Reaming rocker bushes

Information relating to the Matchless G12 or AJS Model 31 650cc twin
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Reaming rocker bushes

Postby Yves.Astein » Tue Jul 16, 2019 6:01 pm

Hi to all,

I have just received my ordered rocker bushes from the jampot spares club. Within the package, there is slip stating that if required I should ream them to correct size.

Can anybody explain the Idea behind that ? Are they oversized to accommodate worn rocker spindels ? If so, what would be the desired clearance between spindle an bush.

I do have all the tools, adjustable reamers and precise measuring tools for inside and outside diameters. If I wiuld fail it would probably be due to a lack of experience.

Thanks for any Help on that.

Yves

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Re: Reaming rocker bushes

Postby clive » Tue Jul 16, 2019 10:38 pm

Not sure about the specific items but normally if you install bushes they will shrink internally as they are fitted and so may need reaming to allow the shaft running in them to move without restriction.
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if it ain't broke don't fix

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Re: Reaming rocker bushes

Postby Rob Harknett » Tue Jul 16, 2019 11:11 pm

I have had to ream small end bushes. The most bushes I have fitted have been on King pin bushes. Always had the ream them. They had two bushes. On one occasion it was noticeable, bushes were not quite in line. Reaming solved this.

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Re: Reaming rocker bushes

Postby Yves.Astein » Wed Jul 17, 2019 8:29 am

Ah ok, yes I had the same problem when renewing the cam shaft bushes. One cam shaft was hard to turn after I had put together the bottom halfs. A little ream helped there as well.
Ok, then I guess I should be able to work that out.

Is there a special method to remove the bushes from inside the rocker arms. I would guess heating them up will help to get them out.


@Clive: I was talking about 014245 BUSH PLAIN FOR ROCKER ARM
http://www.amoc-parts.com/store/comersu ... duct=21089

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Re: Reaming rocker bushes

Postby clive » Wed Jul 17, 2019 10:58 am

Yves, I understood what you were replacing what I meant was I have never replaced those particular bushes but based my advice on replacing others elsewhere on our bikes.
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Re: Reaming rocker bushes

Postby Yves.Astein » Wed Jul 17, 2019 12:05 pm

clive wrote:Yves, I understood what you were replacing what I meant was I have never replaced those particular bushes but based my advice on replacing others elsewhere on our bikes.


Got it. Thanks

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Re: Reaming rocker bushes

Postby Rob Harknett » Wed Jul 17, 2019 12:20 pm

Just something I noticed on one of my old prewar bikes. The bike had exposed valve springs and rockers. Just lubricated with grease. They started making a noise. I noticed a rocker arm nut was a bit loose. So I tightened the nut a little and re peanned it, as I saw it had 3 punch dents round it. This stopped the noise. So I guess it was end play making noise, not worn bushes.

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Re: Reaming rocker bushes

Postby Yves.Astein » Wed Jul 17, 2019 12:47 pm

Hi Rob,

well the thing is, I have redone almost everything: cams, cam followers, valves, valve shafts and I am getting, what sounds to me like a rattling valve (or strong ticking, more a high pitch metallic sounding noise with the rythem of a valve ) when the bike gets hot. (when the oil has reached good temperature )

For one thing I do have a little bit of a lacking oil flow to the right inlet rocker. So this is something I will have a look at by checking the head and gaskets below. Might be a clogged oil Passage. I did see more ware on the right inlet cam follower when I replaced them, but I did not have the noise before I have redone everything. So I don’t believe this is the reason for the noise. Also the rocker does get some oil and the noise not there when the oil is cold and thick.

The noise could also come from one of the rocker spindles being stuck at one of the shims in the assembly. They tend to get stuck and not fully slide into their right position. This would corospond with your experience of to much sideplay, which ist the result of the spindle not sitting right. So I will have to check that as well when I take of the heads.

And since I dont realy have any explanation for the noise which would make sense to me, I had the plan to throw new bushes at the problem.

I did also buy new tappets, since the old ones had loose ends, which I tried to fix with lock tight. This was a tipp from a restaurateur near by. But I dont trust that to be a reliable solution...

So to summarize it, I am throwing parts at the problem...

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Re: Reaming rocker bushes

Postby 1608 » Wed Jul 17, 2019 1:17 pm

To replace the rocker bushes I heated the rockers and used a stepped drift to remove and re-fit them. And , I had to ream them ( 1/2" if I recall ). Also I do believe ( from memory again ) that each rocker has two differing bushes, one has an external annular oil way and the other is plain ! important that they are fitted in the correct way.

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Re: Reaming rocker bushes

Postby Andy51 » Wed Jul 17, 2019 5:38 pm

Hi Yves, I know little about twins as I only have singles, but I have replaced bronze bushes, but not in cylinder heads. If the fit on the shaft is good before pressing in place, but tight in the housing and thus liable to shrink internally, then skim the outside until they are a push fit and insert using appropriate Loctite retainer e.g. 603. This has worked for swing arm bearings and I got this from a classic car repairer who used it regularly for kingpins. If you are thinking of doing this, contact Henkel (Loctite makers) for advice before starting as I do not know if the retaining fluids are suitable for using in a hot location. Cheers, Andy

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