Carb Cleaning -- success

If it's broken or just needs tweaked

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michael_650
Posts: 59
Joined: Tue Sep 06, 2016 6:13 am
Location: Philadelphia

Carb Cleaning -- success

Postby michael_650 » Tue Mar 06, 2018 4:10 pm

Executive summary:
Idle jet passages can be cleaned by boiling the carbs. I split my carbs and did 2 at a time. Remove everything you can. Cover with water, add a cup of Simple Green. Boil 2-3 hours.

Detail and story:
When i bought my CB650C, i noticed two of the exhaust pipes were rusty from the carb to the ground, while the other two looked nice. It raised a flag in the back of my mind but nothing i could put my finger on. Bike was hard to start, but would start. Ran on the rough side, but being new to 4 cyclinders, sound like it might be ok. Both exhausts were pushing out air, so maybe it's ok? On the road, it's a little iffy running, until you open the throttle then WOW it's smooth and powerful and made me fall in love. With a little research, i learned about the three different jets and when each is utilized. Also learned that the piano wire trick doesn't work on the idle jet passage because the jet is pressed in.

Diagnosis:
Remove the bowl and the float and you'll see three tubes coming up from the body. One has a brass jet screwed into it; ignore that one. The middle one is the idle jet. Get a can of carb cleaner, use the red spray tube but wrap the tip in duct tape until it just barely fits into the idle jet opening. The goal is to create a seal. USE SAFETY GOGGLES, don't ask me how i know. Spray. If you hear a gurgle, your jet passage is clear. If it builds pressure and the cleaner squirts back out past the duct tape, it's blocked.

Solution:
Use a kitchen pot that you don't need any more, because this will likely ruin it. Open the windows, turn on the fans. This will stink. Not rancid, terrible, but my lovely bride was not happy (I eventually transitioned to a single corded burner in the garage). Put the carbs in, cover in water completely, add a cup of Simple Green (splash it in, it's not science), turn the heat on high and let it boil for 2-3 hours. Check the pot occasionally; the water and cleaner will boil off, exposing the tops of the carbs. Top it off. When done, rinse well with water, blow out with an air gun, and apply WD40 generously. Repeat the diagnosis, repeat the boiling if needed.

The Simple Green won't corrode or attack the carbs like lemon juice might. SG helps clean faster than water alone.

Hope this helps someone!

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Volker_P
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Joined: Mon Mar 06, 2006 1:53 am
Location: southern Germany

Re: Carb Cleaning -- success

Postby Volker_P » Wed Mar 07, 2018 2:43 am

Thanks for this nice report. :D
Well, and this:
michael_650 wrote: Open the windows, turn on the fans. This will stink. Not rancid, terrible, but my lovely bride was not happy...

should not be a problem any longer: https://simplegreen.com/products/all-pu ... -lavender/ :lol:
Cosky's great (free) online manual: http://cosky0.tripod.com

forum links to common technical issues

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Folsoml
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Joined: Sat Apr 07, 2012 9:02 pm
Location: North Florida

Re: Carb Cleaning -- success

Postby Folsoml » Wed Mar 07, 2018 7:09 am

Use caution with the carb bodies. The holes on the bodies where the choke shafts fit have felt "washers" inside them. They will come out fairly easily when the shafts are not in place. Without them, you could have air leaks.
Have a problem with your CB650? Have a technical question? Click here!


My Current Bikes: 2005 HD FLHTCUI Electra Glide Ultra Classic, 2007 Yamaha Vino,

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michael_650
Posts: 59
Joined: Tue Sep 06, 2016 6:13 am
Location: Philadelphia

Re: Carb Cleaning -- success

Postby michael_650 » Wed Mar 07, 2018 12:56 pm

Crap, didn't know about the felt washers, unless you mean the one just under the ... what's the thing on top with the diaphragm inside... CV? i took two of them out. Wondering if i lost the other two... i might be in trouble. They're under a black plastic part that is held in with one screw. If not those, are there others?

Lavender smells sweet. Maybe i'll cook some up just for fun! LOL

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Folsoml
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Joined: Sat Apr 07, 2012 9:02 pm
Location: North Florida

Re: Carb Cleaning -- success

Postby Folsoml » Wed Mar 07, 2018 7:40 pm

The felt washers are in the holes in the carb bodies where the choke shafts fit.

Image
Have a problem with your CB650? Have a technical question? Click here!


My Current Bikes: 2005 HD FLHTCUI Electra Glide Ultra Classic, 2007 Yamaha Vino,


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