another problem on my Nevada

[shepped]

Hi All

Having solved one problem with my Nevada i seem to have found another
After deciding to adjust my tappets to the correct clearance noticed then when adjusting the air intake side the rocker arm did not seem to want to adjust even when the valve was closed. (bike did run ok before). So i thought i had sussed it put it all back together only to find the pushrod had come out of the cup. Fearing the worst thought i had bent the rod checked it and it is still straight. Took the the rocker arm assembly off and yes it was like the air in take side bearly moved and hence no chance of adjusting unlike the exhaust side moved freely.
Dont understand how it ran before...could i have done damage??There is now definatly a problem with the intake as the bike ticks over poorly. I have ordered a new rocker arm assembly (or a good used one) but now fearing the worse.
Please be gentle with me as i am still learning about this bike and do appreciate there are much more knowledgeable people than myself.

[guzzisteve]

I would pull the head & check valves, could be a chunk of carbon stuck on seat. What you described is weird. I would not think something in the rocker assembly. You have the nuts off of most for pulling head and have a look see. It's a Heron head so real simple(to me).

[tris]

I don't want to teach my grandmother to suck eggs but did you have the cylinder on the correct timing marks?

I know that I got confused once and tried to set the clearances on the wrong part of the stroke

[John A]

Did the pushrod come out of the tappet socket? Check for that before you get too excited. Hopefully it’s just not seated down there

[shepped]

Thanks Guys for all your replies
I have purchased a used rocker arm assembly so coming from Germany...mine one when i took it out was really stiff as thou it had seized
When i took the push rods out they literally just pulled out and i just placed them back in after checking they were both straight....i think that is all i need to do correct me if i am wrong???
As far as the clearance i took the plug out and with a long screw driver felt when i was at tdc and both valves were closed...from memory exhaust gap was at 0.20mm and air intake gap was at 0.15mm
point to mention when i put it back first can hear what is air leak/pressure so i guess i have messed up somewhere with the intake...i have ordered a new gasket here too
mentioned about taking the head off to check for carbon... a little bit out of my comfort zone never done that before is it straight forward?
thanks again for all your replies

[shepped]

Did the pushrod come out of the tappet socket? Check for that before you get too excited. Hopefully it’s just not seated down there

this is making me think i might not have seated it correctly??..i might have another look at this tomorrow

[Tom H]

Let me make sure we have this correct. The intake rocker is excessively tight, like seized, to the rocker arm shaft?? Correct??

When you rechecked the rocker. You found the rocket adjuster not seated in the push rod and the push rod cocked to one side?

Without knowing if the rocker moved freely on the rocker shaft before your adjustment. And if this above is correct. The rocker could have lifted up enough and become stuck in the lifted position to allow the push rod to get cocked to one side?? But, then again the rocker would have had to hold the valve down while this happened.

So IF the valve was held down and the piston came up, could the piston have banged the valve? Not sure if there is clearance on that model with the valve open It might not hit and you could be lucky.

If it were me at this point. I would measure the height from the head to the tip of the valve and see where your at. If at least very close, a MM or 2, I would do a compression test to see if the intake valve may be stuck open at all. Or at the least make sure your at TDC with the valves closed and blow compressed air in the spark plug hole and see if the air comes blowing out the intake manifold or TB.

If the compression is good. I would fit your new rocker assy. and note how much thread is showing on the in. and ex. valve rocker, they should be about the same. Then I would hand crank the engine through.

If good so far, I would do another compression test and if good, go for a start up.

Just my thoughts,
Tom

[chuck peterson]

Double check what stroke you’re on when adjusting the clearance…sounds like the wrong one?

Normally when you’re at the correct Top Dead Center, you can feel the clearances on both valves with your hands

It sounds like you were at the top of the other stroke when adjusting but the description is a little unclear

What kind of experience do you have doing this?

[shepped]

Let me make sure we have this correct. The intake rocker is excessively, like seized, to the rocker arm shaft?? Correct??

When you rechecked the rocker. You found the rocket adjuster not seated in the push rod and the push rod cocked to one side?

Without knowing if the rocker moved freely on the rocker shaft before your adjustment. And if this above is correct. The rocker could have lifted up enough and become stuck in the lifted position to allow the push rod to get cocked to one side?? But, then again the rocker would have had to hold the valve down while this happened.


