i am haveing problems with my 1973 honda cl350?

Question

i have a 73 cl 350 the carbs were rebuilt, tuned up, valves and timming chain adjusted. when you get it on a pull around 3rd gear it startes to miss and hesatate. both pluges get carboned bad and turn black then the pluges file out. could this be the coil everything else was replaced.please help me i am going nuts. the honda dealer can,t even find the problem. thanks .jerry

Answer 1

Normally that would sound like an ignition problem.

Either dirty contacts on the ignition points,,,
or sticky on their pivot.

The Age of the bike makes it a Good possibility that youre right to suspect a failing ignition coil.
Or,,the condensors mounted on the coils---"Nobody" ever changes those,they're traditionally neglected.

On the Carbs on your bike,,,they have a rubber diaphragm which raises the air slide "On Demand".

They can fail in several ways which are obvious to the eye when rebuilding them.

But they also fail by tearing away from the Slide ,,
which is NOT so apparent to a casual inspection.

A bad Vacuum Diaphragm WILL produce symptoms you are experiencing.
The Vaccum Leak fails to raise the slide to the correct position.

As the engine speed rises,,,and demand for Air/Fuel Rises,,,
The Intake Tract vacuum goes way High.
But the SLIDE does Not.
It hangs LOW,,,BLOCKING OFF INTAKE AIR.

Basically,,,the Throttle AIR Slide becomes a CHOKE.
Engines is under High Vacuum,,,with LOW air volume being admitted.

So it sucks in even MORE Fuel than Normal,,,
and with way less air than normal.
Faster the engine goes,,the worse it gets.

It becomes a MEGA CHOKE.

It's worth Carefully checking the slide diaphragms.

That would be my 1st suspect

Answer 2

I've been riding for 20 years and my first bike was a 73 CL350. I still own & ride a 73 CB350! (backup-bike to my 79 Bonneville) I doubt the coil is your problem. Coils will either work, or not work. It's most likely a carb issue. It sounds like your carbs are running rich. If you have a manual. (Clymer was my favorite) follow the instructions for adjusting your carbs.

If you don't have the book....

You should see a little screw on the side of each carb, just under the intake manifold. ( Not the idle adjusting screws that move up & down as you twist the trottle) Turning the screw inwards will make the carb run rich & create carbon fouling, outwards will lean it up. Start by turning both screws all the way in, then turn each screw out 2 1/2 turns. This is only a baseline starting point. ( I'd have a few spare plugs on hand, or clean up & reuse your fouled plugs). Start up your bike, warm it up & ride it around a bit. Then recheck the spark plugs. If theyre blackish & still fouling, turn the carb screws out by a 1/4 turn each & repeat the test. Keep doing this till you get a nice tan color to your spark plugs. If you bike begins sputtering & popping while engine braking, or is running too hot, you're too lean. Turn each of the screws back in a 1/4 turn each. Keep checking your plugs til you get that tan color.

The other 2 screws I mentioned are your idle screws.. You want to make sure they are both moving up & down at exactly the same time when you twist the throttle.

Your Honda dealer probably cant find the prob, because he doesn't want to deal with it. Alot of the dealers wont mess with the classic bikes anymore, or don't have the people on hand who know how to work on them.

Despite what the other numbnut said, the CL350 is a great bike. It'll run forever & still be on the road long after his new bike is the the junk heap....!

Keep on riding...!

PS. The other posts made some very good points. Check the air filters & then try adjusting your carbs first before you start taking them apart or checking any other possible scenerios. You can easily check the condition of the vacuum diaphram by removing the 4 screws from the chromed cover on top of the carbs (watch out for the spring inside each carb). It should be soft & subtle with no holes or cracks.
( jcwhitney.com ) sells the Clymer manual for around 30 bucks. I recommend the investment...!

Answer 3

The spark and lights all run off the battery, Old batteries won't charge properly and when it dies you're stuck. A new battery is a good idea. Also with old bikes and old wiring, other issues can arrise, for example the rectifier solenoid on those old Honda's can be problematic and loose efficiency. Typically it's a good idea to have a dedicated battery tender to plug into if you're leaving it be for more than a few days just to keep your ignition juiced up. Searching around in the Yahoo groups there are a few vintage Honda motorcycle groups. It's possible to wire up your engine to run without the battery.

Answer 4

You need to find a mechanic who works on vintage bikes. The honda shop is used to "plug and play" replace with new parts, and off you go. They work on time = money. Less time they spend, more money they make.

It could be many things.
intermittent air leak, the carb manifolds are old, and may be cracked

jetting not quite right

old air filters

timing issue Maybe the wrong weight springs on the advance mechanism

Cam timing may be off

Coil could be intermittent

there are many possible reasons with an older bike. You should find a local mechanic who specializes in vintage hondas.

Answer 5

--Pistons & rings. Check the cylinder compression.
--Leaking valves. Maybe the mech adjusted them improperly. Perform a cylinder "leak down" test.
--The bike's old enough. May need valve guide seals.
--Running rich. Check the air cleaners. They may need replacing.
--Ignition timing adjusted improperly. New bikes don't need the timing checked, so new mechs don't even own a timing light. The timing has to be adjusted when new points are installed.
--Cstatman mentioned the advancer springs could be weak. Also check that the advancer moves freely. When the points cover gasket wares out, moisture gets in and corrodes the camshaft.

Answer 6

My first was a '74 CL360. Loved that thing.
You have gotten some fine suggestions here. People seem to know exactly what they are talking about. I've been going through your answers, and thinking about the problem as you describe it. It seems to be ignition related. It is not the coils, you have one for each plug. I'm leaning toward the advance mechanism, as it seems your problem occurs when the ignition should be advancing the spark.

Answer 7

The way you describe the problem it just keeps pointing back to the carbs

Answer 8

The problem is that it is a 1973 model. It is old. It is not meant to last that long. Buy a new bike. It will crank right up.