Carb question I'm stumped

Hi guys i'm new on here just picked up an '82 seca 650. it had been sitting for around 2 years when i bought it. pretty much its only supposed issue was that the carbs needed cleaned. i took all the jets out and the flute looking tubes and soaked them in cleaner. i then cleaned out the different passagways and whatnot. after reassembly i got the bike started again(i did get it to run before disassembly but was very rough). with everything back on it starts pretty easily. it wont quite idle itself though, and when i give it gas it seems like it almost has to wind up to higher rpms(only to 5k) rather than have crisp throttle response. and then when the engine is put under load to take off it bogs down until it dies. does anyone have any ideas as to what the problem may be. i do currently have the airb0x boots off the carbs, but i didnt think it would make this big of a difference. thanks to all

 

You need the air box and boots to have the right air flow into the carbs. It will not run right without them. Put them on and try it. You might want to wet set your floats first and polish the carb bores where your slides are.

MN

 

Bench syncing is also necessary, then a running sync after they are back in with the airbox.

 

alright been thinkin the airbox may be the culprit. i was trying to out the boots back on been its been kind of a b***h to get them in there any tips? what exactly should i use to polish the bores and slides? I may sound kinda dumb at this point but if it helps anyone out the first time i had the carbs back together the air jets were all reversed and the bike almost ran better. it was at least able take off and ride around the yard it ran very lean when the given heavy throttle though. any ideas on why that would work almost better than it does now?

 

Ummm.. what makes you think the jets were reversed? The Haynes manual shows them in the wrong positions, if you followed the Haynes they are NOW reversed.

Also there's a lot more to carb service than just cleaning. Your float levels need to be very precisely wet-set; and you will need to do a running vacuum sync once the carbs are ready. For this you will need to have your valve clearances in spec.

 

well they were because i put them back together wrong when i was reassembling the carbs the first time, i didn't realize i did it backwards until i was surfin around here yesterday morning and saw a diagram saying that the big one went on top and the little one was in the middle. i knew that i had mine in reverse. now they're in there right but it almost seems to run worse. Sorry if i sound dumb this is my first go around with working on old bikes.

 

Just have to go back to having the carbs off and finish the steps in order.

FIRST - you have to check and adjust the valve clearances
Second - if you have adjusted the valves (that's how important step one is), bench sync the carbs
third - wet-set the float levels. There is only a 1mm variance either side of spec where these carbs will work correctly. This is almost as important as step one. You did do step one I hope.
Fourth - see where your pilot screws are by turning them in and counting the turns. Factory spec is to set them at 2.5 turns out, but we aren't done with them just yet.
Fifth - start the bike and do a running sync. Search the forum for "running sync" and "homemade manometer"
Sixth - adjust mixture screws by either colortune, or plug chops. A Colortune plug is about $50 to buy, but it is worth soooo much more.

Then do another running sync and tune, and it'll run like a r@ped @pe


How close are you to, say, Detroit? If someone is close enough they may be willing to help you out.

 

well i live just outside of south bend, Indiana. And thanks for the steps. i did check the valve clearances, and most weren't too bad only a few were out of spec. I guess i didn't know it would make this huge of a difference so thanks for that little piece of info, I'll get right on getting those shims out and find the ones i need. My pilot screws have not been uncovered yet either, what is the best way of going about exposing them? what exactly is special about a colortune plug?

 

The colortune plug LOOKs like a spark plug fires like a spark plug BUT has a clear see through top that allows you to see the color of the ignition spark or flame. This allows you to set the fuel air mixture to set up you carbs. It CAN NOT be used in place of a spark plug it is used at LOW rpms just to adjust the settings.

 

Is there a specific kind of colortune plug i need to get for it to work with my bike?

 

and what is involved in a plug chop? just curious because i don't feel like buying a 50 dollar colortune plug.

 

Hey trduff, I live in South Bend. I've done the valve adjustment, but can't really help you with the carbs as I havent attacked that part of the bike yet. If you need help with other aspects of the bike let me know.

 

Do you happen to have the tool that holds the shim down so they can be removed? thats the only thing holding me back from getting those changed.

 

I got mine running last night after hours of trial and error. These guys are right. Make sure your float levels are set right along with the jets in the proper place. It makes world of difference. Even after I had the jets right and bench synced, it still wouldn't start or run right until I had all the float levels in the proper setting. Then it fired right up and no longer did that rev way up like it was in the past.

 

you don't need the shim tool... search for the zip tie method

EDIT: I'm feeling nice today: http://xjbikes.com/Forums/viewtopic/t=2 ... ethod.html

 

MIXTURE SCREW PLUGS: use a small drill bit in a Dremel and just touch the surface of the plug. It should pull them right out. DO NOT go at it with gusto, the screws are juuuuust under the surface of that plug.

COLORTUNE: They are ordered by size, you need 14mm.

PLUG CHOP: Basically what you do with a plug chop is warm the bike up, then while the motor is under load, not idle, you'll rev it to around 5,000rpm and then kill the engine. Let the plugs cool and then pull them and take a look at the ceramic on the electrode end.

white plugs - lean
brown paper bag plugs - perfect
black and dry - rich

You may need to do this twice, or you may need to do it a dozen times. With the colortune you are paying for convenience of just being able to set them right, then do a plug chop to double check the color.

You can do a search for the shim tool on ebay, amazon, or PM member chacal for a price. I got mine for $15 shipped

 

I also forgot to mention your valve cover gasket. The 650R does NOT use the rubber gasket and donuts. It is a plain paper gasket. If you need one, order it from chacal. Chances are if you order from any other source you'll end up with the gasket for the YICS 650, which won't work on our secas.

 

You can also loosen the top cam bearings about 1/4 inch (don't need to remove them) and lift the cams just enough to get at the shims. May not be the 'preferred' method but it works.

 

thanks to all. i will update when i get some of this stuff done. there is one thing im still not exactly sure how to do the wet set. i understand you put a clear tube on the drain hole, where do you measure from then?

 

You hold the tube up against the side of the carb and the measurement is in millimeters down from the joint between the float bowl and body.

See: http://www.xj4ever.com/setting%20fuel%20levels.pdf you do each carb individually, and precision is important.


Also: I would not recommend "lifting up" the cams to pull shims. If the lack of "the tool" is holding you up, there are alternative methods: http://xjbikes.com/Forums/viewtopic/t=29209.html