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Discussion Starter · #1 ·
First of all, great forum! I’ve been reading/using this site a lot. I’m a novice so any help I can get would be greatly appreciated.

I have a 2007 VTX 1300R that I bought new in 2008. I had Cobra pipes put on by the dealer when I first got it
I’m not sure if they adjusted the A/F when they installed them. It’s always seemed like it‘s run lean when idling.

For the past year or so, it’s been backfiring when I ride and then let off the throttle. Based on other posts, it sounded like I needed to adjust the A/F mixture to make it richer. So I bought Glen’s permanent Mount A/F screw. I installed it per the instructions, including backing it off about 2 turns as a starting point.

When I started the bike up, it runs extremely rough when I give it some gas, but dies if I let it go down to idle. I’ve tried adjusting the A/F down to 1.5 and up to 2.5, but it doesn’t seem to make a difference. I made sure that I got the spring, washer, and grommet out with the old A/F.

Any suggestions on what to try next? Thx for your help!
 

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Are you equally sure that you installed the NEW spring, washer, and o-ring and that you got them in the correct order?
 

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Discussion Starter · #3 ·
Yes, I did that very carefully to make sure I got it right. I matched it to the A/F valve that I took out I.e., the order you reference above. The only other thing I did was replace the vacuum hoses with hose I got from Advance auto. They matched it to what I took off (5/32).
 

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I think your next step is to rejet the carb. You can find lots of advice on here for how to do this. If you do this, use ONLY a Factory Pro jet kit and NOT a Dynojet jet kit.
 

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If the bike is stock, buy yourself a cheap inductive tach off Amazon and do the Honda tuning procedure in the service manual. I had the same problem with mine at it took 5 minutes to get it running like new. You would think with only 1 screw to adjust you could tune it by ear, but I sure couldn't.
 

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If the bike is stock, buy yourself a cheap inductive tach off Amazon and do the Honda tuning procedure in the service manual. I had the same problem with mine at it took 5 minutes to get it running like new. You would think with only 1 screw to adjust you could tune it by ear, but I sure couldn't.
I will believe I will try this also
 

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I will believe I will try this also
Also if it's stock and you haven't done the desmog like mine, it will pop, and it will pop more in cold weather. I believe it has to do with a cold exhaust manifold and recirculation through the par valves. It's all pretty normal for the bike. Going over high passes in the spring when it might be 80 degrees at the bottom and maybe 55 up top with snow on both sides of the road it will pop a lot up top. I understand that as normal. You really want to read your plugs for proper mixture. Anyway if it's stock after doing the remote af adjustment, which is a cool mod anyway , the Honda tuning procedure should fix you right up.
 

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I ride a 2009 VTX1300C. It is rejetted, Glen's AF screw, no desmog. It runs so good, pops a bit on decel but I don't worry about it. Before the rejet it had a lean stumble. If you're interested in my jetting specs hit me up and I'll check my records.
Cheers, Caveman
 

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Discussion Starter · #10 ·
I would be really interested if you can dig up your specs mrbaumann1! I think I’m gonna rejet next.

For those of you up for a laugh, I figured out my first problem (I told you I was a novice)…when putting the air box back onto the carb I didn’t click the idle adjuster into the slot at the bottom of the airbox. So I think it was pushing the airbox out away from the carb a little bit which I’m assuming meant the carb was getting too much air.

Once I fixed that it ran mostly normally. I then got a cheap tach from Amazon (thx for the suggestion galiziap!) and got it I running at about 900 RPMs. Then I backed off Glenn’s AF about 2 1/4 turns and it seemed to be running better.

My new problem… after getting it adjusted, I went to take it for a test ride and got it about halfway out of the garage and it died. It seemed like it wasn’t getting gas. I’ve already replaced the Petcock and vacuum hoses with hose I got from AutoZone. Any thoughts on why standing it up and moving it back 10 feet might suddenly cut off the gas?

thx again for everyone’s help!
 

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Pinching a vacuum line or a vacuum line not connected somewhere. If any vacuum hose anywhere in the system is not properly connected, the entire vacuum system will not hold vacuum and, thus, the petcock will not operate properly.
 

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I would be really interested if you can dig up your specs mrbaumann1! I think I’m gonna rejet next.

For those of you up for a laugh, I figured out my first problem (I told you I was a novice)…when putting the air box back onto the carb I didn’t click the idle adjuster into the slot at the bottom of the airbox. So I think it was pushing the airbox out away from the carb a little bit which I’m assuming meant the carb was getting too much air.

