QuestionHey Chris,
The Tank Was Replaced before anything was done. I also got two used coils, plugs, relays, carb boots. I have not changed the oil as I have been waiting to warm up the engine a little first. The CDI was the only part that I have been hunting for but since there seem to be a limited number of cb450s on ebay...
The next steps that i have been considering has been pulling the carbs and inspection them, needle jets, floats, etc... It has KEIHIN duo carbs which I haven't been able to find any info on. (I had a book but it is still at the Pro's place. Each carb has a small knotched screw on the bottom (possible idle adjust), and a large screw between the two (possible fuel flow adjust) which were the ones I tinkered with to get it to run at high rpm. Unfortunately I live in upstate NY so the weather is stating to bottom out and my intention was to pull the bike into the basement but with the fumes, black and white smoke I want to continue with trying to get it to run out side before pulling inside. My hope is that It is all just carb.
I am not familiar with the Stator coil but I hope to put the back and try again
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Thanks for the quick response, this is a follow up based on a little tinkering I did this morning. The bike once again started fine but idled ruff (sputtering) and needed to have the throttle opened full to keep it from stalling which it ultimately did several times. I Checked the spark plugs and there was oil deposits on the plugs. (To back track, when I got the bike, The original tank was filled with water and the rusty goo dripping from the feeder hose in the area of the left spark plug. The small engine guy put alittle oil in the cylinder in case there was rust/corrosion inside the engine. A technique that I have also seen suggested in the winterization of a bike. This I believe is why white smoke billowed out of the exhust pipes as it ran.) I started to play with the knobe on the carb and to my surprise the engine jumped up in RPMs and billowed black smoke before whinding down and stalling after i released the throttle. This happened twice and then the old girl refused to start. The effect was like the battery was dischared, a simple click and all the lights went off until the starter button was released. Satisfyed that more progress had been made today then any other point in since i've gotten her I stopped there and put the battery on for a trickle charge.
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Greetings, I'm a new cycle hobbyist with better then novice mechanic skills. I have been restoring a nighthawk with the help of a small engine pro who helped to rebuild the carbs, check the timing (lifters) and spark. Although there was a weak spark issue and intermittent firing issue which was self correcting, We got the sucker to start and fire on both cylinders however the idle was always rough and the throttle would have to be held opened all the way to keep it from stalling. Usually the engine would start to stall faster as the exhaust heated up. I have since lost the aid of my pro who said the carbs needed to be tuned but the problem seems to be more then just a tune . I think that there is a fuel starvation problem to and/or weak spark problem. Please help.
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Hi Mike.
Start with the weak spark issue. It could be a short in the system or a failing component.
Get the repair manual out and start by checking the ignition system from power to plugs and make sure that there are no shorts or faulty components. The manual will have testing specs for the coils.
If it is related to the ignition system, a worst case scenario would be the CDI box failing. They are not known to just fail like that, but it can happen.
Also make sure that the exhaust headers are secured properly to the heads. A loose pipe can cause similar issues as well.
Start with that and let me know what happens.
Good luck and ride safe.
FALCON
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Hi again, Mike.
During the restoration process, was the tank cleaned and resealed? If not, then do that immediately. It may not be the only problem, but it would definitely be a HUGE contributor.
Next, I think that the carbs may not be set for the correct idle, so set the idle up a bit and start the bike. If it does not idle like it should, then adjust it accordingly. It may require multiple starts to do it.
Next you will need to check the stator coil output to see if the battery is charging properly when the bike is running.
The battery could be discharging completely if the stator is bad. It sounds like that could be a very real issue.
Let me know what happens.
Good luck and ride safe.
FALCON
AnswerHi Mike.
Used parts are a very dicey proposition. Particularly when they are electrical or electronic. You are always better off with new ones.
As far as the screws on the carbs, the one between the two carbs is the idle adjustment. If I am understanding your description correctly, the one on each of the carbs may be mixture. If that is the case, then those need to be reset to correct factory setting (or as close as possible) before trying anything else.
Go ahead and change the oil anyway. If you have a couple of space heaters, then set them up near the engine to warm it up to a reasonable temp and then change the oil.
Good luck and ride safe.
FALCON
