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DR-Z "hesitation" in top gear at about 78mph

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Hi all.

 

I'm pretty new here. Been riding quite awhile but not particularly savvy with diagnostics -or wrenching for that matter. Gradually improving as garage time and patience allows.

 

I recently purchased an '04 DR-Z S model with about 10K miles on it and have added close to another 1k in the last 6 weeks.

 

I've noticed that while the bike starts, runs and idles perfectly across all gears and RPMs it has a very noticeable "hesitation" or intermittent pulling in 5th gear starting at just about 78mph. Near as I can figure that's around 7500 rpm (and that is a guess because there is no tach). This is always when I'm holding steady on the highway.

 

The previous owner said the bike was totally clean, including carbs, had been running great and he kept up with all regular service intervals plus some professional re-jetting. The sprockets and exhaust remain stock.

 

The only conclusions I came to on my own were potentially clogged fuel line or a slightly fouled or loose plug. Haven't checked either yet. I also thought about the possibility that the bike is hitting the rev limiter but that seems preposterous as the revs really don't seem that high. I'll be changing the oil/filter this week too but don't expect that will make a difference unless the plug was getting fouled.

 

Thanks for your contributions.

 

Evan

 

 

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Keep it @ 77mph and you wont have an issue. :rolleyes:

What is your gearing? Are you sure it's not the rev limiter?

Gearing calculator here, http://www.thumpertalk.com/topic/569080-calculate-speed-based-on-gearing-changes/

Could be that the float is too low and is starving for fuel, or there is some contaminate obstructing the needle tube @ WOT.

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better or worse with air box side cover removed...?

 

So it's had some good old professional re jetting....we will see...

Edited by Craigo 485sm
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better or worse with air box side cover removed...?

So it's had some good old professional re jetting....we will see...

"professional"

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"professional"

 

ya, that's the first thing i suspected too

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Does it rev out in a different gear without issue?  My suspicions are the same as everyone else's, a jetting issue.  Maybe the main jet has some debris in it.  Keep in mind too that the stock carb doesn't really work well in the high RPM range.  Only the FCR will allow you to tap into the power in that part of the rev range.

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