Seeking general advice - carbs, exhaust

[Anonymous]

Hello...

So I've been having fun with the SEARCH function looking things up about the various issues I'm working out with my 82 GS650L. I'll summarize what I've found, ask a few more questions, and see if anyone has even more advice.

1. I have a dead front brake light switch. Through posts in this forum, I found my way to bikebandit.com, the part number for the switch assembly, and ordered a new one. I've already been inside my existing switch and found the broken parts inside, so once the replacement arrives, that problem will be solved, and maybe - just maybe - I could pass state inspection, if I'm lucky...

2. Carbs - isn't that what everyone's problem is? Background info - the bike sat, unused, for 2-3 years before my friend gave it to me. It's got issues, but the price was right. I have it running now - replaced a battery, gas, oil, oil filter, air filter (it had disintegrated), and spark plugs (wires looked good). The bike will start and run, but requires a lot of choke to stay running, even when warmed up. And even then, it conks out over 1/4 throttle.
I've poured fuel system cleaner into the gas tank and ridden it a while - seemed to help a tiny bit, but not nearly enough. I learned about the "Italian carb cleaning" trick - whack open the throttle, then block the intake to create a vacuum and blow the crud out. I'll give that a try.
Beyond that, I'm probably looking at a rebuild. I've never had a vehicle with carbs before, and now I find myself with four little ones that most likely need cleaning. I've been trying to do some reading and learn how they work before diving into cleaning them. I could give it a go myself, or just take the carbs off and find a bike shop to do it for me. Not sure which would be the better choice. (Does anyone have a recommendation for a reputable, GS friendly shop in central MA or southern NH?)

3. Exhaust. To prevent the whole bike from dying again, I've been starting and running it for a while every couple of weeks or so. When I first start it, it smokes a little - no big surprise. But lately I've noticed much of this smoke coming out underneath the exhaust midsection joint, rather than out the back of the pipes. Am I looking at a repair, or a replacement? Where might I find a replacement exhaust? Stock is fine - I'm a new rider, and don't need any more power than I've already got, or noise for that matter.

Unfortunately, the snow is flying every few days, and I haven't gotten to ride for quite some time. I'm hoping to get the thing decently rideable over the winter, so that when spring comes around I can finally actually enjoy the bike!

This forum has already been immensely useful to me. Thanks to all who have shared their wisdom and experience here!

- Justin

[earlfor]

Re: Seeking general advice - carbs, exhaust

On replacing the front brake light switch: Its a lot easier if you loosen the pinch bolt holding the brake lever assembly on the handlebars and rotate it 180 degrees until the brake light switch is on top. You can just drop the parts in place then and see what youre doing.

2. The carbs: That it starts on choke shows the choke circuits are working and probably fine. That it will not run even when warmed up if the choke is turned off says that the idle jets are clogged or their adjustment screws are closed or not open sufficiently. If the bike was running normally before sitting for so long, its likely it sat with gas in the float bowls and consequently the idle jets have accumulated varnish. The only reliable way I have found to clean a carb is to remove and disassemble it making sure to remove ALL rubber parts ("O" rings) and then to put all the metal parts, carb body, etc into a pan of carb cleaner overnight. The carb soaking solvent can be had at any auto parts store. When you take the carbs apart, write down the number of turns the pilot and airscrews are set to. (lightly screw them all the way in, counting the turns until they bottom out before removing them)

3. exhaust: If you have nothing more than a leak at the joint between the header and muffler pipe and the clamps are tight, sometimes it can be as easy as removing the clamps, folding about a 1" wide strip of aluminum foil into a 4 or 5 layered ribbon, wrapping the seam and installing the clamp over it to get a good seal.

Earl

[Anonymous]

Thanks for the tips, Earl. I hadn't thought of that trick with the brake lever - it's too easy.

Carbs - Actually, now that I'm thinking about it again, I was slightly wrong - it started to have this rough running problem before he parked it for 3 years. He parked it because it was running poorly and he had neither the time, knowledge, nor money to fix it. Still, it sounds like you're right about the idle jets.

Yet another question... above 1/4 throttle, the engine just conks out, completely, regardless of choke. From what I've learned about the carbs, this is the point where some of the other jets come into play, and something just ain't right - but what?

Sounds like it would still be best to just get everything cleaned up, put it back together, and try it from there. It probably needs it anyway, and it would at least eliminate dirty carbs as a potential problem. Still not sure whether to try this myself or not, though. I'm somewhat mechanically inclined, but have never worked on anything like this before. All my cars have always been fuel injected.

