04-30-2020, 12:23 AM
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#1 |
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Join Date: Apr 2020
Posts: 15
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Tao Tao DBX1 PZ27 Carb Pilot Jet
First post, long time lurker... Just had a new DBX1 delivered and it's too lean at my altitude (7,300 ft), it is bogging bad when I snap the throttle open. I pulled the carb to check the size on the pilot jet (turned out to be a k34 pilot and 90 main) and possibly replace with a larger jet. The PZ27 carb has a weird two piece pilot jet. I pulled both pieces of the pilot out and installed a 40 pilot from a typical PZ27. Think it will work?
Eta - fuel mixture screw was 3 turns out from the factory. |
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04-30-2020, 01:43 AM
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#2 |
Join Date: Mar 2008
Posts: 2,436
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Pilot jet in Kehin & clones:
PZ19 (Horizontal, for stock 90-110cc etc), 幻影 WH150-2...  the Shorty CH125 (Spacy) & those water-cooled cousins Helix... / GY6/ CB12T  Typicial CG , CB bike [pz26 /27 /30]  Newer 2-in-1 
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04-30-2020, 01:50 AM
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#3 | |
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Join Date: Apr 2020
Posts: 15
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Quote:
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04-30-2020, 02:48 AM
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#4 |
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Join Date: Mar 2008
Posts: 2,436
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Don't wasting time & $ on some weirdo thingy...
Stock Bashan 250cc had those jets. Some old Bashan thread mentioned where to find it BUT today's int'l mail service  1. Tune the valve clearance to spec 1st. 2.Tune the mixture again. 3. Drills the main pilot jet to ~100 (1.00mm) http://www.chinariders.net/showthrea...944#post298944 (lead free or plumber solder is recommenced if want to fill the hole again -higher tensile than toxic 60/40 | 63/37 electronic solder ) if step 2 still don't had acceptable result... 4. If above don't works: put a proven Mikuni VM22 on it...
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Last edited by humanbeing; 04-30-2020 at 03:18 AM. |
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04-30-2020, 09:46 AM
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#5 |
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Join Date: Apr 2020
Posts: 15
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Thanks for the info! I just found the previous post about them in the Bashan BSR 250 thread. Weird that the would just start using a different pilot jet, I wonder what the reason is? I was planning to order another PZ27 from Ebay, just because I have the jets for a PZ27 already, but figure they might come with the same weird jets. Will probably just order a VM22 but sort of want to see if I can get standard PZ27 jets to work in it...
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04-30-2020, 12:48 PM
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#6 |
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Join Date: Apr 2020
Posts: 15
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Well I started the bike with the 40 PZ27 pilot jet installed this morning and it's running better than with the factory installed two piece jet. I'm a little surprised...
 Plan to mess with it more to warm it up fully and see if the normal PZ27 pilot jet will run right and fix the bogging issue, it seems a lot better on half choke while cold already though.
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04-30-2020, 01:18 PM
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#7 |
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Join Date: Apr 2020
Posts: 11
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If you are looking for pz27 jets i've found the 1997 honda trx250 carb internals are compatible. my honda carb looks like this https://www.amazon.com/iztor-Motorcy...dp/B01M7RO3D0/
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05-01-2020, 06:46 PM
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#8 |
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Join Date: Apr 2020
Posts: 15
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Well I'm cutting my losses with the stock carb. Just ordered a VM22-133.
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05-14-2020, 10:12 PM
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#9 |
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Join Date: Apr 2020
Posts: 15
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Well I installed the VM22 with a 17.5 pilot and cannot get it to idle without the choke being on. Any thoughts?
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05-14-2020, 10:39 PM
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#10 |
Join Date: Aug 2009
Posts: 519
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According to the SUDCO catalog, the Genuine Mikuni VM22-133 comes with a #30 pilot jet, did you put the #17.5 pilot in it?
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05-14-2020, 11:04 PM
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#11 |
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Join Date: Apr 2020
Posts: 15
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That is correct, I saw that people had luck with 17.5 pilot and 110 main on the 140cc. Tried the 30 pilot to start but it wont run well with that either.
ETA: it will idle momentarily with the 30 pilot if I turn the mixture screw all the way out. The mixture screw on the VM22 is an air screw correct? |
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05-14-2020, 11:22 PM
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#12 |
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Join Date: Apr 2020
Posts: 15
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I think I might have figured it out. When the choke lever is up the plunger is down. When the plunger is down the fuel enrichment circuit (choke) is off right? I think I might have ben trying to tune with the choke on...
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05-15-2020, 09:35 AM
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#13 |
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Join Date: Aug 2009
Posts: 519
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Correct, when the lever is UP, the choke is ON
Keep in mind, an off-idle hesitation (or bog) when you wick the throttle is usually a sign of a lean condition on the pilot jet circuit. On second thought, when the lever is UP on this particular carb, the plunger is down in the carb body, meaning the choke is OFF. If you push the lever down, the plunger comes up, correct? Yes, the carb has an air screw - IN to richen, and OUT to lean it |
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05-15-2020, 09:54 AM
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#14 |
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Join Date: Apr 2020
Posts: 15
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Yes, when the lever is up the plunger is down. Lever down, plunger up. I had it backwards, no wonder I couldn't get it to idle...
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05-16-2020, 01:37 PM
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#15 |
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Join Date: Apr 2020
Posts: 15
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So the 17.5 pilot seems fairly close, but the bike still won't come cleanly off idle. Worked the main up to a 120 and needle in all positions. Still getting a lean bog. Valves are adjusted correctly. Not too sure If I should keep going up on mains? Even getting the bog with the 30 pilot that came in the carb.
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Linear Mode
