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Klongstreath
03-07-2016, 7:14 PM
Alright first off sorry if this topic has been touched alot. I have searched and found alot of links that did not work anymore or stuff i wasnt looking for. Now iv had a 79 cb650 that i built into a bobber a few years ago. And now i wanna build another one thats better. So im looking at a 1982 cb650 tommorow at a local shop next to my work. They said in the clist ad that it did not run and is a project. Its all original. Priced at 600$. Hopefully that negotiable. Now iv read on some of the starting issues with thes 80-82 bikes. Im not sure if its electrical or the carbs. Just said it doesnt start. Now if its electrical whats the easiest fix? Iv read the coils were junk and its better to convert to a cb900 coil system? What does this involve? Or should i just clean the carbs, buy new plugs, wires and new replacement coils? And see if i can get it to run that way? Now im just taking a guess sight unseen on what the issue is, i know it could be a number of different things. I havent talked to them yet, ill ask tommorow why it doesn't run and what they think it is. But id like to buy it, and get it running then start building a bobber so i can ride in the next two months. Thanks for any help.

PeteyD13
03-08-2016, 7:27 AM
"Won't start" is about as vague a description as you can get. If you're really into the bike, you should do the basic tests on it, check battery voltage, check compression, check for spark, check for fuel flow, or dirty carbs. It could be as simple as a clogged petcock, or the motor could be grenaded. Too tough to call without any info. If you do pick it up, the I wold go with CBR F2 coils over the CB 900's though. They're a good bike if they're properly maintained and run regularly, they get bitchey if you let them sit.

Klongstreath
03-08-2016, 7:41 AM
I know its vague. And i havent talked to them as to why it wont start, it could cranka nd not fire, or fuel issues like youve said. Im looking at it today, and ill see what it says, as long as its not locked up, and they let me do a compression test ill probably pull the trigger.

iamcornelius
03-18-2016, 4:08 PM
CBR F2 coils over the CB 900's though.

I think I read somewhere you could put CBR coils onto an '80 CB750 and that was a big upgrade - know anything about that?

But back to the bike, if the price is right and you're into a project (and the motor has compression and moves freely), do all those little checks...might not be too far away from running.
I got my '80 CB750 for CAN$900 (which is like 50 bucks American) and it was running...had to do a little carb work of course.

PeteyD13
03-21-2016, 8:33 AM
I think I read somewhere you could put CBR coils onto an '80 CB750 and that was a big upgrade - know anything about that?

Easy swap, makes a big difference. Pretty common in the Cafe circles. check out the cafe or CB750 boards for more details.

JuanCarlito
03-24-2016, 3:19 AM
"Won't start" is about as vague a description as you can get. If you're really into the bike, you should do the basic tests on it, check battery voltage, check compression, check for spark, check for fuel flow, or dirty carbs. It could be as simple as a clogged petcock, or the motor could be grenaded. Too tough to call without any info. If you do pick it up, the I wold go with CBR F2 coils over the CB 900's though. They're a good bike if they're properly maintained and run regularly, they get bitchey if you let them sit.

Agreed. I bought a 79 CB650 and built it last year (Lost & Lovin It - Thread title) and got it for 300 bucks…because "It wouldn't start"….all I had to do was charge the battery and re- connect the whole air intake system properly since the PO had everything un hooked, no filter etc….Then it was fine lol.

farmall
03-24-2016, 11:13 AM
Most no-start problems are due to carbs sitting.

The easy way is to run the same "checklist" one would for a customer bike coming into a shop.

Compression test. Doesn't matter what it feels like, put a gauge on all cylinders and note results. Do that before anything else because if the engine is junk no need to waste time on it. Hold throttle full open.

Spark test. Should have fat blue sparks on all four plugs.

Inspect carbs, carb boots, fuel lines, fuel strainer on petcock and fuel tank. If tank is nasty inside, use a dummy tank for testing.

If the carbs have been sitting, take them off and go through them. Don't disassemble them from the rack, just pull bowls, jets, etc and pull the tops. If diaphragm carbs, inspect diaphragms.
Lots of info on the net so I won't go through how to rebuild carbs. Kits are usually reasonable on Ebay. I run fuel filters on everything.

Pine-Sol is outstanding carb dip and doesn't eat plastic or rubber. Get Pine-Sol, use it straight, and not generic pine oil. Others have good luck with Simple Green. When done dipping (I leave 'em for a couple of days) fill a bucket with HOT water and give 'em a good slosh, then blow out with compressed air.

Do not jump from a running car. If battery is bad, shitcan it. You can jump off a car battery using jumper cables.