Carb ID. Mikuni CV's, BS38, BS34, 70-84

Thanks. I was given this bike back in the 90's by some neighbors who were going to throw it away. I got it going and rode it down the block a few times and then parked it and it's sat since then. My son (the guy smiling on the bike who wasn't even born when I got it) showed interest and I said if he could get it going it was his. So far we have got it running...mostly. It has very weak spark on the right cyl. New coils, wires, plugs, and points. The last item on the list is the condenser and one is on order. Are they all mounted on top of the head like this one is? Took a bit to find it. LOL.

Not an '80? The head tag/sticker says 1980. I'll have to get a pic. Yes, this bike has points.
 
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Well, I was completely wrong! Not sure why I had it in my mind I had seen 1980 on the tag, but this clearly shows it as a 1977 bike. My appologies and thank you for the info. Now to go look up the vin.
 

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Well, I was completely wrong! Not sure why I had it in my mind I had seen 1980 on the tag, but this clearly shows it as a 1977 bike. My appologies and thank you for the info. Now to go look up the vin.
11/77 on the tag means it's a 1978.
Just like new model years on cars fall on the prior year, so do bikes.
 
Yes, it's a '78 Special. The 16" rear wheel and tire shown on the tag were Special only parts. The Standard model had an 18" rear wheel and tire.

As Jim said, production of the new models began in late summer or early fall of the previous year. Also, '78 was the first year of the Special model. In '77, only the Standard was made.
 
Thanks guys for all the great info. Obviously, bike minutia is new to me. I'm a VW guy (see sig pic) and understand the production/MY date as VW did this late summer thing too. So '78 SE it is.

I believe when my son bought carb kits he ordered for an '80. Would those jets be significantly different for the 34 vs the 38's? As I mentioned, we did get it to run and idle, but then it just quit. Still working on this issue. R cyl has very weak spark(all ing. components new short of condenser). A proper test of the condenser is next. I'll post in a different thread, as I just saw one with similar symptoms.

Much appreciated. First ride: Sorry for the orientation
 
I believe when my son bought carb kits he ordered for an '80. Would those jets be significantly different for the 34 vs the 38's?
Yes, significant difference. The first comment in this thread linked to the Carb Guide. It's pretty much the bible of 34's and 38's. I'd suggest studying it 'till your eyes bleed... ;)
 

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Thanks again, guys. The boy has some read'n to do. lol I'll probably read it too. ;-)
 
Thanks guys for all the great info. Obviously, bike minutia is new to me. I'm a VW guy (see sig pic) and understand the production/MY date as VW did this late summer thing too. So '78 SE it is.

I believe when my son bought carb kits he ordered for an '80. Would those jets be significantly different for the 34 vs the 38's? As I mentioned, we did get it to run and idle, but then it just quit. Still working on this issue. R cyl has very weak spark(all ing. components new short of condenser). A proper test of the condenser is next. I'll post in a different thread, as I just saw one with similar symptoms.

Much appreciated. First ride: Sorry for the orientation

2manyxs1bs, covers your questions in post 1. Best write up I have seen for an intro covering novis questions.
 
Hey ya'll, I've got a weird question for you. I have a 1980G and I've been working on the carbs ordering parts and what not. I wanted to replace the drain screw in the bottom of the float bowl but I'm discovering that the float bowl of my 34's have the large brass drain screw of the earlier models. The rest of the carb fits the ID for the 34 perfectly (although I suppose I should actually measure the diameter to be really sure). Would an earlier model's float bowl fit on the 34? Maybe a later model? The bike has certainly been tinkered with but the carbs appear untouched from what I can tell.

I came across this while I wasn't home, so I can update with pictures later if needed.
 
So far I've tried 3 different flavors of the -34 bowls... '80, '82 and a Suzuki carb. They all fit/interchange.
Keep in mind, '79 and earlier XS' used the Bs38 carbs... they will not fit.
I couldn't imagine the 38 bowls would fit the 34 but I was scratching my head as to why they didn't match the rest of the ID. It does remind me of the float bowl on my little GN250, so maybe a swap was done before she got to me. Thanks!
 
No, no swap was done I don't think. The '80 BS34 bowls (1st year of the 34's) had the drain bolt, just like the previous BS38's. That drain screw that mounted in the lower side of the bowl didn't come along until the '81 carbs.
Oh gotcha! So that screw is normal for the year. Thanks for the clarification!
 
Yes, you can retrofit the plastic floats to the 1980 carbs if you like, and it's what I'd do if the original brass ones ever went bad. The plastic ones rarely go bad and can usually be found for a few dollars cheaper than the brass ones. And the Suzuki equivalent is even cheaper than the Yamaha float .....

PlasticFloat.jpg


SuzukiCarbParts.jpg
 
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