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Still have carb problem
Hi everyone

I have a 1985 GL1200 Interstate. I bought Randakk's carb rebuild kit and rebuilt the carbs to try and get rid of low rpm pop at 2000 to 3000rpm. I rebuilt the carbs and then syncronized the carbs. I still had the same problem. I just took them apart again and cleaned them again, this time I soaked them in demineralized water that was heated, and used a sonic cleaning machine. I just put it back together and I still have the same problem. I haven't got a clue what to try next. Other than take it to a shop. The shop I usually go to said I may never get rid of that pop due to the age of the bike. But he is not a Honda shop.

I really could use some help.

Discouraged Sad
#1 09-10-2008, 07:46 AM,
There is a post right under yours by looseeagle (86 Aspy backfires when throttle closed, decellerating) that covers air cut off valve and anti burner valve that could be your problem. Tricky put a diagram in this post that shows how they work and how to test them.
Ride safe have fun and enjoy. Lane
1985 Aspencade
2002 Vulcan
#2 09-10-2008, 09:13 AM,

I did test the slow cutoff, it seemed fine as it was one of the parts that came with Randakk's kit. I didn't test the anti burner valve. Although my carbs don't pop when decelerating, just when accellerating.
#3 09-10-2008, 11:05 AM,
I have found that after the bike is warmed up, I can get it to stop poping or back fireing through the carbs, If I set the choke to about 1/2 way, which at idel makes the engine run at 2000 rpm's.

Does this mean I am getting to much fuel at low speeds?
Any thought's ?
#4 09-15-2008, 01:24 PM,
Bob NE in.

I just replaced the plugs yesterday, as well as replaced fuel and air filter last week.
#5 09-15-2008, 04:00 PM,
Don't get discouraged. Does the bike backfire when it's cold, or only after warm up? If it's only after warm, the choke may be compensating for a lean condition during warm up. Is there any driveability issue when it backfires, like a miss or bogging down? Since you overhauled the carbs, did you drill out and set the idle mixture screws? If so, how many turns? Were you careful to install the "o" rings on the mixture needles?
#6 09-15-2008, 04:27 PM,

It doesn't seem to matter weather it is cold or warm or after a 130 mile ride. It does the same think pop or backfires at around 2000 to 3000 rpm over 3000 rpm it is like a supercharger kicks in and it takes off.

I did not drill out the idel mixture screws as it idels fine.
#7 09-15-2008, 06:04 PM,
Popellis Wrote:I did not drill out the idel mixture screws as it idels fine.
Oooops. The idle screws need to be drilled out, passages cleaned and screws reset. Contrary to popular belief, the idle circuit makes up approx. 15-20% of the total carburetor function. If your idle circuit is plugged or partially blocked, you are running lean. Syncronizing helps the bike to pull equally on all cylinders, but doesn't garauntee correct fuel flow. The fact that it idles @2000 when you choke it (richen it up) should suggest that.
#8 09-15-2008, 07:21 PM,

What I have done is shim the needles on the slides, that has helped but did not eliminate the problem. I guess now I will pull the carbs for the 3rd time check the float settings again. check all the vacuume hoses, to be sure they are tight. And I will drill out the plugs for the pilot screws.
#9 09-17-2008, 07:20 AM,
when you did ur carbs, did you changed the pilot screw oring and washer?, how many turns you used?
85' GL 1200 Interstate - My Picture Thread
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#10 09-17-2008, 05:21 PM,
William_86 Wrote:when you did ur carbs, did you changed the pilot screw oring and washer?, how many turns you used?

No I didn't change them.

But I just pulled it apart now. I did check the floats again and this time I did drill out the plugs for the pilot screws and changed the o-rings and washers. My clymer book says to set them at 2-1/4 turns to start, so that is where I set them. Now it will have to wait until tomorrow to try it as it's 12:30am and i think the wife might get a Little pissed if I start it now.
I actually checked the pilot screws and they were about 1-1/2 turns when I took them out. i hope this works I am getting tired of taking this apart.
#11 09-17-2008, 09:36 PM,
Well Everyone

Here is a strange event. I have removed the plugs that cover the pilot valves, removed the valves cleaned the holes or at least sprayed cleaner to make sure they were open. Replaced with new o-rings and washers from Randakk's kit. I have all for pilot valves closed or screwed in all the way and the bike runs like I did nothing to it. It still pops at 2500 rpm's. I thought it should not even Idel with the valves closed.

#12 09-18-2008, 08:49 AM,

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