Honda VTX 1300 / VTX 1800 Motorcycles Forum banner
1 - 20 of 29 Posts

·
Registered
Joined
·
71 Posts
Discussion Starter · #1 ·
So I have been working on my 2005 VTX 1300s for weeks. It carbon fouls all four plugs within 100 miles of a change.

I have cleaned and tuned my carb, added Glens a/f screw and turned in all the way to 1 3/4 turns out from lightly seated. Still fouling. Still smell fuel.

from what I have read online, I’m beginning to think I have an electrical problem causing a weak spark. If the spark isn’t strong enough the plug will carbon foul. That is what mine are doing.
the weird things are:
1) My bike starts every time without any sign of a weak battery.
2) All four plugs are equally fouling. Since there are two coils on this bike it seems strange that all four would foul.
3) I have checked the connections on the battery and made sure they were wrench tight.

The PO added led accent lights, a phone charger, and Bluetooth speakers. Is it possible that all that is pulling too much load and reducing the spark somehow?

Anyone have a suggestion on how to trouble shoot and/or solve?

Thanks
 

·
Super Moderator
Joined
·
12,178 Posts
To test your current question, disconnect all the aftermarket electrical stuff and run the bike for 100 miles and check the plugs. I think your problem is with the carb tune and/or choke assembly.
 
  • Like
Reactions: rmack2 and Wayfarer

·
Registered
Joined
·
21 Posts
So I have been working on my 2005 VTX 1300s for weeks. It carbon fouls all four plugs within 100 miles of a change.

I have cleaned and tuned my carb, added Glens a/f screw and turned in all the way to 1 3/4 turns out from lightly seated. Still fouling. Still smell fuel.

from what I have read online, I’m beginning to think I have an electrical problem causing a weak spark. If the spark isn’t strong enough the plug will carbon foul. That is what mine are doing.
the weird things are:
1) My bike starts every time without any sign of a weak battery.
2) All four plugs are equally fouling. Since there are two coils on this bike it seems strange that all four would foul.
3) I have checked the connections on the battery and made sure they were wrench tight.

The PO added led accent lights, a phone charger, and Bluetooth speakers. Is it possible that all that is pulling too much load and reducing the spark somehow?

Anyone have a suggestion on how to trouble shoot and/or solve?

Thanks
Here are some suggestions:

What spark plugs do you use? NGK-DCPR6E (Copper / standard) or DCPR6EIX (Iridium)?
Wrong plugs (low temp: < 6) will foul eventually.

How old is your battery? Test the battery!
If output power is too low, especially with all your electric add-ons, there could be weak sparks at your plugs.

Test the onboard voltage while the engine is running. It should be around 14 V. If not, there could be a problem with your alternator or rectifier.

After riding a few miles, make sure the choke lever at the carb is closed (pushed in)!
If the choke is permanently engaged, a rich mixture will result in excessive carbon deposits on the spark plugs.

Going very fast (> 100 mph) will clean the spark plugs (excessive heat burns off carbon deposits).

Check the connection of the spark plug wire at the cap. Those might come lose after a while. Cut off 1/2" of the wire and re-thread. If the cap is cracked, replace it.

There could be a problem with the ignition coils not providing enough voltage. Seek professional help.

Your air filter could be clogged, causing low air flow, ergo rich mix. Get a new air filter or get a reusable K&N filter.

Regular use of SEAFOAM will keep the carb clean, especially the jets.

Hope this will help.
Good luck!
 

·
Super Moderator
Joined
·
12,178 Posts
For a VTX1300, the cheap sparkplugs are more than sufficient. You will gain nothing from using more expensive (e.g. iridium) plugs other than gaining the dubious benefit of a lighter wallet.
 
  • Like
Reactions: CaliVTX1300

·
Registered
Joined
·
71 Posts
Discussion Starter · #7 ·
Here are some suggestions:

What spark plugs do you use? NGK-DCPR6E (Copper / standard) or DCPR6EIX (Iridium)?
Wrong plugs (low temp: < 6) will foul eventually.

How old is your battery? Test the battery!
If output power is too low, especially with all your electric add-ons, there could be weak sparks at your plugs.

Test the onboard voltage while the engine is running. It should be around 14 V. If not, there could be a problem with your alternator or rectifier.

After riding a few miles, make sure the choke lever at the carb is closed (pushed in)!
If the choke is permanently engaged, a rich mixture will result in excessive carbon deposits on the spark plugs.

