SuzukiSavage.com - confused about jet sizes

nickbilljim

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confused about jet sizes
05/24/21 at 09:28:06

I have a vm 38 carb, I was told a 210 main jet is a good place to start ,does this mean a jet with a hole that measures 2.1 mm or a jet with 210 stamped on it?
I took the bike to a garage and he put a main jet with a hole that measured 1.5 mm this equates to a jet that has 300 stamped on it ,it seems to run better ,he said (it may need up to a 1.7 mm jet ) this is a size 380 ,does this sound correct ?
Thanks Nick

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LANCER Serious Thumper Alliance Member Offline Savage Beast Performance Parts Posts: 10606 Oklahoma Gender:	Re: confused about jet sizes Reply #1 - 05/24/21 at 10:53:41 To use this carb on the Savage/S40 you need a genuine Mikuni main jet with a #200 or #210 stamped on it to start with. For a pilot jet you want to start with a #20 on it.
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nickbilljim Junior Member Offline SuzukiSavage.com Rocks! Posts: 56	Re: confused about jet sizes Reply #2 - 05/24/21 at 11:43:07 I have a DR cam , one of Lancers 94mm pistons ,exhaust port is 1.5 inches and I have a RYCA header with internal dimension of 1.62 inches along with the V M38 carb .With these mods am I still in the 210 area as a starting size?
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DragBikeMike

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Re: confused about jet sizes
Reply #3 - 05/26/21 at 12:57:58

Yes, you are in the #210 main jet zone provided your VM 38 is one of Lancer's carbs. If you got the VM38 somewhere else, all bets are off. That's because the size of that main jet also depends on the other components in the carb. You should have the following components:

Needle Jet = 166-Q2

Needle = 6DP1

Main Air Bleed = 0.5

Although it doesn't impact your WOT performance (main jet circuit), you should also verify that your slide is a #2.5.

Please let us know what needle jet, needle, and main air bleed are in your carb?

If your bike runs best with a main jet with a 1.5mm hole (.060"), it indicates that you have an unusual setup on your carb. You are correct, a .060" hole is up in the #300 zone. To be more precise, a #330 VM main jet has a .061" hole. That's really big, way bigger than usual, and it indicates that you have a needle jet significantly different from what we usually run on the VMs discussed in this forum.

Regarding your question about size designation. The main jets for the VM are "Mikuni hex jets". The main jets for the stock carb are "Mikuni large round jets". The VM jets are flow rated; the number designation represents flow. The stock carb jets are size rated: the number designation correlates to a size in mm. The picture below shows a #210 VM jet and a #127.5 stock jet. They are both on a .051" pin gage. They both fit the pin gage exactly. Note that .051" is extremely close to 1.275mm.

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Jets_210_vs_127_5_pin_gage__0512.jpg

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nickbilljim Junior Member Offline SuzukiSavage.com Rocks! Posts: 56	Re: confused about jet sizes Reply #4 - 05/28/21 at 06:20:55 thanks for your help my needle jet is 166r-4 my needle is 6dh20 my cutaway is 2.5 I do not know how to remove my main air bleed to check the size. my bike runs well but I am only getting 37 mpg ,with my old C V carb I was getting over 50 mpg Thanks Nick
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nickbilljim Junior Member Offline SuzukiSavage.com Rocks! Posts: 56	Re: confused about jet sizes Reply #5 - 05/28/21 at 07:57:07 I managed to get the air jet out but I cannot see a number on it
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DragBikeMike

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Re: confused about jet sizes
Reply #6 - 05/28/21 at 15:37:14

NBJ, you have a very unusual jetting setup. It really would help if you could post some pictures.

The needle jets come in two types, "choke type" and "bleed type". Your "R" designation seems to imply you have a "bleed type".

The VM carbs most of us are running use a choke type needle jet. It looks like this. Note there is only one large hole in the side of the jet, and it has a hood that sticks up above the top of the jet.

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Needle_Jet_Choke_Type.jpg

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DragBikeMike Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 4222 Honolulu	Re: confused about jet sizes Reply #7 - 05/28/21 at 15:41:03 The bleed type needle jets have a bunch of small holes in the side of the jet. The bleed type look like this needle jet out of a stock carb.
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DragBikeMike

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Re: confused about jet sizes
Reply #8 - 05/28/21 at 15:57:47

The setup must be consistent throughout in order for us to help you. I'm not even sure you have a VM carb. The Sudco manual does indicate that the VM38 uses needle jets 166 O-0 thru R-8. So if we assume you have a carburetor body that is compatible with the jets most of us are using, then you should be able to convert your jetting to a combination that we know works correctly on the LS650. It's risky but the only way I can think of for you to get a good baseline setup.

I think you would be better off setting up your jets similar to what the rest of us are using. I have had good luck with an outfit called "Jets-R-Us" (easily found with a Google search).

A 166-Q2 needle jet is about $21 bucks.

A 6DP1 jet needle is about $13 bucks.

You can check your air bleed with a #76 drill bit. Use the shank side of the bit, not the flute side. The 0.5 air bleed is 0.5mm (.020"). If its bigger than .020", you can order a 0.5 from Jets-R-Us for about $6 bucks.

Try and post some pics of your components. It would help a lot.

Good luck, Mike

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nickbilljim Junior Member Offline SuzukiSavage.com Rocks! Posts: 56	Re: confused about jet sizes Reply #9 - 05/28/21 at 17:05:30 I have ordered the parts you recommended when they come I will put in a # 210 main and a # 20 pilot jet and see how it runs. Thanks Nick
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nickbilljim Junior Member Offline SuzukiSavage.com Rocks! Posts: 56	Re: confused about jet sizes Reply #10 - 06/11/21 at 12:57:38 I have fitted the parts you recommended,I am now getting over 50 mpg and the bike hits 90 mph easily, thanks for everyone’s advice over the last 2 years I now have a fantastic bike. I have bought a Kawasaki front pulley but that will wait till winter Cheers Nick
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