[staib]

Hi all - so far I've been enjoying the bike too much to 'work' on it, but having cleaned and adjusted the chain, I am planning to do my first pushrod/valve clearance check and adjustment this weekend 

Assuming that I just go for the simpler 'twirl' method this first time (rather than the tank removal and valve gap setting approach) how critical is it to be at absolute TDC - or is more of a TDC 'zone'? 

Also is it enough to feel one's way into the compression/ignition moment with the kickstarter, or is better to remove the spark plug and bring the cylinder to TDC using the rear wheel in-gear...

I don't have any 'TDC tool' - without compression how do we know where TDC is?!

Cheers,   Nick

[staib]

Duh!   I've just read lots of useful tips on another bit of the forum, from just a couple of days ago.  I had been wondering about using a pencil or something to physically indicate the apogee (!) of the cyclinder, but thought you'd all laugh at that one!

And I now know you can remove the sparkplug (if you wish) and just use your thumb to indicate where the compression is - obvious once you've read about it

I also got the impression that TDC is not in practice a specific spot - there is a wee bit of leeway up there.

Cool - great advice.

[clamp]

If we were talking ignition timing then TDC is critical,--very critical,--to within 1 or2 degress of crankshaft rotation and for this the plug should be removed. This is then measured in movement of the piston. An antiquated system for sure.

   Im not a fan of sticking things down plug holes and would prefer timing marks, there  is none. But I dont have this problem because I have an Electra that does it all for me.

    But back to TDC for tappets. You are right in this respect it is not critical  because the back of the cam    ( which is where you set them)  is many degrees.

[Chasfield]

If you look at  the average cam lobe you can see that it is only doing any valve lifting at all for somewhat less than than half its rotation. So for tappet setting, a rough approximation of TDC is fine. The point at which the points open will be good enough because by that time your piston is deep into the compression stroke, so valves must be fully closed.

As Clamp says, you have to be spot on when it is ignition timing that you are looking at.

[REpozer]

Nick,
 I have 1300 miles on my AVL 500 classic. I've set the vales 3 times, I have an Electra lean burn factory manual (a little vague).
 Their are people that set the valves only by removing the push rod adjust cover, and then feeling and spinning the push rod adjuster, but I"m not confident enough to use that method yet.
  So I find it easy to remove the fuel tank  to gain access to the rocker covers and spark plug. ( The rocker covers will be tough to remove it they have never been off so take it easy with a blade to slowly work them off)
 After everything is removed ( spark plug too)you can push the kick starter and watch the valves move in anticipation of the compression stroke.( IE ex hast, then intake, then compression) Hold your thumb over the spark plug hole you will feel the compression blow though your thumb.
  During the compression stoke  is when you use your wood dowel(stick) . Slowly and gently use the kick starter to move the piston to TDC .Be careful not to get the dowel stuck in the engine and use a dowel that is long enough not to fall into the spark plug hole. As the piston rises you will feel the dowel rise , when the piston reaches the highest it will travel you are at TDC. Mark your dowel so you can easily find TDC again ,do this a couple of times to get the feel of it.
 Once you are at TDC use your feeler gauge to Check /set your valves to specs. 0.1mm.( both both push rod adjusters should spin or you are not at TDC)
 Make adjustments then kick the engine though 4-5 times ,go back to TDC check valves again. Do this till you are satisfied. Smear some grease on your gasket covers to make removal easier next time , button every thing up..... test ride.
  Not as hard as it sounds, you will be spot on with your valves with this method.
 Also if you look up Thumper on his page you can click on his maintenance notes under one of his icons .. very well done and very helpful.
  Oh hope the spelling is good, I ran out of coffee and made myself a pot of tea.. not bad, I drink it straight of course

[staib]

Some more great advice there.  I would have been so worried about losing any dowel into the bowels of the engine that I would have used a small safety rope, for sure 

Thanks guys - I really appreciate you all taking the time to answer and pass on your 'learnings' - it makes these important first steps less nerve wracking 

[cyrusb]

Repozer, How do you find your method easy? In the time it took you just to write it up you could adjust you valves twice. Find tdc with your foot and the ammeter, take off the tappet cover, spin and adjust the pushrods, put cover back ,done.

