clymer dominator workshop manual re oil pump

Submitted by roger_wilson on Thu, 17/11/2016
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Heavy Twins

I have a problem with excessive smoking on my '57 dominator 88 and on viewing the exploded diagram on page 15 of the * Floyd Clymer book of dominator twins 1955-65 the gears are reversed compared to my pump. (*Reprint by Veloce 2012 from Pitman original by W C Haycraft)

Does anyone know if the illustration is incorrect or could I possibly have an incorrect pump?

Is there anyone near Southampton with an old pump I could use for comparison?

Submitted by fritz_wettstein on Thu, 17/11/2016

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Previously roger_wilson wrote:

â? the gears are reversed compared to my pumpâ?

What do you mean with ?reversed?.The gears are one to one withouth any change, beside of the direction.

Fritz

Submitted by michael_sullivan on Thu, 17/11/2016

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The only thing I can see is that the two "free" gears are switched top to bottom. The gear with the internal key has to match with the shaft with the keyway.

Mike

Submitted by roger_wilson on Thu, 17/11/2016

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Previously Phil Hannam wrote:

Check attachments for details.

Thanks Phil, I had already seen this from your earlier advice on the forum showing pump refurb in RH 237. I note that my '57 pump has the same cog arrangement as the Commando one, that is the larger cogs at the drive side. Would that be the right pump for my 88? Engine is rebored with n.o.s hepolites and valve guides. My problem is excessive smoking, on second stripdown pools of oil were on top of the pistons! All else in order, however fitted n.o.s. rings and rehoned bores double checked all clearances and reassembled, checked pump again all ok. Still smokes.

Thanks guys for the prompt replies.

Regards,Roger

Submitted by phil_hannam on Thu, 17/11/2016

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The Dominator oil pump internals changed with the introduction of the 650 and Atlas engines. Consequently, there are two pumps which will suit the range of bikes falling roughly into pre-1962 and 1962 onward categories. Those from 1962 onwards had wider gears to increase the output and scavenging volumes. A little later 6 start worm and drive gears were added to increase the flow levels even more.

These extra attachments have more info regarding types and dimensions.

Attachments Oil%20Pump%20Info%202.bmp oil-pump-info-1-bmp

Submitted by gordon_johnston on Thu, 17/11/2016

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It sounds like too much oil is getting to the top end. You can check circulation of the oil pump fairly simply by just looking in the oil tank with the engine running. If you get an intermittent stream of returning oil, at least your scavenge side is working fine. An engine after a rebore is likely to be a bit smoky until the rings bed in. How many miles since the rebore? You may have to consider a restricter in the feed to the rockers. If you have a later high output pump fitted, you may be over-oiling, though I have fitted one to an otherwise standard 88 with no problems.

Submitted by roger_wilson on Sat, 19/11/2016

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Previously Phil Hannam wrote:

The Dominator oil pump internals changed with the introduction of the 650 and Atlas engines. Consequently, there are two pumps which will suit the range of bikes falling roughly into pre-1962 and 1962 onward categories. Those from 1962 onwards had wider gears to increase the output and scavenging volumes. A little later 6 start worm and drive gears were added to increase the flow levels even more.

These extra attachments have more info regarding types and dimensions.

Thank you Phil I can now ID my pump-great info.

Thanks again

Submitted by roger_wilson on Sat, 19/11/2016

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Previously Gordon Johnston wrote:

It sounds like too much oil is getting to the top end. You can check circulation of the oil pump fairly simply by just looking in the oil tank with the engine running. If you get an intermittent stream of returning oil, at least your scavenge side is working fine. An engine after a rebore is likely to be a bit smoky until the rings bed in. How many miles since the rebore? You may have to consider a restricter in the feed to the rockers. If you have a later high output pump fitted, you may be over-oiling, though I have fitted one to an otherwise standard 88 with no problems.

Thanks for this, I used to do rebores and this problem is far in excess of just a running in issue. After identifying the pump I shall move onto the rocker feed possibility.

Thanks to all replies for their input and interest-great forum.

Roger


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