Bonneville America Forums Forums Technical Forums General Tech No gas to carbs - nada - huh?

2004 Speedmaster - black, which everyone knows is the fastest. However, not at the moment

My poor Speedy isn't getting gas to the carbs. She sat for a couple winter months, but nothing out of the ordinary or extended. The gas in the tank is obviously a bit darker yellow and has that familiar 'past its prime' smell, but no clumps or anything unusual.

I immediately thought it must be that stupid little in-line filter hidden in the T-fitting to the carbs... so I yanked the tank and pulled the filter. It wasn't too bad, and didn't seem like it would be the cause of blockage. Figured I'd run some fresh fuel through the carbs to flush things out, but when I open up the drain plugs - nothing comes out. Nada. Them float bowls are bone dry..

I put a hose on the carb fuel "T" and filled it up with Sea Foam, hoping that it would help dissolve whatever it was blocking things up. Hasn't helped yet. Thought maybe it was a stuck needle valve, but I've tried tapping on the carb bodies as well as hooking up a hose to the bowl drain and cycling a vacuum then pressure though it, again,with no results.

Short of yanking the carbs, which I really, really do not want to do, can anyone suggest something else that may get things flowing again? I really hate it when the weather is so beautiful and the bike is out of commission.

Cheers,
Brad

The answer you don't want to hear is...wait for it...pull the carbs. That said, before doing so, does gas flow through the fuel valve in both open positions? If it does, then the float bowl valve seats are likely crudded.

Not sure what you mean by flowing through the valve (which valve? Tank is off the bike))... I'm not getting a flow anywhere! I know there is gas in the carb inlet tube, and I removed that inline filter that is in the 'T' connector. But I cannot get any gas out of the carb drain plug - so it's stopped somewhere between the two and nothing I've done so far has been able to unblock it. Only thing I can think of between them is a needle valve stuck closed... and it is refusing to open up for some reason.

Actually, the gas was not all that bad - it was just starting to turn... so the fact that it blocked up so hard in such a short period of time really has me stumped.

Cheers,
Brad

There is only 1 fuel valve (on the tank), presuming your fuel system has not been modified.

This brave new website apparently does not permit editing. I was referring to the manual rotary fuel valve (petcock, if you prefer...) on the tank...not the float valves in the carbs.

I think the carbs need to be pulled and the float valve assemblies need to be inspected.

LOL - I figured you were talking about the petcock but the tank is off the bike, so that isn't even part of the equation (fuel flows just fine from the tank, in both main and reserve positions BTW). I am still hoping that forcing some Sea Foam around might just get things loose enough to flush through, but my hope are quickly fading. Thanks.

Cheers,
Brad

There are several possibilities, the hidden filter between the carbs could be clogged, the screen on the petcock could be clogged, the vent hose for the gas tank could be plugged or the float issue. I posted before I read everything. You should be getting gas from one drain or the other, both floats being clogged at the same time is unlikely, not impossible, but unlikely. If you have allen screws holding the bowls on, not the oe phillips, you can remove the bowls and inspect with a mirror. I just had my bowls off to check the same think but I think my issue is the CDI. Not bad life for that since mine is an 04 and just now quit.

Hey Ian... thanks for the reply, but I've already removed that hidden filter between the carbs, and I'm trying to flush the carbs with the tank removed - so the filters on the petcock and tank vent are not a concern. Those have been tested and work fine though.

I was hoping it was just that stupid filter. But I'm never that lucky when it comes to mechanical stuff

I guess I should have titled this thread as "No gas IN carb", because the issue is there is no gas getting to the float bowl. And both carbs are showing the same problem. I have apparently made some minimal progress using the Sea Foam, so I'm going to let it soak for another day or so to see if that breaks it up enough to flush out. If not, then yanking them is my last resort I guess.

Cheers,
Brad

I use Sea foam to "refresh" the fuel that has been sitting for awhile, not to "fix" the fuel. I would try something along the line of some kind of carb cleaner. ie... https://www.walmart.com/ip/Gumout-Carb-Choke-Parts-Cleaner-14-oz-800002231W/17128883

The last thing I'm trying to do is 'fix' the fuel!!! At this point, I'm just trying to get it flowing through the carb to flush it out. I was hoping that the Sea Foam would break up whatever was clogging things enough to accomplish that, but it doesn't seem to be working as well as I hoped. I seem to have had some minor success though, as I am now starting to get a tiny bit through the right side carb, but still not sufficient to flush. Carb cleaner would certainly work better if I could figure out a way to get it into the carbs without going everywhere else as well!

