1982 Seca 650 Problem

Ok so I have yet another problem with this bike! Back story is that occasionally when I would drive it last month and before the rpms would jump if I was stopped at a light and in first gear with the clutch in. It normally idles around 1000-1500 and it would go up to 3000+. Then the other day I could feel the power start to go out of it and pulled over and it died. I could start it back up no problem but if I released the throttle it died. Then a few hours later it started and I didn't have to hold the throttle but the throttle response was horrible and it was very sluggish. Then it wouldn't run again unless I was holding the throttle.

Pulled out the plugs and cleaned them because they were pretty black and put them back in and it ran. Are the plugs my problem? It did it again to me today. I cleaned them a week ago. If it is the plugs, will the problem keep happening even if I get new ones, if so what should I do? Any help would be great!

 

Well nobody can help me yet I guess. For a little more info I just pulled the plugs out and two have a lot of carbon on them. especially for just having cleaned them last week. Any thoughts?

 

Could be the plugs. They are cheap to replace. Good starting point since they are only a couple of bucks each. Could also be dirty carbs.

 

Sure. Read this: http://xjbikes.com/Forums/viewtopic/t=24010.html

Follow the advice. Get a service manual and go through the maintenance section. Your problem sounds like a classic case of carbs that need attention, but from your "yet another problem" remark it sounds like you're letting the bike be in charge.

THERE IS a process involved in recommissioning an old bike, you can't just start riding it again. Right now the bike is in charge of your process.

Take control, but in order to do so you have to go big. Just replacing the plugs isn't going to solve anything, just temporarily relieve a symptom.

 

I agree with you in principle, but many people don't have the time and/or money to do a thorough makeover on a bike or car...they just want an answer to a specific problem, and a few easy things to try before major surgery/expense.

Sounds to me like he's running rich as all hell, sunk floats or stuck needle valves, something of that nature.

A lot of people say don't use aggressive fuel system cleaners in old bikes, it will eat the old rubber parts. Well, in my experience yeah it will, if they were shot to begin with. So if you use it and it destroys float tips or seat or whatever, it was time to replace them anyway...nothing much lost.

But if it works, you're good to go for a while. I've used Techron in mine for five years now, and haven't had any fuel system problems...

 

There's one MAJOR difference between an old bike and an old car: when your '81 Sunbird suddenly quits, you simply pull over to the side of the road and are stranded. Depending on the component, a sudden failure on an old motorcycle can KILL YOU.

Additionally, in most cases, there IS NO "simple answer to a specific problem" or "easy things to try." Most of the time, the issues are caused by the cumulative effects of neglected maintenance and sitting for a long period. Gummed up carbs don't have an "easy fix." Valves that have been neglected for the entire life of the bike don't have an "easy fix." Ancient tubeless tires, delaminating rear brakes, corroded electrical connectors--- no "easy fix."

It's NOT an old CAR. There are major safety issues to be concerned with; brakes and tires need to be attended to before any serious riding.

The process is known in the antique motorcycle world as "recommissioning" which is why I use it here. It IS a "process" and one that needs to be gone through before taking to the road. Otherwise it's a death gamble, one that we're not going to advocate anyone take.

Riding an old bike without attending to a LIST of things first is not taking a chance with inconvenience; you're putting your life on the line.

The bike HAS to be SAFE and MECHANICALLY SOUND before you start riding it, that's all there is to it. And quite often it's NOT easy, nor quick.

 

^^Well said Fitz, I'm applauding your very nicely written argument!
Jeffco's observation is not lost however. I don't think Jeff was disagreeing with the idea of wanting to do things right for the right reason, he made an observation of the behavior of a majority of people. They want the quick method and they want it easy and now. This doesn't mesh well with those of us in the fold who know better than that. Your indignation is appropriate but I doubt it will lead very many to rethink their immediate paths (at least we can hope it will). I learned this lesson the hard way (thankfully loosing only money) by trying everything I and my buddies could think of to fix immediate problems without the experience to know that it was a symptom of a larger problem (like lack of proper, timely maintenance). I hope that enlightenment strikes others faster than it hit me.

 

I learned the hard way too. I'm hoping that sharing will save somebody learning the same way. You only lost $$$, not your leg or your LIFE.

I've been doing this (riding bikes older than most people) for a long time.

I've lost a few good friends along the way.

If I can save someone $100 or a trip to the hospital, then I'm sorry if I ruffled a few feathers. "LOL" doesn't cut it in freeway traffic; these are motorcycles fer chrissakes.

"Exciting" is NOT the best description for a flat front tire at 60mph. Maybe somebody else won't have to find out?

Somebody has to raise the safety issue; leave it to the old guy who's been there. I'm not trying to scare anybody off, just maybe scare them SAFE.

<rant off>

 

When it comes to cleaning carbs for these bikes there is no such thing as a "Mechanic in a Can"

If you are using a product to keep your carbs up before they have a chance to fill up with crud that might work and I could agree with that. But if your trying to unplug carbs that won't let any fuel with cleaner through I would think it would be a waste of time. The passages are too small and you could not get enough volume through to do any good. I agree with Fitz, do it right and keep it safe.

