[PeteK]

I hate to have to agree with the diagnosis. Somehow, your cams came out of timing and the piston hit the valves. You can see the witness marks on the edges of the exhaust valves too.

Now the question is why. Did the cam chain tensioner break? It looked okay in the picture above, but check the ratchet mechanism inside. When you get the new cam chain compare it to the old one, is it stretched? That one loose cam chain link is a hint.

 

[pdwestman]

I'll suggest that the exhaust cam sprocket needs to be clamped in a bench vise & the bolt removed. Chances are high that the location dowel pin between cam & sprocket SHEARED due to impact!
If not replaced, the new EX valves will probably get bent during reassembly.

 

[Reveille]

I'm seeing a donor engine in your future. The plot thickens and pretty soon you'll have a basket case... hope not.

 

[KnowledgeLackingRider]

@PeteK no worries, my reply to Dave was mostly sarcasm (with a little self-pity mixed in, admittedly)—I kinda figured I’d have at least one bent valve once you all mentioned it.

As to why, I just double-checked the cam chain tensioner & it’s working properly—each tooth stops the arm from being pushed inward, and the arm extends fully when I stop applying pressure against it.

Is it possible that, when the balancer chain snapped & got jammed into the cam chain, stopping the movement of the cams/valves, the piston continued rising? Even if it was just far enough to bend the valves?


@pdwestman very good to know!! God that would absolutely suck after getting this thing rebuilt lol. I’m heading to my sister’s tonight and I’m pretty sure her boyfriend has a bench vise—I’ll bring it along & report my findings.

Are we talking about part# 610A0410 ?


@Reveille It’s not a bad idea! But the prices I’m seeing for used engines are just not feasible. Not in a single purchase, anyway. For now, I’ve been ordering a certain number of parts with each paycheck. If the valves etc do end up being the last of the damaged parts, I should be able to have everything ordered on my next paycheck this Friday.

Then from there it’s a matter of deciding whether to buy the tools for valve replacement or bring it back to the machine shop I brought it to last year.


Thanks again everybody!
—Pete

 

[terry_g]

Be careful not to damage the sprocket when clamping it in the vice.
Aluminum jaws or soft covers for the vice jaws.

 

[KnowledgeLackingRider]

Thanks Terry!

Also should I clamp the vise against the flat face of the sprocket or am I meant to clamp it directly against the sprocket teeth? And is there a torque spec for that bolt on reassembly? I assume it’s pretty high lol but I can’t find it.

 

[terry_g]

I would clamp the sprocket by the sides not the teeth.
My manual says 36 ft lbs for the sprocket bolts.

 

[KnowledgeLackingRider]

Good stuff thank you

 

[terry_g]

I was looking at the pictures you posted and I see what looks like a serious problem. I'm hoping someone
chimes in and tells me I am wrong. There is a punch mark on the camshaft sprocket on the crankshaft that
should line up with the key-way. It appears to be quite a ways off. This would explain the bent valves.
The arrow is pointing at the punch mark the circle at the top is where the mark should be.

 

[KnowledgeLackingRider]

Wow, good eye! Thanks for pointing that out.

I double-checked the old photo from last year and it appears it wasn’t lined up at that point either, so I assume it’s not a result of the seize. But I’m very intrigued as to what it might mean.

 

[terry_g]

Good That is a relief!
I'm still stumped as to why the valves bent.

 

[Klrian]

Wow, good eye! Thanks for pointing that out.

I double-checked the old photo from last year and it appears it wasn’t lined up at that point either, so I assume it’s not a result of the seize. But I’m very intrigued as to what it might mean.

View attachment 35063

I think the 2 washers/spacers are still on the crankshaft in this picture and covering where the punch mark is.

 

[KnowledgeLackingRider]

I think the 2 washers/spacers are still on the crankshaft in this picture and covering where the punch mark is.

Oh snap! This just keeps gettin juicier

 

[terry_g]

Here is page out of my manual. Can you verify the marks are in the correct spot?

Page out of an online manual.

 

[KnowledgeLackingRider]

Well I’ve removed the other balancer sprockets/weights, but yea the cam chain sprocket on the crankshaft is out of alignment like you suspected—looking at it in person now and the two punch holes are probably 70 degrees off from where they’re supposed to be.

I just wonder if that was some sort of shoddy installation at some point or if that could happen from the impact of the chains seizing up like they did. And I obviously wonder what it means for me going forward.

 

[terry_g]

It wasn't lined up in the photo from last year so it was probably like that from new.
If it had moved since the first picture was take I would be concerned.
You should be able to time the balancer with out using the marks.

 

[KnowledgeLackingRider]

It wasn't lined up in the photo from last year so it was probably like that from new.
If it had moved since the first picture was take I would be concerned.
You should be able to time the balancer with out using the marks.

Idk if you saw @Klrian comment but unfortunately it appears the spacer washers were still on the crankshaft in the photo from last year, so if the punch hole was lined up at that time, we wouldn’t be able to see it.

 

[terry_g]

Yes it does look like the washers are covering the marks.

 

[KnowledgeLackingRider]

New Issue:

Trying to remove the RH cover to get a look at the oil screen. Removed the water pump cover. I can’t loosen the nut on the impeller, since the impeller & shaft simply spin with it.

I’ve looked around online a bit and it sounds like this is potentially due to the balancer chain/system being removed? Couldn’t find a lot of info specific to this problem.

Any ideas/insight would be appreciated!

 

[KnowledgeLackingRider]

Welp. I tried to get creative (read: impatient) about it. Grabbed a pair of pliers, held a fin of the impeller, and tired breaking the nut loose.

sooooo I’ll be adding a new impeller to the parts list