So at this point, it looks like them things are coming off. My last resort was hooking the fuel inlet up to the compressor and hitting it with ~50 psi trying to open up the needle valve, which didn't work. I'm almost afraid to see what is actually in there clogging things up so bad. I'm sure it won't be pretty.

New questions now that I'm going to yank the carbs. First off, does anyone know what carb kit is needed for these? It seems like there are a couple different CVK specific kits. And lastly, I want to replace the phillips screws with some stainless socket head cap screws. I've read they are M4... is that correct?

Thanks!
Brad

they are 4mm X 0.7. I hope you didn't damage the diaphragms with air pressure. Your problem could be created by ethanol, it attracts moisture and is bad to leave sit in carbs untreated. I use Stabil Ethanol Treatment in the fall in all my gas engines that will not be used over the winter. It can cause corrosion in the carb passages. That being said it probably didn't cause enough to clog a float valve, more likely smaller passages but it could if let sit long enough. If it is both carbs for you I would still be looking at the fuel lines back. I really can't see both float valves clogged at the same time. Not impossible but unlikely.

That is exactly what I originally thought, and why I assumed it was going to be that little inline filter between the carbs on the fuel hose. But I now know it's getting good fuel flow to that "T" connector where the filter is, and it's impossible to examine the fuel hose any farther with it installed on the bike. I tried fishing some wire down the connector to see if I could dislodge anything, but again, its location makes it basically impossible.

Having to yank them is becoming my only remaining option it seems. Fortunately, there is a storm system coming through today, so it's a nice rainy day to wrench on the bike.

Cheers,
Brad

Yup, I think you need to pull them off if fuel is good to the T, fortunately you can pull them as a pair and it isn't too bad to do. Hardest part is the cables.

Ok, got them off. What a PITA that was. They fought me the whole way, but I prevailed in the end. I have no idea how I'm going to get them back in though!

And as I feared, it was a mess in there - and for some reason, the gas remaining in them had turned a weird shade of green! Even the floats have been tinted green from it. The float bowl drain holes were clogged, there was visible crud throughout, and the float valves were basically cemented in place; I had to un-clip them from the float and then work them out using a pair of very fine needle nose pliers to break them free.

The float bowl gaskets have seen better days and need to be replaced, and the float valves have some noticeable indentations on the rubber tips, so those need to be replaced as well. I didn't have any problems loosening up the phillips head screws, but I guess now would be a good time to replace them with some stainless socket head cap screws as well.

I tried to find some kind of rebuild kit for these carbs and I couldn't find anything. Can anyone point to a source for at least the bowl gaskets and float valves? I can probably find the replacement screws over at the local ACE hardware store.

As a side note - there are a few rubber bits on the bike that are cracked and/or falling apart that really could use to be replaced. Where can a person find parts diagrams for these bikes so I can trace down some part numbers, and where can you get OEM parts other than my local supermarket dealer that charges a kings ransom for just about everything. Does that Triumph place in Georgia that we went to a few years back sell parts?!? I know they have hats and cigarette lighters

Cheers,
Brad

Hermy's in Port Clinton, PA has always been reasonably priced for me. I would give them a call. Sounds like water damage making the brass parts corrode. Could be from Ethanol, did it sit with untreated gas in it? I use Stabil Ethanol treatment in all my gas engines when parking them for the season. Sounds like quite a bit of corrosion though, hope the passages in the body are still open.

Pull the float bowls and check to see if the needle is stuck. You might also see some crud in the bowls that can be cleaned. Make sure you use a good quality Philips screw driver if the screws haven't been replaced with Allen head ones. Since the tank is off, you could try forcing a bit of compressed air into the fuel line inlets to the carbs to help force any stuck needle valve off the seat.

Edit - just noticed you already have done this so...

Just discovered that I should NOT have disconnected the TPS when I removed the carbs. Did I just royally screw up?

I did look at the TPS adjustment procedure listed in the Tech Valult, but the wire colors are different on my bike (2004 speedy), and I am unable to get to the readings specified; although that may be due to a cheap ass multi-meter.

