Valve springs insulators and mushroom valve adjusters

Sergio

Sergio

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Jan 17, 2020
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My RH10 850/head never had valve spring insulators on intake valves. Is it normal or the bike was built the wrong way?
Another concern is the mushroom valve adjusters. I was pretty happy to put those to ease the valve tip. Unfortunately, after retorquing the head gasket, clearance on exhaust valves was barely .007''. Andover said they never had such an issue even with hot cams. Mine is the standard 06-1084 /850 one. What is wrong?
Thank you for your advices
 
Could be: Your head may have been shaved previously and you did not use the right thickness head gasket. The insulators have nothing to do with the valve adjustment, which you probably already know, but most people use insulators on a stock build.
 
Are you saying there is no more adjustment left to increase the clearance to the recommended 0.08"? My 850 RH10 head did not have the mushroom tappets, just the threaded through with locknut above type. Perhaps you should check if mushroom type are ok on this head?
Also, have the valve seats been re-cut? That will seat valves deeper into head, making stem higher, reducing clearance to tappet. I believe the machinist that did my new guides, new valve and re-cut of seats (not just a bit of lapping) also ground the stems a little to keep geometry and length correct.
 
Sergio said:
My RH10 850/head never had valve spring insulators on intake valves. Is it normal or the bike was built the wrong way?
Another concern is the mushroom valve adjusters. I was pretty happy to put those to ease the valve tip. Unfortunately, after retorquing the head gasket, clearance on exhaust valves was barely .007''. Andover said they never had such an issue even with hot cams. Mine is the standard 06-1084 /850 one. What is wrong?
Thank you for your advices
Click to expand...
Are you saying that the gap closed when you torqued the head (it should) or that you can now only get .007" exhaust valve clearance?
 
I would find out if the head was shaved.
Mike
 
The heat insulators are fitted under the exhaust valves coz that's where the heat is. Though I always fit them I would be surprised if modern springs would be effected.
 
Tornado said:
Are you saying there is no more adjustment left to increase the clearance to the recommended 0.08"? My 850 RH10 head did not have the mushroom tappets, just the threaded through with locknut above type. Perhaps you should check if mushroom type are ok on this head?
Also, have the valve seats been re-cut? That will seat valves deeper into head, making stem higher, reducing clearance to tappet. I believe the machinist that did my new guides, new valve and re-cut of seats (not just a bit of lapping) also ground the stems a little to keep geometry and length correct.
Click to expand...
Thank you for your comments. Yes, new valves and guides were installed. Of course seats had to be reground. Old valves were notched at the tip, so I thought that mushroom adjusters would be better to avoid the damage at valve tip. Of course the edge of the mushroom takes more room and reduce the available gap. I'm not sure what you mean by ''ground the stems''??Do you mean ground the valve tip? If so what happens to hardened tips?
Would it be possible to machine down the rocker arm in order to have the mushroom adjuster screwed deeper?
 
marshg246 said:
Are you saying that the gap closed when you torqued the head (it should) or that you can now only get .007" exhaust valve clearance?
Click to expand...
Thank you for your comments. My RH10 head have never been shaved. My Norman Hyde valves were 50K old and notched at the tip by the original 06-7546AK. Both KW valves and guides were fitted with the mandatory seats recut. I installed mushroom adjusters in order to ease the valve tip. Before running the engine valves clearance was done. The exhaust adjusters were almost screwed in, but I reached the .008''. After about 100 miles I retorqued the head gasket and was no longer able to reach the .008''. Now, .007'' is the max. clearance I can get with the ajusters fully screwed in.
Tornado suggested to have the valve tip shaved. What happens to the hardened valve tip?
I also thought to machine the rocker arm to have more room for the adjuster to be screwed deeper...Do you think it could weaken the rocker arm if let's say .010'' is removed? How much would be safe?
 
Schwany said:
Could be: Your head may have been shaved previously and you did not use the right thickness head gasket. The insulators have nothing to do with the valve adjustment, which you probably already know, but most people use insulators on a stock build.
Click to expand...
Thank you for your comments. Do I understand that insulators don't have a bad effect on the spring compression? If so, I will retrofit insulators on the intake side. I think that I have read somewhere that not all the commando's head have insulators on the intake side. Are my memories good despite I'm a ageing senior? hihi:rolleyes:
 
Mushroom adjusters are a mixed blessing. There is a small possibility of a piece of the mushroom breaking off.