MN

 

I'm not disputing safety items...but where carbs are concerned, I've proven many people wrong, many times. I've taken several bikes from so crapped up they were unrideable to running perfect without so much as removing a bowl, many times.

One trick that's always worked well is to remove the fuel line from the tank (with petcock off, obviously), and let it run until it starves out. Then spray carb cleaner into the line until all bowls are filled and it backs up out the line.

Replace the fuel line, turn the gas back on, let it sit about half an hour.

Start it up (they will run on carb cleaner) and run it through the whole rpm range. You can feel it when the fuel starts to purge the cleaner out and takes over. 50% of the time, the problem is gone at that point. Does a nice induction cleaning of the intake tract as well.

Obviously if you have something non-soluble stuck in an orifice that's too big to pass through it, like rust or a big chunk of Viton something, it's not going to do anything. But for fuel varnishes from sitting long enough for the fuel to evaporate, etc, it works very well.

 

PS you don't have to harp safety to me, I was a state licensed vehicle inspector for 15 years...you're preaching to the choir...

 

Quote: "I've proven so many wrong, many times"

Jeff, I'm not trying to strike a nerve here but in all honesty.
Well here's a challange for you then if your up to it. I guess since your the authority on carb cleaning or corner cutting as it may be. Maybe you should find some crummy old carbs and take some before and after pictures of your "trick" and lets see how well it really works. We can all see and judge for ourselves.
If you don't have an old set of carbs then maybe someone who does could try it and post a few pictures of their findings. Anyone want to give it a try?

MN

 

I just rebuilt the cruddy spare set I had, sorry. (won't be mine much longer either )

 

Here's a better idea. You're the one with doubts. I'm not trying to get anyone to do something they aren't comfortable with. The idea was to save time, labor, expense. Something you can try as a simple option to a labor-intensive teardown.

So it makes no sense for me to jump through hoops to prove to you something works. I don't care if you want to try it or not. What's my motivation to knock myself out proving it?

Instead, next time you run across a bike that is running poorly after sitting around too long, why don't you give it a try before you tear into it, and prove me wrong?

I'll even reimburse the $3 for the carb cleaner, if it fails to improve anything.

 

My point, as far as carbs go, is that pull 'em and redo 'em is fine, and probably not a bad idea...if you know what you're doing, and don't need the vehicle to get to work tomorrow.

But if you got a carb overflowing with fuel through the drain hose, making it run terrible, etc...why wouldn't you do the old bowl smack with a plastic hammer and see if it clears the stuck float/valve problem?

I've had this experience many times with past bikes. Most, it was a one-time deal, never repeated. If it does, yeah, there's work to be done.

I have no qualms about trying the simple, proven, ol' school tricks first...they don't cost anything, and many times work fine.

Comes from growing up poor and figuring things out for myself, not treating a manual as a bible.

 

Jeff,
I just thought since you were from the "Show Me" state the you would not mind showing us.

You can look at all of the hard work that people like Rick, Robert, Fitz, MiCarl have proven methods for Carb Cleaning, Fork Seal Replacements, Speedo repair, Brakes and many other great write ups and pictures to back up every thing they are trying to teach us. So if you have truely found a way to cut hours of carb work why would you not take some pictures of your work and share with us?

I would be cautious not to spout something out here in the forum and not be willing to take a few pictures and share with us. Thats all, nothing more and nothing less.

Good Luck
MN

 

Ok fellas, let's agree that this would be a great idea when someone has the time and a narly set of carbs to try it on. We will all make an honest effort to test this out when we have the opportunity. If we have more than one set of test data, so much the better.

 

It was merely a suggestion, coming from a person with 30 years of practical automotive, motorcycle and small engine experience. It is something to try before committing to a full teardown.

The idea being to try it yourself, if you think it has merit, and not do it if you don't. I have no dog in the fight that makes me wanna prove it to you...I've found it useful, I'm passing it along. Do what you will with it....

And after all, the whole idea is to save labor and NOT have to remove and open the carbs. So why would I do it twice, just to show the results?

You obviously underestimate my level of laziness.

Should the opportunity arise, and I feel sufficiently motivated, I'd do this for you. It might be a small equipment carb, I run across that more than cycles. Would this suffice?

 

I have a suggestion that i have been thinking about for a while. It seems to me that when someone asks a question on here that they almost always fail to put in all the pertinent information maybe someone could make up a fill in form that has to be done in order to post a question to the group.

 

IF ONLY...! Man, if I had a nickle...

 

Ok Robert,
I would like to continue this another time, but It is not helping the original poster of this thread. Maybe he has been following this and put Jeff's method to the test. I would like for him to try it and let us know if it did any good.

MN

 

Agreed, let's hope he got what he needed and will report a favorable outcome!

 

I agree MN-Maxims, and I hope it's tried.

I believe that it may very well give a temperary
fix untill a full brake down is done. and of cource it
will have to be done.
My carbs were not at all that bad when I first cleaned them
and this method may have worked quite well if a jet or passage
was blocked by a small bit of crap untill the real cleaning was done.

Just my 1.5 cents worth lol