[Anonymous]

When it comes to finding replacement parts.. I recommend ebay.. If the part isn't there today.. it'll probably be there tomorrow. I used to live in mass and know how much fun it is finding used parts... A shop is going to charge a lot to rebuild your carbs and then there are no guarantees... Time to get greasy fingers and dive in. The previous post had a good route to take with the carbs. Make sure you get a manual for your bike before you dig in. Have fun... JOE

[earlfor]

Sounds to me like the previous owner had let it sit
for long enough intervals that the carbs had already
started to varnish/clog.

Carbs - He parked it because it was running poorly and he had neither the time, knowledge, nor money to fix it. Still, it sounds like you're right about the idle jets.
.................................................. .............



There are three operating stages in the carbs, the idle jetting, intermediate jetting and main jetting. At idle, only the idle circuit is functioning. As throttle is increased, the next stage is added to the system. As you transition from idle to midrange, engine fuel/air requirements increase. Idle jets will be flowing 100% of their capability, but for power/rpm to increase, intermediate jets must begin contributing. Idle jets are always flowing fuel and air but their percentage of the overall required volumes decreases as throttle is increased. If the idle jets are blocked, then at low rpm transition to midrange, there is not enough fuel flowing for the engine to increase rpm. Part of the midrange circuit is the flow from the idle range jets. There may be nothing wrong with your intermediate jets and the problem is lack of fuel in the transition.

Yet another question... above 1/4 throttle, the engine just conks out, completely, regardless of choke. From what I've learned about the carbs, this is the point where some of the other jets come into play, and something just ain't right - but what?
.................................................. ...........


You will need to get the carbs cleaned out before thinking about any adjustment to them. The good news is that these carbs are pretty doggone simple mechanically. Just take the stack off the bike, spread out a towel on a table and keep the pieces spread out in the order they were removed. Be sure to keep all carb parts segregated to go back into the carb they were removed from.
It may help to start by sitting the stack on the table and staring at it for 15 minutes or so, taking it apart in your head, so you know the sequence more or less. when you start taking the carbs apart, pay very close attention to exactly how thing come apart. Also, as a safety measure, you might take two apart, soak them and reassemble them before doing the 2nd two. That way, if you do get stumped or forget how something went, you have two still assembled to look at. :-) Its not difficult. Mostly, its a matter of paying attention to detail, being careful and taking your time.
If you have any problems, there are plenty of people here that can help you out. Do it yourself, you will know for sure the job is done right and youll save some money. Besides, you cant ride in your weather anyway. :-)

Earl






Sounds like it would still be best to just get everything cleaned up, put it back together, and try it from there. It probably needs it anyway, and it would at least eliminate dirty carbs as a potential problem. Still not sure whether to try this myself or not, though. I'm somewhat mechanically inclined, but have never worked on anything like this before. All my cars have always been fuel injected.[/quote]

[Anonymous]

If you have any problems, there are plenty of people here that can help you out. Do it yourself, you will know for sure the job is done right and youll save some money. Besides, you cant ride in your weather anyway. :-)

That's a really good point. If I can't ride the thing, I might as well tinker with it.

Great explanation of how the various jets work, too. I get it now - if the idle jet doesn't flow enough, nothing's going to work right, because everything beyond the idle jet is already counting on the idle jet contributing its fair share.

I guess it's time to put the bits and pieces of the old Miata engine away (I dismantled it for fun after it spun a rod bearing at the track, then sold off half the parts), and clear the workbench off for a carb disassembly and cleaning. Thanks for the advice and encouragement!

[earlfor]

By jove, I think you got it. :-) :-) If you havent already, take the time to read the carb cleaning "papers" on this site. Youll be glad you did. :-)

Earl

[quote="TetsuoMX5"

I guess it's time to clear the workbench off for a carb disassembly and cleaning. Thanks for the advice and encouragement![/quote]

[SqDancerLynn1]

definately check the carb series in the forum garage. Also for the replacement of all of the little o rings. Check in the tips & tricks forum?
for Robert Barr he sells a complete O ring kit $12 including shipping. Also check the intake boots while you have it apart. I would recomend taking the boots off and replacing the O ring seals, a vacuum leak from the boots can make it run very lean and no amount of carb cleaning will make it run right if they leak.