Jetting question

[azr]

Hey all. I was helping Eddie21 with his 79' 1000S. Rebuilt the carbs and did a valve shim job with a synch. His bike is stock as far as he knows other than it being honed out to 1.0 over, again as far as he knows. The strange thing that I found while doing the carb clean was 120 main jets and the fuel screws were out 3 turns and the air screw about the same. The bike wasn't ridding horribly before, not perfect but not horribly. Anyone have any idea why there would be 120's and screws out so far, is that normal for 1.0 over? The bikes running ok right now, screws are at about 1 each, but there's still some things to do before it can be said there is a problem. Any info on the set up would be appreciated.

[Steve]

Wow!!! Stock jetting is 95.

No pods? No pipe? No need for larger jets.

On a stock bike, general suggestion is to have fuel screw about 3/4 turn out, the air screw about double that, then fine-tune it from there with the air screw.
Having 120 mains and three turns out on the fuel screw is HORRIBLY rich.

What do the plugs look like? Unless they are hotter plugs (B7ES), they should be solid black with that jetting.

.

[Agemax]

yep, unless the bike previously had pods and a pipe, or the carbs were fitted from another bike (which had pods and a pipe) those are radical settings for a stock set up. you shouldn't need to alter anything for a 1mm oversize bore.

[azr]

Thanks for the input guys, it wasn't making sense to me either. Funny thing is his plugs never looked that bad, a little dark but not fouled up by no means, and the bike ran ok, just didn't have the throttle response it should, especially at low RPM. I just wasn't sure if adjustments had to be made because of the oversized bore. Guess we'll be pulling those carbs off again and swapping the jets back to stock. Thanks for the help.

[chuck hahn]

What size are the pilots? As said by the others. You should be ok with the stock defaults of pilots at 7/8 to 1 out and mixture screws out at 2 as the base point.

If the valves are within specs and the timing is set right, all you should have to do is out your color tune in and dial the flames in.

I say 7/8 to 1 on the pilots because my experience with my 1000s is that 3/4 is on the very edge of being TOO lean. 7/8 to 1 will not be too lean because you can fine tune that away with the mixture screws and your colortune.

[azr]

The pilots are stock. It just really threw me to see 120's and both mixture screws out to 3 turns. I thought "ok, either something has been done to the engine or the PO was a ding-bat"...I'm starting to think 'ding-bat'. Maybe this also explains the burnt airbox we found. We'll just throw some 95's in and set it all up to stock and see what happens.

[chuck hahn]

I vote ding bat too....

[chuck hahn]

Was falling on its face because there is just no way that much fuel could be efficiently ignited.

[azr]

Ok, put the stock 95 mains back in with no improvement but have found some air leaks so will fix those first before trying to carry on. So you guys are certain that no jetting changes are needed for a 1.0 overbore?

[azr]

Any thoughts?

[tkent02]

Yes, it won't matter.

[azr]

The plot thickens. I pulled his carbs again, and measured. Turns out his carbs have been bored out to 28mm, guess that's why the big jets are there. Everything's back together and he's going to get the air leaks fixed and we'll go back at trying to set up the carbs. Thanks for the help everyone.