float height

[Miti]

Speaking of setting float heights, I noticed the other day while comparing bikes with Steptoe that his RH had carb bowls with a drain screw and outlet casting on the bottom, and mine only has a drain plug so unless I make up some kind of adapter to screw in place of the plug, I can't check the float level on the bike.
   Does anyone know if the float bowls are interchangable between the different carbs???

That's one of the differences twixt the Mk II's and Mk III's... You can swap bowls as long as you go with the plastic floats, the earlier brass floats from the Mk II's foul the inside of the float bowl and can get jammed up, causing an horrendous fuel leak (normally via the airbox) DAMHIKT..!!

[Eveready1100]

Speaking of setting float heights, I noticed the other day while comparing bikes with Steptoe that his RH had carb bowls with a drain screw and outlet casting on the bottom, and mine only has a drain plug so unless I make up some kind of adapter to screw in place of the plug, I can't check the float level on the bike.
   Does anyone know if the float bowls are interchangable between the different carbs???

[Miti]

carry on explaining,,,,how on earth do you adjust them in situ,,,,,,,,,,,,,,can't get my hand in there let alone my head to see what I'm doing 

You can't adjust them in situ... They have to come off, be adjusted, back on, tested... ad nauseum (actually, just thinking about it is making me sick..!!)

Thing is, the carbs on the XS are pretty easy to get off/on... Comparitively speaking, that is... Anyone who's ever had to do work on the carbs on an early Honda V4 will testify that they really are the Devil's work and that, in comparison, an XS11's carbs are a genuine blessing...

Thing is, that once set, I'm gonna take them off one last time, check the float heights and just go with that measurement ever after... Don't worry, I'll post it up...

Miti

[steptoe]

carry on explaining,,,,how on earth do you adjust them in situ,,,,,,,,,,,,,,can't get my hand in there let alone my head to see what I'm doing 

[Miti]

The RH is fitted with a different model of carb then the earlier "E" model...

Early carb is BS34 MkII, late is BS34 MkIII.  If they've not been "messed about" with, then the easiest way to spot the difference is that the late ones are "tin-tops", whilst the earlier ones are all alloy.

When measuring the fuel height you have to take account of the atmospheric pressure in the carb when it's running... Yamaha recommend that the fuel height be set with the bike running... I've tried to set fuel height with the carbs on the bench, in a vice, spirit level, the whole shebang... Couldn't get a useable reading on the ol' plastic tube...  As soon as the carbs are on a bike and working, up comes the reading...

The biggest PITA about this is trying to get the bike absolutely level... Here in bonny Jockland, there ain't a piece of ground anywhere that's absolutely level..!!

I've been fannyin' about with my carbs for bloomin' years and still can't get the fuel height right... The wife and kids are visiting grandparents next week... Might get stuck into 'em again then..?? I finally got the fuel pipes/octopus all routed correctly and working properly, just before the German XS rally, so that's a step in the right direction at least... I also managed to stop the blighters giving my precious K&N filter a regular fuel bath... 

Next has got to be fuel height as I reckon mine is MUCH too high... THEN I can try to sort idle mixture...

Don't you love old bikes..??

Miti

[Fred]

Hey Chris,

when you get good at it let me know.
I've got two sets on the shelf for a '78E that I can't be bothered to do
Maybe this winter it'll happen.

[netbikes]

well I did the old blow up the fuel line and yep I found a leaking needle/seat, good method, thanks for the tip.
Did the same on a set off a GT750 Kawa today, no leaks in that one. Seems all I do these days is clean carbs, doing a set off a CB350F next week.

chris
www.netbikes.com.au

[netbikes]

melbxs,

what i do to check for leaks, take the float bowls off, turn the carbs upside down,
in this position the floats  should all seal, put your mouth onto 1 of the fuel intakes
and blow, if they are leaking you will hear, see and feel it coming out, you can then tilt the carbs
to open and close the floats, do this for both fuel intakes and again after the float bowls
are fitted. ive never had a problem doing it this way and have found and rectified leaks doing it.

Thanks I will do that tomorrow, and while they are open and upturned I will spray the seats with diesel, I have bid on some carb kits from the US so hopefully (if I win them) by the time they arrive I will have the old ones out:-)

chris
www.netbikes.com.au

[petejw1966]

it was used on some of the bikes
in the states as well,
i think it was the 80 carbs.


i worked on a guys 78 standard that had the oil cooler,
i think they must have all come out with oil coolers.

be good to start a thread to point out the differences
in the models.

[melbxs]

Pete,

The mention of different tubes was from one of the UK guys. I am guessing that early Standards in the UK did not have oil coolers, so they richened up the middle pots. Certainly all the Sports and RHs had oil coolers.

Did all Aussie Standards have oil coolers from day 1?

[petejw1966]

melbxs,
not sure, i thought all the bikes that came out here
had oil coolers, but i could be wrong.

from what i know, the emulsion tubes were different only
when they had richer main jets fitted to the inner 2 cylinders.

netbikes,
they're a pain in the butt to pull out at the best of times,
i use a small needle nose pliers and grab it from the top of the seat, work it back and forth and twist, and spray some wd in there as well.
to clean the seats, grab an ear bud with some chrome polish.

what i do to check for leaks, take the float bowls off, turn the carbs upside down,
in this position the floats  should all seal, put your mouth onto 1 of the fuel intakes
and blow, if they are leaking you will hear, see and feel it coming out, you can then tilt the carbs
to open and close the floats, do this for both fuel intakes and again after the float bowls
are fitted. ive never had a problem doing it this way and have found and rectified leaks doing it.

[melbxs]

Pete, emulsion tubes probably different on the bikes without the oil cooler??

[netbikes]

with regards to the float levels if your pulling the carbs id recheck the
heights again without the gaskets just to be sure.

under the seat there is an o ring which can also leak fuel.

yep double checked that today. 

The seats are really stuck fast and I can't budge them without excessive force so I am waiting till I get new ones before I do any more on them now. As I haven't found any yet it may be a week or two before I work on them again.

chris
www.netbikes.com.au

[petejw1966]

different carbs from overseas models had richer settings
for the inner 2 carbs 2 keep them cooler,
our 81 bikes had all the same emulsion tubes and main jets.

with regards to the float levels if your pulling the carbs id recheck the
heights again without the gaskets just to be sure.

under the seat there is an o ring which can also leak fuel.

[netbikes]

For the 81 rh set it at 23mm without
the gasket in place.

25.7mm float settings are for the earlier carbs.

so it would be 22mm with the gasket which is what I have them set at, still leaking so thinking needle and seats although they look good??

cheers.chris
www.netbikes.com.au