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Discussion Starter · #1 ·
Hello,
So I bought my first bike recently about a month ago from a guy who gets old bikes and fixes them up to run. It is a 74 CB350f, I know absolutely nothing about bike mechanics and am trying to figure it out as I go. I adjusted my throttle cables the other day and that is about the extent of what I know.

Now, The bikes does run and it ran well the first day I got it but I'm having some issues now. First off the bike wont hold a charge. It starts if I leave the battery on the trickle charger but other than that I need to put it back on and let it charge for a bit before starting again. Secondly I am having a weird backfiring when I accelerate in any gear. I have read online that it might be a mixture issue and was wondering if I could fix this issue by trying to tune my carburetor? I do not have a tachometer and was wondering if there was another way to tune it without one.

Next my bike is doing this ghost revving when I pull in the clutch after I have been riding for a minute, not long though. I read online that it is probably due to cable crossing of my clutch and throttle cable, but when I adjusted my throttle cable the other day I checked for that but did not see anything that looked like a crossing issue. I will check further if you all think that is about the only issue. I want to work on the bike myself and not have someone else look at it until I have exhausted all options of fixing it myself.

Any tips would be greatly appreciated.
Will send pics of the bike if it will help!!
 

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Look at your frame/engine numbers, to see which 350 you have, then someone can help you out.
 

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Discussion Starter · #11 ·
I am sorry if I am frusturating but I reallly know nothing of bikes or engines in general, But I am eager to learn!
 

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Discussion Starter · #12 ·
If anyone cares to still listen I took it out the day that I fixed the throttle cable adjustment and when I was out I stopped to look at a house and the engine completely died on me. Due to the battery issue I am having I couldn't start it back up and had to push it back to my house. Could the engine have died due to the battery being weak or some other extenuating circumstance?
 

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As you now know, you have a cb360 not a 350f.

put the battery on a charger overnight, then unhook it and let it set for a few hours. Check the voltage with your meter, if its less than 12.6, your battery is bad.

if the battery is good, then you need to look into the charging system.
 

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At least it's got proper air boxes on it, not those stupid aftermarket cone air filters, you may be actually able to get it to run properly. Use the search button there are some pretty tutorials on here concerning tune up and troubleshooting info.
 

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Hi and welcome. I'm a former 450 owner but the following is applicable to you. Do a compression check. If the psi are below spec per cylinder, nothing I spent time typing below will change too much. A motor well below compression specs requires new piston rings, pistons, or...a topend rebuild. Backfiring on acceleration indicates timing issue or a fuel delivery issue; lean running meaning fuel starvation.

1. Check your spark plugs. Research the ngk plug chart and it shows details photos of plugs which can at least give a slight idea of how your bike is running.

2. Take off your carbs. The jets, passages where has flows are tiny and clog easily. These need to be perfectly clean in order to function properly. There are also brass floats which control had amounts. The height of the floats must be spot on to ensure proper gas levels.

3. Ignition timing! Oh boy...your bike utilizes an advancer and points that open and close at certain intervals for spark; proper running and firing on time. Your bike is purely mechanical so things move and get out of adjustment. There is no electronic ignition whatsoever or fuel injection, your bike has carefully stated specs for this. Please download a shop manual.

4. These bikes hate modern gas. Modern gas goes stale within a few weeks. Fill with fresh 93 premium and always top off with a fuel conditioner or stabilizer; Sta-bil or Star-Tron fuel enzyme treatment.

5. The charging system on these bikes was adequate at best. If the battery is even slightly used up, your bike will run poorly. Test battery with a multimeter. Rev the bike while testing battery; there should be some voltage increase. If not, bad battery, suspect coils, rectifier. Electrical issue.

6. Vintage bikes require a lot of patience. You are not simply turning a key and riding. You will be wrenching. These bikes get oil changes every 1,000 miles and carb cleanings similar intervals if not more. Points degrade over time and need checking. Timing changes and needs confirmation.

Valve adjustments are critical. I am not good at that adjustment. Cam timing as well, again, not my forte. When everything is aligned, these bikes run well! However, it takes a lot to keep them there.
Good luck!
 

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Discussion Starter · #17 ·
Hi and welcome. I'm a former 450 owner but the following is applicable to you. Do a compression check. If the psi are below spec per cylinder, nothing I spent time typing below will change too much. A motor well below compression specs requires new piston rings, pistons, or...a topend rebuild. Backfiring on acceleration indicates timing issue or a fuel delivery issue; lean running meaning fuel starvation.

1. Check your spark plugs. Research the ngk plug chart and it shows details photos of plugs which can at least give a slight idea of how your bike is running.

2. Take off your carbs. The jets, passages where has flows are tiny and clog easily. These need to be perfectly clean in order to function properly. There are also brass floats which control had amounts. The height of the floats must be spot on to ensure proper gas levels.

3. Ignition timing! Oh boy...your bike utilizes an advancer and points that open and close at certain intervals for spark; proper running and firing on time. Your bike is purely mechanical so things move and get out of adjustment. There is no electronic ignition whatsoever or fuel injection, your bike has carefully stated specs for this. Please download a shop manual.

4. These bikes hate modern gas. Modern gas goes stale within a few weeks. Fill with fresh 93 premium and always top off with a fuel conditioner or stabilizer; Sta-bil or Star-Tron fuel enzyme treatment.

5. The charging system on these bikes was adequate at best. If the battery is even slightly used up, your bike will run poorly. Test battery with a multimeter. Rev the bike while testing battery; there should be some voltage increase. If not, bad battery, suspect coils, rectifier. Electrical issue.

6. Vintage bikes require a lot of patience. You are not simply turning a key and riding. You will be wrenching. These bikes get oil changes every 1,000 miles and carb cleanings similar intervals if not more. Points degrade over time and need checking. Timing changes and needs confirmation.

Valve adjustments are critical. I am not good at that adjustment. Cam timing as well, again, not my forte. When everything is aligned, these bikes run well! However, it takes a lot to keep them there.
Good luck!
I appreciate all the information! The battery is bad so I have one coming that will be here the end of this week. I also have a tachometer coming in as well so i can try to tune the carbs. I have a buddy who is a mechanic and he is going to help me take the carbs apart and clean them to try and start from ground zero. I will post updates as to any new issues I come across.

Thank you all so very much.
 

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Discussion Starter · #18 ·
As you now know, you have a cb360 not a 350f.

put the battery on a charger overnight, then unhook it and let it set for a few hours. Check the voltage with your meter, if its less than 12.6, your battery is bad.

if the battery is good, then you need to look into the charging system.
I did this and the battery was shot. I have a new one coming so hopefully this fixes this issue.
 

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You might have learned all this already, but...
It's important to make sure there's a little slack in the throttle cable when it's relaxed (ie. when you let it roll off and close.) So there should be a little slack in the single cable from the twistgrip, and each of the individual throttle cables to the carbs also need an amount of slack equal to each other, so that as you twist the grip, both carbs start opening together. It's not good if one starts opening before the other. You will find that each carb has an adjusting screw (often called 'throttle stop') which keeps the throttle open a tiny amount when you let the twistgrip go. The other adjuster on each carb is a 'mixture screw' which adjusts the fuel/air ratio when the engine is idling. That screw doesn't affect the mixture at larger throttle openings.
 

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Discussion Starter · #20 ·
A bit of an update i replaced the battery and the bike now has full power and starts perfectly every time. I also installed a tachometer with a buddy of mine to try and sync the carbs up to hopefully stop the backfiring when idling, accelerating and decelerating. I have seen a toolkit online for a 360 carb sync is that a good investment or is it all not necessary?
 
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