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Discussion Starter · #1 ·
'88 shadow vlx, dual carb. Hole saw mod.

Bike was running beautifully before carb clean.

I tried to start her one day and gas was pouring out of the left carb float bowl. Took it apart, it looked like the gasket was worn. Since I had it apart I figured why not clean it out, and I installed new float valve and seats for both carbs.

I looked at a lot of clips and tutorials and I ended up boiling the carbs for a couple of minutes to clean them out.

Fired her up, no power beyond low end. Took it apart, adjusted float positions. Fired her up, suuuper rich fuel mixture. Took it apart, realized I had installed the float with the tang on top of the valve clip. Re-installed to factory specs (calipers). Just fired her up and I have limited top end power. Like nothing in the final 1-4 throttle. Keep in mind I used to reach 85 if I kept on it (I rarely go that fast), but now I can't get beyond 75, and it takes a good 30 second to go from 65-75. Weird thing is I feel I have plenty of low end power. Is this a float position thing or do I have a deeper issue?
 

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Discussion Starter · #3 ·
I was just thinking that I didn't remove the jets when I boiled them, they have o-rings don't they......
 

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Nope, don't think so. The vacuum slides have rubber diaphragms, and I believe the air cut off valve has a rubber diaphragm. Possibly the A/F mix screws might have o-rings also. The problem you are describing sounds like a vacuum slide issue. Either the diaphragms were damaged or installed incorrectly.
 

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Discussion Starter · #6 ·
I watched a few of his vids when I did the job (he has some great tutorials!). I removed everything but the jets, a/f screws, and drain screws for the bowls. I may have installed the diaphragms wrong or damaged them, but I felt I did ok. I mean, I must have done something wrong if it doesn't work correctly. What strikes me as weird is that it doesn't sputter or pop at all, runs better than ever at the lower speeds & throttle. It's just at wide open throttle that it doesn't seem to have the power it has at lower throttle. At least you've given me a direction to go in, I'll take it apart and check the diaphragms and vacuum slides.
 

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run it for a bit at the higher RPM, Then hit the kill switch and pull a plug, if its black you may have set the float to high or issue with the valves not sealing

whitish looking too low float level or blockage still somewhere..
 

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Discussion Starter · #8 ·
Man I love this forum, I'm never stuck because you guys always offer some form of direction I can go in. I'll get to it tomorrow and let you know what I find
 

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Discussion Starter · #10 ·
Took off the diaphragm cover and saw the edge not sitting in the groove. I'm not sure if it was sitting this way under the cover but do you think thus would contribute to a vacuum issue that causes lack of power only at the top end? Checking the other side now....
 

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Discussion Starter · #12 ·
Ok I hope I can describe this without being to confusing...

After painstakingly re-seating the diaphragms, and with the carbs put together but still off the bike: Wen I push on the diaphragm piston I hear the air compress and it takes a second to return the needle to its closed position. I seem to remember it taking a shorter time to return to this position before I re-set the diaphragm. Maybe I'm dreaming it (wishful thinking because I'm almost at wit's end), but I'm hoping that contributed to a possible vacuum problem.
 

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Discussion Starter · #13 ·
Thanks Harryc, so many times I feel like I've landed on an issue only to learn that what I found does absolutly nothing......
 

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What you are describing sounds like normal vacuum piston operation. As long as they are both equal and there are no hang-ups and they operate smoothly you should be good to go. It almost sounds like a sucking sound when you operate them by hand, and when they return you hear an audible click. If I am wrong I apologize in advance, but no top end is a classic vacuum slide problem. If that's not it we'll think of something else.
 

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Discussion Starter · #15 ·
Ok, All back together. Gonna get rid of all my ammo so I don't blow my brains out if it still doesn't work right.........I think I'll sacrifice a goat first so that all my bases are covered before I fire her up.
 

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Discussion Starter · #16 ·
That was it!!! She flies!! Better than ever. I took that lil 583cc faster than I feel comfortable for sure. Thanks Harryc, I owe you a beer. Or, since I'm on the central coast, a wine bottle. I hope someone has the same problem and finds this thread. Check that the diaphragms seat properly in their grooves.
 

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With age those thin rubber diaphragms can stretch or shrink.
I think it would be good insurance against a leak to put a very fine film of silicone rubber sealer in the bottom of the groove (but not in the vac. hole) and let it set for a bit to make sure when the cover goes on it will still be in place. It would be easy to clean out later if the diaphragm needs to be replaced. Might save a lot of head aches.
 
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