Troubleshooting advice - 1983 GS550L

[Guest]

I'm a brand-new member of the Forum, having just purchased a 1983 GS550L. Have to say first off that I'm not that mechanically inclined, but have a pretty good mechanic. We're both stumped a bit by a problem I've been having. The bike starts fine and I usually let it warm up until it idles steadily with no choke. After I take off, the bike is fine for awhile, then it begins to hesitate and run rough and stall when I come to a stop. It seems to be missing. After awhile, the problem disappears and then the bike runs like a top for as long as I want to ride it. But every ride is the same pattern - runs fine for a short while, goes through a shorter-or-longer period of running rough/hesitating/stalling, and is then fine. What could cause this problem to come and go like that? My mechanic has cleaned and adjusted the carbs and installed new plugs.

Any advice or insights would really be appreciated. I apologize in advance if this issue is covered elsewhere in the Forum. I looked as much as I could, but there's a LOT of stuff here!

[MelodicMetalGod]

Welcome to the GSR!

Just a guess here, but I'm thinking valve clearances would be worth a check. My logic being that it sounds like the trouble is during the time AFTER the engine is no longer cold and BEFORE the engine is at top operating temps.

There are better troubleshooting minds than I here, so be sure to check back for post by some of the more "genius" level GS mechanics of the GSR.

Best of luck!

[SqDancerLynn1]

Welcome to the forum. Our resident greeter should post soon with LOTS of info & links. Don't worry about the valves yet. The first thing I would check is the petcock. Check the vacuum line for gas, it should be hooked up to the #2 carb. If the petcock diaphram is bad it will flood the #2 cylinder with fuel. (another way is to plug the vacuum line at the carb and run the petcock on prime for a test. Don't forget to turn it back to the on position. Also make sure the gas cap vent (in the cap) is not blocked with crud..

[Kerry]

Thanks for the suggestions. I was thinking petcock based on other information I've seen on the Forum. I'll have this checked out and let you guys know what transpires.

[BassCliff]

Hee Haw Howdy!

Hi Mr. Kerry,

I'm the resident greeter.

Here is your mega-welcome!

Let it be known that on this day you are cordially and formally welcomed to the GSR Forum as a Junior Member in good standing with all the rights and privileges thereof. Further let it be known that your good standing can be improved with pictures (not you, your bike)!

Perhaps you've already seen these, but I like to remind all the new members. In addition to the carb rebuild series, I recommend visiting the In The Garage section via the GSR Homepage and check out the Stator Papers. There's also a lot of great information in the Old Q&A section. I have some documentation on my little BikeCliff website to help get you familiar with doing routine maintenance tasks (note that it is 850G-specific but many tasks are common to all GS bikes). Other "user contributed" informational sites include those of Mr. bwringer, Mr. tfb and Mr. robertbarr. And if your bike uses shims for valve adjustments, send an email to Mr. Steve requesting a copy of his Excel spreadsheet that helps you keep track of clearances, shim sizes and other service work.

These are some edited quotes from one of our dear beloved gurus, Mr. bwringer, with ideas on basic needs (depending on initial condition), parts, and accessories.
***********Quoted from Mr. bwringer************
Carburetor maintenance:

Replace the intake boot o-rings, and possibly the intake boots. Here's the procedure:

http://bwringer.com/gs/intakeorings.html

Here's an overview of what happens with this particular problem:

http://cycleorings.com/intake.html

You'll also want to examine the boots between the carbs and the airbox. There's a good chance these are OK, but check them over.
And finally, if things still aren't exactly right, you'll want to order a set of o-rings for BS carbs from the GS owner's best friend, Robert Barr:
http://cycleorings.com
Once you receive these rare rings of delight, then you'll want to thoroughly clean and rebuild your carburetors. Here are step-by-step instructions that make this simple:

http://thegsresources.com/gs_carbrebuild.htm

***********************************
Every GS850 (and most other models) has (or had) a set of well-known issues that MUST be addressed before you have a solid baseline for further troubleshooting. It's a vintage bike, and it's quite common (as in, every single GS850 I have had contact with) that there are multiple problems that have crept up and slowly gotten worse over the years. It's not like a newer vehicle, where there's generally one problem at a time.

