Motogadget loom project

[pepeducat]

Good job 

[ducatigirl100]

Advice needed    

I've done the horizontal cilynder and it's superb.

But I've begin the vertical head. I've shim the intake properly but the cams do not turn over completely.  Even when I push direcly on the valve it seam to block....  there's some sort of mecanical unterference

When theres no shims the cam turn over completely whitout blocking but the second I put shims on it just block when I try to turn it ??

My guess....
Unproper rebuild order?
Starting whit the wrong valve  intake -first or exaust first?
Unproper shims ( closing shim to spec but just to big... to high in my words) ?
Is there a starting point for the cams (point if reference ) to start the process ?

Half rings (chanel lock for the valves) seated but on the wrong side .... if theres a side ?

[Speeddog]

~~~SNIP~~~

My guess....
Unproper rebuild order? See below *.
Starting whit the wrong valve  intake -first or exaust first? Doesn't matter, you can start with either.
Unproper shims ( closing shim to spec but just to big... to high in my words) ? If the closing shim is too big, the cam will only turn when that valve is open
Is there a starting point for the cams (point if reference ) to start the process ? No

Half rings (chanel lock for the valves) seated but on the wrong side .... if theres a side ? The half rings do wear, slowly. Inspecting the half rings closely, you can see wear on the inside part from the valve, and the outside from the closer shim.

* Are you using the same shims as it had before cleaning?

[ducatigirl100]

Tanks for all the advice

All the half rings are new

On the  horizontal cylinder yess.... but  since I lap the valves I add to miss match them to get them to fit ... I also bougth a few...

[Speeddog]

Try assembling with just the closer shim on one valve, and all rockers in position.

Confirm closer clearance, and easy cam rotation for a full 360 degrees.

Then do the opener shim on that valve.

Repeat until done.

Sometimes the half rings will jam in the closer shim, and not seat all the way.
Usually that's an issue only with 7mm closer shims.

Some of the newly manufactured half rings have a burr on one end from the cutting operation.
Inspect closely and dress off the burr as necessary.

[ducatigirl100]

Try assembling with just the closer shim on one valve, and all rockers in position.

Confirm closer clearance, and easy cam rotation for a full 360 degrees.

Then do the opener shim on that valve.

Repeat until done.

Sometimes the half rings will jam in the closer shim, and not seat all the way.
Usually that's an issue only with 7mm closer shims.

Some of the newly manufactured half rings have a burr on one end from the cutting operation.
Inspect closely and dress off the burr as necessary.

Tanks . I'll have to whait for the weekeed to do that bit I tink you solve the problem .. 

[Speeddog]

With all new half-rings replacing worn ones, that will reduce your closer clearance all by itself.

How much reduced depends how worn the old ones were.

Lapping the valves increases closer clearance.

So for shims you're pretty much starting from something fairly close to the ones you had before.

[ducatigirl100]

The heads hare done ... finish !!!

Now to my next problem I've order the rings for the high comp piston from JE .  Also,  I want to order the rigth set of pistons .... doe's someone have the JE part number ?

[koko64]

I will look at a JE box tomorrow. I saw the piston kit on the JE site recently msrked for Ducati 904cc.

[ducatigirl100]

I will look at a JE box tomorrow. I saw the piston kit on the JE site recently msrked for Ducati 904cc.

Tanks ... I was planing on saving some money tinking the rings would fit the stock pistons.... nah ... it dosen't work  ... because of the L shape compression ring ...  and all the rings are to loose

Now I have to get the hole kit ! 

[DarkMonster620]

~~~~
Now I have to get the hole kit ! 

this WAS the way to go from the beginning . . .

[ducatigirl100]

this WAS the way to go from the beginning . . .

Sadely...  now I know  .....   

If I look at it on the positive side....I'll those High-comp pistons 

[koko64]

I thought you had JE pistons. Yes may as well buy the whole kit now.
How much were the rings?

[koko64]

 
If you are changing to hi comp pistons you should retard the ignition at least 3 deg and use premium fuel.

[ducatigirl100]

If you are changing to hi comp pistons you should retard the ignition at least 3 deg and use premium fuel.

Tanks, I've read somewhere there was some ping issues but I did not look into it .

For now I'll have to wait for a month or two to have the money to get the pistons ...... I'll lost almost all the bike season .... Montreal -Canada... yess it's snows here in the winter....

I'll put on my running shoes and run instead for this summer...lol