Re-torque heads and adjust valve clearances – 22 Feb 2017

I’ve now ridden about 230 miles since doing the work to change the cylinder head gaskets on The Fire Bike so, it’s time to retighten the six nuts securing each head and barrel. I like to do this around the 200, 500 and 800 mile mark. That’s about 320, 800 and 1290 Km.

Before doing anything, I wanted to check something out. My Moto Guzzi factory manual for the V7 700 and 750 models and the Chiltons’ Manual both quote the torque figure for the nuts as 27.5ft.lb (3.8Kg/m). This just feels a bit low. I checked the Guzzi factory manual for my V7Sport and this quotes 29 to 32ft.lb (4 to 4.5Kg/m) for the same fixings. They’re basically the same engine so I thought I’d get some advice from members of the Loopframe Guzzi Group. The consensus was that I should use 32ft.lb (4.5Kg/m) and, given the size of the fixings this makes more sense to me. So, on to the job in hand.

The first thing I do is remove the dynamo belt cover and the spark plugs so that I can turn the engine over with a 26mm spanner or socket. The engine rotates clockwise seen from the front.

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I started with the right hand side and removed the rocker cover. Turn the engine (clockwise) with something resting on the piston to tell when the piston is at the top of its stroke. If the rockers are loose then it’s on the compression stroke which is what you want. If not turn the engine till the piston comes to the top again.

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Once you’re sure you’ve got the piston at the top and both valves shut work can begin. A word of warning. Be careful what you rest on the top of the piston. You don’t want to get anything jammed in there or to damage the piston or spark plug hole. I used a long Allen key this time.

The reason I find this setting is so that there is no pressure on the valve gear when I remove the rockers and shafts to access the cylinder head nuts. I would have to do it later anyway to set the valve (tappet) clearances.

To remove each rocker you have to take out the locating screw.

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Then slide out the shaft.

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Above each rocker there’s a spring and washer.

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Keep the sets of components together and put them to one side. The pushrods can be left where they are.

Remove the 26mm blanking plug over the sleeve-nut at the top then slacken the 6 nuts just a quarter turn.

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Do this in the reverse of the diagonal tightening sequence. So

  • Top (10mm Allen sleeve-nut).
  • Bottom (below spark plug).
  • Bottom right.
  • Top left.
  • Bottom left.
  • Top right.

Now get the torque wrench out, set it and do them all up again. This time the order is

  • Top right.
  • Bottom left.
  • Top left.
  • Bottom right.
  • Bottom.
  • Top.

Check the state of its crush washer then replace the 26mm blanking plug.

The rocker gear can go back on now. Often the adjusters have to be slackened off a bit because, having tightened everything down, the gaskets have been compressed a bit more and reduced the clearances.

Adjusting the valve clearances.

Before going any further, I always re-check that the piston is at the top of its compression stroke. I generally turn the engine backwards a little way then forward again while checking for the top of the stroke with a rod again.

Settings are 0.15mm inlet and 0.25mm exhaust.

Use a feeler gauge between the face of the rocker and the valve stem to check the gap and adjust this by turning the top of the adjuster with a slotted tool and locking it in place with the nut on the adjuster. You’re looking for a snug, sliding fit. It should be possible to remove the gauge and then reinsert it. If the feeler gauge is gripped then the gap is too tight.

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Often tightening the lock-nut will mess things up. I never seem to get it right first go!

With the rocker cover back on I can turn my attention to the other side then finally replace the belt cover and put the plugs back in.

Other stuff.

I don’t know what was going on with my voltage warning light the other day as it’s now working properly again! All the same, one day I’ll wire it via a relay because it’s always been affected by a voltage drop across the ignition switch contacts.

I’ve got to paint that ding in the tank. I’ll probably just use a small brush to fill in the damage.

My V7Sport needs an MOT test but I might leave it for a week or two so that it comes around each March instead of every February.

I did manage to get hold of a small lathe and have been spending a bit of time cleaning it up and sorting out the motor arrangement. It came with a big but slightly wobbly home-made metal stand which I shan’t be using. I’ll make something more suitable with some second-hand timber salvaged from some work I’ve just done on the house. My friend, Bunny, has been busy producing stuff for it on his bigger lathe.

It’s not been a bad Winter but Spring will be here soon, the roads will be free of salt and the riding, camping and show season will be upon us.

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The cylinder heads are done – 5 Feb 2017

It’s taken me some time but The Fire Bike is now back together. As indicated last time, I did buy the posh type of exhaust nuts with a lock ring. Here’s one alongside my repaired original type.

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Before fitting the new ring-nuts I made up a longer version of the c-spanner needed to tighten them. I didn’t want to have a repeat of the thing slipping and hitting the tank again because of my ham-fistedness!

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Some time I’ll thread the hole in the tube and threadlock a grub screw in it so that I don’t need to have the head of the bolt or a nut sticking out but, for now, it worked well.

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I removed the rocker covers again to adjust the valve clearances. I’ve written about doing this on my other Guzzis but not the V7 700. I’ll write this up when I have to do it again (after re-torqueing the heads).

Thick rocker cover gaskets were coated in grease and the rocker boxes refitted. I find that by doing this the gaskets last ages.

I went out for a shortish run on the bike today. I had to speed up the tick-over a little to stop it cutting out. It looks like I’ll have to give the bike a good tune up soon.

The other thing that happened was that the voltage warning light, which I fitted when I got the bike, was flashing away showing a low voltage although the bike ran well enough and the original dynamo light never came on. When I got home I let the bike stand for a bit over an hour then checked the battery voltage. 12.95V is good and suggests that the problem was not with the charging system but the voltage warning light so, that’s something else to have a look at.

My trip out had been to buy some “Fiat Racing Red” paint. I’ve got to make good the damage caused by that slipping spanner.

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There is a suggestion that the tank was blue once upon a time.