Honda OEM carb info collection

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mousewheels
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Re: Honda OEM carb info collection

Post by mousewheels »

When doing the air pressure test as per the Honda Shop Manual ... should it be air tight or what is an acceptable leak when doing the pressure test?
True, there is not a leak down spec. The air valve is a sliding fit with no sealing seat or rings, so it's going to leak.

In my opinion:
  • Slight leak of the air valve from input to output (bypassing the carb slide) will not have much impact on idle speed or mixture. If the air bleed screw gets turned in much further than the service manual, then look for air leaks - wherever they may be.
  • The fuel side is not impacted by minor air valve leakage. Leakage between the engine side and bystarter causes slight airflow. But the air bleed holes in the fuel pickup tube break suction until air flow is greater.
Fuel_Pickup_air_bleed_holes.jpg
Fuel_Pickup_air_bleed_holes.jpg (40.52 KiB) Viewed 7002 times
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Re: Honda OEM carb info collection

Post by GSX1400 »

Thank you. In order not to pollute this subject, I'll give feedback on my subject.
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Re: Honda OEM carb info collection

Post by mousewheels »

-- Emulsion tube visual identification --

Note: Only the Elite Unrestricted tube is shown. It has two sets of holes at 90 degrees. Pic shows both views
Emulsion_Tube_Elite_94_up_SA50_A.jpg
Emulsion_Tube_Elite_94_up_SA50_A.jpg (39.65 KiB) Viewed 6956 times
Note: Aero has two sets of holes at 90 degrees. Pic shows both views
Emusion_Tube_Aero_NB50_A.jpg
Emusion_Tube_Aero_NB50_A.jpg (31.1 KiB) Viewed 6956 times
Note: Sporee has two sets of holes at 90 degrees. Pic shows both views
Emulsion_Tube_Spree_NQ50_A.jpg
Emulsion_Tube_Spree_NQ50_A.jpg (29.44 KiB) Viewed 6956 times
Note: Gyro has only one set of holes
Emulsion_Tube_Gyro_TG50_A.jpg
Emulsion_Tube_Gyro_TG50_A.jpg (27.16 KiB) Viewed 6956 times
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Re: Honda OEM carb info collection

Post by GSX1400 »

mousewheels wrote:-- Emulsion tube visual identification --

Emusion_Tube_Aero_NB50_A.jpg
The emulsion tube with the most holes is the unrestricted one, yes?
The part number indicated is the restricted or unrestricted part number?

Thanks. :thumbwink:

PS : did you get to use the video I had made for the leak test on the by-starter?
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Re: Honda OEM carb info collection

Post by ped »

:shock: saved,
Life's a trip enjoy the ride.
94 elite SR, 86 spreedio, polini corsa, keli variator, 8.4, jet. speed 65 mph
spreedio video. https://www.youtube.com/watch?v=BZr46_-douQ
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Re: Honda OEM carb info collection

Post by mousewheels »

The emulsion tube with the most holes is the unrestricted one, yes?
The part number indicated is the restricted or unrestricted part number?
Thanks - I've updated the posting to clarify. I have only a un-restricted emulsion tube and its got two sets of holes.
PS : did you get to use the video I had made for the leak test on the by-starter?
Can you point me to the video again? I will add to the wiki. Thanks!
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Re: Honda OEM carb info collection

Post by Wheelman-111 »

Greetings:

Mouse is the Master. Can you re-size my giant pics in Fab Flash thread? Or better still, tell me how?
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"ISO": '03 Vespa ET4 Malossi187 74MPH
Flash 9: 2001 Elite SR Contesta 72 ZX Tran, 9:1 Gears, Stock Airbox/Carb/Pipe 58.8 MPH
Punkin: 2010 Vespa/Malossi S78, 61MPH
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Re: Honda OEM carb info collection

Post by GSX1400 »

mousewheels wrote:
The emulsion tube with the most holes is the unrestricted one, yes?
The part number indicated is the restricted or unrestricted part number?
Thanks - I've updated the posting to clarify. I have only a un-restricted emulsion tube and its got two sets of holes.
PS : did you get to use the video I had made for the leak test on the by-starter?
Can you point me to the video again? I will add to the wiki. Thanks!
At the end of this post, you have the video : http://www.hondaspree.net/phpBB3/viewto ... 20#p251818

Do you think there is a big change between a restricted and an unrestricted emulsion tube?
I have a restricted Aero. It has been derestricted by the ramp plate and the washer in the pipe.
I have not changed anything with the carb though.
Was wondering...
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Re: Honda OEM carb info collection

Post by mousewheels »

Do you think there is a big change between a restricted and an unrestricted emulsion tube?
Sorry - still something I'd also like to know. I have not yet had a emulsion tube from a carb with the id tag from a restricted scooter to compare.
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Re: Honda OEM carb info collection

Post by mousewheels »

Pilot Jet orifice measurement (approximate)
Using a set of pin gauges (seller says accurate to "-0.0002")
I found anything up to 0.013" would pass through, and the 0.014" would not

