[twopoint71]

All,

So, my VTX has run like crap since I got it. Basically, the transition from idle to main jets it about as bad as it an be with all the "coughing" the engine does. Even goosing to squirt a bit of fuel from accelerator pump is not helping. Three turns out on the A/F screw makes it less painful, but that's bad ju ju in the long run.

I need to pull the carb and give it a good once over. I have already dropped the fuel bowl and gave the jets a good cleaning (they were barely dirty), but to no avail, so I suspect the fuel flow is inhibited elsewhere.

With that said, I want to know about others experiences with rebuilding these carbs.
Did you buy a carb kit?
If you bought a kit, which one and why? (I see several on the market) (This one from J&P Cycles looks good http://www.jpcycles.com/product/zz40834 )
Is a carb kit even necessary? (When I dropped the fuel bowl, the seal looked pretty good)

What is the most commonly gunked up parts of the carb (outside of the idle jet).

Sorry for all the questions, I'm just looking to plan the best approach before I dive in again.

Thanks,
Bob

 

[RamRod68]

I would suggest to pull the carb and disassemble and clean all passages, check diaphragms for deterioration and crack's, fuel inlet filter, and petcock filter and that should give you enough information on what you need. Since you are running awful lean I would suspect filters first.

 

[mjklaser]

All,
So, my VTX has run like crap since I got it. Basically, the transition from idle to main jets it about as bad as it an be with all the "coughing" the engine does. Even goosing to squirt a bit of fuel from accelerator pump is not helping. Three turns out on the A/F screw makes it less painful, but that's bad ju ju in the long run.
I need to pull the carb and give it a good once over. I have already dropped the fuel bowl and gave the jets a good cleaning (they were barely dirty), but to no avail, so I suspect the fuel flow is inhibited elsewhere.
With that said, I want to know about others experiences with rebuilding these carbs.
Did you buy a carb kit?
If you bought a kit, which one and why? (I see several on the market) (This one from J&P Cycles looks good http://www.jpcycles.com/product/zz40834 )
Is a carb kit even necessary? (When I dropped the fuel bowl, the seal looked pretty good)
What is the most commonly gunked up parts of the carb (outside of the idle jet).
Sorry for all the questions, I'm just looking to plan the best approach before I dive in again.
Thanks,
Bob

Hi Bob,

Before you start digging into the complexities of rebuilding your carb, you’ve got plenty of other things to do first (the low-hanging fruit). First, tell us how your air-intake is configured – is it stock? Modified? After-market cleaner/intake? Very important for us to know these things to be able to help you. Second, do you know if your carb was ever re-jetted? If it was done wrong, that alone could be the source of your problems. As you said, 3 turns out on the Pilot screw is way too much – there is some problem going on here. Third, fellow Café member, Crosis, currently has a gunked-up fuel system, so thoroughly read all the advice that has been given in his thread, some of which will be repeated below: http://www.vtxcafe.com/showthread.php/215465-Carb-issues

Addressing some of your statements - since you have a 2007C, there is no fuel pump – after 2003 model year which had a fuel pump, these are gravity-fed. Next, instead of needing to rebuild your carb, you might simply have clogged fuel strainers/screens at either the petcock inlet (inside the gas tank) or at the carb inlet, as suggested by RamRod68. Here is the fiche diagram from partzilla, showing the components of the petcock: http://www.partzilla.com/parts/sear...VTX1300S'04-'07)+(VTX1300R'05-'07)/parts.html

Here is the 'fuel strainer screen' that’s on the petcock assembly inside the tank:


Here is the inline fuel screen at the fuel line entrance to the carb:


Showing OEM part number and razor blade for scale:


Here’s a pic of this inline screen shown ‘in-situ’, originally provided by MR VTX (Jason) in his excellent carb tear-down thread on the 'OA (you can link to it from here: http://www.vtxcafe.com/showthread.php/45937-carb-and-what-affects-what?p=2647105#post2647105 ):
[/QUOTE]

Here’s a more zoomed-out pic from MR VTX so that you can discern where this fuel inlet port is on the carb:


After you read the ‘Crosis thread’ for the other sage advice given by others as well (like using SeaFoam gas treatment to dissolve crud throughout your fuel system), my recommendation is that you make sure that these two fuel filter/screens are not clogged thereby preventing the free flow of fuel. Then report back what you find and we can all jump in on the conversation and advise you from there…

Mark

 

[Silver F]

also replace the vacuum hose.. to the petcock .. a small crack can cause an intermittent ON/OFF on the vacuum control valve. just and FYI.

