Tuning help on my new XS650-1B

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Deandestcroix

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Hello Everyone, please see my new ride. Quite the find and I am so incredibly happy. Have done a few long weekend rides and cant seem to keep from riding it. I have much experience with bikes but this is my first XS.

The bike from what I can tell is mostly original even down to most of the bolts etc. but I have noticed the jetting was screwed with in a really bad way.

Mismatched pilots - way too lean overall and completely wrong needles etc. I have installed a stock rebuild kit to bring it back to normal.

Question I have is - I have purchased the stock pilots as a starting point - but also one step up richer as I am assuming it is jetted a bit too lean to begin with. The bike ran okay if not a bit too lean early to mid throttle. So I put in the richer pilots (#45).

It was only after this I realized the needles were incorrect and actually longer by about 1 cm than stock - I would have guessed wrong jetting but never thought they would have put in the wrong needles. Anyway it looks like the stock needles will now make the bike much more rich. Should I start by going back to the standard pilot jets (#42.5)??

I guess what I am saying is what sort of stock starting point for all original jetting do you guys suggest starting at? I am at about 1000 feet above sea level.

Thanks,

Dean

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Gorgeous.

Put everything back to stock. Stock jetting is fine. Looks like you discovered how crappy rebuild kits are. Nothing works in them.

I guess I should also add....is that the original carb set? Every year almost got a jetting change from factory...
 
Compare what you have to the 5twins chart. like cdntx sez

CarbSpecsReducedSize.jpg

Use the correct parts for the year watch out for worn, eroded, aggressively cleaned brass parts.

I wouldn't assume too lean on an early 70's bike, this is completely Pre EPA they were still tuning for what ran best... Premix 2 strokes were still legal!

It's kind of normal for an occasional "hiccup" on the early bikes. They had a rather hot cam and 4 stroke carbs were a work in progress for Yamaha
 
PPS BEAUTIFUL 1B!
If she's been a garage queen put on some miles, I seem to find the running improves after I've gone through a few tanks of gas no matter what all has been done before I start riding it.

another 5twins exclusive :wink2:

650PilotJets.jpg
 
PPPS.... use only genuine mikuni brass the other stuff may not flow the way you expect it to according to the marking. One less variable to deal with!
 
She actually sat in the guys living room for 20 years... He never touched it and it started right up with a new battery. I am finding a bunch of really little things and everything needs to be tightened but for the most part it is all there. Some minor work was done before he got it I can see. Im not convinced the seat cover is original but the pan is. The odo said 1200miles so it might be. It had original tires on it. The shocks and forks work great and the brakes looked like they were new. I have put lots of miles on it in the last few weeks - and suffered the float -pin hole - and two broken wires due to the age - easy fixes. Even the high beam light works fine. The cool thing is that even if work had been done prior to 20 years ago at that time it would have been replaced with all original equipment. It was a great great find and I tell you - I love how the bike rides - looks and handles. I had a very japanese guy come up to me at a gas station and tell me exactly what year it was and how it was all the rage in Japan when he was growing up. He loved the little Yamaha two stroke twins himself. He said to me... "This Yamaha is like a musical instrument and America has their Harleys... we had our Yamahas..." Very cool. The only upgrade I made was slightly lower bars with less sweep - mirror and some new AVons which are wonderful. The front is a bit too low profile for me but it handles great.
 
Will do. I have the benefit of a grandmother-in-law who ran a shop in the 70's - Yamaha shop and she has a bunch of cool little rebuild items - new old stock - Before you ask. If I told you I would have to kill you.
 
Welcome to the forum, Deandestcroix.
That's a beautiful example of a 1971 XS1B!

Can't tell from your pic, but first lets make sure that those carbs are indeed the unique '70 - '71 versions.
The first telltale sign is the metal band that interconnects the starter (choke, enrichner) plungers.
Carbs-70-71.jpg

Then there's the fuel well for the starter pickup, on the left side of the carbs.
All later 72-79 BS-38 carbs have this pickup well on the right side.
Carbs-XS1-XS1B.jpg

Lastly, see if you can find the carb ID stamped on the front of the carbs.
Hopefully, you've got the E3 versions.
(From the 70-73 service bulletins:) http://www.xs650.com/forum/showthread.php?t=31022

full
 
If I were riding an early bike (and I do) I would look at preemptive re-enforcement of the rear loop to fender area, the fender hole where the loop "pin" bolts through cracks and wears away. Also the rear fender loop front/bracket weld is inadequate and tends to break, especially the RH side for some reason. The fender is also held in place by rubber "caps" and they get hard/shrink, I have not come up with a replacement but cane tips come to mind. I like to smear protect anything rubber with silicone lube I like the sil glyde that NAPA sells.
 
Thanks, I just checked. The choke is correct and the fuel pick up is on the left. I can find no markings on the carbs at all. Just noticed it has the wrong plugs in it too - right plug but wrong heat.. range they are 7's. What is the recommended plug gap?
 
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Thanks again for so much help. One of the Grandmother things is that she had the original parts manual and shop service manual sitting in her basement for me so I have those but no mention of proper plug gap.
 

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