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Old 05-03-2009, 08:54 PM   #1
uniter OP
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Really weird head issue on my XL600

Sorry in advance about the novel, just trying to get as many details about it in as possible.


Hi Everyone, This is my first post on this forum. I've been riding and working on off-road machines for about 7 years now.

I just bought a 1987 Honda XL600R, bone stock. When I bought it, it started up with 3 kicks when cold. I got it home and it took considerably more kicks, like in the range of 20-30 . Then the day after the only way I could get it going is by jump starting it. It had a weak spark and after reading of all the stator issues I got a Ricky Stator and put it in. Had spark, still wouldn't start. I took the carbs off, they were clean but i cleaned them anyway. Put them back on, choke on, still wouldn't start. I pulled the plug, there was a light amount of fuel on the plug (like what it should be), still sparked. I noticed some backfiring through the carbs.

I also noticed a hissing coming through the carbs when I slowly pushed through the compression stroke without the decompressor attached. I checked the valves, adjusted clearances, noticed the intake valves where tight against the rocker arm, couldn't get a .002 feeler in it, adjusted it, but it didn't fix it. I watched through the open valves covers while I cycled the engine, everything was working. I then noticed with the right intake valve cover off, I noticed no hissing through the carb so I thought I'd kick it over without the cover on to see if it started, 3 kicks and away it went! Turned it off, put the valve cover on, wouldn't start and hissed through the carbs. So now I'm thinking the valve cover is pushing on the intake valve and keeping it open when installed or whatever crazy obscure reason.

I get O-rings to put on the valve covers to give them more clearance and put them on, didn't start, took them off, didn't start. rested the right intake valve cover on the hole with the others sealed. Gave it a kick and the cover blew off from air pressure in the valve/cam compartment. Also noticed hissing coming from the valve/cam compartment. With the covers on the hissing went through the carbs and with them off it blew through the valve cover holes. All this while the engine still has ok compression at the start of the kick but if I keep putting pressure on the kickstarter the compression leaks out of it through somewhere in the head.

Now if it only leaked through the carbs, ok, burnt intake valve(s). I could see this being caused by the fact that the intake valvestems were tight against the rocker arms before I adjusted them. It also has the blasted stock lean jetting and stock exhaust, with a UNI filter. I'm thinking it's been exposed to heat. What gets me is that with the valve cover on, it hissed through the carbs and with them off, it hisses through the valve/cam area then valve cover holes.

Would this odd condition be cause by the head being cracked near the intake valve and extending into the valvetrain chamber?

This is really taking me for a ride, I just bought it a bit over a week ago and it ran fine the day I bought it and when I jumpstarted it last Saturday and rode it around for an hour and a half, it ran fine once it was started. Took it home, turned it off, tried to start it again while it was still hot, didn't go, hasn't run since except or that 3 second spurt with the valve cover off (I purposely turned it off because I didn't want it to run without a valve cover).

I any of you fine people would be able to help me it would be greatly appreciated. :)
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Old 05-04-2009, 07:25 AM   #2
uniter OP
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Does anyone have any insight to this? I just bought this bike and now this, I feel like I could cry...
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Old 05-04-2009, 07:32 AM   #3
larryboy
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Sounds like you have it figured out, but don't know it yet. You had a valve with zero clearance and you're getting compression into the valve cover. Sounds like a burnt valve/seat to me. Pull the head and check it out. Staring at it won't get it fixed, it's time to tear into it. Pick up a manual and get your hands dirty.

Good luck and let us know what you find.

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Old 05-04-2009, 07:41 AM   #4
uniter OP
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Thanks Larry, what has me is that the compression is not just leaking into the intake port, it's actually leaking into the valvetrain compartment. I thought if an intake valve was shot the compression would just leak into the intake port and that the valvetrain compartment was sealed off by the valveguide seals and such, it also never burned oil so the valve guide seals are fine. Sorry if I'm being a pain, it's just that the leaking into the valvetrain compartment has me befuddled.
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Old 05-04-2009, 07:48 AM   #5
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Have you looked into the decompression system on top of the valve cover? Maybe spray the linkage and the two cables with some lubricant of your choice and make sure that it is freed up?

I do not have much experience with motorcycle heads. All that I know is that hopefully that is not your problem .

