Collecting XSJohn's Wisdom

[cooltouch]

Visegrippe, I unzipped the files and took a look at the pdfs. They look good, and I suspect will be plenty sufficient for getting quotes. Thanks for your help on this.

I also sent an email to the home that performed John's funeral services, briefly explaining what we were doing and requested that he forward the email to John's widow or son, requesting that they contact me. Hopefully I'll hear back from one of them soon.

 

[5twins]

I have a set of John's needles in my '78 BS38s. I was the "guinea pig" for this set. I had to return them for a re-grind to get them just right. Yes, they do more for equalizing the temps than performance on my 38s. They do help a bit with performance, though. The bike is less prone to upper midrange stumbling with John's needles compared to the stockers. I only need to shim his 1/2 step leaner than stock as compared to needing a full clip position leaner on the stockers.

Have you compared the modded 34 needles to a stock pair? You should. I did with mine and really couldn't see much difference if any. I could tell they had been ground because they had a textured appearance. Maybe that textured finish contributes?

I recently ran a set of '76-'77 carbs for a few weeks while I cleaned the originals. I took cylinder temp readings and was surprised to find very little difference, like 10 to 15°. John sent me a set of needles for these, too. I tried them and they were worse than stock. I've come to the conclusion that the '77 and older carbs don't need this mod.

 

[cooltouch]

Regarding the '77 and older carbs, that would jive then with what I have been told.

I haven't compared John's needles to stock ones. I have an '80 SG sitting in my garage, and one of these days, I'll get industrious and pull the carbs off, then I can take a look and compare. My set of John's needles have a sort of brushed or ground look along the non-tapered portion, but the tapered portion was machined on a lathe -- the turning marks left behind by the tool bit are slight but evident.

 

[5twins]

You can remove the slide/diaphragm with the carbs in place, just pull the tank and carb top. My set was a "prototype" so to speak, so maybe he did them by hand.

In answer to an earlier question, a fatter needle (or section of one) usually means leaner. It plugs the jet more and allows less gas to flow by.

 

[cooltouch]

I've prepared another drawing so that those of you who can take measurements of your XSJohn needles will know how I measured mine and we'll all be on the same page. It also explains how I arrived at the values shown on the taper graph (warning: basic math on display). In retrospect, I suspect I could have just used the raw data and arrived at much the same results.

As is pointed out in the drawing, I've grossly exaggerated the proportions of the needle to make things more clear. Horizontal measurements are to scale; vertical ones are not. Example data is shown for the Right (Red) needle.

To insure reasonably accurate locations for taking the measurements every 1/10" inch, I used a rule that reads in tenths and, beginning at the start of the taper (and not the tip of the needle), I marked the 1/10 graduations using a Sharpie marker with a new tip (thus finer lines). There are 13 measured intervals, thus 1.280" is 0.020" short of 13 even 1/10" intervals, and I decided to "lose" the 0.020" at the tip.

 

[650Skull]

Here is the original needle John was working on, He was posting his development at 650rider then removed this information, for obvious reasons. As you say 5twins very little has to be taken off. I read in one of his later posts that the needle was modified again so that is probably when he was working with 5twins.

 

[cooltouch]

Very interesting, Skull. The stock needle looks quite fat by comparison, doesn't it? Now that I'm getting all into this, I'm gonna have to take some comparison measurements. All I have to compare John's needles to at the moment are themselves and a linear taper, but we all know that the BS34 or 38 needles' tapers are far from linear.

 

[cooltouch]

Speaking of comparing needles, I decided to redo the chart showing the needle tapers. Call this one v2.0. Instead of crunching a bunch of numbers, which I did to get everything to meet at "zero" at the end of the chart, I just plotted the raw numbers instead. I also found a bad data point on the Left (Blue) needle, which I corrected.

Now, it sure looks to me like there isn't much difference between the two needles -- maybe even within tolerance limits? Will just a few thousandths of an inch make an appreciable difference in operation?

 

[650Skull]

.Now, it sure looks to me like there isn't much difference between the two needles -- maybe even within tolerance limits? Will just a few thousandths of an inch make an appreciable difference in operation?

Going by the original pic of Johns, then the thickness of the anodizing would be minimal. A few thous at the most. Buy a needle for the 34's and compare them with what you have and the pic i posted

 

[cooltouch]

Yeah Skull, I think you're right. After giving John's notes that are in the pic of the needle a more careful read through, it would appear that this mod is probably quite easy to do. Apparently just a few thousandths can make quite a difference. In which case, the slight difference between the left and right needles is no-doubt significant.

Quoting John, "Not rocket science" and "I did it the first time." So maybe this is a mod that we can just teach ourselves how to do, following John's lead, and we won't need to have his needles fabricated after all.

I guess I need to remove the needles from my '80 SG's carbs not only so I can compare them with John's, but so I can try my hand at modifying them, following his instructions.

Oh, that reminds me -- I have two sets of '78 BS38s. I should open up one of the sets and play around with them some. Don't have a running bike to put them on, but I can at least get a feel for what John was talking about.

 

[5twins]

CT, I'm the carb guy. Try those '78s. When I tell you this, I really mean it. It was written (this sounds almost Biblical, lol) that the '76-'77 carb sets were the best. I've tried them. They're good but I don't think they run as well as my original '78 set. Even though the E.P.A. had their fingers into the '78-'79 set, I still think they're better. As to the "whys" and "why nots", I can provide that info if you're interested. Most aren't. If it starts and runs, it's good - and I really hate new owners like this. They never service the bike and it suffers a slow demise.

