Inner Primary

Supartslist · Jul 25, 2021

Hello all. Attempting to remove the Inner Primary cover of my ‘73 850. I thought I had done all the hard work by removing corroded on engine sprocket and woodruff key. I have removed the three set screws with tab washers and the nut on the rear of the centre stud. According to the manual the inner primary chaincase should lift clear. Well it is certainly not doing that - it is rock solid. Have I missed something?
thanks

kommando · Jul 25, 2021

There is gasket between the cover and the crankcase, if some goo of some description has been used on both sides of the gasket the cover will not budge. What level of force that will beat the goo but not damage the inner cover is the question I can't answer.

Supartslist · Jul 25, 2021

kommando said:
There is gasket between the cover and the crankcase, if some goo of some description has been used on both sides of the gasket the cover will not budge. What level of force that will beat the goo but not damage the inner cover is the question I can't answer.

Thanks Kommando. On close inspection there does not appear to be a gasket - instead someone has used silicone. Great. Anyone have ideas how to dissolve the silicone. Chemicals, heat?

Bernhard · Jul 25, 2021

You could try boiling hot water, chemicals you want to avoid!:-(

Reggie · Jul 25, 2021

Silicone doesn't seem to like paraffin in my experience, but it may take some time to work through the joint.
A block of wood and a hammer as near to the "stuck" area as possible is what I've used in the past.

concours · Jul 25, 2021

A single edge razor blade tapped into the part line with a small hammer. Works every time, leaves no trace.

Supartslist · Jul 25, 2021

concours said:
A single adge razor blade tapped into the part line with a small hammer. Works every time, leaves no trace.

Thanks for all your replies - appreciate them. Let you know how I go.

maylar · Jul 25, 2021

concours said:
A single edge razor blade tapped into the part line with a small hammer. Works every time, leaves no trace.

I keep a 1" putty knife with the tip sharpened to a point in my toolbox for that.

Tornado · Jul 25, 2021

Lots of readily available silicone sealant remover products out there, safe for many surfaces.
In addition to the suggested razor or putty knife being tapped in, hit it with WD40 or penetrating fluid as part of the hold is due to suction effect, the fluid will help eliminate the vacuum between faces. Lots of knocking with rubber mallet for good vibrations should get you there.

maylar · Jul 25, 2021

The inner primary is long enough that pulling on the clutch side should give enough leverage to break the seal. I can't imagine any sort of RTV being tenacious enough to resist that.

ashman · Jul 25, 2021

Tap it with a soft face hammer normally gets it moving, light tapping around the inner case and some light leverage is all I have ever done.

Tornado · Jul 25, 2021

maylar said:
The inner primary is long enough that pulling on the clutch side should give enough leverage to break the seal. I can't imagine any sort of RTV being tenacious enough to resist that.

Though not strictly an RTV silicone sealant, polyurethane sealants make it extremely difficult to break parts away from surfaces. Need to use some of the removing liquids that can break down the chemical linkages of PolyU. This stuff gets used lots on fiberglass/gelcoat boating fixtures, hopefully for more permanent work.

mean gene · Jul 25, 2021

RTV hates lacquer thinner! But if there was a , by accident, a shrink fit between the engine case shoulder and the inner primary's bored hole you will have to heat the inner primary, just the primary not engine case. Good luck patients wins every time!

Supartslist · Jul 25, 2021

mean gene said:
RTV hates lacquer thinner! But if there was a , by accident, a shrink fit between the engine case shoulder and the inner primary's bored hole you will have to heat the inner primary, just the primary not engine case. Good luck patients wins every time!

Thanks for the help guys, it is off with no damage. Not sure what did it but used WD40, heat, and some technical tapping.

kerinorton · Jul 25, 2021

I have seen a lump of clear silicone sit on an exhaust manifold for years. It turned gold but never went hard.

Silicone is a good glue. The silicone used in your case has squashed up to the extent there is no clearance to get a silicon dissolver in there.

Pity a gasket wasn't used as that could have split and helped here. Make sure you put a gasket back. Your case is a good reason to use a gasket.

You were lucky as normally some sort of thickness of silicone allows a sharp scraper to get in between and slice it out..

kommando · Jul 25, 2021

If when you refit the cover you use the gasket then you will also need to reshim the central mounting stud or you risk cracking the inner cover.

YING · Jul 26, 2021

kommando said:
If when you refit the cover you use the gasket then you will also need to reshim the central mounting stud or you risk cracking the inner cover.

Don’t forget to do this as far as re-fitting the inner primary like kommando says!Instructions are easy to find.

Inner Primary

Supartslist

kommando

Supartslist

Bernhard

Reggie

concours

Supartslist

maylar

Tornado

maylar

ashman

Tornado

mean gene

Supartslist

kerinorton

kommando

YING

Pittsboro,NC

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