I picked up a semi-running 82 cb650 nighthawk a week ago for $500. It seems to idle fine and revs somewhat freely, but around 4500-5000 RPMs it stutters all over the place and isn't really smooth throughout the RPM range.

The guy I bought it from said he just cleaned up the carbs but hasn't had them synced yet. It also is missing the air box and filter. I haven't been working on bikes for very long but I'm thinking that the carbs need to be synced and they also may be running lean from having no air filter on the bike right now. I plan on putting K&N pod filters on rather than trying to find a good condition airbox for the bike as well as having the carbs synced. Is there anything else I should look into to get this thing running smoothly? Thanks.

Nate

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'66 Ford Mustang
'02 Suzuki Bandit 600
'80 Honda CM400E
'82 Honda CB650 Nighthawk

Hey, Nate. I think your assumption is correct. These bikes run pretty lean to start with, and when you factor in the absence of filter and airbox, well... You'll be amazed how it runs when you get the carbs sync'd, too.

If you go with the pods, since they flow better than the stock setup, there's a chance you'll have to replace the main jets with the next larger size. To check the condition of the fuel mix, pull the spark plugs and check their color.

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Let me get this straight... it's one down and four up, right?

Thanks for the info. My question is now should I take it somewhere or if I bought a carb syncing gauge should I be able to do this myself? I've messed with holley's on my mustang but never 4 carbs on one vehicle. If a gauge is $80 and the labor is going to be at least $100+ for someone else to sync them, I would rather buy the gauge if I can do it myself. As far as jets go, I would be able to order those right? They're Kei-hin carbs.Thanks.

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'66 Ford Mustang
'02 Suzuki Bandit 600
'80 Honda CM400E
'82 Honda CB650 Nighthawk

I'm betting you could handle a carb sync job. Here are a few things I thought of that you'll need:

1) The sync tool, of course. Mine's a cheap MotionPro... I think it cost me $40. Works great.

2) Service manual for your bike, if you don't have one already. There's always a section in them telling you the sync procedure.

3) Since you have to remove the tank for this, an auxilliary fuel tank. I use an old tank off a dead lawnmower. The kind that have a shutoff are the best.

4) A big fan to blow on the motor while you're dialing in the carbs... gotta keep 'er cool!

Oh, yeah... you shouldn't have any trouble finding a jet kit. One thing to remember... since they usually run a bit hotter, the #2 and #3 cylinders almost always run on different jets than #1 and #4.

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Let me get this straight... it's one down and four up, right?

I think you might get a way with not jetting if you still have your stock side covers.

I've been playing with a 80 cb650 that some one put a 87 650 night hawk motor in.

Of course the air boxes didn't line up so I put a set of UNI clamp ons on with stock jetting and the side covers on I haven't seen a any problems

Stalk night hawk exhaust as well.

Where did you get the UNI clamps from? I was pricing out some K&N pod filters but would be like $120 for a set of four which would make it cheaper to go with piecing together a stock airbox. Probably gonna mess with this in the next 2 weeks now. Hoping it turns out well cause I think it would be a fun diversion from my bandit should the need arise.

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'66 Ford Mustang
'02 Suzuki Bandit 600
'80 Honda CM400E
'82 Honda CB650 Nighthawk