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06-13-2016, 07:31 PM | #1 |
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Location: Columbus, Ohio
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Zenith rebuilt. No power past 40mph
Greetings. I am a jewelry who used my ultrasonic and steam generator to clean and inspect (10x magnification) a few old zenith carbs, pieces and parts to make two good units. The two run really well, new gaskets, i set the float but i did not perform a flow test for lack of equipment. Of the two carbs one has little power beyond 40mph, when i accelerate i hear the vacuum but just doesnt have the oomph. Might there be a chance that i do not have enough volume of fuel in the bowel? I shrived to adjust to 5/8" fuel level from the top however that took two gaskets to set the float needle to get the adjustment. No popping or backfires. So i dont believe its a rich flow issue. Any advice?
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06-13-2016, 07:42 PM | #2 |
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Re: Zenith rebuilt. No power past 40mph
Does opening or closing the GAV at speed make any difference in engine performance?
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06-13-2016, 07:46 PM | #3 |
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Re: Zenith rebuilt. No power past 40mph
Use this site as a step by step guide to reassembly and operation
http://www.modela.org/main_jet.html and buy a set flow tested jets and a fuel level gauge from renners http://www.rennerscorner.com/index.html Make sure your throttle shaft has 0 play or it will suck air... If so install an oversize shaft, most carbs need it |
06-13-2016, 08:13 PM | #4 |
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Re: Zenith rebuilt. No power past 40mph
Utopia- I did turn the GAV open up-to two turns then back down to damn near off. Not a substantial change. All while running 40mph made an impact when open, some popping.
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06-13-2016, 08:18 PM | #5 |
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Location: Columbus, Ohio
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Re: Zenith rebuilt. No power past 40mph
Mitch- I read the attached link to the main jet artificial on rebuilding. Appears to address my issues with high speed power. Without flow testing I am left with purchasing calibrated jets. I didnt know if there was an additional testing method while performing under load.
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06-13-2016, 08:18 PM | #6 |
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Re: Zenith rebuilt. No power past 40mph
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06-13-2016, 08:26 PM | #7 |
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Re: Zenith rebuilt. No power past 40mph
I agree with George. Double check your timing before buying new parts. Ron W
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06-13-2016, 08:26 PM | #8 |
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Location: Columbus, Ohio
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Re: Zenith rebuilt. No power past 40mph
Mr Miller, good point. I recently replaced dist., points and cap and button. All adjusted to spec along with TDC of #1 on contact. Let me let her cool off tonight and Ill check the timing.
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06-13-2016, 08:42 PM | #9 |
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Re: Zenith rebuilt. No power past 40mph
Did this engine run OK before? Ron W
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06-13-2016, 08:42 PM | #10 |
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Re: Zenith rebuilt. No power past 40mph
Check your point gap and ensure it is within the specified 0.018-0.022" range. Going outside of that range affects timing and results in poor performance. Make sure the indent on your timing gear is centered exactly in the timing pin hole, too. (I know you asked about Zenith carbs, but like the guys say make sure your timing is spot on.)
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06-13-2016, 09:26 PM | #11 |
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Re: Zenith rebuilt. No power past 40mph
If I understand you correctly, you have two carbs; one runs great, the other runs great below 40, but gives you trouble above 40. If that is correct, it would suggest that the problem is not ignition. If is was, you would experience the problem with both carbs.
I would agree that the likely culprit is a problem jet. I would suggest this... swap out the jets from the 'good' carb to the 'bad' carb. If that solves the problem, it would confirm that it is one or more bad jets. If you do buy new jets, I agree with Mitch, get the ones from Renner. Good luck, Ken
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06-13-2016, 09:46 PM | #12 |
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Re: Zenith rebuilt. No power past 40mph
George, you stole my line......
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06-13-2016, 09:57 PM | #13 | |
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Re: Zenith rebuilt. No power past 40mph
Quote:
I'm still waiting on mine also. |
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06-13-2016, 10:31 PM | #14 |
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Re: Zenith rebuilt. No power past 40mph
I believe this is your #1 problem with that carb, " ...i did not perform a flow test..."
Here is a checklist to follow when rebuilding carbs,
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06-14-2016, 03:05 AM | #15 |
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Re: Zenith rebuilt. No power past 40mph
Yep, I had one or two of those about 10 years ago, and also thought it was original.
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06-14-2016, 05:06 AM | #16 | |
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Re: Zenith rebuilt. No power past 40mph
Quote:
That's how I read it also.... |
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06-14-2016, 05:27 AM | #17 |
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Re: Zenith rebuilt. No power past 40mph
The rennerscorner website doesn't appear to be working. Has anyone contacted them recently?
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06-14-2016, 05:39 AM | #18 |
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Re: Zenith rebuilt. No power past 40mph
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06-14-2016, 08:16 AM | #19 |
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Re: Zenith rebuilt. No power past 40mph
Tried it again and got in, but then no luck when I tried a different page. I'll keep at it.
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06-14-2016, 09:25 AM | #20 | |
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Location: Columbus, Ohio
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Re: Zenith rebuilt. No power past 40mph
Quote:
Morning-I used the heated ultrasonic and each passage was blown out with 70psi of steam (a steam boiler we use in the Jewelry industry which has a fine tip outlet) and yes all jets were removed, cleaned and inspected. As for the float valve gaskets_ i added the second one to get the proper height of fuel in the bowl when the valve shuts off. However there may not be enough fuel once it gets both jets flowing at high speed... |
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