high end acceleration

[bdcastrantas]

So i've been tackling this one for two seasons now.

Around 9K with WOT, my bike chokes up, lurching and hesitating through the power band.

I'm riding a 2004 600, which is stock except for a DandD slip on. I've attempted the following things:

Valve adjustment
Carb sync and tune (2.25 turns)
Checked for vacuum leak
Changed the inline fuel filter
new plugs
new coils

No luck solving the problem there so i took off and cleaned the carbs. I wasn't sure how to set the floats at the time so i left them alone.

After that didn't solve the issue, I removed the inline filter and played with the idle screws. I tried 2.25, 2.5, and 2.75 turns and the same thing happens at the same 9K RPM. I can't find a vacuum leak. I've checked all hoses, end caps, vacuum caps, the air box, and velocity stacks. I've sprayed carb cleaner all over and don't notice any jumps in the rpms.

Thinking it might be something I didn't clean or adjust properly in the carbs, but wanted some advice. I haven't been syncing the carbs each time I changed the mix because I'm just trying to diagnose. Any ideas??

Also, anyway to get rid of the gurgle on decel. from the DandD?

[Newbie2it]

9k to WOT is purely main jet, However some things could be going on. You could be starving for fuel. Wrong main jet size or lack of fuel deliverance at high RPMs.

Are you sure its stock? Decel pops usually a lean condition.

Did you buy the bike new? Not so sure on what information your giving thus far. A slip-on wont cause major changes in a motor. Its why I ask if you are the original owner.

BTW, a synch now and then wouldn't hurt. Will help keep you on a semi-even keel while trying to trouble shoot.

[bdcastrantas]

I bought it used two years ago and it had this problem then (prior to the slip-on).


I'm fairly confident that it's stock due to the fact that i had to drill out the EPA caps. I figured that if it was re-jetted then whoever installed it would have tuned it. Perhaps this assumption is incorrect though.

The pops are a separate irritation. It seems to pop less at 2.5 and 2.75 turns, but since I'm under the impression that it's stock, I thought 2.75 would be too far out.

[Newbie2it]

Float height adjustment isnt hard to do. turn the carbs upside down and measure from where the bowl gasket meets the carb body up to the top of the float thats sticking up in the air.

What color are your spark plugs?

[bdcastrantas]

OK i'll try that next time I get time to take them off.

The plugs are good, brownish gray color.

Any other possible culprits? I'll check the jets as well too, but i'm not sure what i'm looking for. Just want to got an idea of where your head is going on this one.

[Mat0302]

maybe it's the D&D pipe. new pipes make the bike run lean, maybe it's too lean above 9k. try rejetting, i recommend Ivans or Factory Pro kit

[The CyberPoet]

Needs either:
(A) a jetkit (best solution); OR
(B) at least a half-shim washer under each OEM needle; OR
(C) The removal of the D&D pipe.

Cheers,
=-= The CyberPoet

[bdcastrantas]

But the problem existed PRIOR to the D&D pipe.

[The CyberPoet]

Then the jetting on the carbs is off; could be as simple as dried fuel build-up at the main jets (fuel system cleaner would take care of that), or a minor vacuum leak.

Which air filter are you using (OEM, K&N, UniFoam, etc?).

Cheers,
=-= The CyberPoet

[arsenic]

don't say K&N, don't say K&N, I can hear it now, well I'll be the one saying it but still.

[bdcastrantas]

The filter is OEM and the carbs have been completely taken apart and cleaned with no improvement or change in performance.

I haven't been able to find a vacuum leak at any of the locations mentioned in my original post. Is there anywhere else i should be checking?

[The CyberPoet]

Then next obvious step is to throw the bike on a dyno with an exhaust sniffer and see what she actually reads in the bad zone in terms of fuel-air mixtures. For some reason, she's not fueling (or breathing) right at those RPM's -- 9200 RPM should be golden, although power does start to drop off fairly rapidly above there...
Note that if you have a California model for some reason, and it ran too lean, it could have melted the substrate on the catalytic converter and it could be blocking up the exhaust partially I thought the catalytic converter didn't arrive in the Cali models until 05...

Weird thought: have you checked the inside of your exhaust headers to see just how bad the weld-seams are? Doubt it's at fault, but just might play into it... CyberPoet's "How to grind out your exhaust header weld seams"

Cheers,
=-= The CyberPoet

[bdcastrantas]

I rejetted with an ivans kit and i'm still having the same problem. I'll check the header welds when I get a chance. I'm really leaning towards this being a vacuum leak but i can't find it anywhere. sometimes it seems like carb cleaner bumps up the idle a little, but i can't seem to isolate a location, and the bouncy idle makes it tough as well

[arsenic]

if the idle is bouncy, I would agree it's probably a vacuum leak. But, what do I know

[Cheriff]

What's the best fluid for spraying around the engine to check for a vacuum leak? I've heard WD-40, starter fluid, ect. Anything more preferred?