Great photos for that filters job.

 

[Vinish]

I've never heard of anyone who is having carb problems on a VTX1300 needing a "carb kit". I think you would be better off cleaning and rejetting with a Factory Pro Stage 1 or 3 jet kit (unless a re-jet has already been done with an FP kit). Also make sure that the large rubber diaphragm that holds the needle (under the top cap) is installed correctly and has no slits or tears.

 

[FRNKCAT]

All of the above... KISS...
Pull the main jet and see if it is stock or ??? Easy with fuel bowl off..
Check needle for stock or if it has a washer under it (Scar Mod)...
The Scar Mod would be a first step to solve any altitude or lean conditions. (free)
I Solved a friends dead spot/hesitation with simple Scar Mod...
Washer under needle... Little more fuel.
A/F should never go out more then 2 1/2 as it gets to weak on the spring tension and may just fall out....

 

[Crosis]

^^^^ all this stuff. These guys will get you through it. :cheers:

 

[twopoint71]

First, tell us how your air-intake is configured . . .

Stock intake.

Only a V & H Big Shot Staggered exhaust with the quiet baffles. (which I will happily to trade to anyone on this forum for unmodified factory pipes)

I'll dive into the carb / fuel system (good thing the tank is low) and make sure ALL the fuel passages are free and clear of debris and junk, and I'll stop by my local Honda dealer for a strainer.

Thanks for the information. I'll let y'all know how it goes.

Thanks,
Bob

 

[Vinish]

Make sure to post in the appropriate classifieds section that you will trade your pips for unmodified stock pipes. I suspect you will have a line of members vying to take you up on that offer.

 

[Bassdude404]

I've never heard of anyone who is having carb problems on a VTX1300 needing a "carb kit". I think you would be better off cleaning and rejetting with a Factory Pro Stage 1 or 3 jet kit (unless a re-jet has already been done with an FP kit). Also make sure that the large rubber diaphragm that holds the needle (under the top cap) is installed correctly and has no slits or tears.

All this...Been seeing more and more of the diaphragm issues as these bikes get older...

Also, 3 turns out is the point of the A/F screw falling out of the carb...

 

[twopoint71]

Hey all,

Thanks for the advice so far. I finally had a chance to dive into my carb this weekend. This time, I took the top half apart on the chance the slider diaphragm may be damaged. Last time, I followed Two Wheeled Rocco's guide.

Things I found:
1) No fuel filter at the fuel inlet port on the carb, or on the outlet port on tank.
2) The slider diaphragm looks good on visual inspection, no obvious tears.
3) Some buildup in the slider piston . . . "slide" so I polished it out a bit.

The trouble I've had so far is the lack of finding anything obvious at all. Last time I had the carb apart, the jets and fuel bowl were all sparkling clean.

This time I shot carb cleaner all around and burned through a tank of gas with some seafoam treatment. All passages I could see are running in the clear.

When I put everything back together and fired it up till warm, I left the air cleaner cover off. I was able to observer that if I slowly rolled on the throttle, the increase in engine speed was steady. If I quickly roll on the throttle (not goose it), the engine seems to stall and the slider piston rapidly moves up and down unable to find a good adjustment. This "fluttering" running condition is permanent unless I roll off and roll on again more slowly.

Other than the lack of a fuel filter, what do I need to fix this problem?

P.S. I'm at 2 turns out now on the A/F

Thanks in advance, and thanks for reading,
Bob

 

[FRNKCAT]

That sounds like a Vac leak in slide???
No expert at all just putting in my 2 cents....

Check that Diaphragm again real close, hold it up to light and gently pull it out smooth while you look.
These bikes are getting some age on them and things are going to go bad & break etc...
I Would also check all the Vac hoses, although other issues would be apparent if they were bad or off. But wont hurt to see if your bleeding Vac at another location.....



.

 

[Crosis]

When I put everything back together and fired it up till warm, I left the air cleaner cover off. I was able to observer that if I slowly rolled on the throttle, the increase in engine speed was steady. If I quickly roll on the throttle (not goose it), the engine seems to stall and the slider piston rapidly moves up and down unable to find a good adjustment. This "fluttering" running condition is permanent unless I roll off and roll on again more slowly.

