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New to me XS 650...
- Thread starter Kevin Werner
- Start date
Is moving the circlip just "pry out" with a jewlers screwdriver?
Easy to move it just one and add another later. 6 of one, half dozen of the other.
That clip has magical powers... it can land 3 counties over from the point of launch. I generally half wrap it in a rag to coral it.
Those little suckers have some stored kinetic energy. 6 of one half a dozen of the other? Yes. This seems really rich and I don't see a jet size from the slide bore. I make presumptions that the builder went rich for safety. I will run it next time weather allows. Then I will revisit 5Twins input on main jet and the other jet #s. The issue is I am starting with a non original set up. My "play with the needle" routine is because I have all the parts I need. This will give me some feedback I hope. I may have to go back to step one; primary, secondary, main. Did I say that this motor is really alot of fun on throttle through the gears?Easy to move it just one and add another later. 6 of one, half dozen of the other.
That clip has magical powers... it can land 3 counties over from the point of launch. I generally half wrap it in a rag to coral it.
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Yes, the '76-'77 carb set has a wonderful midrange because the needle jet is so large. Again, refer to that chart I posted and you'll see the Z-8 needle jet is the largest one fitted to any of the 650 carb sets. These BS carbs differ from most others as the main and pilot jet are both mounted in the float bowl, not up into the main body of the carb. Here's some pretty crusty ones I removed recently .....
All back together. 14.2 v from the regulator. The idle at traffic lights is steady. It doesn't die. The bubbling at 35 to 45 is mostly gone. All around improvement. I hadn't mentioned dieing at traffic lights because I wasn't sure if it was warmed up or if the clutch adjust is a little off and that was killing it. Plugs were still black after 15 miles of mixed rural and town riding. I will put in a new set and read them again.
14.2 volts revved I hope, not at idle? What slot did you end up using on the needle?
For removing needle e-clips, I grasp them firmly with a good, serrated needle nose pliers and just pull them off. To install, I place the e-clip part way into the slot then lay the needle down on a hard surface, e-clip open side facing up. Then I just "snap" the needle down into the clip.
For removing needle e-clips, I grasp them firmly with a good, serrated needle nose pliers and just pull them off. To install, I place the e-clip part way into the slot then lay the needle down on a hard surface, e-clip open side facing up. Then I just "snap" the needle down into the clip.
Rechecked, 13.9 revved to ~4k. However after 1/2 hr of riding the battery is at 12.52v. I will have to recheck output. Battery tender get it to 12.52 overnight. Seems low.
I dropped the Needle two notches from the picture above. I will install new plugs and recheck.
Well, the needle setting is only part of the carb tuning equation. You really need to get into the bottom of your carbs and check the jet sizes. I'm sure the P.O. must have re-jetted some for the mods he did but who knows what he put in there, lol. When I first got into these 650s, I didn't know anything about re-jetting them. There were wild claims on the internet from some guys running like 170 or 180 main jets. So, I popped some 170's in to try and didn't even make it to the end of my block before the bike was misfiring and bogging down. I turned around, went back home, and pulled a plug. It was blacker than a moonless night, lol. So much for those huge main jet increase recommendations. A few sizes up from stock is all these bikes need or can use. In your case, you'll be hard pressed to get much above the mid 130's. It's not so much the size of the main but rather the number of sizes above the original. Now, you may read recommendations for mains in the low to mid 140's. That can work on some of the other 650 carb sets but that's because they had larger mains to begin with stock (130 - 135). You'll never get that big on a '76-'77 carb set.
15 minutes of riding later and battery is up from12.52 to 1265. So charging is good.. Brand new plugs have a tan center insulator. 10 miles is not a test but encouraging. I'll pull the plugs after another 50 or so miles.
Thanks 5twins. You and the rest have been great help. Yes, who knows what else has been done. Getting into the bottom of the carbs may be a next season or winter project. I am using the garage bay that I would like to park my car in when the snow flies. But.... I could rearrange some stuff....
As I mentioned earlier, there's no need to pull the carbs out or off to get at the jets, just drop the float bowls, carbs still mounted, using a stubby screwdriver. Or, if the bowl screws have been switched out for Allens, a set of these 1/4" insert bits .....
https://www.ebay.com/itm/123730058825?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649
..... combined with one of these finger bit holders will do the trick .....
https://www.ebay.com/itm/123730058825?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649
..... combined with one of these finger bit holders will do the trick .....
As I mentioned earlier, there's no need to pull the carbs out or off to get at the jets, just drop the float bowls, carbs still mounted, using a stubby screwdriver. Or, if the bowl screws have been switched out for Allens, a set of these 1/4" insert bits .....
https://www.ebay.com/itm/123730058825?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649
..... combined with one of these finger bit holders will do the trick .....
The main screws out. The needle jet is just held in with an O-ring. From the Carb Guide: The BS38 needle jet is the large perforated brass tube that hangs down from the middle of the carburetor body. It is secured by an O-ring. Using solvent to free it if necessary, pull it free of the carb, soak, and follow with compressed air. Avoid marring or deforming the needle jet with tools. Replace using a new O-ring.
The needle comes out the top of the slide.
The needle comes out the top of the slide.
Just noticed your drawing shows an emulsion tube and a needle jet. On the BS34's they are one in the same. Don't know for a fact but I suspect the 38's are too.
That drawing is a "generic" CV carb.
Go Chiefs!
Go Chiefs!
All needle jet's I've dealt with had the number stamped on the side. I recall some without a number, but I don't think that was Mikuni.
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