what kind of carbs??

[Fatman]

I'm new here, ran across you all while back and been following ya a while. my son picked up a basket case"S" 2 eng 3 frame 5 wheels . One eng has carbs on it, looks like its a 78 the other says 81 other frame is a 750. can you tell me what these are? yes one is bigger, think it came from a 750??If it is will it work on a 650 with open air pods and short/open pipes? Yes I have looked all over ya site, eyes be bleeding
Think I done this right....

 

[Fatman]

 

[Fatman]

 

[XSLeo]

Maybe they were to big.
There are several places to reference the frame numbers to find the year. The year on the white sticker is the manufactured date. It is often a year before the model date. You could have a 79 and 82 frames.
The engine number is on the upper crank case by the front engine mount. This number matched the frame from the factory.
The later 750 engine was a three cylinder. If you have two good 650 frames and two 650 engines, why try to use the 750 frame?

 

[Fatman]

they was to big, we got one frame into a hardtail (sort of LOL), the 750 frame has the 3 tube backbone going on... and eng mounts are alot of work

 

[XSLeo]

Just saw your pics of the carbs. The ones with the gas line coming up from a tee are 80-81 BS34 The choke knob is giveaway.
The other set is a late 78-79 BS38 The lack of an over flow is the giveaway there.
Using the right set of holders these carbs fit most any year.
The 81 frame is for sure a "s" Special. The 81 would be an XS650SH.
The 79 could be one of three models The Standard XS650F, the Special XS650SF and the Special II XS6502F. the main differences were the wheels and seats.
Can you post pics of the frames?
Any titles? You can have lots of fun rebuilding those bikes. You will learn a lot and the father son bonding is priceless. It's not impossible to get a title and put the bikes on the road, if you don't have one, it's just easier when you do.

 

[XSLeo]

At the top of the page, click the Tech. It takes you to a list of links, You might find a lot of your questions answered by looking through them.

 

[Fatman]

Thanks, I been all over the tech pages. Lot of great stuff, got titles on all 3. Never past a frame and title LOL. Son is pushing 40, his is 15. I started my boys on a 250 drit bike and a 400 twin,then got them a xs650. I loved the way it looked by it went by the way side years ago, we was looking for his son a bike when we found these and I talked him in to getting them LOL, Got pic of basket case on his facebook will try and get them. he's in Ks and I'm in mo so it might be a long winter LOL. But the bigger carbs (bs34 will work, it is bigger "bore" thought it might be from the 750. Now I know, Thanks again.

 

[XSLeo]

Both carb sets are good working carbs when tuned right. Don't have a link but Grizld1 and 5twins wrote a carb guide and it is very good. It explains how to tear them down, clean, rebuild and tune them. It's over at The Garage.
I'm sure either of them will give you a link to it when they see this thread.
I have it downloaded and I read it a lot. it helped me with my carbs. Rereading it helps me better understand what they are telling me.
It also covers the Mikuni VM carbs.

 

[Fatman]

parts and pieces

 

[XSLeo]

Looks like you got some fun coming up.