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Re-jetting

349K views 980 replies 145 participants last post by  mikesmacey 
#1 · (Edited)
I have a new 1332 just traded in a brand new 9-28 (it was way underpowered, trading in a brand new machine cost me $800 bucks) I still felt the 1332 was underpowered so I increased the primary jet by .002 and it woke the machine up. From what I have read California emissions has forced Honda to run the engine on the lean side (engine is lazy under load).

I suspect some of the clogging issues are a result of the engines running so lean.
 
#5 · (Edited)
...Personally, I'd order a replacement jet and do the .6mm mod on it and test, knowing you have a good (.2mm mod) one in your pocket. You can't go back if it starts to pig out, and then you're stuck. I guess if it were me at the point you are, I'd watch the plug for bit. See if you get some darkening, or just pay attention to smells and sound as you get more snow to test.
Good idea jt.

orangputeh, you can get an OEM stock jet at the usual suspects like boats.net https://tinyurl.com/ya5vcsls ($3.57), PartsPak.com https://tinyurl.com/y72th6se ($4.63), hondapartsnation.com https://tinyurl.com/yb3tdcx3 ($4.43), jackssmallengines.com ($5.27).

I found this supplier for aftermarket jets that has a chart that may be accurate (would jtclays and northeast verify this?) Replacements jets for about $2.95:

https://tinyurl.com/y9xnhvvo

Main Carburetor Jet for Honda, Clone, or Predator Engines - Select Your Size | RLV50** | RLV RLV5008 | BMI Karts and Motorocycle Parts

Carburetor main jet used on the Honda GX160, GX200, Predator 212cc, GX340, GX390, Predator 420cc, and many other clone 6.5 HP 196cc engines.

FYI: Stock jets on GX200s are .028.
FYI: Stock jets on GX390s are .036-.038.
Use a larger opening jet if you're running lean and a smaller one if you're running rich.

Options
SKU Size Number
RLV5010 .032 #81
RLV5011 .034 #86
RLV5008 .035 #88
RLV5012 .036 #91
RLV5009 .037 #93
RLV5013 .038 #96
RLV5014 .039 #99
RLV5015 .040 #101
RLV5016 .041 #104
RLV5017 .042 #107
RLV5018 .043 #109
RLV5019 .044 #112
RLV5020 .045 #114
RLV5021 .046 #117
 
#4 ·
I purchased the drill bits (2 bucks a piece) and drilled it myself. It is easy you take out the jet and hand twist the drill bit. There is no need to use power tools your fingers will work fine. Make sure you clean out any brass shavings before reinstalling. I will post the drill bit sizes later today.



The engine had no audible change in the exhaust note when underload now with just a .2 change you can hear a change. I think it can use more and will play with it the next storm. It takes 5 minuets to change it.

I have 22 customers and the machine has to move snow. I also own a 2015 ariens hydro 28 and that machine made the Honda look silly last storm. I run them side by side and the ariens destroyed the Honda I had to figure it out and hope this does it.
 
#6 ·
I appreciate input like this. Going from a GX240 to a GX390, while nice, I can tell there's more to the 390 than what I'm seeing.

I like the idea of hand reaming. Just go easy.

I purchased the drill bits (2 bucks a piece) and drilled it myself. It is easy you take out the jet and hand twist the drill bit. There is no need to use power tools your fingers will work fine. Make sure you clean out any brass shavings before reinstalling. I will post the drill bit sizes later today.

The engine had no audible change in the exhaust note when underload now with just a .2 change you can hear a change. I think it can use more and will play with it the next storm. It takes 5 minuets to change it.

I have 22 customers and the machine has to move snow. I also own a 2015 ariens hydro 28 and that machine made the Honda look silly last storm. I run them side by side and the ariens destroyed the Honda I had to figure it out and hope this does it.
 
#13 · (Edited)
:smile_big:

Thanks for that.

"This is a Honda carburetor tuned for high performance with a richer emulsion tube and 110 main jet. This is the carb we use for the bored/reworked version of the 390 carb. "

Just havin' a little fun with good ol' Photoshop.

