What now??

[t4tiger]

Hi,

Just got back from a 50 mile trip when the bike ran fine.  Just getting home and it started to stutter before cutting out.  Would not restart.  Then noticed petrol dripping from bottom of engine.  I have noted that the fuel appears to be coming from airbox drain hole.  Does this mean that the fuel is somehow getting into the airbox instead of the...where it should!   What do I need to do to rectify this?  Many thanks in anticipation.   

[JayDub]

Stuck carb float/needle valve?

[GavD]

Had this last year on my '98 (Keihin carbs) faffed about for ages moving the rubber tipped float valves around and cleaning up the seats, but the problem used to come and go. in the end i got fed up with getting the carbs in and out so bought 3 new ones from Sprint manufacturing. No re-occurrence since.

I assume it was the tips going hard over the years and not seating properly.

[t4tiger]

hi again, thanks for the info.  Does that mean I have to strip the carbs again?  Is it a simple job of buying the new needles and just swopping them or will it need setting up in some way?  What about the petrol in the air box?  It's new, do I need another new one?  many thanks. 

[threepot]

May just need new needles,or it could be a dislodged float assembly? as what happened to me once! No need to change filter,unless it needs a one?

[Sin_Tiger]

Get a set with all new O rings from Steve at Motocarb in Liverpool. You should only need to set the float heights. If the air filter is old it might have suffered, otherwise you might be lucky and it's just dribbled down inside  cheaper solution would be a K&N filter.

[t4tiger]

Hi sin, looks like he only does mikuni.  Also, I'm reading slightly different descriptions here. Is it float valves or float needles or something else?  And what o rings do I need? Do I have to take the carbs out or can I work on them in situ? Do I need to do each carb? Will it be obvious where the problem is?  Sorry for all the questions, my one and only delve into carbs ended up at dealer and a few more grey hairs. Thanks

[London_Phil]

Look here, about 3/4 down the list for Keihin parts.

http://www.triumphparts.gbr.cc/index.php/26/435297

Not cheap, but this is the only place I have found Keihin parts, and there a good supplier.

Pulling the carbs is "Fun" so perhaps worth blitzing it.

I'd probably just try

Keihin float needle
Product code: J553

and

Keihin float chamber seal
Product code: J552


Good luck

[GavD]

If you've got Keihins, you do not need any o rings. You'll def have to pull the carbs to do it.

Get e'm on a bench turn them upside down and strip the bowls off (may be a good idea to have 3 new seals ready). Where the floats pivot you can push the pin out and lift out the float assembly with the valve hanging off the little tab in the middle. Replace it and put it back in. Do all three then check float height by tipping the carbs backwards until the pin in the valve just stops the floats (best to youtube this to see what i mean). Adjustments are made by bending the little tab very slightly. Once done, get them all back together then I recommend checking the float height again by setting up your fuel tank on the bench above the carbs, connect 'em up and turn fuel tap on. Again, youtube the next bit to see what I mean, but you need a clear tube attached under the carb that turns up alongside it, then open the drain screw to see the level. Do each one in turn.

The only problem I found was that the haynes manual refers to mikuni float height only of 14mm. I researched the Keihins as they are used on some jap stuff and found their height was different. It's in one of my posts somewhere, I'll find it and post later. I couldn't work out how to relate this to where the level should be when you use the clear pipe, so I plumped for approx 2mm below the float bowl surface (i.e where it seats to the carb body).  Once i'd finished I left them set up on the bench with the fuel switched on for a longer period, I did get a little bit of fuel seeping out the back of one carb through the little holes that are part of the pilot circuit, but it was only a little bit, not enough to have the original problem we both had of fuel pouring out of the airbox.

It all sounds complicated but it's not really, spend a bit of time watching you tube to get your head round it first.

I would def recommend spending a bit more time checking them on the bench to make sure, cos it's bloody frustrating getting them back in only to find out you'll need to pull them again cos you've got one wrong.

