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4th Gen carb jetting. What jets when near stock?


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So I'm curious about the jetting on a stock vfr.

 

I was told that the 94-97 had #40 pilot jets and #125 mains. I recently read some info that the fronts are #125 and the rears are #128. Any truth to this? I find it odd they would be different being liquid cooled.

 

I'm also curious also about jetting. Many people say they (94-97) are lean from the factory but others say it is rich. I have removed my snorkel, which doesn't do much, but my muffler is stock with baffles removed I believe as it is much louder than stock. I'm not sure if that qualifies for changing jets or not. But if it is lean from the factory wouldn't a small bump for WOT be ok? Like going with #128 main all around? 

 

I'm pulling my carbs soon and if I find #130s in there I'm going to change them as that is too rich for near stock. If the pilots were changed I will change them back to stock. 

 

 

As for needles. When people change jets do they change needle positions? I haven't found much about needles so I guess they leave them be?

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  • Member Contributer

A Canadian VFR should have #125 front and rear, where California has 128 front/125 rear. 

jetting.png

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Thank you!

 

What was the reason they made them #128 on the front?

 

Maybe I was reading threads that were talking about the 90-93 VFR being jetted rich from the factory with #130 mains.

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90-93 VFR750F RC36-1 has 36mm carbs. 94-97 VF750F RC36-2 has 34mm carbs.

 

The 2mm larger air intake on each carb of the RC36-1 require a large jetting..

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But if the VE has been reached wouldn't that mean at low-mid rpm it would be less efficient due to poorer fuel atomization and at WOT it would just mean slightly richer than the smaller carbed 94-97? Well doesn't really matter. 

 

Is there a way to know if the needles have been changed from stock? I have no idea how the adjustments of the needles work

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There’s no provided adj, U have 2improvise w/tiny flat washers under head(top) of needles, add spacer(washer) to raise needle=richer mid-range

comparison w/stock part “taper” profile could show aftermarket item

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Jetkit needles have multiple grooves for adjustments while stock needles have no grooves.  with a jetkit, your jet numbers may not correlate exactly with stock jet numbers.

 

Nate, alot of what you say you don't understand is explained and illustrated in the FSM, which you probably haven't read. :unsure:

 

you don't want to try running stock jets with jetkit needles.

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I have the full service manual downloaded from here but it doesn't always help when you are not familiar at all with bike carbs. They don't have a section on what to look for if someone screwed with your carbs and changed things from stock ;)

 

 All I'm asking for is to share some knowledge! I'm not annoying others who replied and are trying to help. Hopefully my questions will help others in the future as I have used the search function (before it is suggested) and couldn't find answers to my questions.

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A reasonable resource to locate is the Honda Common Service Manual. This is a generic document and explains more about the function of things like carbs than specifics related to models.

 

If you are not happy with how the bike runs, getting it back to stock (or confirming it is stock) is a good starting point. 

 

https://www.dropbox.com/s/xz39vanvr66jqeq/Honda Common Service Manual.pdf?dl=0

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