Author Topic: CB350F acts like its getting no gas and loss of power (Read 4161 times)

XxDarkEuphoriaxX · « **on:** August 12, 2009, 03:41:03 PM »

Hi, I FINALLY got my CB350F back from the shop... it was never ridden before the tires were just put on it and gas tank re-done etc. in the last 15 years. The guy at the shop rode it around the block a couple of times and said it had a loss of power mabe like it wasnt gettin gas... I have a odd set-up without a petcock but when I take the gas line off of the shut off valve and fuel filter gas flows freely...it does have to make a slight up hill journey but I don't think this is affecting the problem I am having...

sometimes I have to have the accelerator turned alll the way back just to maintain 2nd gear if the rpm's arent high enough... I have just been riding it out in the yard havent been on the road yet...

it idled good but with slight variation the first few times I rode it but now it wont idle at all UNLESS I am giving it gas .....

HELP
thx,

1974CB750rider · « **Reply #1 on:** August 12, 2009, 03:55:01 PM »

This sounds crazy but have you checked the plugs? If the bike has been sitting foor a while and if your running NGK plugs they can give you problems. Try running some champions in it for a week or 2 then switch back to ngk. I had the same problem on a cb450. The carbs had been cleaned and synched by an actual retired Honda tech, valves adjusted, timing and points set etc. But when you rode it it had no power. I put the champions in and it was like a whole new bike the little critter would pull a wheelie.

XxDarkEuphoriaxX · « **Reply #2 on:** August 12, 2009, 04:04:25 PM »

it is on its 2nd set of new spark plugs tho.... the first ones were only on for a month and it wasnt even ridden with them on it.. the only reason new ones were put in was because they couldnt get the bike started and that was because it wasnt getting gas right....

mlinder · « **Reply #3 on:** August 12, 2009, 04:06:50 PM »

You just got a bike back from the shop, and it isn't running correctly? What did it go into the shop for?

XxDarkEuphoriaxX · « **Reply #4 on:** August 12, 2009, 04:36:32 PM »

it went into the shop for new tires and chain and carb adjustment... it is a good shop according to many people...

it wasn't doing this at the shop...

it only did this after running around the house 5 or 6 times...

mlinder · « **Reply #5 on:** August 12, 2009, 04:43:27 PM »

OK, start at the beginning:

First, get a petcock.

Have you:
Checked to make sure it's firing on all 4?
Checked for carb boot air-leaks?
Made sure there is fuel in all 4 carb bowls?
Checked for spark on all 4 plugs?

cleaned carbs?
synched carbs?
adjusted cam chain?
adjusted valve clearances?
Checked and adjusted points?

XxDarkEuphoriaxX · « **Reply #6 on:** August 12, 2009, 04:50:46 PM »

with the tank I have, it can never have the original style petcock installed...

haven't done a lot of the things listed below... will need to..
edit: carbs have been cleaned and synched...
will adjusting the cam chain possibly fix the problem?

mlinder · « **Reply #7 on:** August 12, 2009, 05:02:57 PM »

You need a petcock. Figure out how to put one on.

Synching carbs without completing all the other things on the list is a fruitless and pointless.

Again, have you checked to make sure it's firing on all 4?
Have you checked for carb boot leaks?

Adjusting the cam chain alone will not help you.
You need to do ALL of these.
You cannot even begin to trouble shoot until all these things are done, and chances are, you wont NEED to troubleshoot after all these things are done.

XxDarkEuphoriaxX · « **Reply #8 on:** August 12, 2009, 05:17:28 PM »

OK dad just pointed out that the two left exhaust pipes looking at the bike from the front are considerably cooler, BUT STILL HOT, than the 2 right exhaust pipes, I mean u can touch the 2 left ones but cant at all touch the 2 right ones :0

update: actually u can rest your hand on the 2 left ones without getting burned...

mlinder · « **Reply #9 on:** August 12, 2009, 05:22:18 PM »

You are firing on 2 on a 350cc 4.

That's your power loss problem.

So, now you need to check WHY.

Are you getting spark on those plugs? (3 and 4)
Is there fuel in the bowls of those?