Dunno whether you have a manual or not but to get 'em out it's like this;
side fairings off
tank off
seat and seat side fairings off
battery out
side pods of airbox off
remove choke cable
undo jubilee clips to airbox and head rubbers (leave head rubbers attached to head)
pull back airbox as far as possible
start wiggling and remove carbs to the right hand side
once out it is then easier to get throttle cable off.

Hope this helps, I'll go find that float height

[GavD]

Here's my old thread to read
http://www.tigertriple.com/forum/index.php/topic,13366.msg102239.html#msg102239

[t4tiger]

Hi Gav,  This is so helpful, thank you very much.  I will replace needle floats and float bowl gaskets. I think I have it but just a couple of things I'm still not sure about.  Hope you can help.  If I have it right when I put it all back together:
The main jet should be hand tight after cleaning?
The pilot jet should be backed off so many turns (I intend to take them out, ensure they are clean and then put them exactly the same)
Once the carbs are back in do I sync them using carb tune type thing and then adjust the air/fuel using the appropriate screw or the other way round?  Is there only one screw to adjust both air and fuel? Do I do this by ear for all three carbs until it sounds sweet?
Is there anything I have missed?

[threepot]

The only screw you can adjust(mikuni)is the idle mixture screw..the screw at the bottom of photo,between the 2 holes!. Mustang suggests 2 -21/2 turns out. Get them all the same,then synchronize carbs using a Morgan carbtune.
http://www.tigertriple.com/forum/index.php/topic,7600.msg52526.html#msg52526

[Mustang]

The only screw you can adjust(mikuni)is the idle mixture screw..the screw at the bottom of photo,between the 2 holes!. Mustang suggests 2 -21/2 turns out. Get them all the same,then synchronize carbs using a Morgan carbtune.
http://www.tigertriple.com/forum/index.php/topic,7600.msg52526.html#msg52526

only if you have smaller than #40 pilot jet
for a #40 and especially a #42 I'd stick with 1 1/2 turns or even better use an O2 gauge to set them .

Kiehins on the other hand like to be at 2 turns at least on the mixture screw .

Steamers like mikunis that are left stock .

[GavD]

Hi Gav,  This is so helpful, thank you very much.  I will replace needle floats and float bowl gaskets. I think I have it but just a couple of things I'm still not sure about.  Hope you can help.  If I have it right when I put it all back together:
The main jet should be hand tight after cleaning?
The pilot jet should be backed off so many turns (I intend to take them out, ensure they are clean and then put them exactly the same)
Once the carbs are back in do I sync them using carb tune type thing and then adjust the air/fuel using the appropriate screw or the other way round?  Is there only one screw to adjust both air and fuel? Do I do this by ear for all three carbs until it sounds sweet?
Is there anything I have missed?

The main and pilot jets, which are inside the carb should be screwed in tight, it's the pilot air screw that needs to be screwed out approx 2 & 1/2 turns. This is similar to the Mikuni pic posted by 3pot, and is accessible from outside the carb.
You can see it here as item 10
http://www.worldoftriumph.com/triumph_motorcycle_parts_locator.php?block_01=&block_02=100058916-1-2&block_03=23773

I didn't really do much tuning of them, as I found that Mustangs suggested jet sizes and setting gave me pretty good running. I seem to remember turning the pilot air screw out about another 1/8th turn just to improve things a bit at small throttle openings.

I never messed with the sync, as they all come out bolted together and in theory you don't need to reset it. Might be a good idea to check it after if you have a morgan tune to hand.

Hope this helps, sorry I can't offer more info. Mustang may do later.

Incidently, my jets were 38/98 as stock, but I went to 40/105 as suggested by mustang primarily because I slung the rotten exhausts and fitted Motad Venoms.

[t4tiger]

Many thanks everyone.  I will let you know how it goes....if I manage to get the carbs back on afterwards