Other than the lack of a fuel filter, what do I need to fix this problem?

P.S. I'm at 2 turns out now on the A/F

Thanks in advance, and thanks for reading,
Bob

Mine did this too. What I found was with the air cleaner off I was getting too much air. When I put the cleaner back on the bike ran like a champ. No more stalling or sputtering.

 

[twopoint71]

Mine did this too. What I found was with the air cleaner off I was getting too much air. When I put the cleaner back on the bike ran like a champ. No more stalling or sputtering.

This could be part of my problem. I notice the air filter has a "K&N" knock off vibe. Guess, I'll be after a new air filter as well.

So, I went through the carburetor like crazy. Performed leak down tests on everything with a vacuum port. Inspected and tested the vacuum lines and connectors. Made sure the diaphragms were perfect and perfectly installed. Everything on this beast is just right. For what it's worth the bike runs perfectly with the choke open a little, but that adds more air velocity under the diaphragm, along with air and fuel to the engine. The only modifications I've realized so far are the Vance & Hines Big Shot Staggered and after market air filter; given these mods, maybe I need to re-jet according to the carb and what effects what post. I observed some backfire in the manifold during flutter at night (when I could see it happening). Could this be exhaust reversion issues?

Will get an air filter over the weekend and keep ya'll posted.

Thanks,
Bob

 

[mjklaser]

Hi Bob... in re-reading your posts, you've stated that you're stock except for the V&H pipes and the air filter, and that carb passages look clear and carb parts look clean. You’ve not explicitly stated whether you verified the sizes of the jets or the configuration of the jet needle, which I presume that you have done in order to claim ‘stock’ – but let’s just check – my reasoning is that if it was re-jetted when the pipes were put on as some have done, then it’s possible that the compression spring behind the diaphragm/vacuum piston was replaced with a shorter (5-1/4”) spring since some kits (Cobra, DynoJet) came with one, or some have even cut their stock spring down to that from the stock length (of 7-1/2” I think) – and if so, that weaker spring could be responsible for the “fluttering running condition”.

This pic shows the stock Keihin 195 main and 55 pilot jets from my bike – do your jets have these exact markings?


Here’s the full view of the stock jets and jet needle:


Here’s a comparison of the stock jet needle vs. a Factory Pro Stage 3 jet needle:


So, does your carb hardware match these pics? Anyhoo, it’s just a thought I had to get confirmation from you so that we have all the pertinent info to help you troubleshoot the fluttering – and still keep in mind, as Crosis found, this could simply go away when you put the filter cover back on. However, I’ve run with cover off and no filter plenty of times and mine’s never done the “fluttering running condition” thing…

:cheers: atriot:

 

[FRNKCAT]

I am not as knowledgeable as many Carb guys here, Just been in mine so many times I could do it in my sleep. And a couple of friends Carbs (VTX)...
MAssive reading and research done here and VTXOA (Where by the way Charlie D is still a member)..

OK here goes: That backfire through carb is usually (usually?) An indication of Lean mixture. So the filter being off 'could' have caused it or made it worse..
But with all the original issues, It may not be the problem at all...
If your Needle and jets (as asked above) are stock. Know that these bikes are set very lean from Factory to meet Smog Standards (especially in Calif).... Also every bike seems to run a just 'little' different.

What would I do??? I would start with a Scar Mod and add a washer or two under the needle "IF STOCK"...
Open the A/F to 2 1/4 turns out. Try that....... Adjust accordingly ~ 1 washer, 2 washers Maybe even 3?? ALso adjust A/F from 1 1/2 to 2 1/2 and try each setting (1/4 turn at time)...

If it adds enough fuel to the mix, all is fine..

If the problem is still there (im thinking lean Mix here).

Then I would purchase the Factory Pro Stage 3 Jet kit, and follow The Carb Post by Charlie D....
it isnt a slam bam and takes some time & effort, but the results will be worth it (trust me on that)...

Also check the Intake ports and Y manifold, it is held on by rubber like extensions that have Hose clamps. Make sure all are seated properly and tight (At heads and Carb), could be just a little Vac leak there also...

Trouble shooting these issues can make ya crazy.......................................



.

 

[twopoint71]

Thanks for the updates guys.

I was in the carb again today. This time to make sure the accelerator pump was trouble free and clean as a whistle which is the case. Also, I picked up a stock air filter from Honda which fits way better than the odd-ball aftermarket job that came with the bike. I think the air filter made a huge difference. I don't have the flutter issue at all. It's fair to say the bike runs like a raped ape at this time.

