Why did my top end go?

[Upbasher]

Too lean right

 

[Fast6hand]

Result of plug chop

I would step it up on the main one size. Looks a little lean. It's almost there.

 

[Herpderplol]

How long were you on WOT ? Did you press on the rear brakes at all?

To me it looks like you may not have held it at WOT long. But when in doubt, up and go again

 

[Blaaster]

Go up at least 2 sizes on the main!

 

[jus_me]

Looks just a smidge lean, go up 2 and see how it goes. You are real close though. Good job..

You may only need the next size up but go 2 and see where you are..

 

[Upbasher]

I held it wide open for 12 seconds. I dont have a bigger jet so Ill probably just put the airbox lid back on amd try again

 

[Upbasher]

Would moving the needle up one notch do the same thing as putting a bigger jet?

 

[MURPH]

No it will richen the 1/4 to 3/4 throttle range the main jet mainly does 3/4 to full

 

[rich1]

Just remember that too RICH does not sieze an engine ..but too LEAN will. ALWAYS start rich, plugs are cheap!

 

[Upbasher]

Alright I got it so it rich sputters just a little bit at 3/4 to full throttle. I dont wanna rebuild it aghain so Im leaving it right where its at. I dont mind replacing plugs

 

[dirtysquared]

Keep it a jet rich. It's just good added insurance.

 

[Blaaster]

Alright I got it so it rich sputters just a little bit at 3/4 to full throttle. I dont wanna rebuild it aghain so Im leaving it right where its at. I dont mind replacing plugs

I guess that you have done a plug chop to confirm that rich sputter.

A lean mix can too produce a stutter when on the main jet.

Does that stutter sound like a plug breaking down?

 

[Upbasher]

I guess that you have done a plug chop to confirm that rich sputter.

A lean mix can too produce a stutter when on the main jet.

Does that stutter sound like a plug breaking down?

Yeah its for sure rich. The airbox lid apparently makes a HUGE difference from what I have found out here.
And no on the plug breaking down it just sounds like its getting a bit too much fuel, kinda like a gurgling

 

[Upbasher]

It was too lean with the lid off and a 300 so I went down to a 280 and put the lid back on.

 

[Herpderplol]

Do a plug chop on both and see whats better

 

[Larry's Shee]

So you were lean with 300 and lid off? Nothing bigger? 310-320?
When jetted correctly you'll make more power with lid off.