Flat spot at about 4500 rpm.

[Bill Seward]

Well, the replacement fuel lines seemed to cure the occasional carb leaking on my '85. Been at least 1000 miles with no problems. Bike starts instantly, and runs strong. Yesterday we were out for a ride, and were on a long stretch of divided highway. Cruising between 70-80 mph. At this speed the VMax barely has the throttle open from idle, and I was getting the occasional flat spot, where it seemed the bike was just barely slowing instead of holding speed.
This was the first time I noticed this - the ride to Thunder was perfect..

Giving a bit of throttle made the bike accellerate strongly, with no misfire. At 60 mph, no flat spots...

At the light throttle opening needed to hold 75 mph, any ideas about the flat spot? I'm thinking it may need a bit more idle mixture screw. I'm about 2.5 turns out - maybe give it another 1/4 turn out?

 

[Coffinator]

If you run a stage 7 kit, insert the DJ190 PAJ2. Had the same problems, solved it for me..

 

[naughtyG]

My '86 had that problem, lil' shims under the needles clips solved it. Easy to do too - no need to remove the carbs, just pull out the slide, unclip needles, add washer, put it all back in.

From memory the shim thickness was .04" but don't quote me on it

 

[Bill Seward]

G: I'll try that. The problem is very minor, and intermittent, probably not worth the trouble, as I don't spend a lot of time droning along a freeway at 75 mph.

It's been so long since I've been in the carbs, I forgot that there weren't alternate slots to put the clip in to raise the needles... .004 probable is all I'd need. What did yopu make the shims out of?

Coffinator: Carbs are stone stock. Stage 7 is only a dream at this point! but thank you for the advice!

 

[naughtyG]

I think you just go to your closest hardware store and grab some thin washers of the appropriate diameter. 0.04 might even be a bit too thick, it might have been 0.4mm which was 0.025"

 

[Diablotin]

I developped the same issue at 2.5 turns. As 2.75 turns it gets better and completely disappeared at 3 turns.
I'm still checking my new plugs at 2.5, if they are good I will probably shim the needles instead of putting 3 turns.

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