Carb questions

[Deni]

Hi, all. I bought a '79 XS standard late last fall to restore (18k miles). I drove an XS750 and XS850S back in the '80s in Florida in school, and guess I miss them. I've read a good deal of advice from all you great guys on this site and have already replaced the fuse box, grips, bulbs, air filter, plugs, hoses, intake manifolds, and rebuilt petcocks. Changed fluids. Also, added a fork brace, winshield, and luggage rack. I bought another carb set from a '79 special because I saw all the jetting and specs were identical to the standard. This carb was from Arizona, so it was in better cosmetic condition than mine, and I figured it wouldn't be bad to have 2 sets. I cleaned the new (special) set from the special and have it on now. Everything that could have been clogged, was clogged from sitting for who knows how long. The bike runs with the special carbs on, and I think I have them balanced pretty well. I have the idle mix set to specs (1 1/4 out), but think it may need tweaking. The throttle seems to be a little "held back" from the other set of carbs, but we'll see after playing around a little more. Timing is dead on. So, I'm making progress, but noticed a difference in the inner two needle jets. They are all X-2, but the inner ones are labeled "301", instead of "266" like the outer two. All four in the standard carbs are labeled "266." I read in Blaine's Carb FAQ that in some models the inner two could be different from the outer two, presumably to richen the mix of the inner ones to keep them cooler, which makes sense. The "266" jets have 4 holes on each side, which I guess mixes in more air than the 2 and 3 holes/ side on the "301" needle jets. I would like to know if anybody has experience with this, and if using this carb on my '79 standard will suffer any ill effects. I thought that the '79 standard and special engines wer pretty much the same, and that running the inner 2 cylinders a little cooler on the special might have been an improvement that would have no ill effect. Any comments appreciated. Thanks.

[Deni]

Not "held back" anymore

Just wanted to say that I found out why it was a little sluggish. I put a tach on all the spark plug wires to see if they were all getting consistent spark. Number 3 wire was intermittent. End cap was the screw-on type and it was loose. Tightened it and rebalanced things. Now runs like a demon, and just took it for a short ride. Works better than it ever has since I've owned it.

I still would like anybody's comments on the needle jet difference on the '79 special carb that I now have on my '79 standard.
Thanks.
-Deni

[skids]

Sorry, I do not know about the main nozzles right off hand. Do a search on this site and you will no doubt find your answers! Good find on the connector problem.

[Deni]

Thanks

Thanks, Skids.
I did a search, but since these things are called several names (e.g. emulsion tubes, needle jets, main screws, etc.) I guess I need to keep searching.
-Deni

[skids]

Re: Thanks

Hmmm, I looked at the off-site tech tips for Chris Rawson's site, as that is where I think the carb specs were. The link is a "cob-web" site. Dead. Sorry.

Originally posted by Deni
Thanks, Skids.
I did a search, but since these things are called several names (e.g. emulsion tubes, needle jets, main screws, etc.) I guess I need to keep searching.
-Deni

[TopCatGr58]

Hey there Deni,

Here's the breakdown on the main nozzles :

78E
2H7-14941-02-00 NOZZLE, MAIN (X-2)

79F
2H7-14941-02-00 NOZZLE, MAIN (X-2)

79sf
2H7-14941-02-00 NOZZLE, MAIN(X-2 EXCLUSIVE FOR CARB 1,4
3H3-14941-02-00 NOZZLE, MAIN(X-2) EXCLUSIVE FOR CARB 2,3

80G
3H5-14941-02-00 NOZZLE, MAIN

81H
3H5-14941-02-00 NOZZLE, MAIN

81SH
3H5-14941-02-00 NOZZLE, MAIN

Looks like Yamaha used the different main nozzles first to attain that staggered cooler inner 2 cylinders effect while using the same sized main jets, then later in 80-81, they used the same main nozzles, but used different sized jets to get the same effect, but surprisingly, they used it for the Standards, with 115 and 120 jets, but the Specials were 110 straight across!?