These common issues are:

1. Intake O-rings (install NEW OEM or Viton only - common nitrile O-rings will quickly deteriorate from heat)
2. Intake Boots (install NEW -- these cannot be repaired)
3. Valve clearances (more important than most people think)
4. Carb/airbox boots
5. Airbox sealing
6. Air filter sealing
7. Petcock (install a NEW one)
8. On '79 models, install new points or Dyna electronic ignition (or at least verify that the old points are working correctly)
9. On all models, it's fairly common to have problems with the spark plug caps. These are $3 or $4 each, and often worth replacing if you're keeping the stock coils/wires.
10. Stock exhaust with NO leaks or holes -- good seals at the head and at the junctions underneath.
***************************************
OEM Parts/Online Fiches:

I would definitely double and triple the recommendations to use Cycle Recycle II and Z1 Enterprises as much as possible. These guys are priceless resources. Z1 tends to have slightly better prices, CRC2 has a wider range of goodies available. If you're near Indy and can bring in an old part to match, CRC2 has a vast inventory of used parts.
http://denniskirk.com - Put in your bike model and see what they have.
http://oldbikebarn.com - seems to be slowly regaining a decent reputation, but it's still caveat emptor. They don't have anything you can't get elsewhere at a better price anyway.
http://www.babbittsonline.com/ - Decent parts prices. Spendy shipping. Don't give you part numbers at all. Useful cross-reference if you obtain a part number elsewhere. Efficient service.
http://bikebandit.com - Fastest. Middlin' prices. Uses their own parts numbering system to obfuscate price comparisons -- can be very confusing for large orders. Cheapest shipping, so total cost usually isn't too bad.
http://flatoutmotorcycles.com - Slow. Cheapest parts prices, crazy shipping costs. Don't expect progress updates or much communication. Real Suzuki part numbers.
http://alpha-sports.com - Exorbitant parts prices. Different type of fiche interface that's quite useful at times, especially with superceded part numbers. Real parts numbers. Shipping cost and speed unknown due to insane, unholy pricing.

Stainless Bolts, Viton o-rings, metric taps, dies, assorted hard-to-find supplies and materials, etc:

http://mcmaster.com - Fast, cheap shipping, good prices. No order minimum, but many items like bolts come in packs of 25 or 50. Excellent resource.
http://motorcycleseatcovers.com - Great quality, perfect fit (on original seat foam), and available for pretty much every bike ever made. Avoid the textured vinyl -- it's perforated.
http://newenough.com - You DO have riding gear, don't you? Great clearances, always outstanding prices and impeccable service.
***************End Quote**********************
Additional parts/info links:

GSR Forum member Mr. duaneage has great used upgraded Honda regulator/rectifiers for our bikes. Send him a PM.
New electrical parts:
http://stores.ebay.com/RMSTATOR or http://www.rmstator.com/

http://www.ricksmotorsportelectrics.com/index.php

http://www.electrosport.com/

For valve cover and breather cover gaskets, I recommend Real Gaskets (reusable silicon):
http://www.realgaskets.com
The Rice Paddy (salvage/used)
http://www.ricepaddymotorcycles.com
Carolina Cycle
http://www.carolinacycle.com
Ron Ayers Motorsports
http://www.ronayers.com
MR Cycles
http://www.mrcycles.com
Moto Grid
http://www.motogrid.com
If all else fails, try this:
http://www.used-motorcycle-parts.org/
Used bike buying checklists:

http://www.amadirectlink.com/roadride/Riderresc/checklist.asp

http://www.clarity.net/~adam/buying-bike.html
Lots of good info/pictures here:
http://www.suzukicycles.org
http://www.cyclechaos.com/wiki/Motorcycle_Wiki
http://www.bikepics.com
Basic motorcycle maintenance/repair:

http://www.dansmc.com/mc_repaircourse.htm

Thanks for joining us. Keep us informed of your progress. There's lots of good folk with good experience here.