Start cheap and work your way up to expensive.

Have you checked the intake manifold for cracks. Mine had a huge crack on the left side carb intake. I ordered a new one from eBay. I have heard that air leaks in the carb's can really make these bikes run poorly.

Good luck,
Jack

Get a factory service manual, those things are perfect. I think that I paid about $40 on eBay, a little expensive but that thing will teach you how to do anything on these bikes.

POST SOME PICS!!!
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Old 05-04-2009, 07:57 AM   #6
larryboy
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Yeah, maybe so.

Breather system in good shape?
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Old 05-04-2009, 08:14 AM   #7
uniter OP
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I've checked the decompression system. I totally disconnected the cables and saw through the exhaust valve cover how it actuated the exhaust valve and it is not touching the exhaust valve, the valve is sealed. I've had the carb off and the intake manifold is perfectly fine.

I know I'm going to have to pull the head eventually anyway, I'm just praying it's a scorched valve and not a crack. But even if it was a crack I figured it would leak into the intake OR valvetrain compartment. The only thing I can think of is burnt intake valve And cracked head, in the sense that the compression leaks out the path of least resistance. If the valvecovers are on it leaks through the intake valve and when they're off it leaks through a possible crack into the valvetrain compartment.

It's just really weird how it was running fine and that one day when I kicked it with the valvecover off and it fired up. I'm going to pull the head tomorrow I think, I just hate having to buy all new gaskets because of this. Even worse if the head's cracked, I'm going to try to avoid having to find and buy a new head and try to fix it with that thermosteel cold weld stuff, I've heard of some success with it.

Breather system as in air cleaner or crankcase?

OH that's it! The air through the valvecover would be cause by the piston motion in the crancase pushing air up to the head! I really hope it's just a scorched valve, although it wouldn't explain why I don't hear hissing though the carb with the valvecover off :(

Will post pics when it's done. While I'm doing this top end job I'm thinking I might as well put a new piston and rings in. Might as well only put new gaskets on once. I suppose I should get a pipe and jetting kit to prevent excessive heat also. This is getting expensive :(

uniter screwed with this post 05-04-2009 at 08:19 AM
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Old 05-05-2009, 12:18 AM   #8
fargodroid
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Quote:
Originally Posted by jgrady1982
27cdb6e-ae6d-11cf-96b8-444553540000" width="0" height="0">Have you looked into the decompression system on top of the valve cover? Maybe spray the linkage and the two cables with some lubricant of your choice and make sure that it is freed up?

I do not have much experience with motorcycle heads. All that I know is that hopefully that is not your problem .

Start cheap and work your way up to expensive.

Have you checked the intake manifold for cracks. Mine had a huge crack on the left side carb intake. I ordered a new one from eBay. I have heard that air leaks in the carb's can really make these bikes run poorly.

Good luck,
Jack

Get a factory service manual, those things are perfect. I think that I paid about $40 on eBay, a little expensive but that thing will teach you how to do anything on these bikes.

POST SOME PICS!!!
Good advice, been following that most of my life.
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Old 05-06-2009, 07:33 AM   #9
uniter OP
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UPDATE: After some simple tests I have found the following:

Compression is passing by the rings. I put oil in the spark plug hole and compression didn't really increase dramatically but there is definite hissing from the crankcase breather tube which blows out the valvecover if the cover is off...for obvious reasons.

Intake valves are toast. Compression is also passing by the intake valves. With the carbs off and my hand sealed over the intake ports there is pressure on my hand when pushing through the compression stroke. When feeling the valvestems with my fingers I can feel that the right intake valvestem is all corroded and rough (but why only the right?).

I'm thinking of putting a Wiseco 11:1 piston in it, Kibblewhite valves and maybe springs. I'm also thinking I should get a pipe and jetting kit. I don't even want to start this thing up without a better flowing pipe and non-lean jetting, especially with that 11:1 piston in there. So, I know I need a new piston/rings and valves/seals. While I'm in there should I put in a new valvespring kit?
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Old 05-06-2009, 06:11 PM   #10
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Quote:
Originally Posted by uniter
UPDATE: After some simple tests I have found the following:

Compression is passing by the rings. I put oil in the spark plug hole and compression didn't really increase dramatically but there is definite hissing from the crankcase breather tube which blows out the valvecover if the cover is off...for obvious reasons.

