Topic: CB350F trouble

[Vlad]

Hello folks,

I bought a CB350F today.

After riding it out of the guy's driveway and going down the road for about 2 miles the bike started bogging down until it eventually died.

I had trouble starting the bike but once started I got back on the road for another 2 miles or so when it "bogged down" and died.

I did it once more, then again it "bogged down" and died.

I use "bog down" in quotes because I don't know how else to explain it.

The bike starts with the kickstarter after a few tries, and runs if I rev the engine but it won't rev past a certain point (3 - 4K) and once off throttle it dies.

The bike also dies if I keep revving the engine for a long enough period of time.

What do I have to do to fix it?

What have I gotten myself into?

Thank you all.

[fmctm1sw]

Could be a fuel delivery problem.  Clean the carbs and look at the inside of the tank maybe?

[Vlad]

The inside of the tank is coated.

There's an inline fuel filter, it seems to be pretty clean.

IF it's not a fuel delivery issue, what else could it be?

The bike doesn't idle off-choke.

[kck3]

Sounds like carb issues.  Pull plugs and look at them as well.

[Ross Davis]

Sounds like it could also be a fuel delivery problem.  To test open the gas cap and see if it runs futher, just enough to vent the tank.

[Vlad]

Quick update,

I got the bike to idle - albeit roughly.

But when I try to rev the engine it dies out.

There is fuel flow, I pulled the tank and opened the petcock and gas is flowing.

There are some holes in the fuel line ... not massive or anything and fuel isn't leaking out but could they be part of the problem?

[bender01]

There are some holes in the fuel line ... not massive or anything and fuel isn't leaking out but could they be part of the problem?

Yeah. If there are holes and gas isnt leaking out of them Id guess that something is in the fuel lines stopping it up.

[jaguar]

just because there is fuel flowing from the tank doesnt mean that there is the proper flow into the motor.

sounds like its time for a good tune up
new plugs
clean carbs
check points

[camelman]

Yeah bud, I'd guess fuel is not flowing well.  It can be from a bunch of different reasons, but I'd look in this order:

1) pull fuel line off carb and open petcock to see if fuel flows quickly and easily - if not, then clean out petcock
2) If fuel flows easily through petcock, then remove carbs and clean thoroughly.

That's pretty much it.  The reason the bike is dying after running is because not enough fuel is making it into the carbs to keep the bike running.  If you let it sit, then the fuel leaks in slowly and fills up the carbs... allowing it to run until fuel runs out again.

Good luck, and make sure to search on how to clean/rebuild carbs for those bikes.  It is pretty easy, but you have to know what to do.

Camelman

[Ross Davis]

My point about the gas cap is that it has a vent on it to allow air into tank.  If it is clogged fuel will not flow well.  Then as it is not running the level in the bowls returns to the correct level and runs for a while again until it uses that fuel and runs low.  Like the Camelman said.

[flybox1]

101.  download the shop mannual from the forum.
102.  complete a 3k mile tuneup.
once done, and if you are still having problems, post back and we'll help you in more detail.

I will agree with the above that you have a fuel delivery issue, and it is between your tank an your carbs.  A thorough cleaning is needed.

[camelman]

1.  download the shop mannual from the forum.
2.  complete a 3k mile tuneup.
once done, and if you are still having problems, post back and we'll help you in more detail.

I will agree with the above that you have a fuel delivery issue, and it is between your tank an your carbs.  A thorough cleaning is needed.

Flybox1, you have encroached upon my copyrighted "numbered bullet list".  My lawyers will be contacting you.


;-)

Camelman

[flybox1]

Cameldude..
from now on i'll refrain from using numbers less than 100  
you can have up to 99.
(previous post edited to prevent cease and desist orders )

still, we can agree Vlad the Impaler has a few 'fuel to carb' related things to do  

[Vlad]

I'm working tonight but tomorrow I'll pull the carbs of the bike and take a peek inside.

[GreenHorn]

Hey Vlad, just bought a 350F about a month ago- neat little bike.

Last summer, I bought two cheap, clear, inline fuel filters and put them between the tank and the carbs on my 750.  The setup worked great all summer, until Labor day weekend.  I, like you, could only go a couple miles and the bike would loose power then die.  I stood on the side of the road for 5 minutes, gave her a kick and she would start right up.  I had rebuilt the carbs two months earlier, and had just changed needle clip position a few days before.  When I got back to the shop, I pulled the line from the carb and I had flow from the tank THROUGH the filter.  It seemed like enough flow, too- enough to make a mess in the 10 seconds I had it opened.

Long story short, I eventually did pull the filters off- the bike ran fine after that.  Just my two cents.  As for hitting a wall at a certain RPM, I'd take the advice of the carb guru's around here.