I realize that some people have disconnected theirs... so should I be concerned about this? Should I just put it in the middle of it's range and hope for the best? Buy a better multimeter?!? Can you 'tune' the TPS by ear like you used to be able to do on old vacuum advanced carbs? Damn, I'm bummed now.

Should be able to run without it, many do. I would opt for a better meter, probably won't be the last time you need one so not bad to have anyway. I have a cheap one I use often because the cheap one buzzes for continuity testing and I haven't found anything it can't do that my better ones can.

^ What he said...you can run w/o TPS, however I suggest using it if you can. Calibration is not difficult.

Got a better meter today.. and it turns out my cheap meter wasn't too far off after all.

So I still can't dial in the numbers specified in the procedure. Using the yellow/blue wire pair, it says I should shoot for 4.42K with the throttle closed. The LOWEST I could get it was 5.17K with the sensor turned fully CCW. All the way CW ramped it up to 5.72K.

So then I tried using the yellow/black pair, and did manage to get it set for 0.81K (as the procedure indicates) with the throttle closed... but when you open up the throttle, it runs up to 4.8K, well past the 3.96K it says I should be looking for.

Any thoughts? I'm inclined to leave it as it is and see how it runs. I'm doing the testing with the carbs on the bench, so WOT may not be as much as I'm giving it by hand, so the open throttle number may be a bit overstated. Not sure by how much though. Grrr....

Well...try it on the bike using the actual throttle.

I ran my 03 America with the TPS disconnected for years. It eliminated the decel popping completely. Originally mine was acting up causing misfiring and stalling. My TPS resistance values were all over the map. I simply unplugged it leaving the old TPS bolted to the carb. Don't leave it plugged in if you plan on only unbolting the TPS from the carbs. The ECM will see only that one throttle signal and get confused. Apparently electrically disconnecting the TPS changes the timing (not confirmed) to a default setting which seemed to work for many of us. I think I put close to 40K kilometers on it disconnected with nary a problem.

Oh, from what I remember, I'm pretty sure I messed up my TPS with a pressure washer and was actually glad I got to disconnect it because I hated the decel popping and this got rid of it immediately.

LOL - wouldn't matter if it was hooked up to the handle or not for the closed throttle readings.. that is taken with the idle speed adjuster completely backed off and the butterfly completely closed - so it is a fixed, known position. I also measured the resistance range (sensor fully CCW, then fully CW), and that closed position 4.42K stated in the procedure just isn't possible on the yellow/blue pair as it's outside its range (5.17K to 5.72K).

However, I did get the yellow/black closed position reading dead on... but the WOT reading is high. If I am correct, that sensor is just a 6K potentiometer (reads 5.98K between black and blue), and the yellow wire is the wiper. Given that it doesn't appear to harm anything to completely disconnect the sensor and, with what I have now, it's roughly in the middle 3/4 of travel, I think it will be fine.. I hope :-)

I'm going to try and get the carbs back on today... and I am taking the opportunity to give the poor thing a much needed cleaning. Think the last time I did a good clean was when I got back from the 2006 Georgia rally! Also figure I'll do an oil change and brake fluid flush while I'm at it. Weather has been fantastic and I'm itching to get back on the road.

Cheers,
Brad

Good to know that running without the TPS actually helped things! I do have some slight popping on decel, but I attributed that to swapping out the stock exhaust with some short TOR's.

AFAIK, the sensor is still working fine, and the readings are pretty consistent. I removed it because the carbs were in such bad condition and I was going to dunk them in an ultrasonic cleaner, which I didn't think would be good for the sensor. It wasn't until after I removed it that I read in the service manual to just disconnect the harness, not remove the sensor... Doh!

I saw what disconnecting the TPS did to the AFR my modded 865 and I was not happy with the outcome, so I promptly reconnected it. YMMV.

Well... success, kind of

Clean/rebuild consisted of a good ultrasonic cleaning, new float needles and float bowl seals. Pilot jets were plugged up, so I unclogged them as best as I could, along with unclogging the choke circuit and running carb cleaner through every orifice I could find.

Got everything back together and she fired right up. But... at low RPM (idle), the motor runs really erratic. Once past about 3K, she purrs like a kitten. In addition, the idle speed will bounce around almost randomly. One minute it will be idling around 1K, then all of the sudden it will spit/pop and then jump up to 2K+, stay there for a bit, then come back down.

