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The TTR250 FAQ web pages -> TTR250 -> Carb stuff -> Freeing off a jammed choke
Post Info TOPIC: Freeing off a jammed choke
TTRfan


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Freeing off a jammed choke
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After breaking a couple of shafts (they are only made of brass) in the past trying to free a seized choke I decided to try a different approach today and it worked so I thought I would share it. 

I firstly took the top off the carb to see if there was any way of freeing it from inside but I don't believe there is. Please correct me if I am wrong!

The pic below shows the choke in its closed position. I sprayed plenty of WD40 onto the offending part but it didn't help.

Choke_stuck_pics 002.jpg

I decided to try to attack the problem from the exhaust side of the carb. I drilled a hole about the same size as the small diameter brass rod at the end of the choke mechanism.

Choke_stuck_pics 004.jpg

Drill very slowly and carefully as there you only have to remove a small amount of material. Go too far and you will be drilling into the choke mechanism.

Once through, I used the end of a broken drill bit (don't ask disbelief) to tap the choke mechanism out. It didn't need much force and I was pleased and relieved to get it out without damage biggrin

 Choke_stuck_pics 006.jpg

The following pic shows the crud that was causing the problem. You will see that the "needle" part on the right is undamaged - phew smile

Choke_stuck_pics 007.jpg

I found a nail that was a tight fit in the hole and cut off about 1/8th of an inch to block the hole. My camera didn't want to focus for the next two pics - sorry!

Choke_stuck_pics 012.jpg

I then made up a small mix of Araldite and smeared the nail head and then tapped it into the hole. 

Choke_stuck_pics 013.jpg

I am letting it cure overnight but everything seems to work. The choke returns fully home and, after cleaning it up with some fine grade wet and dry, it is working as it should.

Job done!

I hope that helps somebody.

Brian



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TTRfan


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barra8 wrote:

Mine was worse though & needed to be brazed once out.

 I got a couple like that hence my search for a better method of extracting seized chokes! Might get mine brazed as it's a shame to lose a carb just because of a broken choke shaft blankstare



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barra8


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TTRfan wrote:
barra8 wrote:

Mine was worse though & needed to be brazed once out.

 I got a couple like that hence my search for a better method of extracting seized chokes! Might get mine brazed as it's a shame to lose a carb just because of a broken choke shaft blankstare

 It does seem to be quite a problem if the choke is not used. Athough if it's used regually & serviced now & again ie. copper slip or lithium grease it does'nt seem to have this problem. Also the seal at the end of the choke can perish. I used an old cdi plug cut with scissors & had success.

 

Brazing can be very difficult as keeping it straight while brazing can be a nightmare doh

Good to know there is inexpensive fixes available though.

....................

Jarrah.



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TTRfan


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I have a customer whose TTR is running slightly rich. Upon stripping down the carb he found the rubber seal/washer on the inner end of the choke assembly had come adrift.

Choke rubber.jpeg

Choke missing rubber.jpeg

 

Sorry abut the poor photo but the choke end should look like this:

Choke end rubber.jpg

 

Hope that may help someone at some point!

Brian

 



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heffh084


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Ah, hey Brian and fellow carb fettlers!

I recognise those photos!  Yes, I was scratching my head over this one for a few hours.  The O-ring isn't shown on the  carburettor schematic, and seeing as the choke was sliding in and out smoothly, it never occurred to me to take it all the way out until I had nothing else to try.

But on disassembly of the throttle lever and removal of the choke, I looked down and saw what looked like a lump of grime, but after a little bit of poking, that squished o-ring popped out.

I've knocked up a replacement out of some silicone sheeting I had lying about, hopefully that'll stay put as its certainly sorted my sooty plug out!  And now, she's much easier to kick start too!  Bonus!

IMG-20160329-WA0009.jpeg



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TTRfan


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Having had a disaster with a carb where the choke seating was damaged (I am guessing the choke "needle" had welded itself to the carb body) I have devised a quick check to make sure that the repair is good and no leak!

The fuel to the choke is fed from the float bowl via a small brass tube as shown in the photos below. I tested for a leak by slipping a small bit of plastic tube over the brass tube and sealing it with a bit of WhiteTac. Blowing through the tube with the choke in and out soon showed that the choke was seating and sealing properly in the closed position biggrin

Checking choke operation 1.jpg

Checking choke operation 2.jpg

Checking choke operation 3.jpg



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katana


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Good plan!

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