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writing_to_chris · ‎03-13-2006

Hi, I've got a 1992 Yamaha XJ600 Seca II/Diversion. It had some trouble starting this morning (even trying to push start it), and when I did get it started I had to keep the throttle open so the engine wouldn't cut out. When I started riding, I noticed that there was really low power and acceleration, the engine noise was a weird rumbling sound instead of normal, and one of the exhaust pipes was blowing out hot air and became very hot to the touch after a short ride. Any ideas? Could it be a flooded engine?

bazango · ‎03-13-2006

Lean lean lean. IMHO

bazango · ‎03-13-2006

I think that rich enough to cause these symptoms would make your eyes water and you'd see smoke. But I defer to the more knowleadgable folks who will soon join in.

91xv920rh · ‎03-13-2006

Hot pipe is may be lean.

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Being intentionally vague and repeating Parrot Points adds little to nothing to the discussion.

bazango · ‎03-13-2006

Hot pipe is may be lean.

91xv, when did you become asian? :^O

91xv920rh · ‎03-13-2006

Too much Yamaha. I go now........

“All opinions are not equal. Some are a very great deal more robust, sophisticated and well supported in logic and argument than others.”
-Douglas Adams

“Everyone is entitled to his own opinions, but not his own facts.”
- Senator Daniel Patrick Moynihan

Being intentionally vague and repeating Parrot Points adds little to nothing to the discussion.

writing_to_chris · ‎03-14-2006

Um...what exactly is lean? It sounds and feels like it's not running on all four cylinders perhaps.

dodogas · ‎03-14-2006

Lean is a lower than ideal fuel/air mix.

If it was a higher than usual fuelto air it would be a rich mixture.

Shiny black sooty exhaust residue in pipe end is rich, whitish gray would be leaner.

bazango · ‎03-14-2006

Fuel flow problems, leaking boot between carb and head, clogged jets, etc. cause a lean mix. Actually, on rereading your OP, other thoughts come to mind. Was the bike sitting prior to this? If it just happened suddenly, It could be a bad exhaust valve.

trident_t150 · ‎03-14-2006

What ever the cause, Chris, a lean engine condition can take out a piston really quick. You need to get this checked out right away, before riding again.

writing_to_chris · ‎03-14-2006

Thanks for all the great info. I'm thinking though...could it just be fouled plugs? I am a newbie to riding and for the first few months was starting the bike with the choke out and giving it throttle, which may have flooded the engine and fouled the spark plugs. Before I take it to the shop, I'd like to try and replace them myself. I do have a manual, but the info is very limited on how to do this (though I know it's probably real easy for some of you guys). I don't even know how many plugs there are or what tools to use, do I need a specific spark plug socket or can I use a regular hex 16mm wrench? I see where you unscrew the cap...are there multiple plugs in there?

bazango · ‎03-14-2006

Um... aren't the plugs under rubber boots with wires running to them, about the middle of the cylinder? One plug per cylinder. Separate, on top of each cylinder.

The running symptoms you describe could sure be a fouled plug or plugs. The "hot" pipe in that case would only be hot in comparison to the one that is cool because it's only got one cylinder feeding it. I mean, they are normally pretty hot, right? Hard to know from your description.

Definitely couldn't hurt to replace plugs. What you need to be careful of, though, is that you don't do damage by getting in over your head. The two greatest worries are that you might get a plug cross-threaded (very easy to do) or that you might overtighten and strip a plug (heavy-handed shade-tree mechanics often do).

What you want to do, on installing new plugs, is to put a bit of anti-sieze lubricant or even teflon lube on the threads, being careful that it is only on the threads and won't end up inside the cylinder. Then run the plug in by hand several revolutions. If it won't start by hand, you are cross-threading it, and putting a wrench on it will end your fun until after an expensive repair bill.

Hope that helps.

bazango · ‎03-14-2006

Oh... and then you take your spark plug socket and run it down the rest of the way. When it gets to the end, you just want to crush the little metal gasket. 15 ft-lbs, if I remember right. So find something that weighs 15 lbs and lift it. Now apply that same force to the end of a 1-ft. wrench. A torque wrench is nice, but it can be done by hand with adequate accuracy (don't tell my A/P instructor I said that).

trident_t150 · ‎03-14-2006

It appears from your posts that you have very limited knowlege of engines. You can do a lot of damage in a hurry if you don't know what you are doing, but we all learned from experience.

I would check your local community education and see if there is a class on basic engine maintainance, which should include how to read plugs and pipes, oil changing, spark plug replacement, simple carb tuning (such as on a lawn mower). It's a place to start.

Then get a shop manual for your bike - the manuals that come with a cycle, as you found out, are very limited in scope. You can probably find one here on ebay.

A fouled plug would give you a cold pipe, not a hot one.