R100RS airhead top end rebuild

[GreyHairedWombat]

I'm about to replace gaskets and oil seals on a 1976 R100RS (reg. Jan'77) as have numerous leaks. Mileage 37,000. I would appreciate some advice:

1. Fit gaskets with RTV silicone or not? Various U tube videos show with and without

2. Push rod tubes surface rust. Replace with stainless steel (Motorworks) or clean, neutralise rust and paint? I've watched the videos. If I did replace concerned how critical it is get the depth correct

Thanking any you for advice in advance

Richard

 

[mikeyboy]

I always seat the pushrod tube rubbers on a thin film of high quality rtv such as wurth.
And on the barrel / crankcase joint.
Nothing on head gasket.
Push rod tubes are straight forward enough,they need to be @1.5 mm below the top of the barrel and be equal to the eye.
Heat the barrel to @150 deg C ,they will normally just pop out,without any scuffing.
When fitting heat the barrel again,freeze the tubes and use a bit of rtv where they enter the barrel,helps to lubrcate the tube and stops them grabbing

 

[GreyHairedWombat]

I always seat the pushrod tube rubbers on a thin film of high quality rtv such as wurth.
And on the barrel / crankcase joint.
Nothing on head gasket.
Push rod tubes are straight forward enough,they need to be @1.5 mm below the top of the barrel and be equal to the eye.
Heat the barrel to @150 deg C ,they will normally just pop out,without any scuffing.
When fitting heat the barrel again,freeze the tubes and use a bit of rtv where they enter the barrel,helps to lubrcate the tube and stops them grabbing

Many thanks Mikeyboy, much appreciated

 

[timeandtide]

I always seat the pushrod tube rubbers on a thin film of high quality rtv such as wurth.
And on the barrel / crankcase joint.
Nothing on head gasket.
Push rod tubes are straight forward enough,they need to be @1.5 mm below the top of the barrel and be equal to the eye.
Heat the barrel to @150 deg C ,they will normally just pop out,without any scuffing.
When fitting heat the barrel again,freeze the tubes and use a bit of rtv where they enter the barrel,helps to lubrcate the tube and stops them grabbing

Horse’s mouth

 

[Mad Hatter]

He’s had enough practice

 

[GreyHairedWombat]

I always seat the pushrod tube rubbers on a thin film of high quality rtv such as wurth.
And on the barrel / crankcase joint.
Nothing on head gasket.
Push rod tubes are straight forward enough,they need to be @1.5 mm below the top of the barrel and be equal to the eye.
Heat the barrel to @150 deg C ,they will normally just pop out,without any scuffing.
When fitting heat the barrel again,freeze the tubes and use a bit of rtv where they enter the barrel,helps to lubrcate the tube and stops them grabbing

Dear Mikeyboy,
Would you mind offering a little more advice?
1. Push rod tubes came easily using Motorworks drift once head was heated. Checked gap before removable and it measured 2.5mm with feeler gauges! Could be one of the reasons why they leaked so badly. Surely the factory would not have set them to 2.5mm? Apologies if a stupid question, assume when fitting the new stainless steel tubes sit them at 1.5mm rather than 2.5mm?
2. Old rocker cover gasket - would there be any harm in scraping off gently with a razor blade?
3. Head badly carboned so will clean, remove and lap in the valves. Any tips for removing the carbon in the head and exhaust port other than lots of elbow grease?
Thank you in advance
Richard

 

[mikeyboy]

Assuming we are both taking the measurements at the same place we are only talking 1 mm difference ,which is neither here or there in this instance,at 2.5 mm the rubbers could be compressed more and could deform or split?
What did the old ones look like when removed?
If the valves are out of the heads you might consider having them aquablasted/wet blast.
Definitely saves on elbow grease and would clean off gasket remnants as well.
Unless the heads have had work done previously I’d suspect the ex guides would need replacement and I’d fit new valves anyway.
A dropped valve normally spoils your day,and wallet.

 

[GreyHairedWombat]

Assuming we are both taking the measurements at the same place we are only talking 1 mm difference ,which is neither here or there in this instance,at 2.5 mm the rubbers could be compressed more and could deform or split?
What did the old ones look like when removed?
If the valves are out of the heads you might consider having them aquablasted/wet blast.
Definitely saves on elbow grease and would clean off gasket remnants as well.
Unless the heads have had work done previously I’d suspect the ex guides would need replacement and I’d fit new valves anyway.
A dropped valve normally spoils your day,and wallet.

Yes, measured as per various U tube video's, between edge of push rod tube flange and bottom of cylinder flange. Rubbers not split but a lot of oil coated around engine/heads.
Ex-guides - do you mean valve guides? Could not feel much play. Bike has done 37,000 miles
I also should have asked, should I fit the push rod tubes with loctite or say a good RTV silicone gasket sealer ?

 

[mikeyboy]

I normally use a bit of rtv on the tubes/head

 

[GreyHairedWombat]

I normally use a bit of rtv on the tubes/head

Thank you