Murphy is always hard at work, so naturally fix one issue and introduce another. Now the engine is running too rich. If I close the A/F screw completely the bike runs best off the fast idle adjustment with little to no black smoke out the tail pipe. I'm kicking myself for only checking one jet size, so I'll be in the carb again later this week to get the idle jet size.
Main jet: 185
Idle jet: TBD
Needle: Looks like the stock one posted in the pic by mjklaser

I get popping at low speeds, not on deceleration.

Almost there guys; what a ride this has been to get the beast working well.

Thanks for hanging in there with me.

Bob

 

[mjklaser]

Thanks for the updates guys.

I was in the carb again today. This time to make sure the accelerator pump was trouble free and clean as a whistle which is the case. Also, I picked up a stock air filter from Honda which fits way better than the odd-ball aftermarket job that came with the bike. I think the air filter made a huge difference. I don't have the flutter issue at all. It's fair to say the bike runs like a raped ape at this time.

Murphy is always hard at work, so naturally fix one issue and introduce another. Now the engine is running too rich. If I close the A/F screw completely the bike runs best off the fast idle adjustment with little to no black smoke out the tail pipe. I'm kicking myself for only checking one jet size, so I'll be in the carb again later this week to get the idle jet size.
Main jet: 185
Idle jet: TBD
Needle: Looks like the stock one posted in the pic by mjklaser

I get popping at low speeds, not on deceleration.

Almost there guys; what a ride this has been to get the beast working well.

Thanks for hanging in there with me.

Bob

So, your carb was rejetted. The 185 main is not an oem/stock size. 2003-07 models had a 195 Keihin main from the factory, while 2008-09 got a 190 Keihin main. You now need to look very carefully at the jet stamping - does it have the 'fat K' (that looks like a four-point star) preceeding the number? If not, then it is not a Keihin, but is likely a DynoJet 185 instead. That is a size that was included in DynoJet and Cobra (re-badged DynoJet) jet kits. Those kits came with the short 5-1/4" compression spring that I mentioned earlier that can lead to diaphragm/vacuum piston 'flutter' with open filters and airboxes. Also, unfortunately, different jet manufacturers use different numbering systems for the sizes of their jets, and this causes much confusion. A 185 DynoJet/Cobra main is equivalent in size to a 210 Keihin (or a 210 Factory Pro). So, if you have a DynoJet 185 main in there, then that would explain the rich running at speed - in other words, a main that is a 'Keihin 210 equivalent' is too big for a stock airbox with a restrictive air filter - too much fuel, not enough air - this is common for those that rejetted their bike with only an exhaust pipes change but no airbox mods. Most here typically agree and advise, don't rejet for only a pipe change - only after pipes plus air intake mod. Also, if you are rich at idle, then the pilot jet might be too big, also - as you said - TBD...

 

[Vinish]

twopoint71, Are you saying that when you close the A/F screw completely, the bike continues to run at idle? If this is so, then there is a problem. Closing the A/F screw should cause the bike to die. A common problem that leads to the situation I think you are describing is that the two small springs in the carb get accidentally swapped. One of these springs is in the accelerator pump but I don't remember where the other one is. They springs are about the same length and diameter but have different spring constants (force needed to compress the spring a unit distance). Did you take the carb apart to the point where these springs were out and is it possible that they got swapped during your reassembly?

 

[twopoint71]

Are you saying that when you close the A/F screw completely, the bike continues to run at idle?

Yep.

I ended up going to Honda and plunking down $20 for the factory main and idle jets. Put them in and the bike runs beautifully after some a/f and idle speed tweaks. And, now the engine stalls out when the a/f screw is turned in all the way.

I tuned the idle speed to this reference video: https://www.youtube.com/watch?v=k9Tcf6kJHuc

My issues were:
1) Knock off K&N air filter in the stock air box letting in too much air
2) A 185 after market jet causing a rich condition

This may not have been an issue, but the new and old idle speed jets had the same markings; however, the old jet had some sort of sleeve inside and appeared to have a smaller opening which I thought might have been due to build up, but I cleaned the crap out of that jet and the hole size was still visibly smaller when viewed through a light source.

Thanks for all the tips and help. I'm so glad to have the VTX running well after purchasing it all botched up.

~Bob