Rocker shims

Well today after a major rebuild, I was ready to fire up the 850. I have fitted JS motorsport piston & rods, new mains & big end bearings. New PM valves etc
Now when I was rebuilding the head, I decided to discard the THACKERY washers, I machined up bronze thrust spacer to fit in the THACKERY's place with 5 thou endfloat.
Well the engine started on second kick, no problems there, and the normal low RPM vibes above normal idle speed are virtual NO THERE! Very happy with that, the engine runs really even and strong. She only ran long enough to establish oil return and look around the engine. I had a pretty good oil leak, out of the left hand banjo in the overhead oiling. Now I am wondering if my solid spacers on the rockers are restricting oil flow, there by creating too much pressure at the banjo fitting.

Can anyone who has done this mod put me out of my misery?

Also so noted, the TOTAL SEAL rings fitted to the second ring land, certain increase compression, an enthusiastic 90KG on the kicker was stopped in it's tracks!

Cheers Richard

Yes my Commando's head has the bronze thrust washer mod. and the banjos have never leaked. The pressure in the rocker feed shouldn't exceed the maximum system pressure anyway.

Are alloy or copper banjo washers fitted? If you re-used the old washers did you anneal them first?

Are you sure the banjo bolt isn't slightly too long so could be bottoming before the joint is fully tightened?

Were the rocker spindles positioned so their end slot correctly aligned with the oil drilling?

Thanx LAB I needed to hear sombody had used this mod without excessive pressure build up. I was starting to think the oil bleed out through the thackery. But I have done this mod before on a mates T120 and it really quitened it down and worked perfectly.

I did re use the copper washers that came from the spindle end caps, they are nice and thick. My gasket set did not include the banjo wahers but had the rocker spindle jobs. I annealed the washers, but maybe the bolt is bottoming out. Ans yes I aligned the rocker spindles.

Thanks LAB

Cheers Richard

stockie1 said:

...I have done this mod before on a mates T120 and it really quitened it down and worked perfectly.

Click to expand...

I have heard of this mod before but please enlighten me —

a) How does the Thackery washer cause noise?

b) why did the factory fit Thackery washers when it could have fitted solid shims?

c) why fit bronze shims rather than hardened steel shims (e.g. Ducati)?

'72 Ms Peel Combat has washers fitted to stablize rocker centering on valve stems.
I had normal oil leaks as prior with RED hot annealed copper washers so switched to the Al kind and normal torque keep that sealed no matter how hard I've run it.
Them Thackery things are just coil springs to save factory time-effort but not the most stable way to hold rockers spaced on spindle. Washers should have no effect of oiling. Spindles are installed to starve off oil excess oil any way.

Now you've toned down the head, its even nicer with header wrap that take the bang-ping-ring out of the front of the bike, so mostly just tinkling of rocker contact and whirly sounds of chains with the deep sounds out behind.

daveh said:

stockie1 said:

...I have done this mod before on a mates T120 and it really quitened it down and worked perfectly.

Click to expand...

I have heard of this mod before but please enlighten me —

a) How does the Thackery washer cause noise?

b) why did the factory fit Thackery washers when it could have fitted solid shims?

c) why fit bronze shims rather than hardened steel shims (e.g. Ducati)?

Click to expand...

a) the noise comes because the rockerarms are moving from left to right and rattle At the same time they never hit the valvestem when the engine is running as where the rocker is hitting the valve when stationary (when you measured the play)
b) Probably because they wanted to save money in not having to shim it Ever done a Ducati head or had it done by a shop?
c) in the race-engines we always used steel ones Never had a problem

Lynxnsu — thanks for the explanation. Fitting Thackery washers to save time on assembly would make sense.

Hobot — by 'header wrap' do you mean the heat insulation webbing for race exhaust pipes? I have this on my Seeley just to stop my knee getting burnt from the high level pipe. Never thought about it being used to dampen noise, but there you go.

Dave

Yes Dave the racer, standard header wrap. The mellowed sounds when at front of bike is mostly noticed when alone in quit place, rather than out in noisy public places or inside resonating room. I mainly wrapped to cover up the ugly rusty weld job on my 2-1 home brew set. Also some hope it might aid exhaust gas to exit better.

While a hot topic I sure wish I knew what was ring with almost identical call to the cave bats here. I was pensive early on 1st Combat hearing the tinkling noises, assuming it was valve train but no back ground to know it it was supposed to be that distinct a sound. So during first weeks use going as slow as I could on THE G. like in 4th 1200rpm to listen to the regular cadence trying to detect any alteration to indicate something amiss, I kept getting same extra tinkle sound pattern out of synch with the the others. Started to get depressed bad decison so slowed up even more on siight up hill, to have bats dive almost under helmet edge, so close I could hear them making a single pattern of sound as the engine! It happened over a few minutes crossing their area so not a doubt in my mind.
I was also surprised they did it so loud and at freq I could hear, just like anyone else on Nortons. At least 4 events, last one with wrap on they got so excited or brave they aimed under tank or through stem area and one got tangled in cables till I lifted cable and it wiggled out... Is it Norton love calls or fighting words to them? No one man or critter can resist a good sounding Norton appeal.

oh yeah, a bat some times comes and buzzes my head in wee hours working on Norton stuff in shed. Half the time it makes its bed on wall above me, ignoring me to point I can pet it slightly and talk to it w/o it leaving. Bat can't see you but they know where you and your Commando are!
[video]http://www.youtube.com/watch?v=zo_tpiBlYqI&feature=related[/video]

Actually bats can see quite well, That's an old myth. Maybe you look friendly Hobot. :wink:

Yeah I'm past spelunker so just teasing by a Halloween phrase I stumbled across looking for a real sound track not kid party sounds. I'm hard enough to believe didn't want my spoofing on bat vision to be taken serious. Good catch.
There is caver-miner carbide lamp in my last Trixie recovery post, just seen between down tubes on floor. Spilled some carbide for Wes and tossed in water and lit it for smelly sooty flame, but no 'blind' bats involved.

My guess is the snugger fit of washer-bushes against rocker may stifle ringing a bit less loud or long vs barely held balanced between light springs rockers. 2nd guess is the lifter bodies taken up slack of valve gap. Then again there's a hint of bicycle rear hub derailer clinking of chain too which may be ringing the hardened sprockets some. I lightened Peels rockers almost as much as Dunstall, so may of raised some sound above my hearing level. I've lost some mid and lot of high range but can hear stuff at higher pitch than my wife, as long as its higher pitch than constant tinnitus from many causes.

Ideally spacers should be custom fit not just off the shelf universal fit set.