Intake valves are toast. Compression is also passing by the intake valves. With the carbs off and my hand sealed over the intake ports there is pressure on my hand when pushing through the compression stroke. When feeling the valvestems with my fingers I can feel that the right intake valvestem is all corroded and rough (but why only the right?).

I'm thinking of putting a Wiseco 11:1 piston in it, Kibblewhite valves and maybe springs. I'm also thinking I should get a pipe and jetting kit. I don't even want to start this thing up without a better flowing pipe and non-lean jetting, especially with that 11:1 piston in there. So, I know I need a new piston/rings and valves/seals. While I'm in there should I put in a new valvespring kit?
Glad you found out what your problem may be. My own opinion would be just to go ahead and do the whole deal,springs included.
Sure it is pricey and a royal PITA but in the end, it will be worth it.
Trust me, I started with a running $600 XL600 and started with broken bolts and ending up with new bolts,gaskets,studs,piston and rings.
For me, I would much rather go thru it right and have the knowledge of what is down there before putting serious miles on her
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Old 05-06-2009, 06:47 PM   #11
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It is a peculiar ritual getting an XL600R fired up. Mine needs the throttle cranked all the way open, pull the compression release and kick through a few times to clean it out. Then you need to kick it at the right spot right after TDC. Just kicking it anywhere in the stroke is only going to flood it soon enough. Try and perfect the ritual before tearing the motor apart. If you have good blue spark AND fuel, you are almost there.
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Old 05-07-2009, 06:43 AM   #12
uniter OP
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Thanks Crag. Unfortunately mine is a bit more than $600, it was more like $2000. It was totally clean, I'd say mint, it even ran fine. After I got it home is when it started giving me grief.

Clay, I really think it's the engine, more kicking, even using the proper method isn't going to help me. It's got around 60 PSI cold, I don't think that's gonna cut it. I've already got everything disconnected, all I have to do is unbolt the engine mounts and lift it out. I'll be doing that tomorrow and tearing it down on saturday.

More info to come after I tear it apart on saturday. This is my first teardown, so it's kind of exciting, I'm just angry about how much it's going to cost me. Piston kit, valves/seals/springs, machine shop work (cylinder boring, valve lapping), and pipe/jetting is going to come to over $1000.

I've read the best thing to do is to give the head with valves still in it to the machine shop and they'll do what you need, but I want to do my own work and inspection besides for lapping the seats. Is it that hard to take off valves/seals/springs and put new ones back on?
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Old 05-07-2009, 08:31 AM   #13
scrminbanshee
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lets see some pics when you tear that thing down i hope.....
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Old 05-07-2009, 01:18 PM   #14
Reposado1800
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Quote:
Originally Posted by uniter
Thanks Crag. Unfortunately mine is a bit more than $600, it was more like $2000. It was totally clean, I'd say mint, it even ran fine. After I got it home is when it started giving me grief.

Clay, I really think it's the engine, more kicking, even using the proper method isn't going to help me. It's got around 60 PSI cold, I don't think that's gonna cut it. I've already got everything disconnected, all I have to do is unbolt the engine mounts and lift it out. I'll be doing that tomorrow and tearing it down on saturday.

More info to come after I tear it apart on saturday. This is my first teardown, so it's kind of exciting, I'm just angry about how much it's going to cost me. Piston kit, valves/seals/springs, machine shop work (cylinder boring, valve lapping), and pipe/jetting is going to come to over $1000.

I've read the best thing to do is to give the head with valves still in it to the machine shop and they'll do what you need, but I want to do my own work and inspection besides for lapping the seats. Is it that hard to take off valves/seals/springs and put new ones back on?
I did mine with an automotive valve spring compressor and a socket to take up some slack.
On my bike I ended up needing a hone, rings and cam chain tensioner. I also did the valve stem seals and decarboned the valves. I also needed a new stator but that was after the motor was back in.
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Old 05-07-2009, 07:13 PM   #15
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Yeah, I was also wondering about the camchain, I know they wear out. There's no way I'm doing a bottom end job though. I didn't think the tensioner would wear out though, all it is is a curved piece of steel and a spring. I guess the spring would lose it's springyness. I guess it's another part I should replace while I'm in there....
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