Good luck.

[Vlad]

Hey Vlad, just bought a 350F about a month ago- neat little bike.

Last summer, I bought two cheap, clear, inline fuel filters and put them between the tank and the carbs on my 750.  The setup worked great all summer, until Labor day weekend.  I, like you, could only go a couple miles and the bike would loose power then die.  I stood on the side of the road for 5 minutes, gave her a kick and she would start right up.  I had rebuilt the carbs two months earlier, and had just changed needle clip position a few days before.  When I got back to the shop, I pulled the line from the carb and I had flow from the tank THROUGH the filter.  It seemed like enough flow, too- enough to make a mess in the 10 seconds I had it opened.

Long story short, I eventually did pull the filters off- the bike ran fine after that.  Just my two cents.  As for hitting a wall at a certain RPM, I'd take the advice of the carb guru's around here.

Good luck.

I bought new fuel lines and a new in-line filter today, I will put them on the bike later and see how it runs.

The carbs will have to come off regardless.

By the way:

does anyone here have a copy of the owner's manual? Not the shop manual, the owner's manual - in electronic format if possible.

Thank you all for the good advice.

P.S. If you're ever in Chicago, don't go to Champion Cycle (Addison & Western). They're butchers. And overpriced ones at that.

[jaguar]

in the manuals thread there is a huge file with everything from service, owners manuals as well as old adds

[Vlad]

in the manuals thread there is a huge file with everything from service, owners manuals as well as old adds

Ah, thank you.

So, the choke is open in the down position, and it's closed in the up position? Because the arrow on the lever is saying the exact opposite.

One more question: is the Honda dealership the best spot to get NOS gasket sets for carb rebuilding or is there a better place?

Thank you all, please excuse my noobishness.

[GreenHorn]

Vlad:

If I remember correctly (don't have the bike in front of me), the choke is on when the lever is down, off when the lever is up.

Carb rebuild kits... try these:

Old Bike Barn
Parts n More
Z1 Enterprises
http://www.siriusconinc.com/

Just a note, and I'm NOT bashing Old Bike Barn, but I don't believe they have the correct float bowl gaskets.  That's all I needed for my carbs and I ordered from OBB; they sent me a round O-ring that was about 1/2" too long.  Who knows?  Maybe I've got some odd carbs...  Try Sirius.  I've only dealt with them once (out of Canada), but they sent me the correct, pre-shaped float bowl gaskets and they were cheaper.  Seems like the float needles and seats (sometimes not included in carb rebuild kits) are decently priced also.  I've had the best luck with the above vendors.

[fmctm1sw]

Just a note, and I'm NOT bashing Old Bike Barn,

Your too late.  They have already been sufficiently bashed in the "Bad sellers" forum...

[Vlad]

I went with the OEM Honda gasket kit.

You were all right, the emulsifier tubes were gummed up something fierce, but the rest of the carbs were actually not all that bad.

Another question: do CB400F throttle cables (cable A - pull) fit the CB350F? I'd like to go with an OEM solution but 350 cables are nigh impossible to find.

[hoodellyhoo]

Another question: do CB400F throttle cables (cable A - pull) fit the CB350F? I'd like to go with an OEM solution but 350 cables are nigh impossible to find.

I don't know for sure, but I don't think so. Pretty sure they are different part numbers and the 400f had lower bars so the cables will be shorter. There are oem 350 cables on ebay.

[Vlad]

Quick update:

Carbs are spotless, they're back on the bike.

She starts up, the carbs don't leak, but as soon as she starts the idle shoots up to 6K rpm.

That's about 4K more than I need (normal idle is around 2K, right?).

What's the problem here? How do I fix it?

[flybox1]

does it stay there?
if yes..turn down your idle and close your choke

if you bench synched your carbs, did you set your slides too high?
( i would guess if your idle set screw cannot be adjusted down, you set your slides too high)

does idle bounce around?
if yes, check for air leaks in your boots.

it should idle real nice around 1200-1500 after vacuum sync

[Vlad]

does it stay there?
if yes..turn down your idle and close your choke

It stays there for a couple of minutes then it comes down lower than 2K.

Then if I rev the engine, it'll go back up.

if you bench synched your carbs, did you set your slides too high?
( i would guess if your idle set screw cannot be adjusted down, you set your slides too high)

The idle set screw is out all the way.

I used a 1/8" drill bit to set the slide height on the airbox side.

does idle bounce around?
if yes, check for air leaks in your boots.

It doesn't really bounce around, just stays pegged at 6K then at some point it'll decide to come down lower than 2K.

it should idle real nice around 1200-1500 after vacuum sync

I still have to vacuum sync it. I don't have the right tools for it.