Problem starting after rebuild 83 550e

[sabu]

So I dipped the carbs due to really rough running and found tons of crap. Put them back together and the bike will crank, never catch, and then backfire. The Clymer manual is pretty obtuse. Any suggestions? This is my first time venturing into the realms of carburetion.

[BassCliff]

Greetings and Salutations!!

Hi Mr. sabu,

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Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", "Top 15 Tips For GS Happiness", the Carb Cleanup Series, and the Stator Papers. All of these tasks must be addressed in order to have a safe, reliable machine. Now let me roll out the welcome mat for you...



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Thank you for your indulgence,

BassCliff

[JEEPRUSTY]

So I dipped the carbs due to really rough running and found tons of crap. Put them back together and the bike will crank, never catch, and then backfire. The Clymer manual is pretty obtuse. Any suggestions? This is my first time venturing into the realms of carburetion.

Do you have the airbox and exhaust installed?

[tatu]

Have you made sure that fuel is coming out of the tap? Prime position? and is the choke mechanism working correctly?

[sabu]

It had K&N filters, not an airbox on it, but yes, that and the exhaust are installed.

I've tried "prime" and "on", yes fuel is flowing. I'll double check the choke mechanism tonight.

[spyug]

Now not to belabour the point but how long did you dip the carbs for and when you reassembled did you a)blow out the passages with compressed air b)poke out all the holes in the jets and emulsion tubes c) use fresh o-rings d) bench synch the carbs? All of which are important.

Likely the biggest problem with carb cleaning and rebuilding is that the carbs are not dunked for long enough and there is still dirt in the passages. Another mistake commonly made is to asume the o-rings are ok and reuse them (done it myself). If you distort the rings you will likely find them cracked which makes them useless.

A further common issue which makes starting very hard is not bench synching the carbs. The throttle butterflies need to be a 'skosh" open when at rest ( skosh= width of a paperclip).

GS carbs can be temperimental with regards to airboxes and or filters. They need a certain amount of air restriction and you might not be getting the correct amount from your setup. What I have found to be effective is to use cling film over the mouth of the carb with a small hole poked in the center. When cranking the carb may actually flood temporarily but that won't hurt. Once the bike runs the film can be removed. Once it has started and run you can then reinstall the filters and then synch the carbs.

Sometimes you have to crank a bit to get the carbs to work and you will find the bike battery is not powerful enough. I always add a full size car or boat battery for extra cranking power. Just make sure if you use the one in your car, the car engine is not on or it could fry the bikes electricals.

A couple of years back, I had this exact same problem with the carbs on my Katana project. I tried for days to get them to run and I had soaked them for a week and had used fresh o-rings. On a close examination, I found I had not bench synched properly (3 butterflies were jammed shut) and on the recommendation of one of the guys I tried the cling film ( I was running pods too). Fixing that she fired right up, no fuss no muss.

Have a look at what I've mentioned and let us know.

Good luck with it,
Spyug

PS I have the same bike and I've been trying to get pods for it. Can you tell me the model number of those K&Ns?

cheers.

[sabu]

Both carbs were in the dip for at least 48 hours. I blew out every passage I could see with compressed air, and also poked out the holes with a bristle from a wire brush. I replaced all the o-rings I saw, although I didn't use every one from the cycle-o-rings kit, so I might have missed some.

I'll try the film idea and if that doesn't work I'll pull them and re-check the bench sync. I'll also see if I can find the model numbers on the filters. There wasn't much documentation provided with the bike so I'll see if there is one on them somewhere.

Thanks for the in-depth response!

[kevsgs]

I've been having to mess with my carbs a lot here lately, and this may not be an issue for yours, but I had replaced sparkplugs and after just starting and running the bike a few times but not very long I was having problems getting it started. Pulled the plugs and everyone of my new plugs were fouled and had to be cleaned up with a wire brush then no problems. Like I said may not be your issue but I would have never guessed that my new plugs would be fouled.

[sabu]

Oh, I did also replace the intake boot o-rings. They were completely flat and had no flex left in them.

[JEEPRUSTY]

Check the plug wires to assure they are attached to the appropriate plug.

[BassCliff]

Hi,

Did you remove the cap from the idle mixture screws, remove those screws, and make sure that passage was clean? There's an o-ring in there that should be replaced too. You'll find the proper procedures documented in detail on my little website. There's even a 450 carb cleaning guide.


Thank you for your indulgence,

BassCliff

[sabu]

It's alive! Thanks for all the suggestions - we found one mis-connected hose (thanks to the manual on BikeCliff's site!) and a bunch of other little stuff that wasn't quite right. It's idling stably and running better than it did before I started tearing it down. Luckily we had some warm weather on Saturday so I was even able to road test it before dropping it off for state inspection and new fork seals. Yes, I found the fork seal replacement procedure but was feeling a little gunshy about trying it at the moment.

Thanks again for all the helpful advice!