ago and the manufacturers now know what they did wrong, (don't you chaps?). Given a properly formed plunger the wear shown should take many tens of thousands of miles to occur. It would be useful to know from cletrev whether the original specification plungers were also incorrectly designed.

 

[Little Honda]

Yes, yes - tell me, how!

 

[vibrac]

Interesting. So will the spares company machine us some plungers with the ClevTrev undercut(s) on them for us then?

There seems to be a misunderstanding about parts production, parts are not made on a whim, As I understand it all parts are subject to the VOC drawings committee.Although unsung hero's, this part of the club is as important as the spares supply. Many are not old enough to remember what it was like when every Tom Dick and Harry were making parts without reference to original drawings, just fitting to last available pattern part. the mismatch still occurs when a correct to drawing part meets a 'pirate' part still on a bike or purchased from a doubtful source and often the 'correct to drawing part' gets the blame.
Clev trevs mod has a lot going for it (now I understand it ) perhaps it could be put to the committee

 

[Bill Thomas]

Hello Trev, Would your Mod' allow a two start worm to be used with a single start plunger ?, I have just seen a photo of Marcus's plunger which to me looks like a single start in the latest MPH, And he says he is fitting it to a Twin start worm !! , I know you have said in the past that the Factory never made a twin start plunger, Marcus has ground one part of the plunger down. Cheers Bill.