...Now get back to re-jettin' :smile_big:

 
#15 ·
#17 ·
I opened it up to .041 and it’s a completely different machine. It is exactly what it needs. I said it was lazy now it’s a beast, open it up you will not be disappointed. You will not even recognize it. You guys getting the picture here. Lol

I will run it this way for a bit but may go to .043 worse case scenario is I buy a new jet and go back to .041 but I have a feeling it wants it.
 
#18 ·
Very cool.

Would .041 be a No 59 bit?
 
#33 ·
Hey Guys, Great Thread here. Try these links. I use them frequently. Awesome knowledge, and parts. Jetting Kits available, cross reference charts....... You get the idea. Grab a beverage and dig in. Great stuff by modified guys without re-inventing the wheel.

GLuck, Jay

https://www.ombwarehouse.com/Racing-Jet-Kit.html

https://affordablegokarts.com/pages/how-to-drill-the-main-jets


https://affordablegokarts.com/collections/fuel-systems

https://www.ombwarehouse.com/performance-parts/honda-clone-gx160-gx200/carbs-and-parts/
 
#36 ·
So, what's recommended for a safe upgrade?

I'm located in the Northeast about 300' of elevation. I like many have been underwhelmed with my new HSS1332ATD. I know next to nothing about modding an engine and I'm afraid I'll just pick "this one goes to eleven" which will cause me heartache down the road. I just want to get it working the way it should. I'm not looking to drag race.

What size is on the current stock engine?
 
#40 ·
Since we are looking to enrich the mixture, you can’t do any damage. Worst thing that could happen is a fouled plug and rough running.

Further leaning the mixture would risk pre ignition and damaging high cylinder temps.

When tuning carb jetting, it’s all about small changes. Feel how the engine runs and check the plug to see how things are burning.

I think the laziest part of a small engine is the governor. It’s based on spring pressures that dont dynamically adjust to load using rpm data.

The EU generators have a standard carburetor but a computer controlled throttle plate. It utilizes a circuit to detect engine speed, monitors load, and adjust the throttle as needed.

The basic carburetors on small engines do exactly what they need to do and do it well. Provide sufficient fueling under minimal conditions.

Car carburetors have to provide proper fueling under a variety of loads ranging from decelerating, cruise, and a variety of acceleration loads that change rapidly.

I imagine that Honda will eventually incorporate fuel injection into their small engines. Currently their iGX engines use carbs with electronic governors as I described.


Kudos to Northeast for experimenting and bringing up this discussion.
 
#47 · (Edited)
OP I believe has an HSS version. The below reference is for HS models and not sure if the series are the same. Honda (boats) lists a stock jet and then high altitude (leaner jets) for ~ >5,000 ft and >10,000 Ft.

http://cdn.powerequipment.honda.com/pe/pdf/pubs/pci54675.pdf


HS724 - (GX200) Part # 23. Regular is #75 with a 72 and 70 listed for high altitude alternates.
All Years HS724 TA Honda Snowblower CARBURETOR Diagram and Parts

HS928 - (GX270) Part #26. Regular is #92 with a 90 and 88 for high alt.
All Years HS928 TA Honda Snowblower CARBURETOR Diagram and Parts

HS1132 - (GX340) part#34 Regular is #98 with #95 and #92 for high alt.
http://www.boats.net/parts/search/Honda/Snow Blower/0/HS1132 TA/CARBURETOR/parts.html

hs1332 -(GX390) part #34 Regular is #102 with a 100 and 95 for high alt.
All Years HS1332 TA Honda Snowblower CARBURETOR Diagram and Parts
 
#49 ·
This is all the snow I could gather up. Notice the exhaust note is much deeper and does not sound lazy. I am going at about half speed. Previously it would bog way down and dribble out the snow not now.

https://www.youtube.com/watch?v=-5GADh3k55o&feature=youtu.be
You definitely seem to be on the right track. After years of jetting for power with racing motorcycles, both 2 and 4 cycle, I religiously relied on "reading" the sparkplug. If you put in a brand new plug and run the engine under load and your chosen RPM, wide open I'd guess for good lubrication, then post a closeup picture of the sparkplug, I'd love to see it. As much of the weather conditions you can provide are relevant too. You're looking for that sweet spot between torque and horsepower where the engine responds cleanly to an increase in load without hesitation or a temporary rich condition.
 
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