Fixed Bike and it runs but you won't believe what was wrong!!!

OK so I need some help to diagnose an issue, or at least a starting point. Need to fix it by Friday to sell it to get to barber.

1982 CB450T Honda. Was running super fine but the headlight was flickering on and off. Traced all the wires and cleaned everything and found out the filiment was broken but not burned otu so it was on and off. New bulb, fixed it.

Now went to start it up and it won't fire??? What I checked so far:
Fuses all good
Petcock flows fuel, fuel in carb bowls
changed oil as it was milky
check valves, in spec no issues there
charging battery as we speak.
pulled plugs and have spark at each when I hit the starter button
Put new plugs in too as the ones in the bike were pretty old and worn
I don't have a compression tester but did the thumb over hole trick and it blows off so there is enough to run at least.


So my guess is fuel or carbs, but what could change for this to happen all of a sudden?
Bike just turns over and over without a hint of firing?

It is a CDI bike, one coil with 2 wires, could the CDI fail yet still give spark? I am going to pull the carbs tonight to make sure there is nothing funny there but I am kind of stumped.

Any help would be much appreciated, What might I be missing?

Re: Fixed Headlight, now bike won't run?

Did you make sure when you were checking everything that you put the right wires back on the right plugs?

Re: Fixed Headlight, now bike won't run?

Have you tried it with the headlight unplugged?

Will it try to catch with a squirt of starting fluid?

If you were in the headlight, it is possible that something got unplugged/crossed/pinched in there.

I feel for ya, man. You seem to be getting squeezed from all sides this week...

Re: Fixed Headlight, now bike won't run?

Yep but I will double check that again. Every bloody wire does run through the headlight bucket. or at least it seems to. It seems like the kill switch is off so I will check that curcuit to make sure everything is good.

Re: Fixed Headlight, now bike won't run?

Plus on on flatcurve, also check to make sure your ground is connected well. Believe it or not, most 12v problems is bad connections and everyone always forgets about the ground cause it doesn't zap you haha!

Re: Fixed Headlight, now bike won't run?

I am going to get in there at lunch and see if anything is a miss. Funny thing is though I have spark at the plugs, whether it is at the right time may be in question and handled by the CDI. I do have a spare so while I am at it I will swap it out.

Funny thing is I tried to sell this bike one other time when we were hard up for cash and that is when the cam tensioner broke and I stripped the head bolts trying to replace it and then ended up getting some overtime and got the bills paid so got to keep the bike and found a new motor for less than the cost of fixing the stripped head bolts. It's like if I try to sell it, it goes to hell on me.

Re: Fixed Headlight, now bike won't run?

flatcurve said:

Did you make sure when you were checking everything that you put the right wires back on the right plugs?

Click to expand...

Pretty sure I am ok on this, I only ever disconnect one wire at a time, clean it an put it back in the plug before doing another, that way stuff stays where it should be.

Re: Fixed Headlight, now bike won't run?

I should also mention the bike did run for a few minutes right after the headlight was fixed, I shut it off and then had the above problems about an hour later after I changed the oil etc.

Re: Fixed Headlight, now bike won't run?

maybe a needle is stuck all of a sudden or got a piece of trash in the line starving it for gas? I'm just brainstorming here..

Re: Fixed Headlight, now bike won't run?

ronnie said:

maybe a needle is stuck all of a sudden or got a piece of trash in the line starving it for gas? I'm just brainstorming here..

Click to expand...

That's what I am looking for, I have a short window of time and any logical or weird places people have experianced can help me get to the issue quicker. I was able last night to check the petcock, it flows fine, drain the float bowls and they both had lots of gas. So if it is fule it must be after that meaning clogged jets etc.

it just isn't even sounding like it will start. it is like I am hitting the starter with the kill switch off, you know when you forget to look at it then sit there for 2-3 tomes hitting the starter and nothing but the motor turning, then you go Shit, flick it and it fires right up, that is what I got only the kill switch is ok.

Re: Fixed Headlight, now bike won't run?

Went home at lunch and pulled carbs, clean as a wistle and full of fuel. Not the problem. I have a suspision, right after I fired the bike with the fixed headlight, the cam chain was a bit noisey so as the bike was idling per the procedure in the manual I have done a few times in the past, I loosend the tensioner bolt, let the chain slack a bit then when it gets quiet, tighten the bolt back up. The bike stalled during this process, I figured I didn't have it warm enough but I had tightened up the bolt so I figued it was fine, I then got called into the house and I shut off the key and went inside, then after the honey do list was done I went back out to fire up the bike and take it for a ride and found the no fire problem. I wonder if I loosened the tension too much and the chain jumped off the pully? I will have to pull the valve cover again and check the timing marks, has that ever happened to anyone?

Re: Fixed Headlight, now bike won't run?

Did you run the bike with the tensioner not tightened down? If so, that sounds likely. A compression check (or, even better, a leak down check) should tell you if the valve timing is significantly off.

Re: Fixed Headlight, now bike won't run?

yes I did as the tightener is spring loaded, so at idle, you loosed the retaining nut, then it gets loud, then the spring pulls it and tightenes it to the right tension then it gets quiet and you snug the nut. I may have over loosened the nut. I know better but I was in a bit of a hurry and going over everything to figure out wht might have happened, the bike may have stalled because it jumped and the timing went off. So I am going to pull the valve cover and look at the marks, it is easy enough to check if they line up. If they don't I will loosen the tensioner and move the cam gear back to where it should be, at least I hope if it could jump, it shoudl go back. I can remove the head if I have to while the engine is in the bike but I would rather not have too.

Re: Fixed Headlight, now bike won't run?

For what it's worth, my manual doesn't say anything about running the engine with the tensioner bolt loosened.

It just says to loosen then bolt and then retighten it.

Re: Fixed Headlight, now bike won't run?

I got the clymners and it may be stupid. However the local old honda shop does it that way, with the bike running at idle.

OK, went out pulled the valve cover, checked timing per the manual, way the fuck off holy hell like 6 teeth! How the F did that happen, well I am about to try to figure out how to fix it and i am lining up the stator marks to get the "T" on the mark then figure out how to move the cam and chain to get the line right again, well I go a bit past, but I got the plugs out etc so I just back it up a bit, then I notice the stator moved but the cam gear didn't? so I back it up a bit more, then forward, timing is closer, WTF so back and forward until everything lines up? do 4-5 rotations forward and all is well, timing is staying put, I say ok, put the valve cover back on, tighten up everything I need to, cross fingers, open petcock, pull choke, hit starter, vroom! OK no funny noises, let her warm up while I get my helmet and jacket, go for a ride take it easy for a few minutes, everything is ok so far, hit a straight, open her up, take her to 9500 RPM, shift, do it again, get to 75 mph, back off cause that it about 40 0ver the limit, ride her for a bit more and everything is fine. It had to have happened when I did the cam chain tensioner, not ever going to do that while running, I will do it manually turning the engine over. Well the bike is running well again, has a new light, new plugs, new oil, valves set so it is ready fro a new owner.

Few, feel better now but not sure why it happened.