XxDarkEuphoriaxX · « **Reply #10 on:** August 12, 2009, 05:47:45 PM »

the 2 plugs that were on the sides with the hot pipes were sparking and not very black but slightly....

the 2 on the cold pipes were very black looking and sometimes sparked but not nearly as much as the other side...mabe once or twice and thats it...

could it be due to the carbon? perhaps I should get yet another set of spark plugs and try it again? I cleaned the points once... could one of them have gone out?

fuel rapidly flowed out of all of the float bowls when the screws were undone enough to come out of the hole where the screw went in...

not thru the overflow tubes, that arent original but clear flimsy ones.. would it hurt to remove them completely? or just have short ones where the fuel flowed on the engine if fuel was to flow out of the carbs? this would only be done before storage once a year...

thx adam

XxDarkEuphoriaxX · « **Reply #11 on:** August 12, 2009, 05:55:04 PM »

well i switched the boot or spark plug, since I cant remember

and the OPPOSITE PIPE GOT HOT
so its either the spark plug or more likely the spark plug boot... hrm

XxDarkEuphoriaxX · « **Reply #12 on:** August 12, 2009, 06:00:54 PM »

just switched the boot from a hot pipe to a non hot pipe and there was no difference?

it may be the spark plug then even tho they r new? they are NGK's

Zaipai · « **Reply #13 on:** August 12, 2009, 06:06:19 PM »

Just a thought, I had a very similar thing on my 4, turns out that the points for the two that were not getting good spark were grounded, simply put the wires on the points correctly fixed it. GL hope you get it going.

XxDarkEuphoriaxX · « **Reply #14 on:** August 12, 2009, 06:19:18 PM »

switched boots no result switched plugs opposite pipes hot

hrm? the plug that i originally thought was bad started working ...

i dont get it?

XxDarkEuphoriaxX · « **Reply #15 on:** August 12, 2009, 06:25:29 PM »

what do u mean put the wires on the points

Zaipai · « **Reply #16 on:** August 12, 2009, 06:48:21 PM »

Well I am not sure this is your problem, but it sounds very much like mine. Anyway here is a picture of how the wires on the points should be, note that the wires are protected from the metal by non metal washers.. This is from a CB550 so not sure yours is setup this way, but the idea is the same. One way to tell if the points are shorting out is run the bike for a few minutes, then feel the coil, if the points are shorting out the coil(s) will be warm/hot to the touch.

Thanks to Hondaman for the image..

XxDarkEuphoriaxX · « **Reply #17 on:** August 12, 2009, 06:57:09 PM »

are the brown things the non metal washers

tomsweb1 · « **Reply #18 on:** August 12, 2009, 09:06:41 PM »

it sounds to me like the black plugs are fouled. Clean them with a wire brush, and sandpaper, they might work fine. This is caused by too much fuel in the cylinder. Check your float heights.

XxDarkEuphoriaxX · « **Reply #19 on:** August 12, 2009, 09:26:08 PM »

the guy at the shop was supposed to adjust all of this...
dont rly know how to adjust float heights but I guess I can find out somewhere....i am going to put all new champion plugs in per recommendation and if that doesn't work, then new spark plug boots, they are probably worn out anyway, then go from there.

btw. a new air filter was put in from the original when I got the bike home, and the problem did occur after that but not directly after that...mabe something is really out of whack... we will have to see I guess

Zaipai · « **Reply #20 on:** August 12, 2009, 09:31:34 PM »

Sounds like a solid plan. Let us know how it goes... GL we hope you get it figured out.

mlinder · « **Reply #21 on:** August 12, 2009, 09:45:54 PM »

OK, it's not coils or points.
1 and 4 (the two on the outside) run off the same coil, as well as the same point.
Same thing with 2 and 3. If the coil or points were bad on one, then 1 and 4 or 2 and 3 would not be firing.
Just for #$%*s and giggles, make sure the coil on the LEFT has a plug going to cylinders 1 and 4, and the coil on the RIGHT has plugs going to cylinders 2 and 3.
This is with you sitting on the bike (for left and right.)
So, now buy new spark plugs. Install them. Check to see if it runs better. Remember to turn the choke off after it warms up, otherwise it will run like #$%* and foul your plugs and thgen run like worse #$%*.
Also, go ahead and check for spark on all 4 BEFORE you start running it (that is, once you've replaced the spark plugs. Remember, spark plugs are cheap, and cleaning them once they've been fouled never seems to work well.)

XxDarkEuphoriaxX · « **Reply #22 on:** August 13, 2009, 06:12:16 AM »

one thing with the choke, every time I turn it on the bike dies....

mlinder · « **Reply #23 on:** August 13, 2009, 06:19:58 AM »

Are you saing it does not require the choke to start when the engine is cold?

XxDarkEuphoriaxX · « **Reply #24 on:** August 13, 2009, 10:30:28 AM »

yes, I would say it does'nt require choke, when I turn the choke on the bike boggs down and dies...

also put 4 new NKG spark plugs in, and now it runs on all 4 cly. has more power than before by far but still seems "slow"
mabe because it is just 350cc. btw it hasn't been ridden more than a mile so far and only up to 45 or so down the road... it has been at least 15 years since it has seen the road. does it need to be "broken in"

also it idles way high, the tach is broke BUT i can definately tell it idles high. i turned the screw counter clockwise on the right hand side of the bike all the way out and it still idles high.

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Author Topic: CB350F acts like its getting no gas and loss of power (Read 4161 times)