Bonneville America Forums Forums Technical Forums Performance Mods Bike Still Broke - Performance (fuel starvation)

Hi all, ongoing problem which some of you will have already read about previously (However i've been in and out of hospital for a bit and still not managed to fix it.

The Preamble
Was doing some modifications on the bike - the most important of these being tank re-shaping (basically cutting out the existing cap and replacing it).

Since that point bike began to exhibit symptoms of fuel starvation : rolling on the throttle swiftly caused a pop and the bike acted like it was starved. If i was very very gentle with the throttle it would be fine.

we originally thought the tank wasn't vented enough :
- ran with the cap open (no difference to performance)
- bored bigger vent in cap (no difference in performance)
- checked filters (no blockages)
- eventually hooked it up to an air flow tester and it _does_ have enough venting.

Since then it has been with a mechanic friend who has done the following to it (before i demanded it back off him because he's had it for about 6 months now).

- Carbs disassembled, cleaned and reassembled (there was some grit but thats sorted)
- Serviced most of the important areas (he's a triumph mechanic).
- Sorted the front brakes because it had been standing for a while and they were locked.

Still no improvement in the breathing problem.
(i should state at this point that prior to the tank it didn't have _that_ many miles on it and was in good condition).

Any ideas? I'm pretty much at my wits end with the bike now and if all else fails will just sell it on the cheap to someone technically minded and buy a 'working' bike.

i'm hopeful that you guys might have any helpful suggestions that might give me a pointer - the mechanic has suggested putting performance coils on it but i'm holding back because it feels like it's 'guessing' at this stage (and it's not _that_ old a bike.)

hoping some wiser heads out there might have some ideas.

All the best,

Ant

Definitely doesn't sound like a coil will help... Is the bike stock as far as air box / pipes etc?

Some undigested research on your problem:

smite mine battery with furious anger (again) May 29 2008

improving starting Aug 12 2008

Post dealer performance drop off Nov 29 2008

Trident Update Feb 10 2009

On one tack,

Sounds like you could shim the jet needles/install larger pilots/up you main jets. What are the current carb specs?

The starvation issue arose after the tank bung. Or did it? You installed the tridents in feb/march'09? Did you do any carb work then? When did you get waylay-ed with the shoulder? Have you really had a chance to ride the bike after the tridents and before the bung?

Scratching my head out loud is all.

Ah, apologies, i missed out the most important parts.

The bike is stock except :
It has Short TORS (not Tridents anymore - my ears couldn't take it).
AI has been removed by me.
It has twin headlights running from a relay provided by easternbeaver (though the problem existed prior to fitting them).
Apart from the cleanout the Carbs havn't been messed with at all.


and the tank...

...the tank basically has had the filler cap cut out and replaced with an Aero (aircraft style) filler cap. The little pipe that once ran from the top of the tank down to the bottom (which then connected to the rubber hose) is now blocked off.

originally we thought the problem was that it wasn't venting enough (because of this pipe being blocked or when i lined the inside) but after running with the cap open and with the painter (alledgedly) getting it airflow tested there seems to be no difference.

I'm getting the bike back (after months now) on Sunday so it'd be good to either try and fix it in one big blast or have a direction to suggest to the _Next_ mechanic who looks at it.

Ant

If you didn't rejet with the tridents, then you're presumably running stock jetting, which is too lean, even for the short TORs.

Yep, on stock. That being said though, have been running the TORS for a while and not noticed any performance drop off (i think the mechanic checked my plugs and they weren't too bad - i'll double check them on sunday though).

is it possible for the jetting to run fine and then cause that problem? (i'm still a newb when it comes to the carbs).

Ant

Have you checked the hidden filter??

That's the one hidden deep between the crabs yeah?
Removed it and replaced with an inline one. (sorry, forgot about that one) .

Havn't checked the float bowls but I believe the mechanic did when he stripped them down.

It's such a bizzare but crucial problem.



Ant

Ask your mechanic what jet sizes you are running. and how many shims. If he can't answer you that... nuff said?

Also, you should have had your spark plugs changed out. @ a buck fifty each, not replacing them is silly. Ask to see the old ones.

