919 is feeling a little sluggish - Wrist Twisters
 
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post #1 of 9 Old 10-12-2008, 10:57 AM Thread Starter
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919 is feeling a little sluggish

After my my 1500 mile trek throught the Ozarks my bike seems to be feeling a little sluggish. Maybe I just got used to the power but I don't think so. I noticed that it was backfiring a little more than usual when I closed the throttle on the highway, any thoughts on what could be wrong? I remember reading something about raw fule coming through a vacuum line to foul one or more plugs, I haven't checked but could this be a possible cause? My bike is an 02 with just under 7000 miles on it.

Is there an easy way to check than pulling out the plugs? I guess the only way to do this is to lift the tank?

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post #2 of 9 Old 10-12-2008, 11:03 AM
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I just turned 8k and noticed a bit more backfiring...also not starting on the first go around. Wondering if that's the same issue?

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post #3 of 9 Old 10-12-2008, 12:28 PM
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I am at 24,658 miles and do not feel like I have lost any power. Try checking your plugs. It is always easier to check the basic things first. I put in the high output plugs in mine about 6k miles ago and the seem to be better, but original plugs still have life left.

'04 919---40k----6/18/10 SOLD

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post #4 of 9 Old 10-12-2008, 01:54 PM Thread Starter
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Well if I'm going to take them out I might as well replace them. What high output plugs are you running?

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post #5 of 9 Old 10-12-2008, 02:24 PM
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the iridium ones are supposed to be the best.. but you have to remortgage to afford them



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post #6 of 9 Old 10-12-2008, 03:03 PM
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Quote:
Originally Posted by barton664 View Post
the iridium ones are supposed to be the best.. but you have to remortgage to afford them
I got some iridiums from here...$7.83 ea...shipping kinda sucked if I remember, but the dealer wanted $11 each for the regular plugs.

http://www.sparkplugs.com/results_ap...=225208&mfid=1

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post #7 of 9 Old 10-12-2008, 04:11 PM
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How many tanks of fuel have you run through since the trip? I have had marginal fuel cause the symptoms you describe which cleared up a couple tanks of fuel later.

The problem you are referring to is the fuel pressure regulator diaphragm develops a miniscule leak which allows raw fuel into cylinders 2 & 3, particularly when decelerating (high vacuum). Tilt up the tank and pull the vacuum hose from the regulator. It is bolted to the fuel rail with a heavy clamped return hose on one side and a vacuum hose on the other. If you smell any fuel in this line the regulator is leaking and must be replaced.

It is unlikely the spark plugs need replacement at this low a mileage. My '02 had the original plugs in it at 48,000 miles when I replaced them, and they looked good enough to put back in.

Rob

If it has already been done, it is safe to assume it is possible to do it.
On the other hand, if it has not been done never assume it is impossible to do it.
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post #8 of 9 Old 10-12-2008, 05:33 PM Thread Starter
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Quote:
Originally Posted by robtharalson View Post
How many tanks of fuel have you run through since the trip? I have had marginal fuel cause the symptoms you describe which cleared up a couple tanks of fuel later.

The problem you are referring to is the fuel pressure regulator diaphragm develops a miniscule leak which allows raw fuel into cylinders 2 & 3, particularly when decelerating (high vacuum). Tilt up the tank and pull the vacuum hose from the regulator. It is bolted to the fuel rail with a heavy clamped return hose on one side and a vacuum hose on the other. If you smell any fuel in this line the regulator is leaking and must be replaced.

It is unlikely the spark plugs need replacement at this low a mileage. My '02 had the original plugs in it at 48,000 miles when I replaced them, and they looked good enough to put back in.

Rob
Less than one and come to think of it some of those AR mountain gas stations were a little shaddy, I probably got more water than gas. I burned through about 4 tanks on the ride home. Most of that gas came from major interstate trusck stops.

If I do have the leak and the plugs are fouled, do they need to be replaced or just cleaned?

Thanks,

JAson

I got no time for the jibba-jabba. - Mr. T
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post #9 of 9 Old 10-13-2008, 06:16 PM Thread Starter
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I had time to look at the bike today and I don't think the fuel presure regulator is leaking. I was unable to get the vaccum hose off the regulator itself but I was able to get it off the #2 and #3 cylinder and there was no fuel present that I could smell. What I did find was that the vaccum hose closest to the FPR valve was kinked. I unkinked it and the performance seems back where it should be. Of course I also took about an inch of slack out the chain and 1/4 inch of slack out of the throttle cable so I'm sure that added to it as well.

I got no time for the jibba-jabba. - Mr. T
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