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2009 VTX1300R, 03 1800R
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Discussion Starter · #1 ·
Hello everyone,

I've never touched a carb before today.

Today I installed a #58 pilot, 210 main, and needle in 4th clip. I used the factory pro hardware.

My airbox is decapped. would adding more airflow add more power here? I could drill holes in the airbox cover/get a hypercharger.

My exhaust is stock and the pair valve is removed.

Does this sound like a good starting point? I've read countless threads and comments on here about this so I think I'm alright.

Should I replaced the spark plugs before I ride it? I don't have a dyno so I'll be checking plugs to tune it once I get the jets straightened out. Should I clean the plugs?

Thanks in advance.
 

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2009 VTX1300R, 03 1800R
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Discussion Starter · #2 ·
I also cleaned every bit of my carb internals that I could get to. Replaced all the relevant o rings. Replaced the plunger, installed glens a/f screw and removed the "choke"
 

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2005 VTX1800 S2
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In order to move more air, you would also need an aftermarket exhaust.
 

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You do not need to allow more air into the airbox than the decap already allows. Do NOT put on a hypercharger. They mess up performance not help it due to the varying air entry as a function of speed due to a sort of ram air effect. The setting you describe are a perfectly fine starting point. Now go and tune/adjust the carb using the method described in the thread here on the Cafe titled something like, "Carb, what affects what". You do not need a dynotune and you cannot tune based on appearance of the spark plugs. Do not get your hopes too high. This is only a 1300 cc v-twin heavy bike. It is not going to be a lot faster - only a little faster. The bigger benefits are easier starting when cold, better fuel mileage, and removal of unnecessary pair valve system that gets in the way of valve adjustments. Yes, you will gain a little horsepower but even with a 10% gain, a VTX1300 is still not a fast bike.
 
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I do not know about the 1800. Of course, you asked about a carb so this thread is about a VTX1300.
 

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I do not own a VTX1800 and am relatively ignorant about them. What expertise I have is mostly for the VTX1300. But why let lack of knowledge interfere with offering an opinion :)

The computer/FI system on an 1800 must have some sort of feedback system to detect combustion products or something and adjust the fuel/air ratio. However, this stock system must have limitations or else people would not install aftermarket fuel managers. At least one limitation of the stock system is likely the desire to run lean (low fuel/air ratio) as this will help reduce emissions and make it easier for the bike to pass EPA requirements.

So the answer to your question is probably (no guarantee) that the VTX1800 stock system has some ability to compensate for the varying air intake of a Hypercharger but this would be improved by an aftermarket fuel manager. But this answer ignores a more important question which is - Why should anyone install a Hypercharger (HC)? In my opinion, they should not. The HC gets in the way of the right leg, can cause problems with optimally managing air/fuel ratio due to the speed dependent ram air effect, causes the owner to have to re-route/modify some of the tubing in ways that are possibly not ideal, and provides just another moving mechanical part to break and all this to achieve zero performance improvement.
 

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2009 VTX1300R, 03 1800R
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Discussion Starter · #9 ·
I do not own a VTX1800 and am relatively ignorant about them. What expertise I have is mostly for the VTX1300. But why let lack of knowledge interfere with offering an opinion :)

The computer/FI system on an 1800 must have some sort of feedback system to detect combustion products or something and adjust the fuel/air ratio. However, this stock system must have limitations or else people would not install aftermarket fuel managers. At least one limitation of the stock system is likely the desire to run lean (low fuel/air ratio) as this will help reduce emissions and make it easier for the bike to pass EPA requirements.

So the answer to your question is probably (no guarantee) that the VTX1800 stock system has some ability to compensate for the varying air intake of a Hypercharger but this would be improved by an aftermarket fuel manager. But this answer ignores a more important question which is - Why should anyone install a Hypercharger (HC)? In my opinion, they should not. The HC gets in the way of the right leg, can cause problems with optimally managing air/fuel ratio due to the speed dependent ram air effect, causes the owner to have to re-route/modify some of the tubing in ways that are possibly not ideal, and provides just another moving mechanical part to break and all this to achieve zero performance improvement.
Yeah I thought that might be your answer. Someone is trying to sell me one but the stock airbox is already in my way.


