Mikuni Float heights

[ngm8x]

HI all
new to the forum, glad i found it as been working on my bike on my own for 3 years with only a haynes manual that i am not sure is accurate.
float height in the manual says 14.5mm from the joint face to the bottom of the float.

I measured it in the middle of the carb as measuring from either end would give vastly different results due to where the flaots pivot from.

Anyway, have seen on other forums that stock float height is 17.5mm

The engine is flooding petrol left on overnight. original heights were 13mm so changed them to 14.5mm but they still leak fuel into the airbox.

Does anyone know the triumph recommmended height as haynes manual were wrong once before with flaot heights on a 600 bandit i had.

Going to checj the needle valves shut off today  but owuld like to know the correct  stock float height,

The bike is  95 tiger with 40k on her.

thanks

[Bixxer Bob]

This is my Mikuni manual, which I bought for my 2-stroke, in PDF form.  Might be useful to others too....

http://www.mikuni.com/pdf/vmmanual.pdf

Sounds to me like they're not shutting off properly. Float height affects mixture - nothing to do with flooding.  Flooding is almost always the valve not seating properly and so not shutting off fuel.  Could be you just have a bit of crap in there, or the rubber seal could be damaged - usually in the form of a groove worn in it.

Mustang will be along shortly with the definitive...

[Mustang]

14.5 mm sounds about right

but do you know that is not how triumph does it ?

You need special tool #3880120 float bowl adapter  and #3880125 fuel level gauge

sounds impressive right  ?
What it really is .is a hose screwed into the float bowl drain and then you hold the hose up beside the carb and the height of the fuel should be at 1.5 mm above the joint face between the carb body and float bowl

That's the Triumph way from the factory service manual

FLOODING can be caused by a couple of scenarios

1. As Bob mentioned crap under the needle  valve
2. worn needle valve  Replace needle valve is the only cure for this
3 . and this is the most common fault on mikuni carb tigers  the rubber o rings that seal the float assembly to the carb body crack with age which let's fuel flow past the needle valve

with the flooding going on the bike is never going to run right
it will run ok but only because you are using some fuel until you get the flooding issue resolved you are chasing your tail trying to do anything with the carbs .

Hope this helps
good luck  it aint rocket science they are pretty basic .

[ngm8x]

well i checked the spark at each coil and ht lead with a new plug held against the engine and they all had good spark.
I then took the plugs leads off each plug one at a time, with engine running (not supposed to i know but...) and when i removed no 3 there wasnt any difference in revs and it still revved the same as before (a bit lumpy and not very responsive.


Put new plugs (DPR8EA)  in all cylinders and it seems ok now, revved smoothly on a test run.
Just waiting to see if the carbs leak fuel into the airbox overnight.
Floats at 14.5mm. The carb did have lots of gunge in there, (orange colour) so hopin the clean up and smooth running may sort it.

will post the results incase anyone is interested for future reference.

[ngm8x]

thanks for the info mustang.
i didnt see that until after i posted mine.

the fuel piep trick to check the level sounds good. i am trying to make a screw with hole in so i can check the level.

Hoping not to have to take the carbs off again so waiting for 24hours to see if the airbox has fuel in it.

if none there i think it should be ok and will take out for a good test run.

thanks
nath

[Mustang]

WELCOME to the Site BTW

and remember that the triumph coils suck balls :shock:
you will swear you have a carb problem when it is really a bad coil on 1 cylinder
and even though they test fine at .6 ohm or show spark the way you tested
they generaly fail under a compression load after the bike has been running for 10 -15 minutes

the problem was the GILL coils were manufactured with cheap wire which corrodes internally in the coil and then it will actually seperate forcing the current to jump the gap in the corroded wire inside the coil until it can no longer jump the break then you will get no joy on that cylinder

like I said it shows itself with age and heat

NOLOGYS are a very good replacement coil all three for 200 bucks and it will never run so good

not saying you have a coil problem but if after you sort the fuel flooding out it still runs weak like it's missing a cylinder it will likely be the coils

[ngm8x]

thanks for the info on the coils.

i am in England, so not sure where to look for those should they be required.

the coils and leads on the bike look in good condition. i know its whats on the inside that counts!! but they dont seem to be showing signs or age realted wear.

The bike i am working on is my friends tiger he just got it.

I have a 95 tiger same model but in black and not had any problems with it yet in stock mode. My straight thru race cans might mean that the carbs need tweaking but i will be investigating that once the red tiger is sorted.

thanks again for the help/advice


cheers

[John Stenhouse]

There is a car race shop in Kent or somewhere on the south coast that is the UK agent for nology, just google it and work your way through. Last time I looked they listed the coils

[ngm8x]

So after leaving the bike over night there were no petrol drips and i removed the air box and looked in- still no petrol.
Replaced the filter with a K&N and took it for a run.

Started on the button and drove smoothly without a blip.

I filled the tank up to half full to see if the weight of the fuel will push through the carbs and flood tomorrow.

I think it was a combination of mucky carbs, float heights too high and a dodgy spark plug.
Although i think it was the plug and mucky carbs mainly.

thanks for the help.
will update if it plays up or not after a while.
am looking for replacement coils just in case though!!
thanks guys

[Sin_Tiger]

Bob, thanks for sharing the Miki carb book  

[ngm8x]

oh well......after a few days she leaked a bit out of the airbox.
still starts and runs ok once its cleared but must be the needle valves and o rings.
will order them.
if anyone knows where i can get some from in the Uk that would be good.
decent price aswell would be good too!!

[Bixxer Bob]

Drop these guys an email:

http://www.nrp-carbs.co.uk/

They stock just about everything!!

[ngm8x]

bike was ok today.
it is running a bit rich i think as when it warms up a bit and the choke is off there is quite a string fumey smell out the exhaust.

Will reducing the fuel level in the bowls help this or is it the air/mixture screw that i need to tweak (and which way-turn it out to let in more air?)

or both?

um.......?

[Mustang]

my guess is the fuel leak is causing the rich mixture ...your chasing your tail until you remedy the fuel leak  :shock:

[ngm8x]

so after about 40 miles of faultless ridig over a few days took the bike out again and after about 1 mile it died. Bogged down.
Had to get it home by running it with the choke out and using the increased revs as if i used the throttle it would die.
Once the bike didnt need the choke i had to wait half an hour so that i could use the choke again to trundle it home.

It wont idle at all and any use of the throttle kills it?

is this the coils??
it sounds like it to me?


bloody bike.....