Jester, I would like to suggest you try something. Remove the inline gas filter you said you installed. Take the bike out for a run and see it this corrects the issue.
I experienced the same problem with a nice glass inline filter after removing the hidden filter( aka pain in the rear). Took it off, threw it in a box and no more issue.
I'm not running any filter other that the pingle in the gas tank valve. Been that way for 3 years.

Going along with both Mike and, as, Kevin Cameron puts it,

Quote:

---

Be aware that paper filters have been known to "prolapse" and block flow. Trust nothing to luck. Inspect everything. Filters, indeed, are good insurance against tiny flakes of tank rust, etc., that can easily stop up a main jet.

---

You can check the slides (where the needles sit) make sure they move freely.
or check this post out where I talked about an old car I had http://www.bonnevilleamerica.com/forums/...p;page=0#448655

Have you done a simple fuel flow test? Open the float bowl drains to see if fuel flows freely. Open them both up for a minutes with hoses attached and drain into a glass. If they don't flow, disconnect the hose from the carbs and drain again. Keep doing it till you find the blockage. I agree about the inline filter acting up.

I'm assuming it is a blockage since your bike ran good until you played with the fuel tank. Have you removed the petcock from the tank and checked the screen?

Mine is an 05 America - I HAD ongoing "fuel" problems for about two YEARS. The shop cleaned the carbs twice, and I did it three times I even had the coils changed by the shop because they said they were both bad. ran fine for about 300 miles and then started up again. Seemed like fuel starvation - Pilot jet problems - high RPMs ran OK. SO - on a fluke I decided to replace the coils (both of them) witht he nology after market coils - two nology coils were cheaper than one OEM gill "POC" All of a sudden all my fule/carb problems have been solved ny replaceing the oem coils. its been 2000 mile and it runs GREAT.

It really did act like a carb problem- just a thought cuz I did every thing you described. and the cils fixed it! Good Luck

Just a quick update -
Got the bike back today and the updated info is :

Apparently the carb is leaking (fuel?) when the engine is running.
He re-iterated that the carbs have been cleaned out and some grit removed
Also apparently only one of the cylinders are firing consistently (the other one is..but only a bit)
He said he sprayed some (mumblename) grease around the choke as it seemed a bit loose (or spitting i can't remember), after that there seemed to be 'some' improvement in the running but not a lot.

The mechanic is still suggesting coils..but seems unsure.

Worth while mentioning, my girlfriend owns a Triumph Scrambler 06 - would the coils be the same? (swappable to test if i _do_ need them?)

I'll also test the float bowls tomorrow and let you know what i get back with.

thanks for your suggestions so far, fingers crossed this can get fixed


Ant

scrambler coils will be all right ...scrambler has same firing as our bike

If the carb is leaking gas while running you have a float issue and the bike won't run right until that's fixed.

omg

6 months and he gives it back to you with a leaking carb? Are you fu@*ing kidding me?

Your mechanic is, to be kind, quite incompetent. How could he clean the carbs and then give you back the bike with the carb leaking? I feel for you. Cannot fathom how he could work on the bike and not correct the carb leak. Speechless. Whatever he told you will not help us help you figure out what is wrong with your bike as to be blunt, your mechanic is a work of art. A very fugly piece indeed.

grrrrr

(Update so far)

So its now been in the hands of another mechanic (this ones a local garage and I've dealt with them before) and they're looking at the carbs and filters again - mostly because they were full of crud.

Excitingly (not) it turns out that the Triumph mechanic didn't put the needles back in the carbs and possibly damaged/didn't put back properly the float bowls.

So two weeks later new needles, filters and bits arrive. They re assemble and apparently it fires up fine. A little while later my carbs start leaking again!

They've had a look at the carbs and apparently the little brass 'seat' that the needles go into (or sit in) isn't holding them in properly. It looks worn apparently (ill see for myself tomorrow).

This is causing the leaking problem as the needles aren't sat doing their job properly (according to the guy).

Worse news - apparently I can't order in that part from triumph separately. They guy is hunting on eBay as we speak but it looks like my hopes of this being an easy fix are dashed.

Heck, I don't even know if that's the underlying problem (the breathing one) or just one of the many that developed when it was with the dealer!