The only culprit I have right now is I noticed a bit of gas weeping from around the vacuum cap immediately behind the cylinder jugs on the left hand side of the motor. I know that a vacuum leak there could be a cause of the backfiring, but could it also cause an erratic idle?

I also routed the wiring for the TPS under the carbs instead of between them, so it should be easier to get to that connector for testing. Could the TPS and it's adjustment be causing these problems? B02S4, what problems did you encounter when you unplugged yours (and was it a carb or EFI model)?

Thanks guys...

There is a very long CV carb tuning thread in the Performance section of this site, which summarizes most of the carb & related tuning I did with my 07 SM 865.

My best guess is the pilot circuits of your carbs are still partially occluded.

Does your bike run with the enrichener (a/k/a "choke") knob fully or partially out?

Oh...and a vacuum leak...

Thanks - I'll go read that thread to catch up.


Yeah, the pilot jets are one of my concerns as well. When I had the carbs apart, they were completely blocked. I had to use a very, very thin piece of wire to unclog them and shot a lot of carb cleaner through them, but I was never really convinced I had them completely clean. I am running a tank of high octane gas mixed with this stuff called Star Tron that was recommended by a few people over at the other triumph site, so am hoping that might clean it up further. It does seem to be helping the more I run it, so hopefully that will breakup and remove any last remaining bits I may have missed.


Yes, it runs with the choke out, although at a much higher RPM than normal. The pickup tubes for it were clogged in both carbs, so they had to be cleaned out as well - but I think I did a pretty good job on those and it seems to be working as it should.

As for the vacuum leak - I put a hose clamp on the vacuum cap, which seems to have helped a bit. I ran it for a few minutes this morning and it seems to have at least cured the backfiring/popping that I was getting. I'll go ahead and replace all 4 caps just to be on the safe side.

Grrr... it now looks like it is the intake boot, not the vacuum cap, that is leaking. She will start right up and run perfect - for about a minute until warm. Then the hunting idle speed begins, followed by intermittent pops and small backfires. It all appears to be on the left hand carb, as I can feel it kick back each time - but not on the right side carb. I was watching it closely when it started doing its sputtering stuff, and now I can visibly see a slight 'puff' of fuel vapor squirt out the bottom of the intake boot on the cylinder head side every time it backfired. That is where the fuel came from that I thought was escaping from the vacuum cap.

I have an set of extra intake manifolds (if that is what you mean) that I am willing to sell. I also suggest replacing the pilot jets. There are also a few very small nozzles in the pilot circuit (you can see the outlets near the base of the throttle plates) that can become clogged up. FWIW...plastic dental pics can be used to CAREFULLY clean out occluded jets & passages.

Dangnabit... now I don't know what to think! I tried spraying some starter fluid around the intake boots (rubber bits between the cylinder intake and carb) and nothing - no change at all - so I'm not sure it's a vacuum leak after all. They seemed perfect when I put them on, with no visible damage anywhere, so maybe I just didn't seat it good enough. I will need to verify that.

But I'm leaning more and more to something still being wonky in the pilot circuit like suggested. It seems like it's just the left side carb that is acting up. I know one of the carbs was a bit more munged up than the other and harder to clean out, and I believe it was the left side. Kind of makes sense, as that would be the one with fuel left in it longer with the bike leaning over to the left on its side stand.

The pilot jets in particular were really hosed up. I had thought about replacing them (Keihin p/n N424-24B-42) when I had everything apart, and now really wish I had.

I still haven't tried disconnecting the TPS or messing with it at all... does any of this sound like something that it could be causing?

So close I can taste it!

First off I want to thank you guys for helping me through this... the wife is absolutely worthless when it comes to mechanical encouragement! I really do appreciate all the help and advice.

Next - I tested the TPS with the carbs installed on the bike exactly as per the procedure. Got the exact same readings I did when bench tested +/- a couple ohms, which is well off what was called for. I have left it disconnected and it seems to have helped a bit.

I've also been running high octane gas through it, mixed with some Star Tron enzyme stuff that was recommended as better than Sea Foam. Thinking that it would work best if I kept things moist with the gas/additive mixture, I've been going out and running the bike for a few minutes every hour or two. Each time, it seems to run just a bit better. At this point, she fires right up first crank, the popping and backfires have gone away completely, as has the wildly erratic idle. It still idles rough between ~1000->2500 RPM, but it is significantly better than before. Kind of weird though because the idle is not consistent - sometimes it is rough, and other times will just purr like a kitten without a problem.