On balance, my suggestion would be to bin them. Others would advise lash caps to avoid the valve stem damage. I'm not keen on them either, they can be difficult to remove from the stem.

It will be many miles before standard adjusters do damage to your new valves.
 
Sergio said:
Thank you for your comments. Do I understand that insulators don't have a bad effect on the spring compression? If so, I will retrofit insulators on the intake side. I think that I have read somewhere that not all the commando's head have insulators on the intake side. Are my memories good despite I'm a ageing senior? hihi:rolleyes:
Click to expand...
I certainly don't use heat washers on the inlet side. But I run a high lift cam.

I can't see an issue with fitting the heat washers with a standard cam, but I can't really see a benefit either!
 
Sergio said:
Thank you for your comments. Do I understand that insulators don't have a bad effect on the spring compression? If so, I will retrofit insulators on the intake side. I think that I have read somewhere that not all the commando's head have insulators on the intake side. Are my memories good despite I'm a ageing senior? hihi:rolleyes:
Click to expand...
Insulators will raise the spring height and increase spring pressure, but the head was designed to use insulators. Check the exploded parts diagram on the Andover Norton site for 750/850 heads. 4 insulators are used, 2 for exhaust, 2 for intake. 1 insulator per valve.

The valve springs currently without the insulators will have lower spring pressure. Not likely to be a big problem unless always riding at very high RPM. You should use them though with stock springs.

I don't have any insulators in my head at all, but I play by a different set of rules that I make up on the fly. Don't do what I do.

The stock composite head gasket crushes down to .021, where a standard copper .042 gasket might end up around .041, or .040. The copper head gasket would give you all the adjustment you need, but they require the surfaces of the head and barrels be very flat and clean to get a good seal. Composite gaskets are somewhat forgiving in that regard.

Edit: If you know how to remove the rockers and are comfortable with the fiddly nature of doing it in situ, you could undercut them a very small amount to get your .008" I've never done it, so don't have a clue if it is a good idea or not.
 
Last edited:
Sergio said:
Thank you for your comments. Yes, new valves and guides were installed. Of course seats had to be reground. Old valves were notched at the tip, so I thought that mushroom adjusters would be better to avoid the damage at valve tip. Of course the edge of the mushroom takes more room and reduce the available gap. I'm not sure what you mean by ''ground the stems''??Do you mean ground the valve tip? If so what happens to hardened tips?
Would it be possible to machine down the rocker arm in order to have the mushroom adjuster screwed deeper?
Click to expand...
The machinist has many years of engine building experience, many makes including moderns. I did not hear that he ground the stem tip on my new KW valves, but they did appear that way.

From KW website:
"12.Can I tip the end of my KPMI® valve to achieve personally deemed proper valvetrain geometry?
In rocker arm type applications KPMI® does allow the tipping of valves not to exceed as follows:

• 0.020" to 0.030" - Maximum
• Whenever tipping a valve in this condition, check to make sure the rocker arm(s) will not interfere with the retainer."
 
While poking around in my spares basket yesterday, pulled out my original valves, 10k miles on them. The tips had caps on them with some numbering around the sides (illegible). There were witness marks and likely some amount of depression. This wasn't why we changed them, as there was some slop in the guides and I recall one valve was tough to pull out its guide, likely a little bent.
 
On an aside from the original post, but in line with combat engines….until I used .060” shorter pushrods I could not fit mushroom tappet adjusters on my combat. The main reason for shorter pushrods is to get the rocker geometry back to normal with .040” shaved from the head.

Valve springs insulators and mushroom valve adjusters
 
When I re-ringed/honed my 850 Commando/installed new valves, there were no heat insulators on any of the valves when I disassembled it. Of course, no telling how many previous owners had worked on the bike and left out/forgot the insulators. :rolleyes:
 
MexicoMike said:
When I re-ringed/honed my 850 Commando/installed new valves, there were no heat insulators on any of the valves when I disassembled it. Of course, no telling how many previous owners had worked on the bike and left out/forgot the insulators. :rolleyes:
Click to expand...
I'm the second owner of my Commando. 1977 I got it, very low mileage and looking like it was in the showroom. Never found insulator on intake side. I doubt I could have lost them..:rolleyes:
 
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