Honda Twins banner
1 - 20 of 20 Posts

·
Registered
Joined
·
240 Posts
Discussion Starter · #1 ·
It's a 1971 CB450. I was riding it one day and it just died in my friveway. After trying to restart it the rectifier green wire burned up. I have replaced it as well as cleaned up the ground connection on the battery as well as the positive. I also replaced the condensor and points just becuase. I fired it up and went for a short spin. It was running great then it started acting like it was running out of gas. then started popping and running like crap. carbs are great and float levels and jets are fine. When I pulled in the garage I tested for spark and had none on either coil. After messing with some wiring I got the right side coil but the left side was coming up bad. New Dyna coils ordered and installed. Fired right up and sounded great. Took off down the road and almost in the same spot it started popping and acting like it was running off of one cylinder and running out of gas. I am completly stumped. Everything dealing with the ignition is new and the only thing I have not donw is the timing. But the timing wouldn't go out like that progressively. Any ideas would be great. Thanks. :x
 

·
Premium Member
Joined
·
5,610 Posts
Have you checked everything fuel related? You mentioned floats and jets are fine, but I'm wondering if they are getting fuel. Any line kinks, blockages? Petcock turned on and functioning. Also, is the tank vent blocked? Mine was blocked once and it ran like you state. How long after starting do the problems begin?

Hows the compression and valve clearances?

Also, is the air filter clean.
 

·
Sensei
Joined
·
27,183 Posts
Sounds like a fuel supply problem to me too..... I'd now guess the cap vent, and/or the petcock being partially blocked by rust or other "mung" inside the tank, etc....
 

·
Registered
Joined
·
240 Posts
Discussion Starter · #4 ·
I thought the same thing about fuel related but it happens about 1/16 of a mile away from home. Once it starts running like crap I take it home and I pulled out the plugs and sometimes they aren't even firing. It is just too wierd because it was running great but then it burned up the rectifier. Replaced that and still running like crap. Is there anything that could cause coils to misfire or be sporratic? Float levels are at 20mm valves are adjusted properly and compression is slightly low on the right side but normal on the right. Both are ok but coming close to needing rings. It's more frustrating because theres only maybe 2 months of riding left before I plan on tearing it down to paint and clean as well as put a custom cafe seat and rearsets on. :evil:
 

·
Registered
Joined
·
240 Posts
Discussion Starter · #5 ·
Oh yeah... to check the vent cap could I just ride with the cap open to check it? Thanks.
 

·
Registered
Joined
·
3,926 Posts
Before trying that just make sure you got a real nice long and smooth stretch of road in front of ya!! ;)


GB :mrgreen:
 

·
Sensei
Joined
·
27,183 Posts
Dirty or corroded contacts inside the "kill" switch can cause sporadic coil/plug firings. So can a weak battery, bad grounds, bad coils, dirty points, loose wiring connections etc, etc.... You will just have to fix/eliminate one possability at a time until it is cured... We all go through this type of frustrations to get our bikes running right....
 

·
Registered
Joined
·
240 Posts
Discussion Starter · #9 ·
I even thought about bypassing the kill switch to see if its the cause. The coild points condensor etc are all new so I know they are good. Back to the drawing board.
 

·
Premium Member
Joined
·
5,610 Posts
I sort of have the kill switch bypassed on my KZ. Most of the KZ guys mod their bike to use a relay instead. The kill switch just powers the relay and so the coils get more direct juice and bypass another connection and possible source of issues.

Its often referred to the WiredGeorge Coil Mod. I did it on mine and it increased the power getting to the coils. Only cost a couple of dollars (bit of wire, relay and inline fuse). I'll do it on any bike I get.

Here's a link: http://www.wgcarbs.com/index.php?option=com_content&task=view&id=12&Itemid=26
 

·
Registered
Joined
·
6,495 Posts

·
Sensei
Joined
·
27,183 Posts
Bill, I mentioned the battery at least twice, as have others..... Originally, I thought that whatever "short" caused the rectifier ground to "fry" was responsable....It could have damaged the battery, but it is just as likely it shorted the rectifier diodes and the current can now flow both ways, "killing" the battery's charge quickly when it's running or "on".......
Problem is, he keeps coming up with "other" somewhat unrelated (to the battery)symptoms....... Wish I could "hold" a meter to his wiring/components from here....
 

·
Registered
Joined
·
6,495 Posts
66Sprint said:
Bill, I mentioned the battery at least twice, as have others......
I know, that's why I asked if he ever actually tried any of the suggestions........
 

·
Registered
Joined
·
240 Posts
Discussion Starter · #14 ·
I have checked and tried everything that 66 suggested. The only thing that hasn't been done is the timing. I'm going to do that on Sunday. So here is what happened. As 66 stated I had a grounding wire that I found in the headlight. That was the initial cause of the rectifier. Once that was corrected a coil had gone bad. Possibly because of the short. While doing the coils points and condensor I had a new carb rebuild kit that I went ahead and threw in. Yesterday I found out that the right side carb wasn't getting enough fuel in the bowl due to a part in the rebuild kit. I changed back to the original parts and cleaned the kill switch connection and as soon as I was going to take it for a test spin I ran out of gas. What a bummer that was. Battery is new by the way. So keep your fingers crossed but it might be fixed. I think I just kept looking at electrical issues because I suck so badly at diagnosing those problems and was frustrated instead of checking the carb too. Thanks again for the help.
 

·
Registered
Joined
·
240 Posts
Discussion Starter · #16 ·
I took it for a spin today. Ran like a champ. I went 15 miles with no real problems other than a slight leak on the left side carb. I think the problem is solved finally. Thanks again for all the help and I would love to post pics but cannot figure out how. Once I do I will send before and afters.
 

·
Registered
Joined
·
240 Posts
Discussion Starter · #17 ·
Timed it up and everything seems fine. The only thing that differed was the right side lit up when it was suposed to but it was on the low side of the cam gear so there was no gap. I am assuming that since they were gapped properly before timing it and the fact that it lit up when it was supposed to and the gap is good when it comes up on the gear that all is good. We shall see if all is good tomorrow. :D
 

·
Sensei
Joined
·
27,183 Posts
Assuming you set the point gaps at their respective "widest" openings,
locked down the points plate when the left point was correctly timed, and ADJUSTED the right side point GAP to achieve correct timing on it, you should re-check the gaps at their respective "widest" openings to see if they are still within specs....
IF they are, you are fine... IF NOT, you have to start the timing over, adjusting the left sides initial GAP to compensate for the discrepancy in the final right side gap.... BOTH must fall within specs when the timing is finished, but they do NOT have to be exactly the same gap...just both within the range....However, BOTH sets of points MUST open EXACTLY at their respective index alignments.......
 

·
Registered
Joined
·
6,495 Posts
owdskl said:
Timed it up and everything seems fine. The only thing that differed was the right side lit up when it was suposed to but it was on the low side of the cam gear so there was no gap. I am assuming that since they were gapped properly before timing it and the fact that it lit up when it was supposed to and the gap is good when it comes up on the gear that all is good. We shall see if all is good tomorrow. :D
If there was no gap, the light wouldn't come on - the juice would rather go to ground through the points instead of through the light bulb (easier).
Something is amiss........
 

·
Registered
Joined
·
240 Posts
Discussion Starter · #20 ·
There was a very small gap just not full gap. I rode for 45 miles today and other than a little carb syncing (I have a small exhaust leak since one muffler clamp needs to be replaced but having a hard time finding one) all is good. Once I figure the pic thing out I wil post.
 
1 - 20 of 20 Posts
Top