I think we need a few spin-off threads here, at least one for the needle reproduction. The carb arguments? Well, that never happens, lol. But I'd like it if did. Even though I co-wrote the card guide, I'm still learning. I'm going to propose an addendum to it, just an update that can be downloaded on it's own.

 

[cooltouch]

Hey 5twins, well I'll try the '78s one of these days. Currently I do not have a running XS to try them on. My '78 E cafe project is destined to sport a pair of VM36es (already bought). My '77 is totally dismantled and may never be more than a parts bike, and my '80 could be made a runner with a minimal amount of effort, but its very low on my priorities list right now. And the '80's the only one I can easily do the carb swap on, which would be interesting btw, comparing the Johned BS34s with perhaps slightly tweaked BS38s.

It wouldn't be meaningful to try swapping carbs on the '78 once I've got it running because the engine is having too many mods done to it -- big bore kit, cam, port&polish, hi-flow exhaust, etc. I would think that a stock motor would be best for these tests.

Actually, I would be interested in the details as to why you like the '78 BS38s better. Especially since I own a couple of sets.

Spin-off threads wouldn't hurt. I guess I envisioned this thread as a "big picture" thread where general details regarding John's advice can be discussed. I've been feeling that I should probably start a separate thread for the needles so that this thread can continue for other ideas.

 

[zimme71]

Great idea in collaborating to continue XSJohn's legacy with the needles...I was shocked to hear of his passing when I logged on tonight, as I had read quite a few of his posts on other XS sites, in addition to this one (just got around to posting something). I know I had been looking for some of his needles for my 81 XS. So are the plans to make more? I also thought the idea of charging a little extra, and have the money go to his estate was worthwhile....

 

[cooltouch]

Hey zimme71,

Well, if you look closely at John's notes on the image that Skull posted, you can see that he apparently did not have to remove much material. So it might be a pretty easy job for you to improve your stock needles. If you're reasonably good with your hands and have the tools he describes -- a drill and a knife sharpening stone plus some steel wool -- then it might be worth a shot just tweaking your stock ones a bit.

As for having some new XSJohn-style needles made, hey, if there's a demand, I do believe we should give it a shot. I hadn't heard back from the CNC shop I requested a quote from as of last night. Haven't checked my email yet today. I should forward the drawings Visegrippe made to them. Perhaps I'll get a faster response. Definitely a more accurate quote.

 

[gggGary]

I hate to rain on the parade but before anyone spends TOO much serious time and effort please note this offering from Mikes XS ;
http://www.mikesxs.net/products-37.html#products
Jet Needle 5IX11
Product Photo
Jet Needle - 5IX11 - Fits:XS650G/H/SH/SJ/SK/SL (1980-84) stock Mikuni BS34
CV Carbs (originally used in 1980 Canadian model BS 34 CV carbs).

Note the needle clip adjustment grooves.
Needle profile is Richer running than 5HX12.


So you buy a pair of these for $12.00 and put the RH needle clip one notch lower. How much are you going to improve on that? I only bring this up because I have been through similar quests on other older bikes.
Thoughtfully,

 

[cooltouch]

Well, there ya go, then. I wasn't aware Mikes had these. I wonder how close this needle is to XSJohn's spec. There's also the Heiden Tuning set Mikes offers. This might be the way to go, eh?

 

[650Skull]

When i bought my carby kit for my Aus 3W6 1980 SG points model BS34's i bought the Canadian Jet Needles 5IX11 and the Needle Jets 336-Y0
thinking my carbs had the Jet Needle - 5HX12 and Needle Jet - Y-O. When i dismantled the carbs and found the Aus BS34's have the same set up as the Canadian 34's. When you look at the difference between the needle jets you will see the US Y-O has 2 rows of 4 and 3 holes in it and the 336-YO has 2 rows of 5 and 4 holes in it. I would assume it was the EPA restrictions in the US.

This would deliver more gas and probably bring down the heat of the cylinders (unconfirmed) but would it balance the temperatures between the cylinders as was xsjohns reasoning for developing his needles in the first place.

I questioned John on this while he was developing his needles but he did not reply to my PM.

Mikes has had these Canadian needles and needle jets for sale for at least 2 and a half years

 

[cooltouch]

I'm not surprised he's had them for that long and I wouldn't know about it. I seldom visit the carb section of his site, since I've never been all that concerned about performance enhancements on my '81, which I left pretty much stock, and since I've got a set of VM36s for my 78 E cafe project.

I recall over at 650 Rider there being some discussions regarding the necessity of balancing temps between cylinders. John was adamant about it, while other folks were skeptical.

 

[salt lake jeff]

fyi: just tried to buy the canadian jet from mikes xs and they are out of stock...

 

[Lunatic]

Well, there ya go, then. I wasn't aware Mikes had these. I wonder how close this needle is to XSJohn's spec. There's also the Heiden Tuning set Mikes offers. This might be the way to go, eh?

Skip the Heiden needles. They are way different and at least for me the bike would hardly run with them. The Heiden needles are about 1/4 inch longer and shaped way differently. I switched back to stock Canadian needles to get the bike running and I've got a set of John's needles (and the corresponding needle jets) to put in soon.