How do I adjust Honda CB160 carbs?

[cjmdjm]

I am restoring a cb160. I took the carbs apart and cleaned them, boiled them in lemon juice and used carb cleaner. I had rebuild kits, but a lot of the original parts looked good so I didn't replace everything.

I don't really know how to adjust the carbs though. Currently, it starts right up, and runs at idle, though its a bit smoky. But if I give it any throttle, it slows down, and will die if I don't return the throttle to idle.

I assume the mid and high speed adjustments must be way off, but I don't know how to adjust them. I just set everything the way it was when I took it apart. I have read some articles online which say to set all of the adjustments to the stock factory settings, but I don't know what those are, or how to find them. Anyone know of any good, detailed guides on how to adjust and tune carbs on a cb160?

Edit: Should also mention I don't have the mufflers or anything on, just bare exhaust ports, which I tape up when I'm not running it. The lack of back pressure wouldn't have an effect, would it? Does make it hard to tell how fast its idling, because its loud at any rpm.

Thanks guys!

[rufusswan]

Go over to hondatwins.net and spend some time. Those folks will have all those details you seem to be missing; specifics on tuning, carb adjustment, tips-tricks-techniques down to where to snag a manual for the bike.

If you're attempting to tune the bike, yours requires correct jetting, incoming and outgoing airflow. Put the headers & muffs back on. Tuning an old bike is tuning a "system" not just setting one or two individual items.

[caponerd]

Check your ignition too.
Your problem isn't related to adjustment. Incorrect adjustment would result in running poorly, but it should still run. If it's the carbs, you've probably got something seriously wrong with fuel delivery.

Just so you know, the mid adjustment will be needle position and taper (shouldn't prevent the bike from running, no matter how off it is), and the high adjustment is the main jet (that also shouldn't prevent it from running).

[caponerd]

Originally Posted by cjmdjm

Edit: Should also mention I don't have the mufflers or anything on, just bare exhaust ports, which I tape up when I'm not running it. The lack of back pressure wouldn't have an effect, would it? Does make it hard to tell how fast its idling, because its loud at any rpm.

Thanks guys!

And don't run it with open exhaust ports. You can warp an exhaust valve that way. You some kind of header on there to isolate the port from cold air.

[cjmdjm]

Figured it out. I finally found a manual online. When I took the carbs apart to clean them, I thought I had fully disassembled them. But one of the little gold colored pieces, which I thought was one solid piece, actually screws apart. Turns out, one half of it is called the main jet, and it was completely clogged inside! Cleaned it out, it runs great now.

Do you guys think I need to sync the carbs? It seems to run quite well now, and I haven't even adjusted the points or timing advance yet. I'd rather avoid spending the money on a carb syncing device, that I would probably only use once.

And my new mufflers came in today, so I put them on, instead of using bare exhaust ports. I hadn't ran it for for than a minute at a time, so hopefully I didn't hurt it to bad.

Thanks for the help guys!

[rufusswan]

If it runs well know then go with it and enjoy the ride. BUT, do some studying on the process of synching your carbs/adjusting the throttle cables. Study the process of setting the timing. When you gain some confidence then set aside some time, a cold brew, and tackle each one.

[chammyman]

a good carb synching can turn a good bike to a great one.

A smoother bike makes a happier rider.