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does this sond like bad fuel?

Old 06-21-2006, 10:53 PM
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does this sound like bad fuel or something else?

hey

heres the prob, wot leaves the motor stumbling below 5k and even above that its not real sharp. been fine uptill a week ago first noticed after a tank of cheap reg fuel. have been playing w/ pilot screws but all back to normal and synced no change.

so in 6th at 70ks (15x43 gearing) open full from 2.5k its at its worst at 3.5 really struggleing and then sweetens out by 4.5-5k and pulls hard from there, if i snap open full from 6k it still doenst feel great but relatively fine.

I have unifilter set up w/ only thin coat of filter oil, open staintunes, tps at 850 ohms at idle, and 35k on the clock. pilots at 2.5 turns out all else standard.

I have already added 100mm of metho and then drained each carbie from the drain scew at the bottom, no change. using 95 oct fuel again , maybe better but prob not.

Any suggestions would be appreciated!

cheers
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Old 06-22-2006, 08:17 PM
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When was the last time she had good power all the way through? What has been done since then? Just gas? If so, then that's probably your culprit.
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Old 06-23-2006, 05:23 AM
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Yeah just before that tank but...I had just synched the carbs added a speedo corrector into the uderseat wiring and reset the pilot screws...so maybe not just the fuel. I have had the suggestion to (when it stops raining ) recheck the wiring under the seat as if I had pulled out things say like the side stand wiring then it can cause a similar type prob...
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Old 06-23-2006, 04:17 PM
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What did you set the pilot screws to?
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Old 06-23-2006, 06:35 PM
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I have had pilots at 2.25 out for a while then recently gone o 2.5 out, this week tyring to rec the problem rode on 2 out then 3 out then 4 out no change at all to the wot prob.
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Old 06-23-2006, 08:21 PM
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ok, suns out so i have taken off the tank and pulled apart the petock, the diaphram is fine, gave it a clean, emptied tank, nothing abnormal found. while the tank was off, bled all the fuel out of the carbs from the bottom drain screw, sprayed some carb cleaner in all holes for good luck and went for a ride to get a new tank of fuel...no change. maybe worse. splutteres loudly till 5k under full throttle and is rougher above 5k than normal. the side stand in in the sytem cause the bike wont start untill it goes up if in 1st...what next?
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Old 06-24-2006, 05:14 PM
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Check your vacuum slides. Usually the problem with WOT is your slides aren't moving at the right speed. If you haven't done this already, spray them with the teflon spray or whatever you prefer to get them unstuck if that's the culprit. There is an additive you can put in your tank to counteract bad gas (gas additive I believe - $1.99) can't hurt.

Do you feel your mixture is off on the lean side or the rich side? i.e. are you backfiring or does it feel starved for air? Is your PAIR system backfiring a lot upon deceleration?

LT
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Old 06-24-2006, 06:13 PM
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Yeah, ihave played with pilot jets and gone way rich to way lean and it makes no difference, taking the vacumn tube off the fuel petock makes no difference to the wot prob, just makes the idle run higher??? going to pull down carbs today.
She idles fine and no popping on decel, i dont have pair system cause its a 99 aussie version...carb sync is good...the diaphram in the tank is working fine...it think its just time to clean some crap from the bowls or reset them or just do a flush out. will repost tonight, thanks for your help people.
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Old 06-25-2006, 04:19 AM
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Angry

Ok, six lads in a shed ( 3 of which bike racers & mechs ) for 6 hours:

1 carbs cleaned & rebuilt (had water & gunk in bowls especially the rear one)
2 ignition timing checked, ok
3 tps checked, ok
4 petock rebuilt, ok
5 spark checked ( just ask one of the boys if the rear cyclinder gets much spark!!!), ok
6 vacumn tube for petock checked, ok
7 no air leaks

still no change apart from it running heaps smoother in general, at low rpm w/ high load the motor makes no power w/ open throttle between 2.5k and 4.5 k and just bogs completely and bucks.

the spark plugs showed heaps of soot around the edge of the outside and burned white on the electrode and centre. the rear was worse than the front, i am pretty sure this is related to the prob as 6 weeks ago when i did plugs they were spot on a light brown colour.

can anyone suggest things to check tommorrow, I am stumped and have run out of beer for the mechanics!!

Cheers
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Old 06-25-2006, 11:55 PM
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1) Your CPU may be damaged.
2) I was referring to the black plastic vacuum actuated slides at the top of your carbs, not the vac line at the tank.
3) Make sure the vacuum port at the front cylinder is sealed. This port is the same as the one that feeds the petcock from the rear cylinder, except the front one is blocked off. Perhaps you missed this when you synched the carbs?

It sounds like your power curve is way off if you have lost that much torque through such a broad part of your power band. If spark is ok, and fuel delivery is ok, something must be wrong with the air intake. Either that or your situation may be mis-diagnosed and the module controlling the spark is not responding correctly or a fuel/air line is improperly attached.

When your power curve gets this far off, you really have to get back to basics and really nail down everything to "perfect" not just "ok". Just because you have spark doesn't mean it's spot on. I'm not tryin' to sound like an ******* here, just tellin' ya what I'd do.

LT
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Old 06-26-2006, 01:24 AM
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Smile

Mate if your an *******, I'd love to meet Santa Claus! Thanks for you help, we are also a bit worried about the module and are planning to get a used one to swap it already and go from there.

The slides seemed perfect, pretty clean and smooth, choke is working both on and turning off, front cylinder vacumn seal is perfect,

Because its such a huge loss of power not just a flat spot, and fuel deliver is there, we are thinking electrical but what can have this sort of effect, idle is perfect, reves hard to redline above 5k but will not make power at 2.5-5k or so when throttle is wide open, its the same hot, cold, with choke, without, air filter in or out ( note to everybody-remove airfilter in is not an mod! ).

I must have damaged some electrical bit, but it seems a foreign task to diagnose an electrical prob at the moment..have reposted. Cheers for you time, cant wait to post the fix ( even if it is an embarrassment ).
Ian
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Old 06-29-2006, 02:42 AM
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HI All
Fixed after another carbie pull apart and go over everything again with carb cleaner and comp air...who knows what it was. Pulls like an animal from 4.5k now.
Cheers
Ian
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