Questions about valve adjustment on an 860 GT

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confusa
Diana
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Questions about valve adjustment on an 860 GT

Post by confusa » Fri Jun 25, 2010 4:58 pm

Pretty familiar with the general concept of valve adjustment from owning old VWs. New to it on a Ducati so a few questions:

From the manual I gather you set the valves at TDC for the particular cylinder. Are there marks anywhere indicating TDC or do I need to use my handy dial gauge to find it?

How do I determine which valve is intake and which is exhaust as they are set to slightly different specs?

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abmartin
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Post by abmartin » Sat Jun 26, 2010 4:48 pm

If you look closely at each cylinder, you'll see an exhaust pipe at the front and an intake manifold connected to a carburetor at the rear. The exhaust valve is the one closest to the exhaust pipe, the intake valve nearest the intake manifold.

You need to find tdc on the compression stroke. At this point the piston will be at the top of its travel and there should be free play in each of the rocker arms. If you take off the camshaft support plate, you will notice that the cam lobes will be at 4 and eight o'clock when compared to the cylinder.

Bruce
1979 900SS
Fredericton, NB
Canada

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confusa
Diana
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Post by confusa » Sat Jun 26, 2010 5:32 pm

abmartin wrote:If you look closely at each cylinder, you'll see an exhaust pipe at the front and an intake manifold connected to a carburetor at the rear. The exhaust valve is the one closest to the exhaust pipe, the intake valve nearest the intake manifold.
Sort of figured that was correct but wanted to make sure.
abmartin wrote: You need to find tdc on the compression stroke. At this point the piston will be at the top of its travel and there should be free play in each of the rocker arms. If you take off the camshaft support plate, you will notice that the cam lobes will be at 4 and eight o'clock when compared to the cylinder.
What/where is the camshaft support plate?

nottonight68
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Post by nottonight68 » Sun Jun 27, 2010 12:28 am

I could be wrong, but going on the nature of the questions and the name- i'm thinking this is a rev up.
And i'm not even going to mention the purchase of a Manual.
so much time--so little to say

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confusa
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Post by confusa » Sun Jun 27, 2010 9:09 am

nottonight68 wrote:I could be wrong, but going on the nature of the questions and the name- i'm thinking this is a rev up.
And i'm not even going to mention the purchase of a Manual.
Ha, yeah, I bought a Haynes which is how I know about needing the valves adjusted at all. It only has one rather simplistic section dedicated to the valves which is pretty straight forward. It just says check at TDC with no mention of determining that. On past bikes I used my dial gauge. The first post mentions taking off the camshaft support plate and looking at the lobes but I am not sure where that is exactly. Only thing in the Haynes that seems close to it is the plate with the "860" on it on the head but I am not sure that is correct.

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abmartin
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Post by abmartin » Sun Jun 27, 2010 4:47 pm

confusa wrote: Only thing in the Haynes that seems close to it is the plate with the "860" on it on the head but I am not sure that is correct.
The camshaft support plate is at the top left side of each cylinder, directly across from the triangular-shaped bevel drive to the camshaft and immediately above the spark plug. It is held on by four screws and should come off quite easily. After removing it you will be able to see the camshaft lobes.

You might also want to withdraw the rocker arm pins to check the plated surface of the rocker arms where they contact the camshaft. On 860GTs that I worked on years ago the chrome plating tended to break up and fall off. Chances are that this has been rectified by a previous owner but it wouldn't hurt to look.

Bruce
1979 900SS
Fredericton, NB
Canada

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