Carb Jetting

[mack]

I just noticed in one of the threads a discussion on stock jetting. I do so many that I made this chart and have it hanging in my shop. This was gleaned from the Yamaha Fiche before they deleted most of the models. Sorry for the delay!


I should state that the E pilot jet may be cause for some discussion. 45 was stock in the carbs I've had that I know came off E's. However the FSM and Clymers call for 42.5! When I did up a couple sets for my E, I put 45's in because I think the cct was designed to give that big burst out of the hole, to match the timing and rear tire size.

[Schming]

Hi Mack,

It seems I'm looking for this info often so just to have it all in one place I hope you don't mind:





Also I can confirm the G's Jet needle is correct in this table @ 51Z7 and not adjustable, not sure about the H though.

[MPittma100]

Jets

I just noticed in one of the threads a discussion on stock jetting. I do so many that I made this chart and have it hanging in my shop. This was gleaned from the Yamaha Fiche before they deleted most of the models. Sorry for the delay!


I should state that the E pilot jet may be cause for some discussion. 45 was stock in the carbs I've had that I know came off E's. However the FSM and Clymers call for 42.5! When I did up a couple sets for my E, I put 45's in because I think the cct was designed to give that big burst out of the hole, to match the timing and rear tire size.

I have been into several sets of E carbs. They all had 45 pilots in them.

[BA80]

I know that some here think that the .org site is the dark side of hell but I tried to get some good info in the "Fixes and mods" and the "part sources" sections.

http://hitechkc.dyndns.org:78/phpbb3....php?f=5&t=268

[BA80]

I have been into several sets of E carbs. They all had 45 pilots in them.

I have 45's in my 79 carbs. It seems more responsive at low end with them.

[Radioguylogs]

Report Different Result for SG

Main jets in my SG Bagger were 110/110/110/110. Seemed virgin.

The marker board shows 120/125.

Clymer's says 110/120 (same as Schming's post).

Check the marker board for SG Main Jets?

[mack]

Well

Like I said, these are off the old yamaha fiche. But really the mains are matched to the needle tapers. Since the emulsion tubes are pretty much static, someone may have used 18 vs 16's for needles so the 110 mains would be fine. I've seen lots of strange configurations so far in all carb years. It's almost like yamaha couldn't make up their mind or they used diff configs for US and Canada. Not too sure but thats the way I send them out now. It's always based on the needles as to what mains I put in them before I test them and send them back.

[Bonz]

Where did 120/125 come from for the SG?

SG HAS 110 MAINS ACROSS THE BOARD, NO DEBATE REMAINS!

That doesn't mean a guy can't put in different sizes, or that Clymer can put out different info, I put in 107.5's at 7200' elevation for a great running bike, but the factory manual that was bought when my bike was new is explicitly clear on 110 size mains across the board.

[mack]

Bonz

Your absolutely right, you can put in whatever you want or need to. The chart was meant only as a resource to the factory spec's. We all know a bikes config and location make tuning a fluid science not to mention the manf. of jet your installing.

[Bonz]

Hi Mack, we are on the same page, and that is my point. 120/125 is not factory spec for any SG. To be an accurate assemblage of information, that needs to be changed.

Clymer isn't factory, parts fiche isn't factory manual either. Factory manual should be the go-to and that is what I am hoping to share in this for the information being put forth.

[Bonz]

1980 XS1100 SG:

5GL16 needle, 110 mains.



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[mack]

Bonz

I have the supplement FSM. It also shows the 16's but with 110's across the board for SG's. So.... who knows, like I said yamaha was all over the place. I stick to the fiche because of all the erros and inconsistencies between the manuals. If I know they are SG or SH carbs I always verify the needles are 16's and go with the fishe spec's before I set them up and put them on my LH to test them. It works good for me here but our gas and elevations are different. I always clean and return the original jets, broke pieces etc. and stuff back to the owners with a few paragraphs with photo's of what I found when I took them apart so they can reuse the jets if they want. It also helps the newer guys to see what they missed when they tried to clean them. It's tough to tune them here and send them out but I know they are sync'd and leak tested before they leave my hands. What happens after that, I have no control over.

[Bonz]

I'm with you, there is a lot of inconsistency. However my factory service manual was made in the year my bike was made, and those microfiche are not an original factory item. They are a compilation of Lord knows what. For new folks on this forum, I think certified factory is the way to go, and that's what I would recommend.

There are way too many carbs discussions about this, and I've been there done that just like you. I guess will agree to disagree on what we should post for the benefit of mostly new people, because old members know what the deal is.

[Radioguylogs]

I think we forgot say.

"Thank you Mack for sharing your information!"

You are probably the most experienced with the carbs and we appreciate you sharing it.

I enjoyed seeing all the various jet sizes in a chart so I could ponder about why and what works better.

[BA80]