New (to me) Honda CB350 twin dies when coming to a stop.

CB350

Been Around the Block
New (to me) Honda CB350 twin dies when coming to a stop. It doesn't matter if it's a stop sign, stop light etc. As soon as I roll off the throttle it dies immediately. The bike fires right back up but it's frustrating to have to restart at every stop. Other than that the bike runs very well, which sounds funny. But, it starts up quickly and goes like hell until dying at a stop. The carbs were just removed and cleaned etc and the problem didn't change at all.

Next I'm going to try setting the timing since I'm sure it's never been done. Any other ideas? Could it be an air leak somewhere?

Overall I'm thrilled with the little twin. It's a 71 and you can see pics of it in the Show and Shine section.

Thank you,

Gerard
 
Well, now it won't start at all. Last time out it ran great but it won't fire up. It's getting gas so the issue must be spark. I checked the battery and it tested just a touch low so I have it charging. Somewhere I heard these bikes run poorly when the battery is low.

Tomorrow I go after the timing since my helper didn't show up today.
 
The CB350 is notorious for it's weak charging system. Could be the rectifier, regulator or stator. Also the coils may not be generating enough power to give a good spark. I've had some success by making my own rectifier with one I bought at an electronic store. Works pretty good. I got the idea from this site: http://www.oregonmotorcycleparts.com/rectifiers.html
 
Forgot to mention, also make sure the battery cables are absolutely tight, especially the negative terminal. I suggest a split washer to lock down the bolt so the vibration won't work it loose.
 
Will do. This is my first go-round with an older bike. I've had my share of old cars but even though bikes are pretty much the same there are some differences. Usually, I start with the simplest issue and then go from there. The battery cable being one of the simplest things to check.

Tomorrow I will get a chance to dig into this and will report back what I find out.
 
Well, we have spark, we have gas, we have no start.........and it's my fault because now I have it titled, I have plates and I have everything legal. It ran great for the two weeks that wasn't the case. Not that I was usually doing more than just firing it up to make sure it would run after the carbs were cleaned. I'll admit I took it on two drives of less than a mile or two in my subdivision after tinkering to see if it would run. It was always insured, I just didn't have the tags.

It's been sometime since I had a "project" vehicle and I remember why I gave up on having one. Even though I buy it knowing it's a project I get mad when it won't start and hammers and other sundry items start flying around the garage.

Still, once it's up and running I smile ear to ear. It's like playing golf, when it's good, it's very, very good, when it's bad, it's very, very bad.

Such is life.
 
OK, I waited until it was dark to do one last test on the spark and no doubt it's getting spark. The plugs are new but already a nice black color which has me concerned. Looks like it's off to the "motorcycle troubleshooting" section of my manual. It has pretty pictures of plugs and what the problem is based on the color. I thought the black plugs were a sign of running rich and that would make sense since the bike idled at 4000RPM until I got the carbs cleaned.

Hopefully, a good clean of the plugs will get things right again and I can start again from there. Who knows at this point? I sure don't.

**** Update, bike won't fire at all now, the battery is charge the rectifer is fine, it might be a gas issue as the right carb seems to be overflowing and forcing gas out where the gas line meets the bottom of the carb*******
 
Rebuilt the carbs and replaced the points today and still nothing - anyone want to buy a CB350 that was running two weeks ago? It bet it's a minor problem I just can figure out for some reason.
 
Now that you changed the points is there any spark? This might sound dumb, but is the bike in neutral, on my CB350 if the bike is in gear the electric starter does not work. Does it crank? Have you tried putting gas directly to the carbs, I use a ketchup bottle to squeze some gas into the carbs. I would recharge the battery again or maybe try to push start it with some help. Check the fuse too.
 
Trust me, nothing sounds dumb at this point. It is in neutral but I haven't tried the gas directly into the carb trick yet. The battery is charging as we speak.

I'm sure I will eventually figure it out. The frustrating part is the bike tricked me by running so well when I first got it and now crapping out. There is spark, there is gas, whether it's the right mix is another story. Tonight I'm going to charge the bike's batter (and my own) and have a crack at it tomorrow.

Don't worry about making suggestions that you think might be insulting - it's been six years since I worked on a car or motorcycle and I'm prone to random acts of jackasssery. I have no idea what fuse you're talking about. Can you elaborate on that? Although the lights all work if that counts for anything.

I did hear something interesting today. A guy at the local Japanese junkyard/parts yard, said we can use Kawi Ninja 500 carbs on the CB350.

The owner races only CB350s so I'm going in Saturday to see if he can give me an advice about why it's not starting.
 
I forgot to answer two of yoru questions. The starter motor just spins when the button is pushed. When the kick start is used the bike makes a couple of puffs, only while the kick start is actively being pushed and then stops. There is no life at all.
 
