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Carb Rebuilds

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TR4

TR4

Jedi Warrior
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Just wondering how long a carb rebuild should last. I completely rebuilt my ZS Carbs on the TR4 back in 2003 and one of them has started leaking fuel out of the bottom so I suspect the o-ring has failed and needs to be replaced. Not a hard thing to handle with the exception of centering the jet so I am not upset, just wonder how often I should expect to do this. Should I go ahead and change the o-rings in both carbs?
 
Those O-rings "should" last much longer than that. However, poor quality rubber is an unfortunately common problem, and modern "oxygenated" fuel seems to make it worse.

Personally I wouldn't bother doing the other one until it starts to leak, but it kind of depends on your attitude.
 
Isn't a fairly common one to fail first the one on the mixture adjusting screw? And (I think) that can be easily replaced by undoing the screw and fitting up a new o-ring. Of course you'll have to reset the mixture unless you counted the turns before removing.
 
The one you describe, Geo, is the one that keeps the oil in the damper well. So if that one begins to leak you'll notice that the damper oil level has been dropping.
Changing it is a little more involved.
I've gone to adding a bit of "Bar's Rear Main Seal Repair" to my damper concoction. Keeps that O-ring plump.
 
there is only two o rings in the bottom of the carb the housing and the mixing jet, both can be replaced easily.
 
poolboy said:
The one you describe, Geo, is the one that keeps the oil in the damper well. So if that one begins to leak you'll notice that the damper oil level has been dropping.
Changing it is a little more involved.
I've gone to adding a bit of "Bar's Rear Main Seal Repair" to my damper concoction. Keeps that O-ring plump.
Click to expand...

But I think for a TR4 its different - its a fixed needle design with mixture adjustment underneath. And when it leaks, you get a puddle of gas where you don't want it!
 
Yes, TR4s are blessed with what may be the simplest carbs known to man.

The lower O-Ring (on the mixing screw) is the one I was referring to -- so easy to replace you can do it with your eyes closed... in fact your eyes might as well be closed for all you can see with your hands down in there.

I got a replacements at Ace Hardware -- they were Nitrile/Buna-N -- size was .290" x .432" or 7.7mm x 11.3mm. My notes show that both carbs got this treatment 2 years ago and have not leaked since.
 
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