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1974 & 1979 carburetors- will they interchange?
- Thread starter Danny
- Start date
yam never made xs400's in '74
any 34mm 400 sohc's will fit. you may need to change jets though.
is that "400S" or "400's" ?
is that "400S" or "400's" ?
It's a 400 Special. The carburetor on it has no numbers, only Mikuni Kogyo printed on it. How do you identify the carburetor in order to get the right kit for it? The diaphram is bad and holes in the floats. Needs a carburetor kit, but I need to be able to identify the correct one for it. I just bought some carburetors on eBay for a '78 400S. Would it have the same kit as my '79 400S?
I don't think there was a moniker with the S on the 400 except for japanese import and they were 80's models.
I think you will be fine but wait till you get the carbs as some had steel caps on the diaphrams and some alloy which have slightly different sizes.of springs. go compare when they arrive!
I think you will be fine but wait till you get the carbs as some had steel caps on the diaphrams and some alloy which have slightly different sizes.of springs. go compare when they arrive!
A little XS 400 terminology that will help us all to be on the same page.
First of all, Yamaha made several different motorcycles with (nominal) 400cc displacement, so specifying XS 400 helps us all to know we are on the same page. Second, Yamaha specified models of XS400 with a letter after the "XS 400" and these roughly followed model years. For instance, a 1977 is an XS 400 D. A 1978 is an XS 400 E. A 1979 is an XS 400 F. A 1980 is an XS 400 G or SG (more on that in a moment). This will be important to know when it comes time to buy parts.
As far model years, keep in mind that date of manufacture only tells you so much and not the whole story. For instance, right now I can go down to a dealership and buy 2012 Chevy truck. Of course, it was not manufactured in 2012, it's a 2012 nonetheless. It's the same with motorcycles. If it was made in 12/79, or probably 11/79 or 10/79, it's an '80 model year and an XS 400 G or SG.
Ah yes, back to the G or SG (on '81s, H or SH). In '80 and '81, there was an XS 400 "Special". That's what the "S" stands for in XS 400 SG or XS 400 SH. The Specials were the economy models with spoked wheels, drum brakes front and back and what elsem I don't know. There was a similar economy/standard model thing earlier, but there the number "2" was used as in XS 400 2E or XS 400 2F.
Here's the fun part- no matter whether an SG, a G, an H, an SH an F or a 2F, the engines were essentially the same. Stick with a SOHC (single over-head cam) XS 400, and most of the parts interchange. Therefore, as Drewpy mentioned earlier, all SOHC XS400 motorcycles had Mikuni BS 34 carbs, though the jets were different with different years- more good news- jets are plentiful and inexpensive.
One last thing to be aware of- Yamaha started selling double over-head cam (DOHC) XS400 models in 1982 and virtually nothing interchanges to the older SOHC models....however, Yamaha did make ye olde SOHC XS400 one last year in 1982, so there was one year of overlap.
First of all, Yamaha made several different motorcycles with (nominal) 400cc displacement, so specifying XS 400 helps us all to know we are on the same page. Second, Yamaha specified models of XS400 with a letter after the "XS 400" and these roughly followed model years. For instance, a 1977 is an XS 400 D. A 1978 is an XS 400 E. A 1979 is an XS 400 F. A 1980 is an XS 400 G or SG (more on that in a moment). This will be important to know when it comes time to buy parts.
As far model years, keep in mind that date of manufacture only tells you so much and not the whole story. For instance, right now I can go down to a dealership and buy 2012 Chevy truck. Of course, it was not manufactured in 2012, it's a 2012 nonetheless. It's the same with motorcycles. If it was made in 12/79, or probably 11/79 or 10/79, it's an '80 model year and an XS 400 G or SG.
Ah yes, back to the G or SG (on '81s, H or SH). In '80 and '81, there was an XS 400 "Special". That's what the "S" stands for in XS 400 SG or XS 400 SH. The Specials were the economy models with spoked wheels, drum brakes front and back and what elsem I don't know. There was a similar economy/standard model thing earlier, but there the number "2" was used as in XS 400 2E or XS 400 2F.
Here's the fun part- no matter whether an SG, a G, an H, an SH an F or a 2F, the engines were essentially the same. Stick with a SOHC (single over-head cam) XS 400, and most of the parts interchange. Therefore, as Drewpy mentioned earlier, all SOHC XS400 motorcycles had Mikuni BS 34 carbs, though the jets were different with different years- more good news- jets are plentiful and inexpensive.
One last thing to be aware of- Yamaha started selling double over-head cam (DOHC) XS400 models in 1982 and virtually nothing interchanges to the older SOHC models....however, Yamaha did make ye olde SOHC XS400 one last year in 1982, so there was one year of overlap.
XSLeo
XS400 Junkie
The manufacturing year for Yamaha is from September 1 to August 31. Any thing from Sept 1, 78 to Aug 31, 79 is an 80. 79's are Sept 1, 77 to Aug 31, 78.
As far as parts go it will be better to use the frame ID number to determine the year.
I'm sure there is a chart listing the frame numbers and what year they are some where out there.
Leo
As far as parts go it will be better to use the frame ID number to determine the year.
I'm sure there is a chart listing the frame numbers and what year they are some where out there.
Leo
campusxs400
XS400 New Member
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I have a question regarding jetting. I'm in the process of rebuilding a 1979 XS400-2F with about 13,500 original miles. It sat in a garage from about 1984 until a couple of years ago when I got my hands on it. It still had a half tank of gas and the carbs needed a cleaning so I sent them to a guy who advertised on eBay. Well, he did a great job of cleaning the carbs, but he broke one of the float pin goal posts and pinned it back together. Well, it took no time to vibrate apart and flooded the engine with gasoline. Long story short, I just picked up a replacement set of carbs on eBay that are described as: XS400 Special #1201 carbs. My question is; do I need to re-jet these carbs to be compatible with the stock 1979 XS400-2F ? Any comments or recommendations appreciated...
