richer main jets on stock XS1100LG

[lvrsnr]

Has anyone tried richer main jets on all four or at least the center two cylinders on a 80 special with the stock air filter / air box and stock mufflers? ... just wondering... bike runs great at all levels, and I am normally of a mind set that says if it aint broke don't fit it. but that doesn't stop me from being curious.

[DGXSER]

Did yours come stock with 120 mains? Some folks run the 120 mains, others run 115 or even 110s. I run 110s in my SH bikes and they love it run great!

[lvrsnr]

Sorry I should have mentioned that my is running 110s in all carbs.

[DGXSER]

As long as you don't mind pulling the carbs out to do the changes, you can easily give 115s or even 120s a shot. They should not be to much for it to run. But you may find the 120s make the top end a bit rich. Only way to know for sure is try it. IIRC, the 80 models, which an LG is, came stock with 120 jets anyway. And for a while Yamaha put the 120 jets in the center carbs on the LH and SH models as well, maybe the H model to, not to familiar with the standards.

[Bonz]

Hey there,

My 80 SG is correctly jetted at stock with 110 mains, so you are most likely stock with 110's as well. I live at over 7000 feet of elevation, and went down to 107.5's this summer when I rebuilt the carbs. Can't tell $.02 worth of difference compared to the 110's in terms of performance, and the fuel mileage didn't change a bit.

Just one heck of a fine running bike in all respects!

[SFerinTEXAS]

In the old days there was a lot of discussion on this. Can not say it was ever resolved. If you look here http://www.xs11.com/forum/showthread.php?t=73 you will see the specials and of course midnights were listed as 1980 SG/LG 1981 SH/LH 110(1&4)120(2&3) not currently an issue of my concern.not saying this is definitive.

[Bonz]

Hey, thanks for checking into that, however that info IS NOT accurate. I don't know why that hasn't been corrected after the discussions that have taken place over the years.

110's across the board ARE correct for an 80 SG. Don't see any harm in doing the 110/120 combo, but it is 100% certain and factual that 110's are the stock configuration on an 80 SG.

[SFerinTEXAS]

110's across the board ARE correct for an 80 SG. Don't see any harm in doing the 110/120 combo, but it is 100% certain and factual that 110's are the stock configuration on an 80 SG.

If that's the case then that's the case. If its wrong then it should be corrected. Not my job. Like I said not currently of concern to me.

Is interesting that on the site I use to look up parts http://www.stadiumyamaha.com/pages/p...and/parts.aspx the mains for the sg and lg are not the same. Go figure. I don't think it is that big of a deal. Like I said, not really definitive.

I do agree with

if it aint broke don't fit it

[cywelchjr]

Hey, thanks for checking into that, however that info IS NOT accurate. I don't know why that hasn't been corrected after the discussions that have taken place over the years.

110's across the board ARE correct for an 80 SG. Don't see any harm in doing the 110/120 combo, but it is 100% certain and factual that 110's are the stock configuration on an 80 SG.

Well, yours may have 110's all the way across, but some came with 120's on 2 and 3. But you're correct that some (maybe even many) came with 110's all the way across. Yamaha did try on some of them though to richen the center cylinders to make them run cooler at higher throttle, I think they found it was not a significant difference and changed that. They also had some 80's with a plug over the idle jets like the earlier carbs, and later they didn't, so how they came was likely based on how far into the model year it was built.

[Bonz]

Here's a quote from one of the tech tips... " '80G & '81H had larger main jets on 2-3 than 1-4 for the same reason, SG & SH did not."

For my info that I am quoting as gospel, I'm going off the factory manual, and what was in my carbs. Has anyone with an SG found anything different than 110's across the board in their carbs? Maybe I missed that being said somewhere, sorry if I did.

Question: Was there a Vetter fairing that went on the Special, or was that a Standard model only deal?

Possibly there could have been somewhat restricted airflow on faired bikes, and Yamaha took the chance that people would put fairings on their Standard bikes and jetted a bit richer on 2&3?

It is what it is, run what you got and enjoy!

[SFerinTEXAS]

Many things are tru and many are fuzzy about these things, 30yrs. Maybe there should be a registry of folks who have owned each model since new and done all their own repairs that can certify what they have found to be stock The carbs are certainly the most controversial. also for sure better to err on the rich side than the lean. Waste a little gas or melt a piston.

[cywelchjr]

Vetter fairings go/went on both standard and special models. AAMOF they use the same mounting hardware. Hard bags are another story however.

[rpgoerlich]

My 80SG had 110's(1&4) & 120's(2&3) and it runs great.

Interestingly enough my 80G had 115's(1&4) 120's(2&3). Replaced all with 117.5's as they were trashed by the PO. Runs great also.

Have been looking at a Dynojet kit for the Venture to see if I can smooth out the top end and get a few more MPG.

[Bonz]

Well, son of a gun, sounds like Yamaha was using stuff out of the parts bin to make our bikes with the variety of carb jets we all have, relative to what we may or may not think we should have!

The factory manual does say 110's for the SG, and the combo jet set up for the G.

I don't know all the nomenclature, so what is an LG (Midnight Special?), an SF, etc? Is there a thread somewhere that tells the nuances between them, or anyone able to post it in this thread?

[rpgoerlich]

LH L=Midnight Special H=81
H=Standard 81
LG L=Midnight Special G=80
SG S=Special G=80
G=Standard 80
SF S=Special F=79
F=Standard 79
E=Standard 78