Z80, Flat spot at top rev's

I have put the larger #76 jet in and have pulled the gutts out of the muffler. Now that the run in period is up I opened her up today and noticed that it was pulling hard then a high revs appeared to be starving for full as it flatted out. Whats the best way to fix this? What about bending up the 2 tynes on the carb float to raise the float level?


Steve

hey cycpro, I don't recommend bending anything, if you just move the "c" clip on the needle to the #1 notch setting. (the 1st slot from the flat end) you'll see a major decrease of wot fluttering,.,.good luck

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Nothing runs like a deere

IMHO you are running too rich. The stock jet is typically too rich at WOT. What does your plug look like after a hard, hot run?

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As I am new to this stuff, what is WOT? The plug is always pretty dark and oily but I have only just started riding it hard/fast. I did move the circlip down one notch on the needle, thus lifting the needle up higher (I guess) I will give that a go after this bloody rain stops but I fear this will make it richer and maybe thats my problem as I have installed a larger jet (0.76mm)
So go leaner you reckon? That would be lifting the circlip up to the highest position, thus pushing the needle down lower?

Steve

WOT = wide open throttle. (Some guys say WFO. Wide flat out, Wicked ****ing Open, etc)

Plug seems too rich.

Your issue is at near or full throttle, you write
The needle is just for off idle and up to WFO control, but if the jet is too large, too much fuel is blowing in - regardless of the needle setting. Yes even the factory setting is rich, so going with a larger jet will cause WOT bog.

I have a fairly modded engine. I run a .65 main jet, ran great at WOT until I got a slantplug head - now it's too rich again. May go .62...........

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By the way, what size jet is std? in metric!

0.70mm (I've even measured it)

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I can't wait for my walbro carb to come in! I spent to days calling around on the phone vi the INTERNET. I do believe I found the right one. When I get it up I will post results!Theres is nothing cooler than re jetting my carb just by turning a screw. Last but coolest high low Idle circuit Just to cool!!

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One can do anything you set there mind to.... Do a good thing...

OK I had a go with the clip in the 3rd spot down from the top and it was too rich, so I moved the clip up to the top spot (pushing the needle further down) and its better. Also I am running the hotter NGK B??5?? plug in lieu of the b??6?? plug. I had it set at 0.80mm and I have closed the gap up to 0.60mm and its a lot smoother. I also changed to the same plug but the one with the longer electrode and it made heaps of diff.
Could somene please explain what this POWER BAND is I keep reading about.
Just putting around my bike runs a little ruff but then I give it a little gas or go up a hill and the engine jumps from chugging to running really smooth and fast and the speed increases dramatically. It normally kicks in at about 25km's and max's out at about 35kms, thats with the 44 tooth sprocket. Even under load at 18 or 20km's this apears to happen too. Is this the POWER BAND?

I agree with Pablo... A smaller jet should fix the problem!

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