The fuse is okay if the lights turn on. In one of your posts, you said it was leaking gas right under where the line meets the carb, maybe not enough gas is flowing into the carb, try pulling out the copper piece that goes into the card. I just fixed this on my bike yesterday, I pulled it out a bit, but once I put it back, it goes in again. You might want to put a small clamp to avoid this, this will fix the gas leak. Another thing to try is using starting fluid use, only a small amount, I believe this can damage the carb diaframs. Something is to do is remove the plugs and burn them using a torch, this will remove any gas is the plugs are flooded.
 
Yes, for a few days gas was pouring out of the left side carb where the gas line meets the carb. IThat stopped today after the carb rebuild. I am going to try the starting fluid and instead of a blow torch I put the plugs over the gas flame on my stove.....when my wife was at the store of course!

With the carbs rebuilt the gas stopped leaking. I'm beginning to wonder if it isn't something odd. My old Kawasaki had a side stand c ut off that went bad one time, or I noticed there is a lot of play in the gear shifter linkage while in neutral. I also have a feeling that if the starter motor wasn't toast it would crank it enough to get it to start.

Worst case is that plugs are only $1.50 so I might just replace them when I get the starter fluid.

Thank you for tolerating all the questions. As you can imagine, it's getting a little frustrating. If this bike is a goner I dont want to spend a lot of money. But, I guess I can pop for a rebuild kit if it comes to that. I can guarantee I will overbore it a little if that happens.

Due to how well it was running (right until it died :p) I can't imagine that it's something very serious. Which is what makes it so flipping frustrating. Eventually, I will replace all the gas lines, the cables, the brakes etc but until I know it's going to run I'm not going to put those type of things on it.
 
Could it be timed so poorly that it won't start? It strikes me as grasping at straws because it was fine - then it wasn't. But it sat in storage for a few years so that makes it more of a possibility in my mind.
 
Ask an expert

I just remember this, and I will share it you and anyone else who ever needs help with these vintage bikes. There is this person named Bill Silver from allexperts.com. This man knows his stuff, unfortunetly, he is not always available for questions. I would post your question here, there are other experts besides Bill. Good luck


http://allexperts.com/ep/837-26814/Motorcycle-Repair/Bill-Silver.htm
 
Great advice - thank you. It's odd for me to be the one of the asking end of the questions. In my other life (my job) I'm the boss and in my other hobby I am an instructor, plus I work for an advocacy group. So, it makes me uncomfortable to ask so many questions.

I will go through Bill Sliver's answers and hopefully stumble across something. If so, I will let everyone know when (if) this bleeping bike is ever running again.

For those of you that are part of the Ohio thread we do need to get together for a ride this summer.
 
When I got my bike home for the first time, I couldn't get it started again. That is until I did a valve adjustment. Turns out they were so tight the engine couldn't make enough compression. Then I went to adjust my timing and found it was retarded as far as it could go. I think the PO was trying to compensate for the lack of valve clearance without properly understanding the problem.

Just throwing ideas out...
 
Does someone know what safety kill switchs are built into these bikes? When I kick it over it almost seems like doing so without the key turned on. It just puffs twice and that's it.

All the starter does is whine when I use the electric starter. Someone earlier mentioned if the bike wasn't in neutral the electric starter wouldn't work. What exactly does it do under those cirucmstances? Here's what I found this afternoon, the cable where it goes into the tranny/clutch was VERY loose. So, I tried to adjust it so it would positvely allow the tranny to shift.

That's why I'm wondering about the neutral switch that only allows it to start in neutral. I looked through my manual but came up empty. There is also a lot of play in the linkages for the foot shifter for the tranny which, again, makes me wonder if that's the problem.

Don't worry about throwing out crazy ideas - I'm at that point. I've been avoiding a compression test because I don't want to find out the engine needs a rebuild - I want to wait until this winter to do that.

Right now, since I have a bike for the first time in 7 years I want to RIDE!!

Again, thank you to everyone for the help and patience. You've all been great in trying to help me. When we figure this out, the beer is on me. Especially if you show at the June 2nd Japanese bike days at the AMA museum in my hometown of Pickerington.
 
OK, I got it to fire, "a little" finally. But, nothing substantial and I've come to the conclusion, yes after all this time, that at the moment it's not getting any spark. It was getting spark and now isn't so I must have broken something else while tring to get it running. I also realized my starter is fine - but doesn't engage when the bike is in neutral. Is that possible? It could be effected by the seriously mis-adjusted clutch cable as well.

I'm still going to take everyone's advice though, I didn't ignore the comment about checking the valves which is my next step. I also still need to get it timed.

Then, it's time to customize a little. I'm thinking clubman bars and some kind of seat.
 
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