A forum for owners of Yamaha TTR250 trail and enduro bikes!

I had a similar problem. Carb got knocked off the bench - fell and broke the post. I took it to a jeweler.

He lazer welded the post back on. looks good as new $40.

With all my carb problems lately, I took it to a local shop.  I've used them before and they are very well known in the trials and enduro scene and come highly recommended, and I've used them before.   Unfortunately they called me to say I need a new carb body as whilst trying to fix it, it sounds like the float pin mount has broken.   they called Yamaha and the price for a new one is £260+vat.  Obviously second hand ones are are rare as an English cricket victory.

then I spotted this post by Jarrah.  It's a same he's not been around as the image links no longer work.  Has anyone by chance got any images to go with Jarrah's post on this?

my preference is to try and get a replacement, but thought this might be worth a try.

I have a few carbs with broken float posts awaiting repair. I am going to use the "thumb screw" technique suggested by Ronridesbikes last year and have taken the liberty of copying and summarising how it works below.

I have bought the thumb screws and am just waiting to find the time to have a try. I will report back when I do

Brian

First a picture to show what we are talking about:

Ron's explanation:

"It's a common thumb screw. I filed the winged sides from it. The drill and tap were $5 as a set. 

Be careful with the tap. The aluminum casting is so soft it gums up the tap threads quickly. 1/2 turn in, 1/4 turn out and remove it to clear the treads every 2 turns. Go Slow. 

I center punched the top of the post and pre-drilled with a smaller bit to be sure I stayed in the middle of the post. Make sure you drill straight down, Check it from two sides as you drill. Again, go slow. Don't drill too deep. Measure the post and put a piece of tape on the drill to set the depth. 

Don't worry about tapping all the way down. Put tape on tap as well. Let the thumb screw cut the last few threads so it sets tight. But go slow. If you feel it binding, pull out and use the tap a little more. 

You'll have to put the screw in once to mark where to drill the float hinge pin hole. Remove the thumb screw to drill the float hinge pin hole. Center punch that too. The drill likes to move around on the chrome finish. 

File the thumb screw wings to within 1/16 of an inch all around the hole so the float bowl will clear and the float it self can pivot the full radius it normally would.

Note - depending on the length of the thumb screw, you may have to cut it down. Make sure you put a nut on it before you cut it so you can clean the threads up before you mount it in the carb. "

 

brian good engineering skills

Good post here and good suggestions. I just rebuilt a TTR 250 carb that had been sitting.........oh not good. When I got to the float pin dilemma, I slowed up and took evasive measure.
I have broke a lot of float pins 40 years ago with a little punch and toooo much enthusiasm. So I:

left the carb on my bench for a couple of day, hitting the pin area with PB Blaster penetrating oil a couple of times a day

Couple of days of prep, I used my offset nose chain materlink pliers to shove on the pin with the post as backing. WOW, way to tight but it finally slid out.

I redrilled the pin holes in both post to a slightly loose fit, and after replacing a nasty looking stock needle and seat, I turned the carb bottoms up and reset my float height with the looser float pin. All good. I have epoxied quite a few broken post over the years without issues.................that I know of, maybe 30 years later it all came apart, I don't know. For a few years its for sure a good fix.

Here is what i have in hand before i start project on post repair