I have a 1970 Yamaha XS-650 XS1 with 16K miles that my father bought brand new when I was 7 years old. We rode different bikes for years, but we always kept the XS. It's still a beautiful machine. Dad passed away 2 years ago, and I've been taking it out only to start it and warm it up and then wheel it back under covers. We've always used fuel stabilizer for winters and kept the tank full and changed the fuel every year in the spring, but beyond that, never drained the bowls or put it away like it was going to be down for a while. This year, I decided to put it on the road as it really needs to open up and breathe as only the 650 can. I love that bike.
Anyway, the bike starts first or second kick when choked. It always has. Lately, when I take it off choke, it struggles to idle and eventually stalls. I read and read many posts and also read through the original Yamaha Service Manual which gives a pretty good basic reference in a 1970 kind of way. I decided to pull the carbs and take a peek as I don't think that's ever been done and the symptoms seemed to justify a closer inspection. Plus I'm bored and curious. Anyway, they're in really good shape physically, but there is clearly some gumming and cleaning that would be in order. Additionally, one of the bowls looks like it hasn't been wet for a long time. I found that interesting. I've also done some other very minor fuel related fixes like rebuild the petcocks with a kit and replaced the dried out fuel lines. I've also tweaked around with some other small things but the bike needs almost nothing.
In fact, this post isn't about helping to solve a "the bike won't this or that"kind of problem. This is about helping me solve a conflict in identifying which carb is on the bike and ordering the right kit.
My confusion come from conflictions I'm seeing between the service manual/original carb (yes, I am 100% sure they're the original, like everything else on the bike) and what Mikes XS is showing as rebuild kit options.
Issue 1: Choke Body Gasket
This is from MikesXS.com (Part #48-2010)
Carburetor Choke Body Gasket Mikuni BS38 CV carb TX650 XS650B
Carburetor Choke Body Gasket - 7 Hole - Fits: TX650A, XS650B (74-75) Stock Mikuni
BS38 CV Carburetor.
Note: 1970-73 650's did not use a choke body gasket
I have attached a picture of the choke assembly from the carb and it obviously has a gasket. Secondly, the gasket Mikes lists that looks identical to the one on the carb, is a 7 –hole, and Mikes shows that not only did the 70-73 not have a gasket, but the bike is a 1970 not a 74-75 which had this specific gasket.
Issue 2: Correct Carb Rebuild Kit?
This is from MikesXS (Part #48-1919) (THIS "LOOKS"LIKE THE RIGHT KIT)
Carburetor Rebuild Kit XS650B TX650A Mikuni BS38
Carburetor Rebuild Kit - Fits: TX650A/XS650B (1974-75) BS38 Mikuni Contains - Slide needle Y-22 (40mm needle) & clip, Pilot jet #42.5 BS30/96, Main Jet #130 Small round N102/221, Float
Needle assy 2.5, Air screw with spring, 7 hole choke cover gasket, Float bowl
gasket 256.
Again, this kit matches the service manual (2.5 on the fuel valve seat, 7-hole choke gasket) but there is one conflict in that the manual shows a pilot jet of 45 not 42.5. Not sure if I need to be overly concerned about that.
Next, is this kit below. According to Mikes, its for the 70-71 XS1 and XS1b. But the specs conflict with the service manual (comes with a fuel valve seat of 2.0 not 2.5 as in the manual, and it also comes with a 42.5 pilot, not the 45 that's in the manual).
Carburetor Rebuild Kit XS1/XS1b Mikuni BS38 CV
Carburetor Rebuild Kit - Fits:XS1/XS1b (1970-71) BS38 Mikuni (Solex) Kit Contains: Slide needle Y22 & clip, Pilot Jet BS30/96 #42.5, Main Jet - #130 Small round N102/221, Float Needle & Seat assembly #2.0, Air Screw with spring, Choke Plunger & spring, float bowl Gasket ( 256). Made in Japan - 1 kit required per carb.
