What is the proper size main jet?

[mlew]

I recently had my carbs apart on my 83 VR to replace the rubber plugs, gas mileage was horrible. I was looking at the main jets and they have 125 marked on them. Just for fun I looked at a parts diagram on line and it said the main should be 117.5. Which one is right? My bike has stock exhaust and intake with no modifications. When I got the bike a few years ago from the original owner he said the carbs had never been worked on. I have no reason to doubt him since it had the original screws that still looked new. Several of them were tamper resistant kind. So I can assume it came with 125 mains.

Should I try the 117.5 or stay with the 125?

[Freebird]

I'm not sure about the first gen but on the second gen, the jets are not the same on all the carbs. That being said, I don't know why anybody would have changed the jets if there were no other changes made. Air filters, exhaust, etc. If it is running good, I wouldn't worry about it but if it is running rich, I would go back to stock.

[mbrood]

These are the numbers garnered a few years back...

http://www.bergall.org/temp/venture/venture-carb-part-differences.html

[BOO]

Yeah the jets are all different I think, at least there are three different sizes and they vary quite a bit in size.

Like Freebird said they are probably the stock jets if it's running good.

BOO

[dingy]

117.5 is stock on the 1200's. The 1300 have 125's in the mains.

 

Gary

[mlew]

Looking at that carb parts list the 83 to 85 Ventures have a 117.5 main jet. I'll try it and see how it does. I know these carbs are from a 83 because they have the air port on the #2 carb for the vacuum advance.

[mlew]

Well the 117.5 s did not run too good. Working on putting the 125s back in, I'm glad you don't have to split the carb rack to change main jets. It will save time re-syncing the carbs.