Loose Exhaust Push rod and Exhaust valve lifter

[vibrac]

Standard proceedure for bump starts
"what were you doing on the grid with your head down by the carb?"
"seeing what cylinder the compression was on"

all that practice bumping to get a few seconds lead, all gone, now any fool can just drop the clutch when the flag drops

 

[davidd]

Eugene,

Yes, it is a long learning curve. I have enjoyed your post because I learned something. I would be interested to see if you find out why the failure occurred. TT and Chankly are always supplying good advice. I have been running a racer and I took out all of the linkages. They can only cause a problem in a racer and I do not have a kick starter anyway. So I use the method Bruce mentioned. put it in gear, let out the clutch and move the bike backwards until you hit compression. I put it on the rollers and it fires immediately. In your case you would kick it. But you should fix the linkage as it is much more convenient. Is the linkage stainless steel? It looks quite shiny.

David

 

[Gene Nehring]

Hi guys,

Firstly the series of replies has been amazing and I am learning so much about my machine. Thank you!

My friend Michael on the island who is a member and owner came over this morning. We removed the steady plate and marked the position of all the timing gear, then removed the cam. I also removed all the non standard exhaust valve lifting gear. Photo attached.

I am lucky nothing major was damaged by the roller coming out of the ET69FAS and the snapped E221 like rod. The rod looks to be stainless so it could have work hardened and snapped.

It looks to me like the bike was rebuilt with Mk 2 cams they are in good order. The push rods, push rod followers are all in good order.

Now I need help to adjust the tappets as I cant seem to get it right I have read through Richardson and the riders hand book and there is still up and down play in the push rod if I do the adjustment at TDC as the books says.

 

[davidd]

Eugene,

It seems to me that you are doing quite well. It is good to be lucky also. I thought the rod might be stainless, which is probably not a good application in this case. I would just take some time with the bike. I am sure you are adjusting the valves correctly with zero lash, but not so tight as the push rod won't spin. See if you can isolate the movement by causing it to move and watch carefully. Hold various parts while you are moving the push rod up and down. You might find it is a rocker moving or something like that.

David

 

[chankly bore]

Amazing how things have changed. I had a plutocratic new Comet owner call by a couple of years ago wanting an E221. I rooted around for a bit and found an old spoke. I was just putting it in the soft jaws (of my vice-not mine) to bend when he exclaimed: "I'm not having that piece of S%#T in MY bike" He probably used stainless an' all!

 

[timetraveller]

It isn’t just TDC. It has to be TDC on the correct stroke, i.e. the firing stroke but as you have the timing cover off you can do even better because you can see just where everything is. Just rotate the engine/cam until the cam followers are in the middle of the base circle and do the adjustment there. However, be warned. A few years ago there were some rubbish cams available which had a 20 thou depression in the middle of the base circle for over 40 degrees. Setting the adjustment to zero there meant that over the rest of the base circle the valve would be off its seat and premature failure and lack of performance were inevitable. Once you have the adjustment correct, rotate everything and make sure that the adjustment stays the same all round the base circle. And there is nothing wrong with using an old spoke to replace the broken part. That is what Vincents used (probably a new spoke) sixty years ago.

 

[chankly bore]

Perzackly my point, old chum.

 

[Michael Vane-Hunt]

How much up and down movement should there be of the valve rocker ET25 when the push rod is removed ?

 

[Gene Nehring]

Thnx time traveller

I found TDC buy using the opening and closing of the points and the TDC firing stroke.

Once set I rotate the engine through (I could not express this properly) the rockers and push rods slacken off a fair bet during the engine cycle and return to TDC fine.

Sorry for the questions ... I just want to make sure its right be for I try and fire it.

 

[timetraveller]

Well genedn, I am not sure that I understand exactly what you are saying. Am I correct that you have zero clearance at top dead centre and then when you rotate the engine there are some places where the clearance of the tappet on top of the pushrod increases so that there is now slop or play at that point? If that is correct then something is wrong. You should see the pushrod stay still until the cam starts to push the cam follower upwards, then the rocker lifts, the valve opens and progressively opens more until eventually the valve starts to close and finally the clearance should return to zero. For the whole of the time the valve is open it should be impossible to rotate the pushrod in its top and bottom cups. If play is occurring can you tell us at what stage of the cam rotation it is happening, e.g. end of lift, start of lift etc. Remember, with your timing cover off you can see where the cam follower is in relation to where it is touching the cam. If my interpretation of your problem is correct then you could have a malformed cam or the cam is not timed up properly to be fully closed at TDC. Just how much clearance are you getting; a thou, ten thou or what?