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XR 600 no / Weak compression

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Hi I have an XR 600 started it up Friday not a problem as  normal but when I tried to start it Saturday to go trail riding it wouldn’t start 

i  checked fuel and spark both fine then lost compression and could turn over with hand then compression come back but no start just backfiring 

I have now stripped down the head thinking am I have a Stuck Valve  but the values are  fine the only thing I noticed was the valve stem oil seals on the exhaust side had been hit and miss in some of the rubber just the spring left not sure what to do next any ideas 

I have a  never head which I have been checking  against and all looks gy

C22A721E-0D8F-46F0-AA52-DFE1F0931AB2.jpeg

8CAA9F3C-99DE-400A-AF3D-01D93C05C96F.jpeg

1173B401-9849-42A6-BA51-1407E9B066EE.jpeg

D72B9FC9-5F0E-4292-B5C6-06028BF901A8.jpeg

D511BAAC-916D-4792-8714-35CE3A14A595.jpeg

8705AC38-7207-469E-AC2B-DE9109104CE0.jpeg

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I've seen some interesting porting jobs but whoever cut those guides down like that needs a smack to the back of the head. 

You're probably losing compression right up through them.  That's also probably (is) why your seal blew off.

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1 hour ago, Hollerhead said:

You're probably losing compression right up through them.  That's also probably (is) why your seal blew off.

????????????

 

B

  • Haha 2

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I'm no expert but that ain't right.  Who does that kind of work?

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37 minutes ago, brianhare said:

????????????

 

B

Lol.

What?  That's not where you store your compression?

Edited by Hollerhead

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9 hours ago, Richyg22 said:

Hi I have an XR 600 started it up Friday not a problem as  normal but when I tried to start it Saturday to go trail riding it wouldn’t start 

i  checked fuel and spark both fine then lost compression and could turn over with hand then compression come back but no start just backfiring 

I have now stripped down the head thinking am I have a Stuck Valve  but the values are  fine the only thing I noticed was the valve stem oil seals on the exhaust side had been hit and miss in some of the rubber just the spring left not sure what to do next any ideas 

I have a  never head which I have been checking  against and all looks gy

C22A721E-0D8F-46F0-AA52-DFE1F0931AB2.jpeg

8CAA9F3C-99DE-400A-AF3D-01D93C05C96F.jpeg

1173B401-9849-42A6-BA51-1407E9B066EE.jpeg

D72B9FC9-5F0E-4292-B5C6-06028BF901A8.jpeg

D511BAAC-916D-4792-8714-35CE3A14A595.jpeg

8705AC38-7207-469E-AC2B-DE9109104CE0.jpeg

Dude, that head is TOAST. You can seel the carbonized leak points on the seats....

Those valves are so mushroomed you could use them on PIZZA..........

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7 hours ago, WILLY THE WORT said:

Dude, that head is TOAST. You can seel the carbonized leak points on the seats....

Those valves are so mushroomed you could use them on PIZZA..........

Exactly...

I hate to be negative but if a person compared that head to another and felt everything looked good I just can't take them seriously anymore.

OP needs a mechanic...and not the same one that ported that head.

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Sorry for Highjacking the thread, but based on the first post It should be welcomed.

Im a newbie in this field and would much appreciate if anyone could point out the problem areas in the pictures. Some arrows and added description on what could be the cause, how to identify and the effects would be awesome.

 

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2 hours ago, Hollerhead said:

Exactly...

I hate to be negative but if a person compared that head to another and felt everything looked good I just can't take them seriously anymore.

OP needs a mechanic...and not the same one that ported that head.

:smirk:

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1 hour ago, Viktor.J said:

Sorry for Highjacking the thread, but based on the first post It should be welcomed.

Im a newbie in this field and would much appreciate if anyone could point out the problem areas in the pictures. Some arrows and added description on what could be the cause, how to identify and the effects would be awesome.

 

There is TONS of information on how to service a Honda 4stroke on the internet, including step by step instructions and desriptions. The factory SERVICE manual is the best there is.  

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23 hours ago, Hollerhead said:

Lol.

What?  That's not where you store your compression?

Ummmmmmmmm  not sure what to say there..

Does that mean i need to be afraid of stored compression  when i rebuild engines now..

 

So,,,about the cut valve guides...CW did this for years and never had an issue......not saying i`d do it..but hacking off 1/4 or so of valve guide over it`s 2 inches of length is not going to cause upper valve stem seals to spontaniously explode and cause loss of compression...

 

Cannibus is legal here tomorrow... you need to move up here,,i`ll take you to get some.... and potato chips too of course..

 

NOW.over reving it...with possible weak springs...and the top valve spring keeper punching the valve seal.beating it to death..that

 could be a "what if"  ..wonder if the cam is high lift..wonder if that valve is bent... hummmmmmmmmmm

 

 

 

 

 

 

 

 

 

lol

 

B

Edited by brianhare
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19 hours ago, WILLY THE WORT said:

There is TONS of information on how to service a Honda 4stroke on the internet, including step by step instructions and desriptions. The factory SERVICE manual is the best there is.  

Of course there is. But I was refering to the pictures in this post. Just beacuse one read how it should be done it doesn't mean you automatically understand what is wrong in this case and in further on what caused it. I understand if it's to basic for the experts, but I had to ask.

Edited by Viktor.J
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Try wire brushing the exhaust side, re-seat the valves (in the sides they came out of!!!) Use a flash light and see if you can spot light leaking through, if you see any then the seat and or valve is damaged and needs to be replaced / recut. While You have the valves out, check them to make sure they're not bent.

Also, what's the condition of the head gasket???

 

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