I actually took the bike out for a quick ride today. Well, not a real ride, but just around the neighborhood to see how she handled. As expected, the low speeds were a bit rough, but manageable. And when the throttle is cracked, she took off like a bat out of hell with gobs of power. Even though it was just a short little test run, it sure put a smile on my face.

At this point, I think I'm just going to continue running fuel additive through the carbs to see if it cleans up more. I have a brand new can of Sea Foam that will get used after I run out of the stuff I'm using now. If that don't work, then at least I know what is involved, and won't be so intimidated yanking the carbs again!

Cheers,
Brad

Glad you are making progress. All other things equal, the higher the concentration of Seafoam to gas, the leaner the mixture becomes.

Ok, so I seem to have taken two steps forward and three steps back now... have put a little less than 200 miles on the bike in the last few days, and it was getting way better - until about the last 20 or so miles. Seems like something broke loose in the pilot circuit and is now hosing things up again. The wildly erratic idle, popping and backfiring has returned, and it seems like the left side carb is cutting out completely at times leaving it running only on the right side cylinder. Only low speed is effected, and after I get past around 3-4K RPM, she runs smooth, strong and hard.

So it looks like the carbs are coming off again

But I do have a couple of tuning questions! The bike is, AFAIK, completely stock with the exception of the exhausts - I replaced the stock ones with some short TORs back when I first got the bike over a decade ago. That means it has a #42 pilot jet, #110 main jet and stock needles with 2 shims each. Pilot screw is the "D" head thing and I have not touched it (don't have the D tool for one thing!).

I plan on getting new pilot jets, as I fear I may have munged them up when cleaning. Should I also get new main jets? They seem fine, but I read that different jets help when running TOSs. I'd prefer not buying them if they really don't make a noticeable improvement though. Anything else I should get. Don't want to do this a third time!

Cheers,
Brad

PS: Are two shims on the needles the stock (2004) configuration? I was looking at the TJP tuning paper (Jekns Bolts), and it says there should not have been any shims?!?

Unless you are tuning with an air fuel meter, just follow the Dinqua jet tuning calulator guide in the tech section (presuming it is still there). Just plug in the closest to the choices you can find...that will get you in the ballpark.

When you dunk cleaned the carbs, did you pull out ALL of the rubber bits first, including the air cut valve (acv) assembly on the port side carb? If not, I suggest pulling the carbs, fully disassemble everything you can, & check everything again. My guess is something did not get done right the first time.

Are you running the OEM airbox & airfilter?

Just trying to get it back to where it was before I screwed it up by leaving bad gas in for too long! I'm not trying to gain any more horses or get off the line any faster. Just want steady and reliable like it was before this mess.

When I cleaned the carbs, I pulled everything off that I could before they went into the ultrasonic cleaner - including the acv and TPS. I did leave the pilot screws, heaters and choke plungers though. Cleaning mix was just water + simple green along with a dab of dawn detergent run at approx. 140á´¼F (60á´¼C). Followed that by liberal blasts of carb cleaner in every orifice I could find, then more ultrasonic. They looked really clean when all was done, but then again, they were beyond dirty when I first opened them up - so there was most likely a lot of parts I could not see that were still in need of some help.

And yes, still running the stock air box and filter.

Just a guess on my part...an educated guess, yes, but still a guess: it is plausible that the pilot screw Vinton rubber o rings are damaged. I suggest replacing them. Replacement cvk pilot screw o rings, washers, & springs are available from CV Performance...CVP is a Harley tuner, but those pilot circuit parts on the cvk40 Harley Keihin carb & our cvk36 are the same.

The next thing I suggest checking are the vacuum piston (slide) rubbers, to make certain they dis not get pinched, punctured or torn.

Unable to edit my prior post...Should be "viton". Darn autocorrect.

Well, I should be getting a set of new pilot jets delivered here in the next day or two. I most likely munged up the ones in there when trying to clean them. I also now realize that despite putting in new float needles, I never bothered to check or adjust the float height, which is probably contributing to things as well.

I didn't touch the pilot screws - so do you think the o-rings could have been damaged anyway? The Haynes manual says that you have to replace them when you remove the pilot screw, but I didn't remove them and just left them alone. If need be, I have a Harley dealership just about a mile from me that I could probably get the parts from.