BS34 Float Help

[bul_racer]

Guru, It Worked! So much easier this way too! The starter even cranked! Not starting yet since I don't have carburetors on yet, or gas tank or a battery but damn! I think I'm gonna spring for a battery now. Wasn't sure I wanted to since I didn't know if it was gonna run.

 

[bul_racer]

I usually don't have too many parts left over after putting things together. However, not sure where these little springs go. I have 2 of them. Probably 1 for each carb. I'm thinking it goes in the top of the slide after needle is placed & before the top piece is screwed on. Anyone know for sure?

 

[kopcicle]

Yes that is the needle spring. Sorry I'm not near a set atm but essentially it presses down on the needle assembly in the slide.

https://www.jadusmotorcycleparts.com/post/2018/05/17/yamaha-sr250-carb-rebuild-maintenance-tuning

edit : best pic/breakdown I could find on short notice

 

[Jim]

I'm thinking it goes in the top of the slide after needle is placed & before the top piece is screwed on. Anyone know for sure?

Yep... that's where they go.

 

[bul_racer]

Yep... that's where they go.


View attachment 195965


View attachment 195966

Yes, but Kop's pic seems to show the needle going through the spring - IOW, underneath the clip, washer & ring.

 

[bul_racer]

I don't think it makes sense to place the spring beneath the clip, washer, ring because that would interfere with engagement of the little tab on the bottom of the ring, ergo, it must go on top.

 

[Jim]

ergo, it must go on top.

 

[gggGary]

One of my favorite BS34 mods is to use a small washer placed between the plastic pill and the clip. It moves the needle about half a groove higher than the stock needle position, helps get rid of the 3K stumble that BS34's are prone to. Warm the plastic pill with a hair dryer and it will push right down the needle. Install ONE ONLY washer and replace pill. If you add more than one washer it coil binds the spring and the needle stops the slide from dropping freely. Guess how long it took to figure out THAT little gotcha.

 

[gggGary]

PS note that you are missing a washer that belongs between the spring and the e-clip.

 

[Jim]

It's there, just fell out of camera frame when I pulled it apart.

 

[bul_racer]

One of my favorite BS34 mods is to use a small washer placed between the plastic pill and the clip moves the needle about half a groove higher than the stock needle position, helps get rid of the 3K stumble that BS34's are prone to. Warm the plastic pill with a hair dryer and it will push right down the needle. Install ONE ONLY washer and replace pill. If you add more than one washer it coil binds the spring and the needle stops the slide from dropping freely. Guess how long it took to figure out THAT little gotcha.
View attachment 195972

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Gary, I sure wish I'd seen this before I took apart the slide & put it back together the 2nd time... Those screws are buggers to get started in those tiny little holes!

 

[gggGary]

Gary, I sure wish I'd seen this before I took apart the slide & put it back together the 2nd time... Those screws are buggers to get started in those tiny little holes!

Yes, yes they are!
My "trick": Use the long thin needle nose from one of those mini needle nose sets, put the screws in the plate, hold the plate in the "other two holes" with the needle nose and place the assembly down into the piston. Still a bit futsy but much easier.

 

[Jim]

Those screws are buggers to get started in those tiny little holes!

Dip the tip of your screwdriver in a blob of grease and stick the screw on it.

 

[bul_racer]

Yes, yes they are!
My "trick": Use the long thin needle nose from one of those mini needle nose sets, put the screws in the plate, hold the plate in the "other two holes" with the needle nose and place the assembly down into the piston. Still a bit futsy but much easier.

Neat trick Gary but I'm not having a problem with this. Just that the screw keeps falling off my screwdriver.

 

[bul_racer]

Dip the tip of your screwdriver in a blob of grease and stick the screw on it.


View attachment 195995

Jim, I tried this but I wasn't using enough grease. Next time I'll load 'er up.

 

[gggGary]

You can quickly magnetize a screwdriver by stroking it in one direction not back and forth, on a magnet.

 

[bul_racer]

One of my favorite BS34 mods is to use a small washer placed between the plastic pill and the clip. It moves the needle about half a groove higher than the stock needle position, helps get rid of the 3K stumble that BS34's are prone to. Warm the plastic pill with a hair dryer and it will push right down the needle. Install ONE ONLY washer and replace pill. If you add more than one washer it coil binds the spring and the needle stops the slide from dropping freely. Guess how long it took to figure out THAT little gotcha.
View attachment 195972

View attachment 195974

This is pretty ingenious! Took me a while to realize that it actually moves the needle UP. Very clever!

 

[Jim]

More-n one way to skin a cat screw.

 

[bul_racer]

I love this! Effective but not messy.

 

[bul_racer]

Finally went back and did Gary's trick of putting a washer between the circlip and pill. There were no instructions on how thick the washer should be so I just used what was handy: a pretty thin washer. Not sure how much difference it will make but hoping for a good result.

Set the float on one carb and did the clear tube test. I'm not experienced with that test so a bit uncertain if I got it right but it seems to be in the ballpark. Guess I won't know for sure until I put the carbs on and fire it up. I'll do the other carb today.

So, I have a question: I bought some cheap Chinese carb rubber boots off of ebay and they're not quite up to OEM. The opening is a very tight fit but I can get it in with a bit of wrestling. My concern is that the inside diameter of the opening behind the carb is 1mm smaller: 33mm instead of 34. These were Very Cheap so it's not the end of the world if I have to order another set. I think even the OEM's aren't that expensive.

Just wonder what the Yamaha gurus think about whether or not this will have a negative effect on performance.