Once I fixed that it ran mostly normally. I then got a cheap tach from Amazon (thx for the suggestion galiziap!) and got it I running at about 900 RPMs. Then I backed off Glenn’s AF about 2 1/4 turns and it seemed to be running better.

My new problem… after getting it adjusted, I went to take it for a test ride and got it about halfway out of the garage and it died. It seemed like it wasn’t getting gas. I’ve already replaced the Petcock and vacuum hoses with hose I got from AutoZone. Any thoughts on why standing it up and moving it back 10 feet might suddenly cut off the gas?

thx again for everyone’s help!
Good to hear your getting close to full resolution. It's pretty funny when I put in remote AF adjustment my carburetor ran dry due to a vacuum line pulling free. I liked my inductive tach so much I found a place to permanently mount it above the speedo. Even though the tach was really slow it helped me improve my ability to know what gear the bike is in at all times. That being said I would recommend against permanent installation. After about 7,000 miles I started noticing the clicking sound of spark jumping to ground. Apparently the ignition wire that was supporting the inductive pulse for the tach started breaking down.
Going back to tuning. I don't know much about it, but here are my thoughts. I actually hope someone with a better understanding like Vinish comments. I think the honda cook book tuning procedure should work fine if you have not done the decap mod, or the desmog. Basically if you still have the same air restriction to the carburetor, the stock jets would still provide the right mixture, so changing the exhaust should not be an issue. I think the reduced load associated with custom exhaust is generally compensated with timing. I'm pretty interested in this subject as I'm thinking of buying a Valkyrie 1500 this winter. I know a lot of them have aftermarket exhaust, but I'm thinking most will have the stock intake setup for the 6 carburetors, so I probably should not have to worry about a previous owners errors rejetting the carburetors.
 

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I would be happy to help but I do not understand the question. Please rephrase and ask again.
 

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I would be happy to help but I do not understand the question. Please rephrase and ask again.
I guess I have 2 questions. If someone makes one change to a good running carbureted bike, which is changing to a less restrictive aftermarket exhaust, should they being expecting to rejet due to exhaust change? If the bike runs poorly after the correctly installed exhaust change, would the cause be more likely timing mismatched due to the reduced exhaust load, or fuel air mixture due to the exhaust change?
 

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Is it possible to adjust the "timing" on a VTX1300? If so, I've never heard of it being done. I know that on some (maybe all) fuel injected bikes, you can install a fuel programmer such as a Power Commander V and the settings in this include adjusting the timing.

Typically if your only change is to put on a more free-flowing exhaust, a carb rejet is not needed. However, you also need to remember that on a completely stock bike, a carb rejet is needed. The bike comes from the factory with the carb adjusted to run very lean to pass emission testing. This causes the bike to run poorly when cold and causes some other problems. I recommend that the carb on even a fully stock bike be rejetted/tuned.

The best things to do are to make all of the following changes at once:
  • Buy and install Glen's permanent A/F screw
  • Buy and install a high flow air filter like K&N
  • Decap airbox or at least remove the "snorkel"
  • Buy and install dimpled block off plates as part of the pair mod (removal of pair valve system)
  • Make any planned exhaust changes (new exhaust, gutted stock exhaust, or drilled out stock exhaust)
  • Buy and install Factory Pro jet kit followed by tuning/rejetting
Do not do the last step until all of the preceding steps are done or you will just end up rejetting/tuning the carb again.
 

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Is it possible to adjust the "timing" on a VTX1300? If so, I've never heard of it being done. I know that on some (maybe all) fuel injected bikes, you can install a fuel programmer such as a Power Commander V and the settings in this include adjusting the timing.

Typically if your only change is to put on a more free-flowing exhaust, a carb rejet is not needed. However, you also need to remember that on a completely stock bike, a carb rejet is needed. The bike comes from the factory with the carb adjusted to run very lean to pass emission testing. This causes the bike to run poorly when cold and causes some other problems. I recommend that the carb on even a fully stock bike be rejetted/tuned.

The best things to do are to make all of the following changes at once:
  • Buy and install Glen's permanent A/F screw
  • Buy and install a high flow air filter like K&N
  • Decap airbox or at least remove the "snorkel"
  • Buy and install dimpled block off plates as part of the pair mod (removal of pair valve system)
  • Make any planned exhaust changes (new exhaust, gutted stock exhaust, or drilled out stock exhaust)
  • Buy and install Factory Pro jet kit followed by tuning/rejetting
Do not do the last step until all of the preceding steps are done or you will just end up rejetting/tuning the carb again.
Thanks for the detailed response. I didn't even know the ICM didn't accommodate timing adjustment until today. I used the timing marks to check my valve clearances last winter, so I assumed timing was adjustable.
 
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