carbs leaking...

[ronin]

Anyone want to shed some light on this one? What's the best way to troubleshoot which carb is failing? Is there a way? Or do I just need to fix em all? This is the first time I've had to deal with four cabs, I know a decent amount, but I'm no expert. It looks like they're all connected.

Let me start from the beginning, bought it cheap from a Harley dealership. I walked in and said you guys cant want that bike here, he agreed. I gave him several hundred dollars and rode off on the bike. Yea, I was getting a little loss of compression, nothing 20 bucks and a new set of exhaust gaskets couldn't fix. Overall this bike was in pretty darn good shape for being 30 yrs old. Someone obviously took really good care of it until they decided to trade it in for a Harley. And, just in case you're wondering, the guy that traded it in, rode it in, not trailered it. This was in April, I've been riding the hell out of it ever since without a single issue. Okay, I had to replace the battery, big deal.

So Labor day weekend I took this girl out for a ride, ran great. The next day when I went to go to work, I started it up, let it idle to warm up (it is old), and I started to smell fuel. Sure enough, it was dripping from the carb. Not pouring out, but definitely leaking. I stood the bike up, it stopped. I rode it around the neighborhood to see if maybe it was just something clogging one of the jets or something. Still seemed to run fine, but again when I put it on the kickstand it started to leak again.

Stupidly, I only bought one carb repair kit, thinking it's leaking from this one, gotta fix this one. Here I am, one carb 'fixed' but still the same issue. Where do I go from here? As I said in the beginning, what's the best way to figure out which one. Or do I really just have to rebuild them all. I know, I know I should just get them all done. But, I gotta tell you, the one I did fix was super clean, only a tiny amount of rust sediment settled on the very bottom of the bowl. I'd already planned on putting a fuel filter on since the tank is old, as well as cleaning the carbs, and fixing one or two other minor things, but I'd planned on doing that in the winter, when I can't ride. Guess that time will be now. Anyway, back to the carb(s), where should I start? Tips, tricks, advice? any help would be greatly appreciated. I don't want to pay someone something I can do myself, but my time is limited because I work a lot, and it's getting colder now. I don't want to rush through it or wind up with an 'effed' up mess, so I'm hoping someone more familiar with an '81 cb650 will help me out. Thanks!

[Volker_P]

There are several options:
- carb bowl overflow due to leaky floater valve. In this case the overflow comes will go through the release nipple of the carb bowl. Usually there are hoses plugged on all four carb bowls that lead the overflow down behind the engine.
- loose/leaky release bolt at the bottom of the carb bowl. Does not start leaking suddenly unless it gets loose. Leakage from same nipple like overflow.
- leaky carb bowl seal. Will mostly or only leak on the side stand. Will leak at the carb bowl seam.
- cracked triple tees may induce carb leaking/overflow (during riding only?), too. Not sure if leakage is at the tee itself or just causes bowl overflow.

[bolo79]

Tips, tricks, advice?

Hi.I located my leak with the help of third parties, and a flashlight.I wiped the carburetors and asked my wife to start the engine,while I shined a flashlight. I quickly located the leak.Questions as to whether to repair one or all depends on the situation.If the repair will require a separating carburetors in my opinion better to rebuild all.I did not do this and after the repair the first leak; two weeks later I had to fix the next one.

[ronin]

Thanks guys for your response. So, I pulled the carbs, cleaned and inspected all of the carbs thoroughly. Figured, might as well while I've got em all off, couldn't hurt. What I did find was a good amount of rust settled in each of the carb bowls. everything looked good seats, seals, needles, floats, etc. So I'm thinking its gotta be the rust settled on the bottom of the bowl blocking the overflows. Happy finding it was a rather simple fix, and realizing I should've put the fuel filter on sooner, I felt much better. So, as I'm putting everything back together thinking, 'this should fix it'. I notice that the 'T' fuel line connecting carb 1&2 and 3&4 is completely cracked and dry rotted! Aha! That's where it's leaking from. Of course, both bike shops by my house are closed til Tuesday. But at least I figured out what it was.

Still leaves me with one question though. Since I found so much rust particles deposited in the carbs, will a fuel filter be enough, or should I look into just getting a new tank?

[Volker_P]

A clean tank is crucial, so clean out the tank best you can. For some how to suggestions see the fuel tank issue thread.
The filter in the petcock is not fine enough, so a fine inline filter is a good idea.
The T-vents are extremely expensive and may be replaced by e.g. aquarium stuff.

[ronin]

Thanks volker. I'm gonna clean out the tank today. Also, thanks for the heads up about the T vents, I assumed it'd be a cheap part, but I guess not. What exactly do you mean by aquarium stuff? Someone told me I could just fill the cracks with some rtv seal, but it'd just be a temporary fix. I'm not looking to put 'band aids' on my bike. I'd rather just fix it right.

[Volker_P]

Many aquarium equipment (filters, bubblers etc.) uses small air pumps. This is why you get also hoses and moreover probably also tees of the proper size at pet shops that sell aquarium stuff.