Forum

[RoSy]

I'll quote this from the latest edition from the Gun and hope they don't mind....quote "Any bikes we received since July 2004 have modified oilways , but if you are suffering over-breathing, check the drain plug and if this problem exists, fit an extra washer to keep the drain plug threads clear of the oilway". unquote. Well when I changed my oil on my 2002 I did notice that one of the drain plugs had two washer, but I only put one back thinking it was a mistake, but I can't remember which drain plug had the extra washer, so which one would it of been?

[stinkwheel]

Could be either of the front two with sock filters in but if it was to be causing over-breathing, the crankcase one (nearest the front).

What our hosts say:

DRAIN PLUG/FILTER: Oil is taken, by means of the return pump, from the sump (where the crankshaft lives) through internal oil drilling's in the crankcase to the front drain plug/filter. Sometimes the threaded part of this plug can restrict the oil drilling by screwing in too far. This can be down to machining tolerances or a washer fitted that is too thin. By careful measurements this can be checked and a thicker or extra washer fitted if required.

They have a picture of the hole in question in their article.

https://www.hitchcocksmotorcycles.com/p ... -08-15.pdf

For what it's worth, I have bonded seal "dowty" washers fitted on the sump plugs of all my motorcycles. They are reasonably thick anyway, are reusable and seal completely at "just nipped up" tightness.

[RoSy]

I bought some of the Dowty washers with my last order 13.5 it says in the book but they were to small, so I had to use the existing washers. I'll order some 14/16mm ones next time.

[Allanfox]

If this drilling was obstructed due to washers being too thin would it mean wet dumping would occur as the sump would not be pumped out?

[windmill john]

As above, I bought a bunch of those Dowty washers from our hosts, all too small!

If anyone can post the part number of the right size, it would be appreciated. bullet 350 2002


John

[ed.lazda]

Have any of you told Hitchcock's about the washer size issue? They're usually pretty good about putting these things right.

[Presto]

This problem has surfaced from time to time with these Dowty seals and Bullet drain plugs.

Bonded seals, ‘Dowty’ seals, are metal washers with a rubber inner ring to facilitate sealing, especially useful where high pressures are involved.

There are two main types of Dowty seal – ‘standard’ type and ‘self-centering’ type. The seal-centering seal differs from the standard in having an inner ‘lip’. This additional lip helps to eliminate off-center fitting, reduces the possibility of leakage and aids installation. This is the type of 13.5mm Dowty washer our hosts currently supply. They appear too small. This is not a fault but in the nature of this type of seal. The inner lip is to be ignored when measuring the i.d. of this type of seal.

The self-centering type, because of this additional lip, appears too small for the application. This is not a proof that the seal is too small but a consequence of the design character of the self-centering type. Some users are consequently reluctant to fit the seal over the correct size thread for fear of damaging the rubber inner lip of the seal. The design however in effect intends for the inner lip to be ‘sacrificed’ in the interests of self-centering and improved sealing.

In applications where the Dowty self-centering seal is to be used with the Bullet oil drain plug a further complication may be met, in that the profile of the plug features a base shoulder of greater diameter than the thread itself. This may create a problem when fitting a 13.5mm Dowty seal of the self-centering type – the seal will fit tightly [as intended] over the thread but not locate over the base shoulder. In such a case a larger [in fact, over-size] seal may needed.

[Adrian]

Later classic Bullets and the Electra-X use a 14 x 1.25mm thread, spark plug size, commonly used in sump plugs on other vehicles. Aluminium as well as copper crush washers are readily available.

A.