So IF the valve was held down and the piston came up, could the piston have banged the valve? Not sure if there is clearance on that model with the valve open It might not hit and you could be lucky.

If it were me at this point. I would measure the height from the head to the tip of the valve and see where your at. If at least very close, a MM or 2, I would do a compression test to see if the intake valve may be stuck open at all. Or at the least make sure your at TDC with the valves closed and blow compressed air in the spark plug hole and see if the air comes blowing out the intake manifold or TB.

If the compression is good. I would fit your new rocker assy. and note how much thread is showing on the in. and ex. valve rocker, they should be about the same. Then I would hand crank the engine through.

If good so far, I would do another compression test and if good, go for a start up.

Just my thoughts,
Tom

yes pretty much correct i was told that this was not an interference engine but of course if it is i may have damaged the valve and so will have to take apart which is well past my comfort zone.
I will get the rocker assembly and see where that takes me and do the bits you have indicated...sounds like an expensive mistake

[shepped]

Double check what stroke you’re on when adjusting the clearance…sounds like the wrong one?

Normally when you’re at the correct Top Dead Center, you can feel the clearances on both valves with your hands

It sounds like you were at the top of the other stroke when adjusting but the description is a little unclear

What kind of experience do you have doing this?

not a lot of experience on doing this and will admit struggled making sure i had tdc.....so obviously took the plug out and with a long screw driver on top of the piston waited until the piston was at the top of the cylinder and both valves were closed (what i thought was closed i.e pushrod side= down). point to make was when i believe i was at top dead centre i could feel a wiggle on the exhaust side but not on the intake side but i am confident there was little to no clearance before i even touched it...very disappointed with myself for even touching it now

[chuck peterson]

It can be fine…maybe can’t tell yet

Sounds like you just need to rotate the engine to the next Top before making the valve adjustment

Just realize there are two points in the motor where the screwdriver method works. You can only adjust the valve on one of them

If you haven’t run the motor for too long you might be fine

I believe your concern on the rocker arm was from being on the wrong stroke.

It’s happened to me…. I readjusted the valve and all good

Let’s hope that’s your case..

[shepped]

It can be fine…maybe can’t tell yet

Sounds like you just need to rotate the engine to the next Top before making the valve adjustment

Just realize there are two points in the motor where the screwdriver method works. You can only adjust the valve on one of them

If you haven’t run the motor for too long you might be fine

thanks Chuck i will get my new part fit it and do other tests that others have suggested and see where i am at..thanks again
I believe your concern on the rocker arm was from being on the wrong stroke.

It’s happened to me…. I readjusted the valve and all good

Let’s hope that’s your case..

[John A]

The closest a valve will get to the piston is the exhaust valve chasing the piston. You may be fine. When you put it together and double check your valve settings, roll it over and watch the valves and it should make more sense. Watch the exhaust valve , it closes. The intake opens.As the intake closes, the piston comes up on the compression stroke. I think the main problem would be if a valve has kissed a piston and bent but after reading all the posts, I don’t think that has happened.

[shepped]

Hopefully get me rocker assembly soon does anyone know the correct torque settings for the 2 nuts that hold it on
thank you

[guzzisteve]

Torque is 32 ftlbs in a 3 step tightening. To replace you need to loosen all head nuts & bolts and retorque to spec. Should be 4 larger & 1 smaller on head.  If you only do 2 you may warp head.

[shepped]

Torque is 32 ftlbs in a 3 step tightening. To replace you need to loosen all head nuts & bolts and retorque to spec. Should be 4 larger & 1 smaller on head.  If you only do 2 you may warp head.

with the bolts that hold the rocker shaft on ?

[Tom H]

Go here and look at the manual. It will have the sequence to torque the head.

https://cadrecycle.com/moto-guzzi-service-manuals/

Tom

[jacksonracingcomau]

I had this happen recently, recommissioning a v65 (Heron head) that had sat for years. On starting it, the rh exhaust pushrod jumped ship, it started shooting flames through the carb, inlet valve acting double duty, in and ex !
The exhaust valve was stuck open on inspection, simply old oil/fuel turned to varnish. Head off, valves cleaned, lubed with moly, reassembled, only new parts were head and rocker gaskets. The other side never did it, oil changed and run on fresh fuel , fixed. Hope this one as easy. Rocker and shaft should clean up the same
Beauty of Heron heads, at least the piston hits the valve square and doesn’t bend it !