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Discussion Starter #1
I have a long, long, long history of breaking things that everyone says are unbreakable [computer biz, personal life, motorcycles... you name it]

so, my k4 dl650 has always been good, but not great... since the beginning with zero miles it has run a little off of 'purrrrfect', lower mpg than most, lower top speed.

so, after delaying a long time I take it to my trusted mechanic [grew up in the harley world, but lotsa metric race-bike experience, full machine shop, you get the picture]... I had an accumulated list of changes I wanted done, and a TBS, leave the tubes in place.

I get it home and not 15 seconds after firing it up i knew something was amiss. it didn't idle right... very rough. for the first time the handlebars are waving in the air on idle. I let it warm up completely, rode around a bit.... if i put the gas to 'er its ok, not terrible, but the roughness is there no matter what. THEN, the most telling symptom... I noticed that the idle was very lumpy, so i twisted the idle screw to bring a constant 3,000rpm drone. The bike cannot hold a steady RPM.... it moves around on its own. This is fully warmed up. It can't maintain 3K, it moves to 3300 or so, then undershoots to 2800 then back to center, then oscillates again. its struggling to overcome something amiss. ALSO, MUY IMPORTANTE: when I listen carefully to the exhaust sounds during this mess, i hear a faint 'cough' every four or five seconds ... its like "drone drone drone <bump> drone drone <bump> drone-drone-drone-drone <whumpppp>

get it?

any clues????? HELP!

z
 

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Hey Zapp are you sure you didn't get one of those "Litre" bikes by mistake?

Just kidding.....Wish I had some answers for you but my 6Fiddy is the "takes a lickin and keeps on tickin" version.
 

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I'm not sure what all your wrenching buddy did but there are several thing involved in a TBS that could cause your symptoms.

-- The TBs are way out of S.
-- One of the multitude of sensors hooked up to the airbox could be tweaked.
-- There is a vacuum leak on one of the tubes (they are plugged, aren't they?)
-- The airbox isn't properly seated on the intakes.
-- Some bit of crud found its way into the TB.

In any case, it sounds quite a bit like a fuel/air mixture problem. Most of my experience is with carbs, though, so there may be some FI mysteries that I'm not aware of.

I would take it back and have it straightened out. If things are seriously amiss, you could end up with some more interesting problems.
 

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I would take the bike back to him and tell him to UNDO everything he did. Clearly he's screwed it up quite nicely. Didn't do this before he put his hands on it right?
 

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Discussion Starter #5
well, i'm hoping its something simple. he says he didn't mess with the airbox, was able to get to the nipples without that.

I haven't done that particular job [obviously]: is there any way you could bump loose a TB boot in the process of peeling away all that tupperware and replacing it? it does sound like an airleak to me..... funny i'm going through the same trauma with my DRZ.... flaky idle. runs fine wide open but will not steady idle. there's a crack in a vaccuum hose/tube i think

z
 

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If he didn't take the airbox off, I would assume, but not guarantee, that the sensors and TB boots are intact. I would start with the tubes and make sure they're plugged and securely sealed on the nipples.

Actually, I would take the bike back to the guy and have him make it right.

Afterward, since he left the tubes on the TBs, you can do the job pretty easily yourself with a home-made $5 manometer.
 

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Discussion Starter #7
well it appears things are not as simple as seemed. I now think my wrench did everything I ASKED him to just right. he simply synced the throttles and that's it. there's a deeper issue i'm sure. there's got to be an airleak somewhere and I just gotta find it.

getting the tps spot-on just aggravated things. makes sense. fix everything else, then do tbs/tvs and tps together. otherwise, the EFI will merely compensate for your tweaking of the tbs, and it will appear 'out' once again. air leak on one side means the two are going to pull non-linear vaccuum as rpm's intensify

today, for the first time ['cause its naked and the tanks way up] i heard it backfire into the airbox. not cool. made me jump. I plan to pull the airbox now and really take a long hard look at the throttle bodies. my theory is this goes all the way back to my crash, when I hit the pavement that hard on the left something may have jarred sideways.

if you guys got any clues as to what to look for, pass it on.
z
 

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In any case of backfire, check the inside of the air filter. I once fixed the cause of a backfire but still couldn't get a bike to run right. It turns out the backfire charred the air filter and the engine couldn't get enoigh air.
 

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Discussion Starter #9
well call me stooopid. i found the cause of the backfire, at least. not the cause of the other problems cause I created thisone myself, like 48 hours ago.

i did not realize that replacement a/F come without the rubber gasket! no wonder the intake sounded a little funny.

the A/F was ok... no charring

now, back to the original problem

z
 
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