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Discussion Starter #1
I'm new to this bike. I recently bought it from my cousin a week ago. It hasn't been ridden much in the last year. Just under 20k miles on a 2005 with stock pipes, intake,and carb. Aside from the addition of a windshield it's stock all the way around.
My dad cleaned the carb before I bought it and put in a new battery.
We just did a 175 mile run together and when we were riding I noticed that I couldn't go WOT without running extremely rich and just falling flat on the top end. If I rolled slowly onto the throttle I could keep up with him on his Harley with stock 96ci engine. But I can't for the life of me get on it without flooding out horrendously. If I let off and get back into it I can kind of get past it. But found it best to roll on the throttle slowly and once I'm caught up it's just fine. I just cannot push it past 3/4 throttle or I experience it falling flat on it's face until I let off and roll on slowly. Almost feels like I'm good under 3k Ron and over that it's flooding out.
Today I went back through the carb with a bike mechanic buddy and we checked all the jets. It's got MS195 and 55S jets. Set it at 2.5 turns. Same issue. Tried choking it, tried running without the air cleaner. No effect to see if we can lean it out.
Pulled plug to double check and she's black so it's definitely rich as can be. What did we over look?
Fuel flow is not lacking. But getting the a/f mix at 3/4 to full throttle is eluding me.

Thanks for any input
 

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Recently had a 1300 running extremely rich. The Air Cutoff Valve diaphragm had a hole in it. The two screw cover with the vacuum hose.
At the top of the page, "Search community" type in "MR VTX CARB 101" that should give you the link. Here it is>>>

I had a problem with getting up to speed, for me it was the slide diaphragm. Many holes therefore no lift of the slide valve.

Welcome to the VTXOA.
 

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Pulling off the vacuum hose and plugging the hose may buy some time. It may also have fuel leaking out from the ACO hose bib. The link to the most recent ACO problem. Need help Houston Tx VTX 1300c. Some carb cleaners may weaken diaphragms...
 

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Discussion Starter #4
I'm thinking it's got to be something with the slide diaphragm. Checked everything else out. All vaccine lines, ports,and jets. It moves freely by hand but must not be opening all the way at 3/4 throttle while in use going down the road. Sitting in neutral in the shop it functions correctly.
 

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Slide diaphragm did NOT cause a RICH running engine..
Pull ACO hose off at carb, If you see gas that is your problem..
It is a rare failure, but a broken ACO diaphragm will allow
vacuum to suck a lot of fuel.. Read the link I added...
 

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Discussion Starter #6
Found air leak on manifolds, put new o rings in and fixed that problem.Bypassed the ACO and no difference.Tried a smaller pilot jet down to a 50. Made it crispy on the start but still falls flat on it's face while still running rich. Going back to stock 55S. So what am I missing here?
 

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You said running rich --that means Black smoke????
Found air leaks on the manifolds---that would LEAN the A/F.
Is the Starter Enrichment valve(aka choke) closed all the way??
It has a spring to push it closed.
The rubber elbow has to go on the nipple that screws into the carb.
Did you look at the ACO diaphragm???
Is the float needle installed correctly???
Go back to MR VTX CARB 101 and review.
 

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Discussion Starter #9
The only thing I cannot confirm is the black smoke. I haven't had anyone following me when the bike begins to stumble and fall flat. Everything else has been verified as done correctly.
 

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The only thing I cannot confirm is the black smoke. I haven't had anyone following me when the bike begins to stumble and fall flat. Everything else has been verified as done correctly.
You do NOT know if it is running rich???? Cannot confirm smoke??? What do your spark plugs look like???
Should be black on the center electrode..... IF it is that bad it should be fouling the spark plug.

When my slide diaphragm began to disintegrate I could only do about 55 mph tops.
Also some backfire at take off.
The Throttle Position Sensor (TPS) tells the ICM to advance Ignition timing. Check it.
 

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Discussion Starter #11
The plugs are black on the electrode. That we've confirmed so that's where the running rich is being stated from the start of this post. As for seeing black smoke I have not had anyone behind me to physically confirm. No backfire at take off either. The bike only begins to stumble at the 3/4 to full throttle going down the road. It will not do it in the shop. I will check the TPS.

I'm very new to motorcycles but my buddy who is walking through this with a fine tooth comb has been in this industry for more years than I have been alive. So I appreciate your help regardless.
 

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Check the accelerator pump diaphragm also.
There are only a few paths that can make it rich..
One more thing, the air filter... Is it clean?? Is it OEM???
Many have used the K&N filter, several have excessively oiled it.. Runs rich!!!!
 

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Discussion Starter #13
We have checked the accelerator pump as well. It's functioning and good as well. Stock airbox with clean OEM filter. We're even looking at downsizing the pilot jet just to rule that out.
I'm almost at the point of just getting new diaphragms all around in hopes that it's something with them that we cannot see physically but happening while running.
 

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Unless the pilot jet was drilled out(rare) the OEM pilot jet is fine.
Verify jet size.... Are the tiny holes clear?? Emulsion tube part...
Is the main jet needle holder correctly installed??

Jackk mentioned using a hose on bowl drain. Use some clear hose and give it a u-turn so it goes up the side
of the carb for a few inches. Open the drain screw and see where the fuel level goes to.
If the fuel level goes above the float, that is your problem.
A picture from MR VTX CARB Cleaning 101, inspect carefully.
 

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Discussion Starter #15
We just tested the TPS and it's not within the proper resistance. So now that's the direction we're going. Although I'm struggling to find a new one in online. Ebay ads galore for a used one...
 

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Two fixed endpoints and a variable wiper.... What resistance were you seeing?? Give me some numbers.... Some VTX parts have come from 90's Honda Civic...
 

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Discussion Starter #17
We removed it and testing off the bike now again. Prior to removal it was .4ohms idle to 4.2 at wot. Now removed starts 0ohms and up to 5ohms in turning it maxed both directions.
 

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We removed it and testing off the bike now again. Prior to removal it was .4ohms idle to 4.2 at wot. Now removed starts 0ohms and up to 5ohms in turning it maxed both directions.
Seems you are using different Ohm scales to measure the resistance.
x1 Ohm setting would show 400 ohms but out or range for 4k ohms.
x1k ohm setting ".4 ohms" = 400 ohms; "4.2" = 4200 ohms


Going to 10k setting lower resolution = 0 ohms and 5k ohms.

Yellow/Red is +5v from the ICM. Blue/Green is the Sensor Ground.
Check for +5v. I may have used a wire to back probe.
You can test the voltage range of the TPS also.
 

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Discussion Starter #20
After retesting the tps. We were able to get it to show the readings you suggested on the bench. We reattached to the carb and shifted it to show the readings before we tightened it down. Using both digital and analog volt meters. We were able to get 1.1 to 4.8 , in order to get the correct readings it has to be all the way to one side. As it was set dead center prior to us taking it off. Also tested voltage and got 9 volts. So that was good. Stock jetting reinstalled... Getting things ready to get it running again for a test ride to see if it's made any difference.
 
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