Thank you for your indulgence,

BassCliff
(The unofficial GSR greeter)

[Dogma]

Thanks for the suggestions. I was thinking petcock based on other information I've seen on the Forum. I'll have this checked out and let you guys know what transpires.

Things that come and go in a strange pattern make me wonder about electricals. Are the connections and wires in the charging and ignition circuits good?

[Kerry]

New problem - bike dies when hot

Interesting, the question about electricals, because now I have a BRAND NEW problem! The bike has begun to die when hot. It will be running fine, then it just dies. Doesn't matter if its at idle or when driving. It just dies. The engine will turn over freely, but will not start. After about 20 minutes of cool-down, it will restart easily and run perfectly. Might this be an electrical issue?

In what order would you guys suggest troubleshooting this issue?

[Dave8338]

Coils / igniter...

[doctorgonzo]

Yep, electrical connection somewhere getting hot, which increases resistance, then failing.

[Calvin Blackmore]

check youir stator output AC side and the output to your battery DC side.
I think its sposed to be 70VAC at 5000 rpm

cant recall the DC specs.

the symptoms of short running follwed by a cooldown are calssic dying battery due to failed charging system reg rect and or stator are likely culprits and are common point sof failure for these bikes

I am on my thrid reg rect
stator always has tested fine
but the test is performed under fairly contriolled conditions not usually after running for half and hour or more at sustained engine speed

the battery if new will cycle through several instances of depletion.
forget what the magic process is called but the fact that it does this can mask the electricla prob making you think its just a heating issue

[Kerry]

Couple of stator questions

Thanks, Calvin. Two follow-up questions. My mechanic is going to test the stator tomorrow. Should this test be run hot - after the bike has "dies from the heat", as it were (assuming that's possible)? Second question: if I indeed do need to replace, is there a non-Suzuki stator that is a reasonable price and fits my bike? I checked the Electrosport website, but I can't find anything for the 1983 GS550L (I can find 80-82 and 85-86). Old Bike Barn has one for $138.13 (US - but with the good exchange these days, I guess price in Canadian dollars is similar). How long to install for an experienced mechanic?

I guess that's three questions...

[Kerry]

Update - electrical problem

My friendly mechanic tells me that the only component of the electrical system that tested out of spec was the signal generator. He quoted a price of over $300 (CAN) for the part alone. I don't know much about the signal generator; why is it so expensive?

[flyingace]

An 'out of spec' signal generator? I'm not sure what that means. By and large, they work or they don't. Don't spend the $ until you are certain about this one.

I don't think it's charging system, because the bike wouldn't recover the next day unless you charged the battery overnight.

The suggestion to check for fuel blockage and petcock operation are good ones - and won't cost $300. A clogged inline fuel filter could let gas in at a rate slower than the engine requires. It will fill the bowls to allow starting to go OK, but once the bowl has drained, a reduced fuel flow could create the symptoms you describe.

[coltrain]

I got my bets on the valves.

dont ask me how i know.
okay okay..! my 79 gs750 had the SAME exact behavior until I finally got the valves within spec.

there.

[Big N daft]

My friendly mechanic tells me that the only component of the electrical system that tested out of spec was the signal generator. He quoted a price of over $300 (CAN) for the part alone. I don't know much about the signal generator; why is it so expensive?

If it's an intermittent electrical problem brought about by heat then it'd be difficult to prove beyond doubt that a piece of kit that tests good isn't actually the problem.

As far as the signal generator is concerned it's just a pair of coils on a base plate that don't really get that much abuse, well not compared to the stator! The signal generator just sits on the end of the crank and as a pair of magnetic pickups pass by these coils they send a pulse to the igniter.

As far as testing them goes get your self a copy of the servce manual (Haynes, Clymer or Suxuki) as there are routines and measurements for testing these and the igniter.

Cliff hasn't got one of the manuals on his site but you can get one here

http://www.bikechatforums.com/viewtopic.php?t=63414

BTW you can get a full boyer bransden replacement ignition set for £100 here in the UK which is about c$150 so whatever you do don't spend on the new generator!


All the best

Paul