Anyway, back to carb tuning. When the bike is idling fine but I give it any quick throttle it dies. My first thought is that the slow jet is too small, too much air. Does that sound right to you? A/f is at 2.5 turns and it's 45 degrees out
 

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2009 VTX1300R, 03 1800R
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Discussion Starter · #10 ·
I've read some posts, there aren't many, that describe my problem. It's possible I have a vacuum leak. I'm gonna start simple. My vacuum lines were cracked and just plain worn out when I took them off so I replaced them. I don't think they're 3.5mm so I ordered some proper 3.5mm lines from the internet. My fuel line is also cracked and I'm amazed it's not leaking. Ordered a new one of those as well. The ones from the parts store are too thick outside diameter and not nicely formed like the OEM.

I'll replace the vacuum lines and see if that's the problem or if it's in the vacuum chamber, maybe the plunger isn't properly seated. Does anybody know what adhesive Honda used to get the plunger/rubber gaskets to stay in the grooves?


My problem, explained again, is the bike idles fine. If I give it very very slow throttle increases I can get up to a high engine speed without issue. If I quickly open the throttle it bogs down. I don't know if it's too much air or too much fuel. I didn't smell any unburnt gas in the exhaust though.
 

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If you are talking about the rubber diaphragm that is attached to the slide that holds the needle, then do NOT use any adhesive to hold this in place in the groove at the top of the carb. With careful pushing, prodding, and poking you can get this diaphragm to sit in the groove. Make sure the "bump" on the diaphragm is fitted into the proper location in the metal groove.

Do NOT try to tune the bike in the manner you are describing with "When the bike is idling fine but I give it any quick throttle it dies.". You must follow the procedure outlined in the sticky thread titled something like, "Carb, what effects what". As this tutorial describes, you must first tune the main jet using a high rpm roll-on of the throttle. Then you tune the needle position using a medium rpm roll-on of the throttle. Lastly, you tune the A/F screw setting using the throttle blip method. Trying to tune out a problem like you are describing BEFORE doing the high and medium rpm tuning is a mistake.

Go ahead and replace cracked rubber parts and lines but then follow the procedure outlined in the aforementioned sticky thread.
 
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Discussion Starter · #12 ·
If you are talking about the rubber diaphragm that is attached to the slide that holds the needle, then do NOT use any adhesive to hold this in place in the groove at the top of the carb. With careful pushing, prodding, and poking you can get this diaphragm to sit in the groove. Make sure the "bump" on the diaphragm is fitted into the proper location in the metal groove.

Do NOT try to tune the bike in the manner you are describing with "When the bike is idling fine but I give it any quick throttle it dies.". You must follow the procedure outlined in the sticky thread titled something like, "Carb, what effects what". As this tutorial describes, you must first tune the main jet using a high rpm roll-on of the throttle. Then you tune the needle position using a medium rpm roll-on of the throttle. Lastly, you tune the A/F screw setting using the throttle blip method. Trying to tune out a problem like you are describing BEFORE doing the high and medium rpm tuning is a mistake.

Go ahead and replace cracked rubber parts and lines but then follow the procedure outlined in the aforementioned sticky thread.
What I'm saying is there's a vacuum leak somewhere, either that or the slow jet is hilariously missized. I believe I put 4.0mm vacuum lines from the petcock to the carb. I'm not sure if that's the cause of my troubles. I don't care who you are, nobody on earth could tune this bike with this current problem. It bogs down and stalls under any throttle load unless I give it very gradual increase in throttle.

If it's not a vacuum leak, then the first step would be a bigger main jet
 
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