Burnt valves

[Flynbryan]

I'm a newbie on this forum. I have a question. Does the engine have to come out of the frame to remove the cylinder heads? Thanks in advance!

 

[Parminio]

It can be done on a Gen 1 but it's more trouble than it's worth. You have to pull the head studs to get them out and man, when you have to do that, you're just better off pulling the motor.

On a Gen 2 I have no idea.

Posted just in case you might have a Gen 1 and posted in the wrong place. It happens.

 

[ShawnD]

At a bare minimum, the front motor support will have to be removed so the motor can pivot down. That has to happen just to get to the cams & I'm betting to get the heads off it will have to be completely free of the frame.

 

[Allen Zielinski]

Just queries. How do you know you have a burnt valve & do you know what caused it? It is a GEN 2?

 

[Stephan]

The gen 1 front cylinder head comes off if you remove the front engine mounts, slacken/remove the rear ones and pivot the engine rearwards in the frame. The rear cylinder head no chance unless you remove the studs as Parminio says, but it would be easier to take the engine out for sure.

 

[Flynbryan]

Just queries. How do you know you have a burnt valve & do you know what caused it? It is a GEN 2?

Not sure if it's gen 2. My thought is this exhaust system offers no back pressure. No back pressure = flame over the exhaust valves under acceleration. It still runs but a constant popping in the exhaust. (used to clear up once it built up temp) Last time out it was missing but if you open the throttle, She makes great power but when it's cold the back 2 cylinders have 30 psi while the front 2 have 120 psi. Smells like exhaust valves to me.....(I think)

 

[MaxMidnight]

Not sure if it's gen 2. My thought is this exhaust system offers no back pressure. No back pressure = flame over the exhaust valves under acceleration. It still runs but a constant popping in the exhaust. (used to clear up once it built up temp) Last time out it was missing but if you open the throttle, She makes great power but when it's cold the back 2 cylinders have 30 psi while the front 2 have 120 psi. Smells like exhaust valves to me.....(I think)

Does it look like this - Gen I



or this - GenII



Whichever it is with those sort of readings the head needs to come off and as alluded to above, easiest way is with it out of the frame.

 

[apsolus]

if you dont know what a leak down test is look into it. so both rear cylinders and low ? i wonder if the timing chain moved. if a bank of cylinders is low i always check timing.

 

[sdt354]

In the frame would be a nightmare. Engine removal isn't to bad. But 1st, +1 to the leak down test. You can get a cheap one from Harbor Freight. With the piston at TDC you'll hear air leaking by the exhaust valves at the exhaust port, if it's the issue . Also, a valve clearance check would be a good thing to do.

 

[Radioguylogs]

I have used my air compressor to do something equivalent to a leak down test. I made an adpter to connect it into the spark plug holes.

 

[Flynbryan]

Does it look like this - Gen I

View attachment 78515

or this - GenII

View attachment 78516

Whichever it is with those sort of readings the head needs to come off and as alluded to above, easiest way is with it out of the frame.

It's the gen 1

 

[DreamV4]

Not sure if it's gen 2. My thought is this exhaust system offers no back pressure. No back pressure = flame over the exhaust valves under acceleration. It still runs but a constant popping in the exhaust. (used to clear up once it built up temp) Last time out it was missing but if you open the throttle, She makes great power but when it's cold the back 2 cylinders have 30 psi while the front 2 have 120 psi. Smells like exhaust valves to me.....(I think)

check compression when engine is hot. Dry compression and wet compression.