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steve(ill) 
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Joined: 11 Sep 2009
Location: illinois
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 Posted: 20 Jul 2025 at 3:23pm |
when you choke it, it will REV UP right ? ... Not something like a timing issue way advanced at high RPM ? .... Sure it is CARB related ?
What if the Intake manifold or gasket had a leak and was sucking air ? ..... Restricting the air ( choke) makes the engine SUCK harder and more monifold vacuum ? Les thought your vacuum was on the low side ?
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Like them all, but love the "B"s.
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dfwallis
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Joined: 09 Mar 2023
Location: DFW
Points: 777
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Posted: 20 Jul 2025 at 3:45pm |
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Replaced the main idle jet in the tsx. Not significantly different running. It was really difficult to get out. The easy outs are too short for brass. Got most out then retapped the hole. Not going to try the main jet. Too hard to get to and these easy outs won't reach. Misses are back but runs all rpms fineish. So, probably going to send the tsx out for professional rebuild. I've replaced everything in it but the main jet. I also tweaked the float to shut off slightly sooner. No change.
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1952 CA13092
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dfwallis
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Posted: 20 Jul 2025 at 3:48pm |
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I think the low vacuum reading was due to cheap uncalibrated meter. But I'll verify when my brother brings a higher quality one.
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1952 CA13092
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dfwallis
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Posted: 20 Jul 2025 at 3:52pm |
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I tried adjusting timing with the Zenith...could not resolve the problem.
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1952 CA13092
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dfwallis
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Posted: 24 Jul 2025 at 3:14pm |
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Brother brought a better quality vac meter. Engine reads 22 in hg, steady. Agrees with my cheap farmer calibrated meter...
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1952 CA13092
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Les Kerf
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Location: Idaho
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Posted: 24 Jul 2025 at 6:48pm |
 dfwallis wrote:
Brother brought a better quality vac meter. Engine reads 22 in hg, steady. Agrees with my cheap farmer calibrated meter... |
Excellent!  That means you do not have sticky valves and your rings are sealing properly.
Once you get the correct carburetor on there with the proper jetting your troubles should be over. Hang in there 
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dfwallis
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Posted: 24 Jul 2025 at 8:07pm |
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Place i sent the carburetor to has been repairing all types of carbs for 80 years...and can actually test them...that part wasn't clear at nearly all the other places I looked at...fingers crossed...
Edited by dfwallis - 24 Jul 2025 at 8:08pm
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1952 CA13092
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dfwallis
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Posted: 30 Jul 2025 at 11:38am |
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In steps, I've increased the jet all the way .082...I no longer have to use the choke to get full throttle range, but any time the governor revs it it still dies unless I recover it by choking. And thats only with the adjusting screw all the way out. Screw it in, reduces the throttle running range.
Seems like a ridiculously large jet for a tiny engine...I may as well see where it goes with further increases. But then again, only a little larger than the tsx 486 new jet size of .780.
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1952 CA13092
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dfwallis
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Posted: 30 Jul 2025 at 12:21pm |
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.089, best behavior so far...starting to have some adjusting screw effect. Super snappy governor as long as it doesn't rev too much...seems far fetched...
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1952 CA13092
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dfwallis
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Posted: 30 Jul 2025 at 1:45pm |
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Hmmm, tsx 486 carb info says the economizer jet is .0775...the main is .0990...#39 drill
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1952 CA13092
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Les Kerf
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Posted: 30 Jul 2025 at 2:11pm |
dfwallis wrote:
Place i sent the carburetor to has been repairing all types of carbs for 80 years...and can actually test them...that part wasn't clear at nearly all the other places I looked at...fingers crossed... |
So, are you now dealing with the TSX unit and was it professionally rebuilt and tested?
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dfwallis
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Posted: 30 Jul 2025 at 2:41pm |
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No, tweaking the budget chinese knockoff zenith...I went all out and bored the main jet out to .0990...it now runs almost normally. It does have a slight wavering behavior at max throttle, but it might actually be usable now. Unfortunately, there's not much meat left on the jet for more boring. But I also now have some control with the adjusting screw. The tsx probably won't be finished before this trip ends on Saturday. Next trip probably late Aug. This carb obviously should not have been marketed as a 486 replacement...should have been 12522...guessing somebody cut and pasted wrong...hey but I got it for less than 1/3 of a zenith...what's a little frustration and anger...
Edited by dfwallis - 30 Jul 2025 at 2:43pm
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1952 CA13092
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