Honda Cb450 NH engine problem?

[Exabes]

I took it for a ride, after a few seconds driving the old problem returned. (still got the wires hanging loose in the headlamp unit). When i open my throttle, rpm goes down. Stationary it will run, but when u drive and open the throttle it will die out. At least it started for a moment..

[Laminar]

What is the voltage across your battery at rest (engine off), idle, 2000rpm, and 5000rpm?

[coffee_brake]

It looks bad in that headlight bucket, Exabes.

I can only assume you have re-grounded a loose connection in the headlight bucket, OR you have wiggled a wire to close a short--and that short WILL return.

If my wiring looked like that, I would take each connection apart, one at a time, and clean it thoroughly, and put it back. And, if your 450 has some grounds through the headlight bucket (this is common), I would take off the headlight and clean the inside of the bucket so the grounds will have clean metal for connections.

[jerjohn]

Well we got the bike started. Do you have aftermarket blinkers? Use the wiring diagram in the back of the clymers to sort the connections out. Like coffe said, unhook each connection and reconnect, you may want to put some dielectric grease in the connections for better conduction. I know its a rats nest in the bucket, i hate that honda put so much wiring in the bucket. I took my time and went through every thing in an afternoon.

As for the engine running badly, have you checked your accelerator pump?

[Exabes]

Haven't check the pump. The headlight looks indeed a bit messy and rusty on the inside. I took off the ground but the connection points were perfectly clean. I got myself some new bougies, gonna try those on.

[Exabes]

I've put in the new spark plugs, the engine started right away and it ran really good when not clutched in or driving. When i drove a bite, again, the engine started to struggle again. When i open the throttle a bit the rpms go down after switching gears. This happened 2 or 3 times and then it died out again.. Still no clue what it could be..

[coffee_brake]

Ya'll think the floats are set wrong?

[SirSeanSean]

I know this might be a long shot; but, how is your choke?

[jerjohn]

Check your accelerator pump. The purpose of an accelerator pump is to provide more fuel into the mix right off the throttle. When a throttle is opened airflow increases immediately but fuel ( which is more dense) does not. The accelerator pump is used to balance the mix. I had this same issue on my 450, it was so bad that if I opened the throttle too quickly while driving the bike would stall. I was forced to open the throttle slowly to accelerate. Turns out the rubber diaphram on my pump had small holes in it, thus preventing the pump from enriching the mix. If the diaphram is good then check the length of the pump rod and the gap between the rod and the throttle plate. The manual has the specs, something like 1-1.5mm but check that.

The floats on the 450 are not adjustable but can go bad. Ebay is your friend.

[Exabes]

I use my choke to fire it up, let it run for a few minutes, open the throttle a bit and i can switch off the choke. Rpm's go down like they should then and the engine runs smooth.

About the accelerator pump, i am able to drive the bike, and when i open the throttle he reacts right away, very quick. But when i keep on driving the engine will die out. Could still the accelerator pump not be working a 100%?

Another question, when i opened the drain screw on my carbs the other day to check, i found a screw right on the bottom of each carb-bowl. They have some kind of fin so your able to twist them one round before the fin hits an obstacle. You can open something up or close it with a max of 1 turn, does anyone know where this is for?

[coffee_brake]

This is your idle adjust screw. This is how much air and fuel get mixed together. It is also the passageway most likely to be clogged up first. The bike will never run right IF it's dirty.
But your bike was running fine and the problem came on pretty suddenly.

When your bike stops running, you say it "dies out." It does this slowly, like it struggles for a few seconds, then quits?
Or, does it very suddenly just turn off?

If it is struggling and then shutting off, I think it is still fuel related. Nobody has touched the inside of these carbs, so I don't think it is the floats out of adjustment.

These carbs have not been removed from the bike recently, right?

I am inclined to check every possible way that fuel could not be reaching the carbs in sufficient quantities.
The gas cap has a vent that can become clogged. Can you ride the bike with the gas cap left open?
If there is rust in the tank, it can clog up the filter in the petcock. Can you pull off the tank, and then pull off the petcock, and verify that the filter is not all nasty?
If the fuel line is old, it can flake apart inside, or it can crimp, and block flow. Can you pull off the fuel line and replace it or verify that it is in excellent condition?
If the vacuum line (the smaller hose from the petcock) is not hooked up, the bike will have trouble running. Can you check that it is hooked up right?
If an in-line fuel filter is installed, it may be too small or clogged. This will be some kind of plastic thing in your fuel line, usually it is clear, or it is a whitish or brownish cylinder right on the fuel line. Do you have one of these?

Can you look at these things and tell us what you have?

[Exabes]

I see, both idle screws are opened up max and indeed it runs. So that should be no problem. I am now trying to find someone for tomorrow or anytime soon to help me check the whole fuel system because today i also filled it up to 75% to be absolutely sure i had enough fuel. It's nice to have someone around who know how to drain everything and properly check it.

I checked the ventilation on the gas cap (closing it and blowing through it) and it seems fine and in good shape.

I made a small video about how it runs at the moment. Maybe this clarifies the situation a bit more.
http://s1158.photobucket.com/albums/p609/Exabes/?action=view&current=Startingup.mp4

[coffee_brake]

I can't go much farther until the questions above have been answered. Seems like it idles OK.

[jerjohn]

Your accelerator pump is fine.

When was the last time these carbs were cleaned?

[Exabes]

I have the motor a few months now (5 months max) i did not clean them. Don't know when it's done the last time.. Anyway i'm working on the list posted above, thnx.

[Brittles]

First and easiest would be to add 2 oz of Seafoam per gallon of gas and ride it. You need to adjust the idle with the bike fully warm. Looked to me like the idle was dropping too low at the end of the video.

[SirSeanSean]

+1 on the Seafoam. It might be possible that some of your jets are clogged. The Seafoam might be able to do a lot on its own. Though, you might want to still take apart the carbs and do an inspection. Even if your carbs have gas going into the bowls, it's not going anywhere without clear jets.

[seeltoe]

Does playing with different choke settings keep it running well?  I have a 1985 CB450SC and I keep it half choked for at least 5 minutes of riding until the carbs are warm enough to push in the choke.

[Exabes]

Yes, as you can see in the movie i posted, rpm goes down as i stop using the choke.
I looked on the website of sea foam, but since i live in Europe i can't seem to just buy it somewhere.
Is this a carb cleaner that you mix with your fuel? And are there alternatives or do you guys really recommend sea foam?

[SirSeanSean]

Yes, it's a fuel additive. I can't think of anything that is a substitute for it. Maybe go to your local auto parts store and see if they might be able to show you some alternatives.

[Exabes]

This afternoon i added carb cleaner in my fuel, i let i ran for 15 mins and turned it off. Later in the afternoon i drove the bike without any problem!!! It seems to be just fine at the moment!
I don't dare to drive big distances yet, i will need to start driving a bit further every time.
Thank you guys so much for helping me out last weeks, i learned a lot about the bike which is really useful. Thanks again!!