Jump to content

Finding TDC for valve adjustment


Recommended Posts

i'm trying to do tappet work on my V11 Sport 2000 and I'm new to Guzzis. I've been poring over the V11 Sport manual to try and find out best practice for:

  1. 1 Turning the crankshaft
  2. 2 Finding exact TDC for each pot

The manual isn't that much help on either of these points.

On other makes (old Meriden Triumphs, Jap bikes etc.) normally you either turn over the crank using a conveniently accessible rotor or crankshaft nut and there is a TDC locking tool or maybe scribed marks somewhere for TDC or something like that. Just can't find any guidance on these in the manual.

So, my best guess for 1 is removing the alternator cover and using the rotor nut to turn it over but I have worked on bikes where putting it into gear and rotating the back wheel is really the best way.

Absolutely no idea for 2. Are there any reference marks anywhere to show TDC without me having to remove the alternator and dismantle the whole timing case? Or is it really just a matter of probing the spark plug hole with a screwdriver and making a best guess?

 

So what do you guys do? Pointers on this most basic of maintenance procedures would be appreciated. Tappet adjustment should be a fairly simple procedure.

Link to post
Share on other sites

Remove the plugs, put in 5th or 6th gear, hold the thumb on one of the plugholes and push the bike forward/backward. It's easy to notice the piston blowing. TDC is reached as soon as this stops. Look into the hole and you'll see the piston. Maybe you want to wait for warmer days, as a frozen engine is really hard to turn over.

 

You don't need a degree wheel for setting the valves. There are markings on the flywheel nevertheless.

 

Hubert

Link to post
Share on other sites

OR...

 

remove alternator cover, there is a 24mm nut, use 24mm wrench to turn over the crank.

Before doing this remove the plugs. You can also watch marks on flywheel - S for Sinistra (Left) D for Destra (right). Don't forger to check that the pistons are in compresion turn - in TDC the piston should be in its verytop. Check this by putting some soft wooden ply in the plug hole. Also check that the push rods are spinning free.

 

Voila, you have the piston in TDC and you can adjust yout tappets. Doing the other side is just the same.

 

Turning the nut in front of alternator seems to me bit more "profesional" and easier that turning the engine by moving the rear wheel, but of course, it is an option too!

 

 

Good luck

 

 

Slavek

Link to post
Share on other sites

OR...

 

remove alternator cover, there is a 24mm nut, use 24mm wrench to turn over the crank.

Before doing this remove the plugs. You can also watch marks on flywheel - S for Sinistra (Left) D for Destra (right). Don't forger to check that the pistons are in compresion turn - in TDC the piston should be in its verytop. Check this by putting some soft wooden ply in the plug hole. Also check that the push rods are spinning free.

 

Voila, you have the piston in TDC and you can adjust yout tappets. Doing the other side is just the same.

 

Turning the nut in front of alternator seems to me bit more "profesional" and easier that turning the engine by moving the rear wheel, but of course, it is an option too!

 

Good luck

 

Slavek

 

As a refinement of the above, I slide a small cardboard wheel over the 24mm socket marked with D and then 270 degrees later S so that once aligned (with reference to the stamped marks) you don't need to keep checking the timing marks ... turning anti-clockwise and starting with D (RHS TDC) turn 270 = L (LHS TDC) then turn another 90 = D again etc (so you can check any adjustment you made on the previous cycle)

Link to post
Share on other sites

Thanks guys, all comments are really helpful.

 

I need to get the alternator cover off anyway to clean it up properly: only four screws so will go with that solution for turning over this time round.

 

I've used several of the methods given above in the past for finding TDC but I recall on one bike getting TDC exactly right was important cos the cam closed the gaps quite close to TDC - not sure why it was like that but it was a right pain - so I wanted to check if the V11 has that same gotcha.

 

I like the special degree disk idea: worth it if I'm doing adjustment like this on a regular basis.

 

Andy

Link to post
Share on other sites

You could buy or make a piston stop which fits directly into the spark plug hole

Once you have done that, turn engine completely one way 'til piston stops, mark that , then turn it the other way 'til piston stops; TDC is exactly in the centre point between both marks.

Link to post
Share on other sites

You could buy or make a piston stop which fits directly into the spark plug hole

Once you have done that, turn engine completely one way 'til piston stops, mark that , then turn it the other way 'til piston stops; TDC is exactly in the centre point between both marks.

 

I'm not sure if that would work as it's not just TDC you are looking for, but TDC on compression (ie valves closed) for adjustment ... and re-reading my earlier suggestion I realise that what I wrote may require some clarification :

 

Starting at S (LHS @ TDC - compression - adjust here)

+90 (anti-clockwise) = D (RHS @ TDC - open)

+ another 270 = S (LHS @ TDC - open)

+ another 90 (450 total) = D (RHS @ TDC - compression - adjust here)

+ another 270 = back to starting point again

 

(On second thoughts I guess you could rotate 270 from D to S with piston stops fitted, but I think I would prefer to keep turning one way completely through each cycle in order to verify any adjustment made on the previous cycle ... if that makes sense?)

  • Like 1
Link to post
Share on other sites

Agreed - use of the cardboard wheel is not intended for accuracy - but it costs nothing and provides a quick visual confirmation without having to look for the marks (except first time) or poke anything into the cylinders ... but I accept that spinning the rear wheel is perhaps a simpler method ... have attached a pic for those that may be interested.

 

Looking forward to the arrival of Spring!

 

Gio

valveadjustwheel.jpg

Link to post
Share on other sites

I always stick a thumb over the plug hole and turn the back wheel until I find compression. Then slowly advance the engine until I see the S or D through the timing window, I turn the engine tooth by tooth using a screwdriver on the starter ring gear which you can also see through the timing hole. I used to do it that way on my old T3, I still do it now as it is almost impossible to remove the alternater cover on the later models as the front crossover gets in the way.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...