Bent intake valve


Information and questions on GL1100 Goldwings (1980-1983)
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bjanz
Posts: 8
Joined: Mon Jun 06, 2011 7:06 pm
Location: Three Hills,AB,Canada
Motorcycle: 1981 GL1100i

Bent intake valve

Postby bjanz » Tue Jul 05, 2011 8:12 pm



I have just entered the Goldwing world and am happy to be part of a group of helpful, knowledgeable owners, judging by the posts and articles I have read.
I just purchased an '81 Gl1100i that had a misfire. On doing a compression test, then removing the left head, I found a bent intake valve on the #4 cylinder. My question is, can I replace just this one valve, or does the entire head need to be replaced? It is a low mileage bike and it looks like it might have happened when it was started after a lengthy storage period. There is a little nick on the piston, but everything else appears to be in excellent condition.
Also, there is no evidence of leaking valve seals, but I read somewhere that a bike of this age should have the valve seals replaced.
Thank you.
Bruce



saltydawg1967
Posts: 28
Joined: Wed Oct 13, 2010 5:24 pm
Location: Waxahachie, TX
Motorcycle: 1982 GL1100A Aspencade

Re: Bent intake valve

Postby saltydawg1967 » Tue Jul 05, 2011 8:55 pm

Just my two cents from personal experience, a lot depends on the mileage. Low mileage it might be ok, but there are two things to consider. One, if you have the head off, go ahead and at least lap the other valves and definitely replace valve seals. Second, if you have a higher mileage engine and take the head off one side and replace the head gasket, 'sometimes' it tends to put a bit of pressure on the other side if the compression is increased. The engine might be a bit 'unbalanced' and you end up replacing the other head gasket anyways due to earlier than normal failure. Basically, I had the same issue and went ahead and pulled both. Found my intakes were pitted and the shop wanted to grind the valves which is a no-no. Buying new ones now.

If you have a low mileage bike you may be ok with replacing valve and lapping. If higher mileage, take the extra step now or pay double later. Good luck!

User avatar
virgilmobile
Posts: 7647
Joined: Sun Sep 19, 2010 5:39 pm
Location: Denham Springs,La.
Motorcycle: 1988 GL1500 I
Previously owned
78 GL1000
81 GL1100
82 GL1100 I
83 GL1100 I
83 GL1100 standard
84 GL 1200 I

Re: Bent intake valve

Postby virgilmobile » Tue Jul 05, 2011 10:08 pm

Just a side note:Valves don't bend themselves.It is an intrusive engine.If the valve timing jumps(bad belt)it can,at least bend a valve.Consider yourself lucky it didn't punch a hole in the piston.

That said..Just as the other post states.Do both sides for equality.Do NOT grind the valves,lapping is OK.
CLEAN,clean and then clean it again.DO NOT scratch or gouge the aluminum .Re-torque "BY THE BOOK ONLY".Replace the belts(use NAPA*Gates*)

User avatar
bjanz
Posts: 8
Joined: Mon Jun 06, 2011 7:06 pm
Location: Three Hills,AB,Canada
Motorcycle: 1981 GL1100i

Re: Bent intake valve

Postby bjanz » Wed Jul 06, 2011 11:54 am

Thank you for the advice. It is a mystery how just that one valve bent. The engine is very clean and obviously low miles (crosshatch on cylinder walls still obvious) and the timing belt looks new and timing is good. There is just a very light carbon on the valves and no pitting. The odometer reads about 30,000. Could it be that a small piece of debris held the valve open just enough for the piston to hit it once?

User avatar
virgilmobile
Posts: 7647
Joined: Sun Sep 19, 2010 5:39 pm
Location: Denham Springs,La.
Motorcycle: 1988 GL1500 I
Previously owned
78 GL1000
81 GL1100
82 GL1100 I
83 GL1100 I
83 GL1100 standard
84 GL 1200 I

Re: Bent intake valve

Postby virgilmobile » Wed Jul 06, 2011 1:09 pm

If you acquired this problem,then it's anyones guess.If the belts "look suspiciously new",the previous owner may have had one break,replaced them and sold it .
It's also possible that a valve stuck open from a very long rest in storage and the piston slapped it back.Be sure the guides are not mucked up before reassembly.




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