OEM Reference #
- 306-14901-00-00
So, the short questions are: Which kit? Despite that I know for a fact that this bike is a 1970 XS1, the carb kit for the 74-75 seems like the right one as all the parts (gasket/fuel seat..) seem to match the service manual and the carb itself? How can that be? Did Yamaha use a variety of carbs on one of the earliest of the 650s? FYI, the VIN serial number is "XS650-1008". What am I missing here?
Thanks for any and all help. This site is awesome.
Anyway, the bike starts first or second kick when choked. It always has. Lately, when I take it off choke, it struggles to idle and eventually stalls. I read and read many posts and also read through the original Yamaha Service Manual which gives a pretty good basic reference in a 1970 kind of way. I decided to pull the carbs and take a peek as I don't think that's ever been done and the symptoms seemed to justify a closer inspection. Plus I'm bored and curious. Anyway, they're in really good shape physically, but there is clearly some gumming and cleaning that would be in order. Additionally, one of the bowls looks like it hasn't been wet for a long time. I found that interesting. I've also done some other very minor fuel related fixes like rebuild the petcocks with a kit and replaced the dried out fuel lines. I've also tweaked around with some other small things but the bike needs almost nothing.
In fact, this post isn't about helping to solve a "the bike won't this or that"kind of problem. This is about helping me solve a conflict in identifying which carb is on the bike and ordering the right kit.
My confusion come from conflictions I'm seeing between the service manual/original carb (yes, I am 100% sure they're the original, like everything else on the bike) and what Mikes XS is showing as rebuild kit options.
Issue 1: Choke Body Gasket
This is from MikesXS.com (Part #48-2010)
Carburetor Choke Body Gasket Mikuni BS38 CV carb TX650 XS650B
Carburetor Choke Body Gasket - 7 Hole - Fits: TX650A, XS650B (74-75) Stock Mikuni
BS38 CV Carburetor.
Note: 1970-73 650's did not use a choke body gasket
I have attached a picture of the choke assembly from the carb and it obviously has a gasket. Secondly, the gasket Mikes lists that looks identical to the one on the carb, is a 7 –hole, and Mikes shows that not only did the 70-73 not have a gasket, but the bike is a 1970 not a 74-75 which had this specific gasket.
Issue 2: Correct Carb Rebuild Kit?
This is from MikesXS (Part #48-1919) (THIS "LOOKS"LIKE THE RIGHT KIT)
Carburetor Rebuild Kit XS650B TX650A Mikuni BS38
Carburetor Rebuild Kit - Fits: TX650A/XS650B (1974-75) BS38 Mikuni Contains - Slide needle Y-22 (40mm needle) & clip, Pilot jet #42.5 BS30/96, Main Jet #130 Small round N102/221, Float
Needle assy 2.5, Air screw with spring, 7 hole choke cover gasket, Float bowl
gasket 256.
Again, this kit matches the service manual (2.5 on the fuel valve seat, 7-hole choke gasket) but there is one conflict in that the manual shows a pilot jet of 45 not 42.5. Not sure if I need to be overly concerned about that.
Next, is this kit below. According to Mikes, its for the 70-71 XS1 and XS1b. But the specs conflict with the service manual (comes with a fuel valve seat of 2.0 not 2.5 as in the manual, and it also comes with a 42.5 pilot, not the 45 that's in the manual).
Carburetor Rebuild Kit XS1/XS1b Mikuni BS38 CV
Carburetor Rebuild Kit - Fits:XS1/XS1b (1970-71) BS38 Mikuni (Solex) Kit Contains: Slide needle Y22 & clip, Pilot Jet BS30/96 #42.5, Main Jet - #130 Small round N102/221, Float Needle & Seat assembly #2.0, Air Screw with spring, Choke Plunger & spring, float bowl Gasket ( 256). Made in Japan - 1 kit required per carb.
OEM Reference #
- 306-14901-00-00
So, the short questions are: Which kit? Despite that I know for a fact that this bike is a 1970 XS1, the carb kit for the 74-75 seems like the right one as all the parts (gasket/fuel seat..) seem to match the service manual and the carb itself? How can that be? Did Yamaha use a variety of carbs on one of the earliest of the 650s? FYI, the VIN serial number is "XS650-1008". What am I missing here?
Thanks for any and all help. This site is awesome.
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