'71 cb450 won't start

CThor said:
I was looking at this battery. Should be plenty small to fit under the seat hump. Anyone know if its got enough juice for the starter?

http://www.gotbatteries.com/items.asp?params=batteries/SLA/1/Powersonic/PSH-1255/PSH-1255F2/SL118/35L118S5
Click to expand...

barely, from what i have been researching on battery,s an 8ah or 12 ah would be better if you are wanting to use the electric leg most of the time

check out your local auto parts store, i know advanced auto has motorcycle battery,s i just bought one there today for $30, i can get you the model number if you want
 
Well I think I found a battery to get today at Batteries plus. Its a 10.5 amp. I finally just got the tracking number for my seat just now and that will be here thursday. So I'll wait til then to see if the battery will work. Then I can get back to checking stuff out.
 
Ok so I'm back to the starting issue. I got my new battery hooked up and it turns over. I'm not getting any spark though at the plugs... Would that be something up with the coils? Can someone tell me how to check them? I have a multimeter. Or if there is something else I need to check.

Thanks
 
Ok not sure if it was right but I checked the black with white stripe just before the coils. It was getting about 1 volt with the switch off and about 13 with the switch on. So I'm thinking that the switch is ok then. Still no spark at the plug wires.
 
So I did a little more research online and found that I needed to check the points. They weren't sparking at all. So I cleaned them up and adjusted one of them. Then I got spark and was getting spark at the plugs too. Guess I'll get some fuel in it tomorrow and see if I can get it fired up.
 
good thread, i;ve been going through all this stuff today on my cb350. i'll keep an eye on this for hints
 
can i hijack the thread now? ;)

i've got a cb350, which when i got it, started, but would only run very roughly at near WOT, and had a rattly cam chain. motor was dissasembled to replace cam chain tensioner. carbs were diassembled and cleaned, new stock jets were put in.
now i'm trying to start it, starter motor turns the engine over, and i can feel cool air pulses coming out the exhaust. i pulled the points cover off because i thought i should be able to see the sparks at night, but didn't see anything. at the moment i majorly suspect it's the timing which is the thing stopping it from starting, but it's pretty much a dark art, though i have found some good guides online.
i've also got a mystery green wire in my loose parts, about 20cms long male bullet point to eye connector. i think it may connect to the battery and then to the mi(U)ddle of the wiring harness... it could also be off the indicators i removed as well. can't remember,

i've got a friend coming round tomorrow and we're gonna buy all the stuff we think we'll need and then get to work.
-i'm going to clean and reset the points,
-trim and recap the spark wires,
-replace the fuel lines with clear lines and inline filters
-pull the carbs and check float level and jet positions
-get new spark plugs


anything else i should do at the same time?
 
The only green wire in my harness that has an eyelet on one end goes to the negative of the battery. Otherwise sounds like your list is pretty much all the stuff I went through and got mine going. My points were getting any spark until I cleaned them up and had to adjust one of them. It fired up after that. I replaced the plugs and caps after that just to have new and one of my caps was ripped pretty bad. Good Luck!!
 
so kinda got a result. cleaned the contact breaker, got spark, replaced all that stuff mentioned previously. then removed the inline filters because they weren't flowing enough fuel. went out and bought more fuel line...

it runs on the right cylinder at open throttle quite slowly, nothing on the left.. both are getting spark, probably getting fuel, i assume compression or valve leakage because the air pulsing out the LHS exhaust is significantly less. before i pull the head and jugs and pay someone to do those, is there anything else i can do to get it running well on the right cylinder?
adjusting the timing got it working, but the point plate is rotated as far to the right as possible, which seems to be getting near the correct timing, but not close enough to run properly. i remember hearing that something in the timing could be reinstalled backwards, how do i check this is not the case?
not really sure what to do about the carbs in regards to adjustment, i guess it could be too rich./lean, i haven't checked float level either, but i figure there's other issues at hand that are more likely to be causing problems..
 
When I got mine running at first only the right cylinder was running. My dad suggested pulling the left side plug and then put a little gas in the cylinder and replace plug. Then try starting it again. If the left side fires then, you know its getting spark and the problem is not getting fuel from the carb. Thats what it was in my case. Since I didn't have my tank on and had just filled the carbs up through their fuel lines. I didn't realize that the way the left fuel line was I didn't even get any fuel into it. Once it was fuel of fuel it started right up and idled pretty good even.
 
my cb450 was a one lunger for a while and with the help from this here forum, they suggested syncing the carbs, i did and it works on both cylinders, so try syncing the carbs :)
 
yeah, I would exhaust all carb and timing issues before pulling the motor apart. Adjust the float bowls. Sync the carbs. Make sure the plugs are gapped correctly. Getting spark? Coils working properly?
 
plugs are gapped, getting spark against the side of the engine, cv carbs can't be synced i have heard?
i guess i should do a compression test, but i don't have a gauge.
i've got a lead on a cheap motor, might get that and switch it in, see if it's better, i need some parts off it anyway.
i'll try putting some fuel in the cylinder today, and write back with results.
 
They can be synced, just not with a vacuum gage. Well, it's as close to syncing as we can get without adding pressure taps and it really helped my bike. I'll see if I can find the procedure.
 
this is the procedure i used to sync the carbs on my 450

http://www.hondatwins.net/forum/viewtopic.php?f=29&t=537

it got both cylinders running :D
 
i gave the sync a shot, i didn't need to adjust them much. then i dropped some gas in the cylinder, and tried starting it, no noticeable difference, i know that cylinder is getting spark, and visibly it's the same as the spark on the other side, and i'm still thinking it's compression related. i pulled the motor, and pulled the head off, upside down i poured petrol in the chambers. after about 5 minutes the fuel level had dropped by a centimetre, after about 10 minutes it was level with the centre of the valve. does this sound like a leak? i'm not sure what speed of fuel loss would be acceptable.
the other thing is, it could be the piston rings. there are no lines or markings on the cylinder walls, it's smooth like a mirror, so i thought they would be fine, but seeing as i'm here already... how do i measure the cylinder to find out what size rings i need to buy?

my little brother just bought a '79 kawasaki z200 on ebay, i'll pick it up this week, so at least i'll have a bike to ride on the road, at least till he gets his license. he seems keen to pull it apart and modify it, but i'm talking him out of it, ;) until mine is on the road
 
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