Jet sizes for a 710/712

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ChickenPinz
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Jet sizes for a 710/712

Post by ChickenPinz »

What carb main jet size have people found is best in their 710/712?

Jim is rebuilding my carbs at this time, and he noted that they have "Euro 3" jets in them, which are apparently optimized for 3,000ft altitude. Wondering what people find works best for them.
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pcolette
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Re: Jet sizes for a 710/712

Post by pcolette »

Jim has rebuilt and re-jetted a number of carbs for me over the years. This is the standard setup that has worked well for me in Wisconsin.

Pinz Carb Jetting.jpg
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Paul C.
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Re: Jet sizes for a 710/712

Post by pinzinator »

I'm sure my 710 is jetted correctly, but am curious now. Can someone post a link or photo as to where each of these jets is located in the carburetor?
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Hotzenplotz
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Re: Jet sizes for a 710/712

Post by Hotzenplotz »

@pinzinator

the jets are located behind the cover
Image

the upper set are the idle jets, bottom are the main jets
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pcolette
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Re: Jet sizes for a 710/712

Post by pcolette »

IMG_3139.jpeg
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Paul C.
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Re: Jet sizes for a 710/712

Post by pinzinator »

The last 2 postings make it easy to verify. Thanks!
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Re: Jet sizes for a 710/712

Post by pinzinator »

My idle air jet and air correction jets were correct (230 and 130), but my idle jet and main jets were one size too small (55 and 135). Where can I buy 4 each of the correct sizes? Any recommendations?
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pcolette
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Re: Jet sizes for a 710/712

Post by pcolette »

I'd give Andre a call. SAV also lists jets on their site.
Paul C.
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'89 Puch 230GE
ChickenPinz
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Re: Jet sizes for a 710/712

Post by ChickenPinz »

pinzinator wrote: Fri Jul 31, 2020 4:42 pm My idle air jet and air correction jets were correct (230 and 130), but my idle jet and main jets were one size too small (55 and 135). Where can I buy 4 each of the correct sizes? Any recommendations?
When you say "correct" vs. "too small", are they "too small" for how you're using your truck and how it's configured?
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Re: Jet sizes for a 710/712

Post by pinzinator »

I use my Pinz mostly at sea level on the road. When off road, it can vary from sea level to 5,000' or so. I don't tow or load the truck.
Changing to the correct jets may be a waste of money, maybe not, It runs good now.
I only need the idle jets and main jets. Mine are 55 and 135 respectively.
boeing7873
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Re: Jet sizes for a 710/712

Post by boeing7873 »

I have played with all fuel and air jets chasing poor idle to power transitions. My conclusion is, if you have 55-135 and your truck runs well, don't mess with them, as they are within specs. As carbs and gaskets get old, minor vacuum leaks develop, (ie shafts, choke covers, carb bases.. etc) and running a little richer makes it run a little better, paying the price in a little less mileage and more emissions. (My truck is running 60-140 and is obviously rich but runs well) Actually, I may have gone to 60-135 now, I forget.)
Idle jets are way more critical in making the truck run well, as you have to also adjust your four idle mixture screws.
High jets have not shown a significant difference in driving when changed between 135 and 140. But I have not checked spark plug colors since I changed them.

I have obtained my jets from this Italian shop. I have actually sent my carb bases to them for shaft work.

https://www.ebay.com/str/alfa1750scarburetorspartsstore
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Re: Jet sizes for a 710/712

Post by boeing7873 »

Watch out for early and late idle jet models, some have o-rings, others don't. I have posted in other threads the differences and correct version for my carbs.
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Re: Jet sizes for a 710/712

Post by pinzinator »

You are probably right, if it isn't broke don't fix it. Leave good enough alone.

I like the carburetor site on EBay!
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heinz
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Re: Jet sizes for a 710/712

Post by heinz »

There are three versions of this carb type on the Pinz (version1, version 2 and version 3). On my rehab I have version 3 and the engine is running fine as long as no dirt is blocking any by pass holes or jets (the version is shown normally by a tag, fitted to a tightening bolt of the carb cover).

I´m driving it in areas fro 2000 ft to 6000 ft.

My carb is version "3" and has the following jets (710M), 712 is little different:
main jet 125
idle jet 55
air correction jet 170
idle air jet 110
ChickenPinz
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Re: Jet sizes for a 710/712

Post by ChickenPinz »

I confirmed with JimL that these are the jet sizes for the Euro3 jetting: 125, 55, 170, 110. Same as noted by heinz.

I'm suspecting this is too lean for sea level operation, versus the normal 140 mains, 60 idle, 230 air correction, 130 idle correction set.
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