Topic: Oil pump woes.

[frodef2]

I am assembling a hi-po cb750 engine and have arrived at the oilpump checkup.
Turns out, both of the pumps i have have signs of foreign objects having passed through.
I bought another of a Norwegian motorcycle breaker, and it also had pitting on the pump gears from foreign objects.

Since i have already bought one used pump wich turned out to be a lemon, i am a bit uneasy about getting another used pump of ebay.

I have also looked into the CNC oilpump that Cyclexchange have for sale. Is it worth its 750$ pricetag?

From what i have read about the stock pump, it is more than adequate if it is in good shape. But a ebay pump shipped to norway would be over 100$, and could be no better than the 3 pumps i already have on my bench.

do anyone of you have experience with the CNC pump?

Frode Johansen



 

[01Thomas]

I have several used oil pumps and IMHO they all have the pitting you speak of - on the tips of the lobes. That pitting does not seem to be much of a problem.

What is far more significant is the clearance between the outer rotors and the casings (on the diameter) and the axial clearance between the rotors and the end-casings - that is where real leakage will occur. Fortunately that is also easy to restore by lapping the casing until the optimal clearance has been restored and the rotors don't rub (bind) on the casing.

[MCRider]

Agreed. I was lucky enough to find an eBay pump with 7500 miles on it and it looked it. I split it open to see and the rotors were pristine. $35!

But at least 4 other pumps I have, have the rotor marks. I think its pretty natural. If one replaces the ORings, tiny shaft seal, and backup piston, I think an old one with those marks is fine.

[Bill/BentON Racing]

I've go good ones, pics available, sent one out last week and one going to Edward Morris this weekend, Bill

[PeWe]

I read Elan's oil pump restore thread  http://forums.sohc4.net/index.php?topic=143857.0
Good info so I bought an used oil pump from an F2 1978 as restore object. It had 45000 km's, less than half as my used one that have had metal flakes in engine twice with broken clutch plate and total of 100.000 km's plus some revvings.

I ordered  Elans repair kit too.
I'll test the upgrade when I have time. Swap pumps later on. Maybe at next oil change. I would not dare to remove my only pump to restore it and damage it without replacement. I tried to open my pump before but did not dare to use the amount of brutal force to open the X-screws keeping it together with my impact screwdriver and heavy hammer.

[MCRider]

I read Elan's oil pump restore thread  http://forums.sohc4.net/index.php?topic=143857.0
Good info so I bought an used oil pump from an F2 1978 as restore object. It had 45000 km's, less than half as my used one that have had metal flakes in engine twice with broken clutch plate and total of 100.000 km's plus some revvings.

I ordered  Elans repair kit too.
I'll test the upgrade when I have time. Swap pumps later on. Maybe at next oil change. I would not dare to remove my only pump to restore it and damage it without replacement. I tried to open my pump before but did not dare to use the amount of brutal force to open the X-screws keeping it together with my impact screwdriver and heavy hammer.

Rather than whacking it with a hammer impact, maybe find an accommodating shop that will blow it open with a handheld air impact. A lot less brutish and should only take a few minutes.  IF you have a compressor, would be worth it to buy one for yourself, pretty cheap these days, really speeds up other work too.

[frodef2]

I have some pictures from the best of the pumps, and i need a 2nd opinion.

All clearances are within spec. Outer rotor to housing is a tight .15mm. inner rotor to outer rotor is less than .10mm and the side clearance is >~0,06mm

here are the pictures of the parts

scarring in the scavenge side of the housing.



scavenge rotor



delivery rotor

[edwardmorris]

Mine probably look worse, but were deemed adequate. Since I'm buddies with Bill, I refused to settle for adequate :p :p

http://forums.sohc4.net/index.php?topic=126735.msg1538228#msg1538228

[01Thomas]

The last time I looked at my oil pump I installed those three x-head screws with locktite. And when I wanted to inspect it a couple of weeks ago (many years later) I couldn't undo them, even with some heat. So I just drilled them out.

I read Elan's oil pump restore thread  http://forums.sohc4.net/index.php?topic=143857.0
Good info so I bought an used oil pump from an F2 1978 as restore object. It had 45000 km's, less than half as my used one that have had metal flakes in engine twice with broken clutch plate and total of 100.000 km's plus some revvings.

I ordered  Elans repair kit too.
I'll test the upgrade when I have time. Swap pumps later on. Maybe at next oil change. I would not dare to remove my only pump to restore it and damage it without replacement. I tried to open my pump before but did not dare to use the amount of brutal force to open the X-screws keeping it together with my impact screwdriver and heavy hammer.

[Elan]

Kawasaki part number 16154-003 is the same rotor available new but it's 4mm wider- need to shave off 4mm and you have a new rotor for the supply side.  But not all the wear is in the rotor obviously..

There's also a couple kawa rotors that might be a direct fit for both sides  but I haven't gotten a hold of them to check.

[Elan]

Also I haven't had a problem with using an impact driver. Just made a jig to hold it properly without putting pressure on the gear. I can't inaginge getting some of those open without it.  I've opebed a half dozen of them with no damage besides pinching that skin between the thumb and forefinger on the top of the driver with the hammer 

[Medyo Bastos]

how'd you get the screen and seal off???

[Elan]

how'd you get the screen and seal off???

The screen is hard not to damage when removing- the rubber is so old and hard, but a couple small flatheads and it'll come out. Just go slow.  Might as well get a new screen. I'm not plugging myself, I make them but you can also get nos ones on eBay, etc.
The best way to get the seal out that I've seen so far is a forum member here bent the tip of a flat head and tapped it out from the back, through the shaft hole. Who was it??  I've been making a small notch behind the seal and using a pick. Next time I'm trying the screwdriver for sure

[Medyo Bastos]

good to know, i am not the only one damaging them, lol!  preciate the quick answer

[edwardmorris]

.......
The best way to get the seal out that I've seen so far is a forum member here bent the tip of a flat head and tapped it out from the back, through the shaft hole. Who was it??........

Jerry H

http://forums.sohc4.net/index.php?topic=126735.msg1531549#msg1531549