Have a 96 f3 with a full exhaust and larger jets, jets are 140 142 142 140 I believe, problem is it doesn't feel like it has much power, I bought the bike with the mods so I'm not sure if any tuning was done, I have cleaned the carbs and everything is pretty immaculate. Last week I changed the filter from a k&n to a paper oem thinking the k&n was holding it back, the paper filter seemed to have helped a bit, I pulled the plugs and wanted an opinion on wether you guys think it's rich or lean or ok, next step is to fiddle with the mixture screws but if it looks lean I don't want to lean it out even more, just looking for some educated opinions as I don't know much about bikes. Thanks in advance

 

Big jets for a 600 but it depends on if it's a full flow exhaust or just stock.

The equation for big jets is high flow airfilter, high flow exhaust set up and at times
cam mods of course.

I'd say you may be over jetted if she seems sluggish, maybe bring the jets back to
130's or less.

Maybe over shimmed needles too

 

Ok, what sizes should I be going for? The exhaust is a full racing titanium exhaust so I'm assuming better flow, also noticed some black soot at the end of the can, it's having a few issues with running, seems to run strong past 9k, will have the front wheel skipping in second, but the low end is where it's having problems, I'm not expecting tons of low end power but it has nothing until about 7k then just rockets, idling is a bit strange as it will idle around 1100 to 1200 normally after about 10 minutes of warming up but if I got for a 45 minute ride and in stop and go traffic it idled around 1500 to 1600, it also rumbles on deceleration but no popping, does that plugs look ok?

 

Anyone have an opinion on the plugs?

 

From the picture, it looks a little rich. But it's kind of tough to tell. Kinda need to get a better view of the ceramics

 

What would I be looking at as a starting point for the mixture screws? I'm running a full race exhaust, and a paper filter

 

Starting point is 2.5 turns out from tight. When you tighten up, count the turns so you know what they were at. I'm curious to see.

 

I'm sure this has been asked a million times on here but is tighter leaner or richer on the screws, and I hear you can tune the mixture by ear if your good at it, is that possible on our 4 carb bikes?

 

turning the mixture screws makes it more lean.

I am having almost exactly the same issues with my bike (F3 engine with F2 carbs) and it hesitates horribly up until 8-9k revs when it suddenly takes off. I have a dynojet kit in with 128 mains which seems better over the 135 stock and the needle position is 2nd from top but as it gets worse when warm i believe its a lean issue (major popping too). I am about to move the needle position down to make it richer but in theory it seems a bit strange making the needle richer and mains smaller but ill do it and let you know what i find.

Do you have the heat shield in place over the plugs ?. I didn't have one and have been reliably informed it can screw with performance so i picked one up from ebay.

 

I do not have any sort of shielding over my plugs, matter of fact most guards and shields on the bike are gone, no wheel hugger, chain guard, and no I guess wind guard over the plugs, keep me posted on if that helps, oh and I got the chance to check the mixture screws and it's at 2.25 turns out but all the screws are about a quarter turn different