setting the float

[trucker chuck]

hello im new here i love this informative site i have a 79 xs 650 with bs34 carbs
i had to change the float and i was wondering bout how you set the level
any advice is appreciated

 

[xsjohn]

22mm black floats 81-84.........27mm brass ones 80......good luck wih all the rest... that myself suffered but no more.......best years for these bikes but the most help that is needed to get them right...........including timing...........

xsjohn

 

[trucker chuck]

do u use feeler gauge to measure it and were do you measure it at

 

[xsjohn]

The book says from the float gasket surface........Of all I have seen that all the gaskets are bonded to the float bowl so what is meant is form the surface (without the gasket) where the gasket goes....to the top of the float surface with the carbs turned upside down and not with the float seat spring depressed at all....just sitting there so to say..........

xsjohn

xsjohn

 

[KevC]

do u use feeler gauge to measure it and were do you measure it at

Have a look HERE for an idea of what XSJohn means, you can use a steel rule or vernier to measure the float height

 

[inxs]

- from yamaha manual...

 

[trucker chuck]

thank you for the help thats the way i did it but #1 carb did not have a rubber plug on the pilot jet and #2 did which way is correct??

 

[breahn riley]

i think its no plug for your year carbs...

 

[xsjohn]

All """BS34's"""" ...80-84 had rubber plugs on both carbs...and have to have them.....

xsjohn

 

[J ray]

Hey truck. Having been into the 34s and 38s more times than I'd like to admit, the 34s need rubber plugs covering both pilot jets. Good luck

 

[breahn riley]

so i think this is correct. on the carb body there is a ridge goin all the way around where the bottom of my calipers were. i stayed just to the inside of that. My original reading was 24mm for both floats but i bent the tangs for them both to read 27mm. now the caliper is just off the float, just enough to not touch it.

 

[09classic650]

where can you get the little rubber plugs i am missing one

 

[weekendrider]

Check with your local dealer part #3F7-14991-00-00.
Or Mikes part #48-5002

 

[hotrdd]

So do you just turn the cRb upside down and let gravity drop the copper floats? then you measure to the top of the float?

 

[xjwmx]

Most people say don't compress the spring in the needle valve. I tlilted mine about 45 degrees so the floats would drop, but not put all their weight on the needle. It's a critical setting - it's surprising what 1mm off can do. In my case. Other people appear to get by further off, maybe by compensating elsewhere.

 

[littlebill31]

Here's a pic.

 

[hotrdd]

On A 1976 When I flip the carbs over the jet needle falls back into the piston valve. Does that sound normal? This means that ever time I tp the Carbs overI need to take the tops off and put the jet needles back in place.

 

[5twins]

Sounds like your slide and needle are assembled incorrectly. The needle w/e-clip should be held fast into the bottom of the slide by a large plastic retaining disc. The disc should be held in place by the large slinky-like slide return spring .....

It sounds like you have the needle w/e-clip sitting on top of the retaining disc, not under it, or you're missing the plastic disc entirely.

The BS38s are rather unique in that they mount their mains and pilots in the float bowl, not up into the main carb body as most other carbs do. This makes measuring the floats a bit easier on them because there is no jet tower sticking up between the 2 float halves. Set your rule on the far side and sight across the tops of both float "bulbs". Check the measurement from both sides because the floats can be tweaked or twisted on their mount bracket. That will make one side sit higher or lower than the other. Measuring from both sides is the only way to check for this and it's more common than you would think. Over half the ones I've checked have been twisted.

 

[hotrdd]

Thanks... In the picture above what are you doing to keep the floats from compressing the needle valve?

 

[5twins]

Nothing, you just let the float rest on the needle valve. The weight of the float will compress the spring loaded pin in the valve slightly but shouldn't do so fully. If it does, you probably need a new float needle valve. Gently push down on the float and watch the action of the spring loaded pin to confirm it's functioning. Sometimes on a carb that has been all gummed up, the pin will get stuck in the compressed position. You can usually clean it up and get it working again but if you can't, you'd need to replace the part.