I proposed the theory that they assumed the standards would be used more for touring, where they might attain higher operating temps due sustained rpms at highway speeds. But then again, they are getting plenty of air cooling affect as well. Whereas the Specials might have been assumed to be used more for in town sport riding, cruising the Blvd. type vs. long distance riding. However, stop and go driving should actually cause more heat buildup vs. highway, so I can't figure out their thinking?

Just watch your plugs, and as long as they have good color without being excessively carboned up, then you should have no problems with using those staggered carbs!
T.C.

[Deni]

Many main nozzle thanks

Hi T.C.,
Thank you very much for the detailed reply. That was just the info and opinion I was looking for. I can also add "main nozzle" to the list of names for those important little devils. I drove it back and forth to work yesterday (about 5 miles each way), pulled the plugs, and they heve super thin coating of light brown (tan). So far so good, but I'll pull them on a regular basis until I'm sure everything is OK. I'm planning on riding it to work regularly in nice weather and have no long trips planned (I'm going to work on that), so I will probably be riding more "special" style than touring style anyway.

I have NGK BPR6EIX iridium plugs in at 0.030 gap. Are these plugs OK? They seem to be fine.

And for my future info, where did you get the main nozzle info you posted? My Clymer doesn't have it, nor owner's manual, nor OEM parts fiche, nor anywhere else I've looked.

Thanks again. I've learned a whole lot over the past few months about my bike (and alot from this website), and hopefully soon I'll be able to help someone else fix a problem I've encountered.
-Deni

[fxrer]

Hi Deni,

In my Clymer's manual, Table 2 ( page 145) has all the jet/nozzle specs for the E's & F's. Table 4 (pg 255) has the same info for G's and H's. No part numbers, though. Those are available the XS part number finder:

http://www.benefiscal.co.uk/index.php

[Deni]

fxrer,
Thanks for the link. Yeah, I saw that Clymer table. But, as stated in my first post, both types of main nozzles are labeled "X-2" but have different numbers on them, that must be a code for the amount of ait they let through the little holes on the side. Higher number (301) must mean less air (fewer holes) than lower number (266, with more holes). That's what was throwing me off because I couldn't find a description to confirm this anywhere.
-Deni

[TopCatGr58]

Hey there Deni,

I found those nozzle #'s on the Yamaha Online Parts Catalog , it's a great resource for comparing part #'s among different models!

As to the spark plugs, the Iridium ones you have are rated in the same heat range, internal reach as the BP6ES stock OEM recommended ones, however the OEM are not resistor. The XS11 has resistor spark plug caps, but with advances in spark plug technology, and the tolerances of the ignition system, folks use resistor plugs with no ill effects, and are nicer to fellow motorist's radios!!

Hope you read the info on the NGK site about HOW TO gap their plugs, due to the brittleness of the Iridium center electrode, you should only pull or tap on the grounding electrode, but put NO pressure against the center electrode to widen the gap.
Keep on learning.....I AM!!
T.C.

[Deni]

Iridium plugs

Thanks, T.C.
Yes, I got the iridium plug as a cross for the standard plug from NGK's website. I thought it was a recommended plug for the XS1100 by them, but I just checked their site and it doesn't list the xs1100 as an application. I wondered about the resistor vs. non-resistor issue, but the guy I bought the bike from had the standard resistor plugs in and it ran OK. Alot of money for potentially taking a chance with the iridiums (iridia?), though. I gapped them by bending the grounding electrode with the little hook thingy that comes on the wire-type plug gap tool. Over time, if they work out well or badly, I'll let people know.

I just ordered Amsoil 20w50 motorcycle oil for changing it next weekend, but I don't want to start an oil discussion here. I have Syntec blend in now, but the Amsoil should be much better for the commuting I will do and for the clutch, since it is JASO-MA rated and, therefore, certified for use in wet clutches.