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How worn is too worn? (carb slides)
#743155 07/25/18 9:05 pm
Joined: Sep 2014
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How do I assess the severity of wear on my T160's slides? They certainly do have some wear, but they don;t look badly worn. I;m used to 900 series carbs and even when new, its possible to move the slides back & forth by hand a bit when the throttle's shut or part-open. These 626s seem to move about the same amount as a nearly new 932 I have lying about.

Is the slide made perfectly circular in cross section? If so, I can compare measurements taken across with measurements taken fore & aft.

Also, are slides made with the reduced diameter portion at the top Concentric with the working surface? If so, this would give an easy way of assessing the degree of wear.

I can;t make a judgement based on how the engine runs as this one's never run in my ownership. I don;t want to put it back together only to find I should have fitted new slides - but I don't want to spend good money on 3 new slides unless I have to (they're more expensive than they should be!)


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Re: How worn is too worn? (carb slides)
Tigernuts #743209 07/26/18 11:04 am
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The real solution is to have the slides sleeved in stainless. And the carb
bodies machined out or skimmed a few thou. Just enough to remove any wear and at the same time provide true round and smoothness. Do this and the carbies last for a very very long time. I'd go as far as to say that the tolerances on the finished product is better than any 'off the shelf' alternative.

Re: How worn is too worn? (carb slides)
tridentt150v #743217 07/26/18 12:22 pm
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That sounds an excellent modification, but not one I want to spend on if I can help it. I don;t even want to buy new standard slides unless I really need to. Not purely through being massively stingey, also because I dislike replacing things when there's no need.

According to my calipers the slide I've checked is round to within a thou at just above the cutaway / throttle stop screw cutouts. That seems good to me, so I think I'll just shove 'em back. Good thing too, because for the life of me I can;t get the bloody throttle rod spring collar off. I might post this as a separate question.


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Re: How worn is too worn? (carb slides)
Tigernuts #743232 07/26/18 1:34 pm
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I know there are chrome plated brass slides for 900 series carbs.I used some on my Spitfire. Don't know if they are available for the 600 ones.

Re: How worn is too worn? (carb slides)
Tigernuts #743257 07/26/18 7:04 pm
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Hi,

Originally Posted by Tigernuts
How do I assess the severity of wear on my T160's slides?

Couple of years ago, I asked John Healy what the minimum body-slide clearance should be. He replied no less than 0.0035"-0.004"

Originally Posted by Tigernuts
I;m used to 900 series carbs and even when new, its possible to move the slides back & forth by hand a bit when the throttle's shut or part-open.

With respect, that isn't a valid assessment, if only because neither bodies nor slides wear evenly - on the body, the most wear occurs just above the venturi on the engine side; on the slide, the most wear also occurs on the engine side but between about 1/4 and 3/4 the way up or down.

Originally Posted by Tigernuts
I don;t want to put it back together only to find I should have fitted new slides - but I don't want to spend good money on 3 new slides unless I have to

While you can assess slide wear with micrometer or calipers, bodies need bore gauges (and someone who knows how to use them?). Because my bikes have a lot of special bits on them, I make a point of knowing at least one (sometimes retired) engineer or machinist near wherever I live, with both special tools and knowledge ... whistle

By the end of this rebuild, if your greatest unnecessary expense was three new slides when you didn't "have to", treat your guardian angel to champagne and flowers ... whistle

Regards,

Re: How worn is too worn? (carb slides)
Tigernuts #753795 10/24/18 3:11 am
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Hi Tigernuts,
The 932s on my Commando were worn when I got the bike ==you could hook your finger under the slide
when the slide was down and feel maybe .020" fore and aft slop at the bottom--where you should not feel much clearance when they are good.
The result was that the idle was all over the map.
Hope this helps,
Kara


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Re: How worn is too worn? (carb slides)
Stuart #753796 10/24/18 3:51 am
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Originally Posted by Stuart
Hi,
By the end of this rebuild, if your greatest unnecessary expense was three new slides when you didn't "have to", treat your guardian angel to champagne and flowers
Regards,

Agreed. Slides are only $30 each
If you can find somebody to replace them for that much it's a bargain. Those stupid spring retainers are a PITA to get out, even with the correct tool, and getting them back in is dang near impossible!
Since you have a T160, perhaps you already have the later return springs? Then again, the way they made these things, maybe not.


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