Going very fast (> 100 mph) will clean the spark plugs (excessive heat burns off carbon deposits).

Check the connection of the spark plug wire at the cap. Those might come lose after a while. Cut off 1/2" of the wire and re-thread. If the cap is cracked, replace it.

There could be a problem with the ignition coils not providing enough voltage. Seek professional help.

Your air filter could be clogged, causing low air flow, ergo rich mix. Get a new air filter or get a reusable K&N filter.

Regular use of SEAFOAM will keep the carb clean, especially the jets.

Hope this will help.
Good luck!
Using NGK standard plugs. NGK DCPR6E
Carb has been cleaned a few times, no gunk, no clogs
Going over 100 mph on a two-wheel machine would likely clean more than my plugs.
Bike never grunts on startup and lights are bright. How would one go about checking the voltage on board and from the battery?
Why would professional help be needed if the coil is bad? Aren't those pretty well plug and play?
Air filter looks fine but I may put a new one on just so I can ensure this is not an issue.

I know the 1800 is famous for a ground issue. When I pull it all apart AGAIN I will be checking the ground points for both coils.

Now to the carb possibility: The jets look stock. If they are, should there be a jet size stamped on the bottom? I guess it is possible the PO put a different jet size in without changing anything else. The SCAR mod has not be done. The tit is intact and the needle has no washer.
 

·
Registered
Joined
·
36 Posts
So I have been working on my 2005 VTX 1300s for weeks. It carbon fouls all four plugs within 100 miles of a change.

I have cleaned and tuned my carb, added Glens a/f screw and turned in all the way to 1 3/4 turns out from lightly seated. Still fouling. Still smell fuel.

from what I have read online, I’m beginning to think I have an electrical problem causing a weak spark. If the spark isn’t strong enough the plug will carbon foul. That is what mine are doing.
the weird things are:
1) My bike starts every time without any sign of a weak battery.
2) All four plugs are equally fouling. Since there are two coils on this bike it seems strange that all four would foul.
3) I have checked the connections on the battery and made sure they were wrench tight.

The PO added led accent lights, a phone charger, and Bluetooth speakers. Is it possible that all that is pulling too much load and reducing the spark somehow?

Anyone have a suggestion on how to trouble shoot and/or solve?

Thanks
What jets are in the carb and what exhaust mods have been done?
 

·
Registered
Joined
·
47 Posts
Brother,
You have a problem with ‘false’ air entering the combustion chamber.
Firts check your choke. If it goes all the way back and closes the airway ‘it is supposed to close’ completely. You can check by looking into this airway or by spraying carb cleaner in that airway, which is on the back of the carb, while the bike is running.
Secondly : check if none of the vacuum hoses leak.
Thirth : check if all the connections from the carb to the cylinder are airtight.
You can check if their are no leakages to your vacuum hoses or your intake system, by spraying carb cleaner on those parts while the bike is running. If the engine rises, (making more revs) while spraying carb cleaner on these parts, it means there is a leak via which the carb cleaner enters the intake system and also your cylinders.
I had the same problem with my VTX 1300 R. And the problem was a stuck choke. While the bike was running without filter housing, I closed the airway that lets air pass the choke piston with my index finger. And the bike started idling better. That’s when I new there was a problem with my choke and why my bike was fouling spark plugs constantly.
 

·
Registered
Joined
·
71 Posts
Discussion Starter · #12 ·
Brother,
You have a problem with ‘false’ air entering the combustion chamber.
Firts check your choke. If it goes all the way back and closes the airway ‘it is supposed to close’ completely. You can check by looking into this airway or by spraying carb cleaner in that airway, which is on the back of the carb, while the bike is running.
Secondly : check if none of the vacuum hoses leak.
Thirth : check if all the connections from the carb to the cylinder are airtight.
You can check if their are no leakages to your vacuum hoses or your intake system, by spraying carb cleaner on those parts while the bike is running. If the engine rises, (making more revs) while spraying carb cleaner on these parts, it means there is a leak via which the carb cleaner enters the intake system and also your cylinders.
I had the same problem with my VTX 1300 R. And the problem was a stuck choke. While the bike was running without filter housing, I closed the airway that lets air pass the choke piston with my index finger. And the bike started idling better. That’s when I new there was a problem with my choke and why my bike was fouling spark plugs constantly.

