Glassed Rocker Covers

Status
Not open for further replies.
Tornado

Tornado

VIP MEMBER
Joined
Dec 5, 2017
Messages
4,529
Country flag
Had a persistent oil seep from around the rocker covers on my 850. Tried new gaskets (fibre) with some Hylomar dressing. This slowed/stopped seep at intake rocker cover, but still got seep at exhaust covers.
Today I pulled them off and set about fairing down the sealing surfaces on a plate of glass with 120-440 wet/dry paper well oiled.
These covers have been chromed both outside and in...perhaps by Dreaded Previous Owner?
The chrome process made a raised edge all around the lip of each cover, basically making the effective sealing section less than 1mm in width. The fairing process slowly got this back to full cover material width...roughly 3-5 mm.
Cleaned up the previous gaskets, new Hylomar dressing, and some polyurethane sealant on the hold down nuts to help prevent seep under them.

Keeping fingers crossed that this works...
 
I saw a tip, maybe from the INOA "Tech Digest", which recommended trimming the gasket to match the inside profile of the cover, the object being to eliminate the small "well" created by the gasket itself. I used sealer to keep the gaskets stuck to the covers, mounted the covers to let it set up, pulled them off, trimmed them with an Exacto knife, and this worked for me.
 
Tornado said:
Had a persistent oil seep from around the rocker covers on my 850. Tried new gaskets (fibre) with some Hylomar dressing. This slowed/stopped seep at intake rocker cover, but still got seep at exhaust covers.
Today I pulled them off and set about fairing down the sealing surfaces on a plate of glass with 120-440 wet/dry paper well oiled.
These covers have been chromed both outside and in...perhaps by Dreaded Previous Owner?
The chrome process made a raised edge all around the lip of each cover, basically making the effective sealing section less than 1mm in width. The fairing process slowly got this back to full cover material width...roughly 3-5 mm.
Cleaned up the previous gaskets, new Hylomar dressing, and some polyurethane sealant on the hold down nuts to help prevent seep under them.

Keeping fingers crossed that this works...
Click to expand...
Who would chrome their valve covers!!! Oh well it sounds like you have got them flat now
Make sure some ham fisted previous owner hasn't over tightened the nuts on the exhaust valve covers with the studs pulling a bump in the head at the base of the stud
Also once flat you should only need grease on the gaskets
 
Sanding down the surfaces is a good first step. Then I would use either JS Eng silicone gaskets, or make your own from 1/16 " synthetic cork.

The latter works for me .... I have never had seepage from the rocker covers ..... and I had mine chromed long ago, as I hate to waste hours polishing aluminum!

Also, I use sealer on the cover surface only. That way the gasket stays with the cover, and I can use again after a tappet adjustment.

Slick
 
Didn't the Atlas and prior big twins have plain cast unpolished rocker covers?
Perhaps the first run of Commandos still had the unpolished covers as seen in some of the promotional materials.
 
seattle##gs said:
After the sandpaper treatment you won't even need the hylomar or any other sealer.
Click to expand...
You seem to have disregarded the possibility that some nit-wit previously used a large screwdriver to pry the inspection caps off at one time, thereby denting the head's mating face(s)...
 
baz said:
Who would chrome their valve covers!!!
Click to expand...

Presumably the same dude that chromed all the engine covers (primary, timing & tranny) and the front mudguard (rear is stainless).
This '74 MK II bike appears to have been sitting as someone's 'eye candy' for decades..as evinced by the 8300 miles witnessed on the clock. Yet it did sustain a fair number of knocks/scrapes/dings and typical frame bends at rear hoop and side stand.
 
After several hours riding around town and up/down a mountain, happy to report I think the oil drips have abated, at least from the rocker covers. Very slight trace from one or two cover bolts. No more smoke coming off hot header cross balance pipe while at lights.

Remaining drips still at primary seal and the two larger inspection caps. Also noted a dribble at the shifter lever opening. And of course the ever present swingarm bushing caps.
 
I thought this post would be entertaining the idea of clear glass rocker covers so the world could view vales , rockers, springs all doing their jobs. Of course clearer oils changed regularly would be required... oh my gawd an oil thread required.
 
Status
Not open for further replies.
Back
Top