Honda305.com Forum

I can't get my cb160 to idle corectly. I have done a full tune but the problem continues. no matter what adjustment I do to the carb the bike will either rev up to 2000rpm or more, or it will just stall. There is no happy medium. Also when I ride the bike it has a bit less power than it should top speed 55mph and when ever I give it a lot of throttle and let go it will stay in high rpm's as soon as I push in the clutch, it will do this in any gear; and it will slowly climb back down the rmps to idle and than to stall. The only way I can make it idle is by continualy giving it a quick jerk in the throttle, if I try to give it throttle slowly it will still stall only a quick jerk works to keep it running no matter how I adjust the carbs.
> > >
> > > I have also had a fantom problem with my spark plugs. with in the last 20days I have changed my spark plugs 3 times. For some reason the spark plugs will not spark, the motor will not start and when I put the spark plug to the engine it shows no spark so I replaced them and than the bike fired right up, but after 20days I had to do this again and when I swap the old spark plugs again they still will not fire but the new ones will, How can I go throug so many spark plugs? The top of the spark plugs is deep black but in my opinio they should spark, there is no corosion, carbon deposit, and the gap is perfect.
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> > > Below I listed all of the things I checked or replaced.
> > >
> > > -compression test: 155psi at each cyliner
> > > -cam chain djusted
> > > -valve adjused to specs
> > > -points very in realy good condition so I just adjusted them
> > > -iginition timing was djusted
> > > -brand new UNI FILTER pods
> > > -carburator was diped in carb cleaner an all passages were cleaned
> > > -carburator main jet size 90, secondary jet 38, idle mixture screw is set at 1 1/4 turns out
> > > -brand new battry fully charged
> > > -all new engine gaskets, and oil seals
> > > -and much more tune up stuff that should not be related to my current problems
> > >
> > > At this point I'm not sure what to do and how to check other things to get this running right. Could I have a bad condensor? bad coil? bad igintion system? carburetor still dirty? float set wrong? bad wires or ground? and what could cause my spark plug problems too, that is jut crazy to me that I would go trough 3 sets of spark plugs. Any help on this would be great, I will buy someone a beer if I can get this bike running right.

I'll go out on a limb here and suggest that you have at least two problems.

remove the carbs and manifolds and make sure the mounting faces are dead flat. It sounds like an air leak there.

While they are off, check the float levels and blow through all the drillings in the carb. Check that both are the same flow in each circuit -use a can of carb cleaner to spray through and compare one to the other.

Make sure the throttle cable is in good condition and that the slides return smoothly when you close the throttle.

Synch the carbs

Are the UNI filters oiled? Are they too wet with oil?

OO,
The spark plug issue may be the result of a rich condition and perhaps a bit of oil present. If you need help with this one, I'm just down the road so to speak. PM me if you do. RW

oo; Two things, sounds like you have a slightly rich condition and a somewhat weak spark. the weak spark is probably a condenser. the rich condition at 1/2 throttle and above is jet needle clip position. have you tried different clip settings to get a clean plug? even a slightly fuel fouled plug will not fire with a weakened spark, when a new plug will fire right off.
Good luck
Randy
Bellingham
65 CB160 X 2

And the needle jets could be worn, it could have skinny Keister needles, the slides could be worn or cut, valve guides could be worn, rings worn, floats could be punctured, coils could be breaking down, corrosion in all the electrical connections, poor ground connections, bad ignition swtich and so teh list goes on.

I'd strongly recommend connecting to a local who can add a second pair of eyes.

I know this thread is old, but I'm having similar issues with a 160 I'm woking on. It either will not idle and slowly dies or it revs around 3k until i turn it off. I have tried the suggestions in this thread to no avail. The carbs have been dipped and new keyster kits installed. Thoughts?

The first problem I see in many of these threads are the words: "was adjusted," or "was rebuilt," or "I had it rebuilt." In other words, you let someone else work on your bike.

If you didn't do the work yourself you should assume that it wasn't done properly. The sad reality is that many self-styled, old-bike experts out there don't know what they're doing. Or, if they do, they're too lazy (drunk, on drugs, etc.) to do the job properly. In other words, if you want it done right, do it yourself. If you don't know how to, learn.

Anyway, enough rant. All trouble shooting starts with a comprehensive tune-up. That is, everything set as per the manual. Here's a partial list:

Points gap set as per the manual. If the bike's been sitting, use a points file or some wet/dry paper to remove the oxidization from the contact surfaces. Clean points, put a small dab of grease on points cam.

Timing checked with strobe

Carbs completely stripped, all metal parts soaked in lacquer thinner then blasted with with compressed air. All jets checked for proper sizes (see manual), all jets free and clear, carb mounting flange checked for flatness, new O-rings on carb manifold (put some grease on them, don't over tighten nuts! That's what the lock washers are for), float level checked, slides lifting simultaneously, fuel flow checked with float bowl off, etc.

Valves adjusted as per manual

Cam chain adjusted

Plugs clean and properly gapped (see manual). Usually no need to buy new plugs, just sandblast them clean and re-use.

It sounds silly, but when everything is right, they run right. It it's not running right, something's wrong (duh!).

Only after you're sure that all the basics are correct can you do effective trouble shooting.

Here's a hint: it's usually the points, the carbs or a bad rectifier not charging the battery.