Looks like I'm going to have to fix then get rid, I just dont have that kinda cash lying around.

Still, weather's nice!

If you mean the float needles, they're a bit pricey but easily obtained. The seats are another matter since they're pressed into the carb body but since the float needle has a rubber tip I find it quite unlikely that yours are unacceptably worn. I'd concentrate on insuring the float height has been properly seat...and, that float tab is easily damaged by ham handed wrench types.

You can try getting a small drill bit that fits in where the needle goes and that is bigger than the hole that lets the gas in and just clean the seats, don't try to take any metal out, just enough to take any crud that has accumulated on the seat. Its worth a shot,if it does not work,replace the seat(s)if that's the problem.

Went down to the local mechanic guy and he showed me the part (which he's removed without damaging the carb itself).

Basically it appears that one of those 'sleeves' was significantly lower than the other one and that was causing things not to sit properly.

He told me he had put everything together with new needles etc (man i'm still annoyed that the last guy didn't have the sense to put it back together properly) and it fired up fine and seemed to run quite well until after a small amount of time the carb started flooding again (thats when he discovered the discrepancy).

So now it appears i have to buy new/second hand carbs _or_ somehow find that particular part - anyone got any experience with that bit? if Triumph don't do them do you reckon it's possible to get them direct from Mikuni?

Images of the part can be found :
http://picasaweb.google.com/JesterMinute/TheBike?feat=directlink

or

<table style="width:194px;"><tr><td align="center" style="height:194px;background:url(http://picasaweb.google.com/s/c/transparent_album_background.gif) no-repeat left"><a href="http://picasaweb.google.com/JesterMinute/TheBike?feat=embedwebsite"><img src="http://lh6.ggpht.com/_gt4f2uCNUjI/SZwjMuHA7TE/AAAAAAAAAVc/5f2xCV2_zoc/s160-c/TheBike.jpg" width="160" height="160" style="margin:1px 0 0 4px;"></a></td></tr><tr><td style="text-align:center;font-family:arial,sans-serif;font-size:11px"><a href="http://picasaweb.google.com/JesterMinute/TheBike?feat=embedwebsite" style="color:#4D4D4D;font-weight:bold;text-decoration:none;">The Bike</a></td></tr></table>

fingers crossed!

(reposting this as computer had a fit).

Cheers for the heads up on the carb type - not sure where i got Mikuni from - having a mad moment obviously.

I think i gave the wrong impression with the earlier post (about it being worn) - i had misheard the guy on the phone. It was in fact in fine condition, just sat at a different level to the other carb (which ran fine) - i'm not sure if it was higher or lower but there was a noticable difference apparently. This difference meant that the needle wasn't sitting properly and caused it to flood.

the needles and float bowls are new - because the previous mechanic had forgotten to re-assemble the carbs properly and had not included them so the evidence points to this irregularity in positioning being the culprit.

the mechanic (who's an older geezer and already is filling me with a bit more confidence) had already removed that one by the time i arrived.

can i just check what you mean by the tang on the float being incorrectly?

thanks for the heads up on SUDCO and the breakers, man this is turning into a trek and a half.

cheers for your help,

Ant

(oh yeah, and i think you asked me for pictures on my headlight setup a while ago? i havn't forgotten - i just havn't had my bike back long enough - if it wasn't you then apologies for me getting mixed up)

Can i just check - in the hope that you know off the top of your head - what type of Keihin carb it is? (FCR or something else?).

I've found a couple of carbs with exploded diagrams that seem to imply i might be able to get the part (Which would be nice as that would save me cash)

cheers again guys...be nice to ride the ****** thing at some point!

All righty, let's see if we can make some progress here.

The floats regulate the amount of fuel in the bowl. They do this by lifting or lowering this device called a float needle:

The needle has a small bail attached to it that fits over a tang in the center of the floats, that tang regulates the height of the fuel in the bowl...which is apparently your problem all along:

if the tang is bent incorrectly, as it seems one of yours is, it malfunctions. Here is the proper setting for you to show mechanic #2 so he can set the float height properly and return your bike to good running condition:

Excellent pics Ed. these should be put in the tech vault for future float height enquiries.