650 CSR carb jetting question

Hi folks. Last fall I bought an 81 KZ650 CSR H1 with 4,300 miles that had been sitting in a garage for 5+ years. The guy who was selling it for the owner started it and gunned the heck out of it trying to keep it running and I think the pipes started to blue that day. I've drained old gas and run a couple tanks of gas with Sea Foam.

It runs pretty decent except it really needs to be half choked for 5-10 minutes till it will keep idling at around 1100 rpm. If not choked it bogs on pulling out. Plenty of snap above 2500-3000 rpms though. Plugs look light tan. I live at 5,800 feet and ride from about 5,000 to maybe 7,000 feet. No reason to suspect jets are not stock. I'm keeping the stock air box.

Looking for carb rebuild kit. They all seem to have 102 mains and #15 pilot jets. Specs I've found online say 102.5 main jets. Considering altitude and blue pipes should I jet it differently? Any suggestions for source for other size jets? Thanks.

Hey, nice bike. I've got the same one.

As far as the choke, my 650 takes a loooong time to warm up. It wants half choke for that amount of time as well.

When you move a bike up in altitude, your air/fuel mixture should actually become more rich. But from the pipes bluing it sounds like you're running lean. It's possible the additives used to lean out fuel in your area might be leaning out your bike a little much. Also, make sure the air filter and exhaust are stock. If they aren't, that might be a cause.

But then again, your plugs are tan, which is relatively normal. Black/Sooty too rich. White/Blistered too lean.

I think you might want to talk to Jeff @ Z1 Enterprises on this one. He's definitely the man when it comes to - well - pretty much everything Z related...He's a regular on the forum, search for Jeff Saunders or Z1 Enterprises.

I guess if it were me I'd up the main jets a size or two and maybe a washer on the needles...I'm not very experienced with jetting, so don't take my word for it.

All I know is, I hacked my pipes off last weekend and I'm definitely running a little lean with my pipes bluing...I know better... but it's oh so loud!

Good luck and happy riding!

del

Thanks for the input. I'm 3/10 mile in from a highway on a firmly packed gravel road that I ride around 25 mph out to the highway. My big KZ 1100 needs

slight

choking out to the highway then runs fine with no choke but the 650 needs just a perfect spot about half way choked to get me there. It will idle in the driveway but if I pull away I need about 2K rpms. Giving it throttle under about 3K bogs it to stall like no gas. Once I turn onto the highway and get over about 2500 rpm I turn the choke off and by 2 1/4 miles at 60 mph to the first stop light it runs nice and smooth till I turn it off and it cools down. My old Honda 750 was fine right out of the driveway. My old Z1 900 needed less than a minute of choke to warm up. The 650 must be a pilot circuit problem.

As mentioned before it has the stock air box and a new Emgo paper filter. As far as cleaning the carbs goes, if it runs smooth as a switch watch from 1000 rpm idle through 6 or 7 grand when it's warmed up wouldn't that indicate a clean fuel system for all circuits?

Checked WG's referred answers on jet sizing and kaw web site. Stock main jet for US was 92.5 and Canadian was 102.5. Since high altitude is less air one would think the 92.5 (leaner fuel) would be in the right direction to match the thinner air. Theoretically a 102.5 would be too big up here at 6000 feet. Someone mentioned gas being of lower octane up here. Unleaded regular at our pumps is 85 octane instead of the 87 I see at lower altitudes.

I do have a seep in the bowl gasket of one of the carbs so maybe I'll just pull the carbs, clean them and replace the gaskets. I can't imagine there would be any worn parts on a bike with less than 5,000 miles. Any other thoughts would be appreciated.

Also, I could not find a definitive answer on the air fuel mixture screw setting. I've seen anything from 1 1/4 to 2 1/4 turns out. They were at 2. I tried 1 3/4 but saw no change. Anyone out there know?

Just an update and thank you for the suggestions. SeaFoam from Autozone and a few days of running the bike and she runs a lot better. Still takes a few minutes to get fully off choke but starts on first bump. 92.5 jets which are stock might be too lean at lower altitudes but a local bike dealer says all those lean EPA tuned bikes run just fine here in the mountains at 6000'. They don't change a thing. Again, thanks for the suggestions.