0.013" is about .33mm, The 'nogo pin' at 0.014" is about 0.356mm
The 0.013" pin is has some wiggle room, so 34-35 is a reasonable figure for the Spree pilot.
Spree_Pilot_Jet_013.jpg
Spree_Pilot_Jet_013.jpg (101.26 KiB) Viewed 3769 times

Pilot Jet size - from other Honda Scooters
The Honda Elite 1987 SE50 manual documents the 'Slow jet' size as a 35
Elite_SE50_1987_Slow_Jet_35.JPG
Elite_SE50_1987_Slow_Jet_35.JPG (37.98 KiB) Viewed 3769 times

The Honda Elite 1988-2000 SA50 manual also documents the 'Slow jet' size as a 35
Elite_SA50_Slow_Jet_35.JPG
Elite_SA50_Slow_Jet_35.JPG (33.71 KiB) Viewed 3769 times

Pilot Jet - aftermarket replacement
eBay seller 'chopchop*123' is selling Spree pilot jets in what he says is the stock size '34'.

Previously he had some oversized pilot jets for the Spree also - to go with his big bore kits.
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Re: Honda OEM carb info collection

Post by mousewheels »

Ed: I reposted this from local files as it was in the wiki and not accessible until recently. perhaps this should be deleted? 03/17/2021

b]Pilot Jet - Orifice Open Verification by Light[/b]
One method mentioned on this board for verifying the pilot is at least 'not plugged' is by light.
Note: Start with an expectation the test requires a bright light and that the pinhole of light remains dim.

Here's a pic of the carb showing a clear Main Jet and no visible light through the pilot jet - even though the pilot jet is clean/clear.
Too_Dim_to_See_Light_with_Clear_Idle_Jet.jpg
Too_Dim_to_See_Light_with_Clear_Idle_Jet.jpg (64.09 KiB) Viewed 3767 times

The reason the pilot jet is so dim relative to the Main Jet, is the light path is indirect.
The carb body idle mixture passage is offset from the pilot jet orifice
Idle_Circuit_Passage_Offset_from_Pilot_Jet.jpg
Idle_Circuit_Passage_Offset_from_Pilot_Jet.jpg (62.03 KiB) Viewed 3767 times

Light from the carb slide side, must bounce off the pilot jet then bounce off the carb body.
PIlot_Jet_Cutaway_Light_Path_sm.jpg
PIlot_Jet_Cutaway_Light_Path_sm.jpg (11.41 KiB) Viewed 3767 times
Last edited by mousewheels on Thu Mar 17, 2022 3:19 pm, edited 1 time in total.
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Re: Honda OEM carb info collection

Post by mousewheels »

Photo setup to verify idle jet
Indoors, I use a bright flashlight, to view the pilot passage, and it's still relatively dim.
Using a camera can help make the light visible, note the camera setting of 1/6s, ISO400.
PIlot_Jet_Backlit_Pic_Setup.jpg
PIlot_Jet_Backlit_Pic_Setup.jpg (135.44 KiB) Viewed 3767 times
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Re: Honda OEM carb info collection

Post by josherl »

Hello all, I have inherited a 1986 Honda Aero 50 that was sitting for a long time and would not even turn over when I got it. Since than, I have been able to start by spaying starting fluid in the intake but it will only run for a few seconds. A little history on the issues. Oil was leaking into the crank causing the piston to not move when cranked and that has been cleaned out. Now it tries to start but won't so i changed the spark plug, carb, battery, fuel lines, and I cleaned out the fuel tank. Checked piston compression, good there. Checked petcock to see if operational, good there. I read a thread that said the exhaust could be the problem so I took that off and same issue. Another thread said, these won't stay running unless if the air filter and box were on so I put that back on with a new filter and same issue. I am stuck and don't know where to look. It's almost like something is telling the motor to turn off. Any ideas? Thanks in advance!
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Re: Honda OEM carb info collection

Post by mousewheels »

Carb Mixture Screw and Idle Screws
Mixture screws in general seem to be no longer available
Idle Speed screws can be found

Most carbs adjustment screws interchange with other models.
Carb_Mixture_and_Idle_Screw_Table.JPG
Carb_Mixture_and_Idle_Screw_Table.JPG (120.73 KiB) Viewed 3073 times
Last edited by mousewheels on Thu Mar 17, 2022 4:38 pm, edited 3 times in total.
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Re: Honda OEM carb info collection

Post by mousewheels »

Carb models with O-Rings or washers on the adjustment screws
In creating the table in the last post, it was noticed only 3 models had o-rings on the mixture screw

Note the p/n between Item 5 'mixture screw' is same between 88-93 SA50 vs 94-01 SA50. The parts fiche may have omitted the washer.
The 94-01 SA50 added an o-ring to the idle speed screw.
Models_With_O-Ring_or_Washers.jpg
Models_With_O-Ring_or_Washers.jpg (184.49 KiB) Viewed 3073 times
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