First plug chop after carb rebuild and adjustment

Don't get me wrong, I appreciate all the information but why would the bike run ok before the carb rebuild and have this hiccup afterwards? Is it because I fixed all the vacuum leaks? Thus changing The AF ratio

[hillsy]

Lift the needles a notch and see what happens. You're in the needle / main jet territory at that rev range (probably more the main jet).

It's the 1980 gs1000, the jetting was increased by the PO I don't know if he changed needle height or not, before I cleaned and rebuilt everything it would pull as far as I wanted to rev it with the larger jets. I guess I need a Morgan car tune and to vacuum sync these bad boys

Turning the mixture screws in will lean things, so you could try a 1/4 turn on each. But really you should vacuum synch the carbs first before you start playing around with things. I guess the first questions should be, what bike are we working with here? since you've already done a nice clean up on the carbs and will be vacuum synching why don't you check your valves while you're at it. As for the jets, I'm not sure what your bike has from stock as I'm not sure what bike we're talking about but if you have the stock exhaust and the only change is a K&N filter to replace the stock one I'm pretty sure you should be using stock jets. If someone has been replacing jets and such I wonder if they played around with your needle height? have you checked. There can be a few reasons for a stumble at 8'000, main jet, needle height and maybe a couple of others but if it were my bike I'd get the carbs back to stock with that setup, check my valves, vacuum synch the carbs and then take it for a ride and see what she feels like.

Does it hit the wall then recover as the revs go higher or is it like that all the way past 8k?

Ir seems to hit the wall then recover

[hillsy]

Does it hit the wall then recover as the revs go higher or is it like that all the way past 8k?

But it's Saturday night doesn't everyone hang around a website for 30ish year old bikes?!?!?!

I'm sure someone more knowledgeable than me will come along to give you some advice. Hang loose...

So??? Back to the drawing board?

Agreed - but it will have no effect at 8k.....

true........

[hillsy]

You'd be amazed at the difference a good vacuum sync makes.

Agreed - but it will have no effect at 8k.....

I did not vacuum sync yet, after all the parts I bought I had to let the ole budget recoup before I purchase a sync tool, When I took them apart I never messed with the sync screws but checked with with a bench sync method and didn't see anything that warranted adjustment

You'd be amazed at the difference a good vacuum sync makes.

I did not vacuum sync yet, after all the parts I bought I had to let the ole budget recoup before I purchase a sync tool, When I took them apart I never messed with the sync screws but checked with with a bench sync method and didn't see anything that warranted adjustment

I didn't see where you have vacuum synched the carbs. Have you? That may help with the high-RPM stumble. The plugs don't look bad at all to me. Maybe a touch rich, but that's better than lean.

Got it all cleaned up and back together it's hard to tell but the pipes were golden and now it has slowly went away