[REpozer]

staib,
 If you want a good  book MC maintenance I recommend Haynes "Motorcycle Maintenance Techbook" #4071. Written from  British point of view, published in England.
 I was pleasantly surprised to find it at my city library
 I  

[REpozer]

Repozer, How do you find your method easy? In the time it took you just to write it up you could adjust you valves twice. Find tdc with your foot and the ammeter, take off the tappet cover, spin and adjust the pushrods, put cover back ,done.

Your right, however there is a confidence Issie,( I know I'm dead on TDC) plus with Lean burn engine can't TDC with amp meter.With time I may do the spin the push rod method.
 I,m 500 miles away from a dealer , none of my friends work on motorcycles, there isn,t another RE MC in my town, so its me and and Electra Manuel and this forum when I need help. I never even heard the roar of an RE till I cracked open the crate my RE came in.
 So is the engine okay with a TAC..TAC sound or is tic... tic better?
Since  I took the time to do a complete valve adjustment/check, I know now my engine should make a nice tic.. tic from the valves and I don't loose sleep wondering if I did every thing correct.

[Joe28]

Here's a method that works for me.
Take it as well as all advice with a grain of salt!
I turn the crank until 1 of the valves starts to open.
If I'm doing the intake, I pull the plug, turn the engine until the exhaust opens a tad, adjust the intake, rotate until the intake starts to open a tad, adjust the exhaust.
You know, maybe a 1/4 of it's opening stroke to make sure the other valve is on the lobe and not the ramp to open of the cam.
Seems to works well for me rather than find T.D.C..
Joe
I ride, therefore I am!

[scoTTy]

i have very long nails.. tdc is ez

[clamp]

Doing the exhaust with the inlet open would mean the exhaust had just shut. Setting the inlet when the exhaust is open would be  just before the inlet opened.

    It will work but you wont be on the back of the cam, even TDC is not exactly on the back of the cams but close enough on a good ground cam.

      Check them the way you want to  and then check them by feel in all positions of crank rotation. If you find a sloppy bit the re adjust at that position.

    Remember a tight valve is not acceptable a slightly slack one is preferable.



 

[Chasfield]

If the exhaust is just open a tad then the inlet will still be well closed - exhaust stroke is yet to happen and we don't want to pump exhaust gases back through the carb.

If the inlet is just open a tad, then won't the exhaust still be open a tad because of valve timing overlap? The exhaust is set to close late and the inlet set to open early because the inertia of the exhaust gas outrush helps draws in fresh charge.

I would be surer of the tappets being somewhere on the back of the cams just by kicking the engine over until strong resistance was felt.

[clamp]

The inlet does remain open a tad when the exhaust is about to close in an attempt to continue the flow.

     Some gasses do go back to the carb slightly ,--this is called reversion and can be caused by sonic waves going down the exhaust system and back up when it will just time it right with an opening inlet. Hence exhaust design being critical for 2 strokes.

    Harleys sell reversion cones to fit in the exhaust outlet pipe.

    At higher RPM this will time better and encourage the continuation theory.

    Again,--- hence 2 strokes hitting a serious power band.

     Not perhaps something to worry too much  about with  an Re though

[ace.cafe]

I don't recommend doing it with any valves partly open.

There's over 60 degrees of overlap on these cams, where both valves will be partially open at the same time.

Much better to be sure both cams are on their base circles when adjusting, by doing it on the compression stroke TDC area..

[clamp]

 on a 4 cylinder engine we used to use a 1 to 8 method.

   Get number 8 valve open and set number 1---open number 4 and set number 5 etc etc.

    No one was suggesting to set valves in an open mode.

[Chasfield]

Dead easy on a typical 360 degree British twin. If LH exhaust is down then you know that RH exhaust is on the back of the cam. Vice versa, and more of the same for the inlets.