The choke (enricher) was one of my first suspicions. I upgraded the spring to a stiffer one. The choke is very tight now. I will check the other issues. Thanks
 

·
Registered
Joined
·
71 Posts
Discussion Starter · #13 ·
I just pulled everything apart again and I have found an issue I hadn’t noticed before. The two vacuum hoses that connect to the bottom of the air box appear to have oil coming out of them. Any ideas of what causes that? It is not a lot but I noticed a shiny spot on the edge of the one associated with the pair valve. I checked the inside of both hoses and they both have oily residue. Is this normal?
 

·
Super Moderator
Joined
·
12,178 Posts
I could be wrong but I am not sure that those hoses are vacuum hoses. Where both of them connect to the airbox, do they terminate in a port that is open to the airbox? If so, these are vents not vacuum hoses. One is part of the pair valve system and the other is the crankcase breather hose. It is normal for the crankcase breather hose to give off a little bit of oil mist. I am not sure about the pair valve hose.
 
  • Like
Reactions: Wayfarer

·
Registered
Joined
·
71 Posts
Discussion Starter · #15 ·
I could be wrong but I am not sure that those hoses are vacuum hoses. Where both of them connect to the airbox, do they terminate in a port that is open to the airbox? If so, these are vents not vacuum hoses. One is part of the pair valve system and the other is the crankcase breather hose. It is normal for the crankcase breather hose to give off a little bit of oil mist. I am not sure about the pair valve hose.
You are exactly right. They are vent hoses. Thanks
 

·
Registered
Joined
·
71 Posts
Discussion Starter · #16 · (Edited)
So I have narrowed it down “I think”. When I screw the a/f in using Glens extension, the bike doesn’t die. When I changed the a/f I took a piece of wire and made sure no old parts (o ring or washer) were left in there from the PO. I knew I had mine out but I wanted to make sure nothing else was in there previously.

I have sprayed carb cleaner around all vacuum hoses with no response while it is running.

Any other ideas on what I might try?
 

·
Super Moderator
Joined
·
12,178 Posts
I have experienced one error that will cause the bike to NOT shut off when run at idle with the A/F screw tightened all the way in. There are two components of the carb that each have their own medium size spring. These are the air cutoff valve and the accelerator pump. Both springs appear almost identical and could easily be incorrectly swapped if the carb was torn down to the degree that both of these springs were loose in your pile of removed parts. However, the two springs have very different stiffness (spring constant). Is there any chance these were swapped by you or a previous owner? If they have been swapped, then the bike will not run correctly and will not shut off at idle when the A/F screw is tightened all the way.
 

·
Registered
Joined
·
71 Posts
Discussion Starter · #18 ·
I have experienced one error that will cause the bike to NOT shut off when run at idle with the A/F screw tightened all the way in. There are two components of the carb that each have their own medium size spring. These are the air cutoff valve and the accelerator pump. Both springs appear almost identical and could easily be incorrectly swapped if the carb was torn down to the degree that both of these springs were loose in your pile of removed parts. However, the two springs have very different stiffness (spring constant). Is there any chance these were swapped by you or a previous owner? If they have been swapped, then the bike will not run correctly and will not shut off at idle when the A/F screw is tightened all the way.
Where are they located? I have not taken the carb completely off the bike but have dropped the bottom off to access the jets. I have no idea what the PO may have done so anything is possible. This plug fouling problem was occurring when I got the bike (although the PO swore everything ran great).

Where would I look and how could I tell if they are right or not?
 

·
Registered
Joined
·
10 Posts
Any chance you over-tightened the main jet? Looks as follows. As well, w/ the Glens adj screw. Is it set up correctly (meaning Spring, washer, rubber) Pic as follows. Lastly, any cracks in this plastic washer (it sucks btw). or is it missing. Pic as follows. On to your fouling questiong. I run a lithium battery. I'm a bit of an elitist on these and have even built my own using 18650 cells. I know there are many who say AGM or L.A. but im'a Lithium fanboi and highly recommend them.
Finally, how foul are we talking? Pure cosmos, or a lil- burnt pizza crust?

Oh,
 

Attachments

·
Registered
Joined
·
10 Posts
idk if you seen the intake gasket when you removed it. If you decide to take it off again, make sure it's fully intact. I doubt it, but if it's nicked, corroded, or protruding I think you'd get extra air. Pic as follows.
 

Attachments

1 - 20 of 29 Posts
Top