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Old Brown
- Thread starter Team Junk
- Start date
When you install larger mains, often you have to lean the needles a step to cure that stumbling. But yes, 135 mains are pretty big. The biggest I could go on a set of '76-'77 carbs I set up for my bike was 132.5. 135s produced stumbling even with the needles leaned one step, and I didn't want to lean them another step. The limiting factor for main jet size on this carb set is the very large Z-8 needle jet. While mains all the way up into the 140s can often be fitted to some of the later carb sets, these large Z-8 needle jets won't allow that on this set. Mid 130s is about the biggest they'll take.
The 78 special these carbs came from was a bike I bought from my mad late friend Ted. This is one bike that I don't really remember the details of acquiring. I know I bought it for the cast wheels. I doubt I ever rode it because of the rototiller bars. Pretty sure it was the bike he took to bike week one year.
I'm baffled by the jetting because the bike is pretty much standard and I don't see how it would of run with that much main jet. Now I'm curious about the engine in the bike. Ted was the one that convinced me to go road racing and he was the most hardcore 650 guy. His race bike was a 77 , over 800cc with large diameter straight drag pipes that sounded awesome around Texas World. I suspect at some point that these carbs were on that bike. The only plausible explanation for the jetting.
I figure 130 mains are still pretty rich but should at least get Old Brown running without turning the plugs black like it has been till now.
I'm baffled by the jetting because the bike is pretty much standard and I don't see how it would of run with that much main jet. Now I'm curious about the engine in the bike. Ted was the one that convinced me to go road racing and he was the most hardcore 650 guy. His race bike was a 77 , over 800cc with large diameter straight drag pipes that sounded awesome around Texas World. I suspect at some point that these carbs were on that bike. The only plausible explanation for the jetting.
I figure 130 mains are still pretty rich but should at least get Old Brown running without turning the plugs black like it has been till now.
Needle setting has a big influence on plug color too, so like I said, make sure it's leaned a step.
Many consider the '76-'77 carb set one of the best of the 38s, so maybe that's why your buddy was running it. That's why I tried some on my '78. They are good but I think the original '78-'79 set is just as good, if not a little better. The needle mounting method was changed on the later set. The needle was spring-loaded and meters more precisely. This smooths out the carb's operation, especially at the lower end.
Many consider the '76-'77 carb set one of the best of the 38s, so maybe that's why your buddy was running it. That's why I tried some on my '78. They are good but I think the original '78-'79 set is just as good, if not a little better. The needle mounting method was changed on the later set. The needle was spring-loaded and meters more precisely. This smooths out the carb's operation, especially at the lower end.
The fuel tank has become a sub project unto itself.
Have correct left right petcocks on way. Will probably disassemble to see if they can be improved ie. finish manufacturing them.
Have gas cap with keys
Trying to figure out this part and what it looks like or a source. Part #13
Have correct left right petcocks on way. Will probably disassemble to see if they can be improved ie. finish manufacturing them.
Have gas cap with keys
Trying to figure out this part and what it looks like or a source. Part #13
I'm not 100%, but that could just be a roll pin. Roll pins are available at hardware stores, sometimes can find the right diameter and then cut to the proper length.
No, I think it's a very small pin that resembles a nail (small head on one end) and has a groove cut in the other end for a small e-clip (part #10).
https://www.partzilla.com/product/yamaha/93430-02001-00?ref=6f3a17c7db974296c7ec23122825b440b32b9d59
https://www.partzilla.com/product/yamaha/93430-02001-00?ref=6f3a17c7db974296c7ec23122825b440b32b9d59
To make that pin since it is unavailable. Instead of a C-clip and groove on the pin...……...There are clips available that push onto pins without a groove, my local hardware store has these clips. Some side cover badges use these clips. I have used them with white aluminum fascia nails to fasten chrome trim to seats.
Find a nail that fits, maybe aluminum, cut and trim, use one of those push on clips. They look like C-clips but are shaped like an O instead of a C. They can be pushed onto a pin/nail with a small socket on a nut driver.
Find a nail that fits, maybe aluminum, cut and trim, use one of those push on clips. They look like C-clips but are shaped like an O instead of a C. They can be pushed onto a pin/nail with a small socket on a nut driver.
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A smaller version of the wheel attachments on a red wagon. That's a good idea. Assembling the cap and petcocks will be a cold day project in the kitchen so I'm trying to gather the pieces together.
I’m unsure exactly what type of gas cap you have. If it is the same as the one on my XS2 I could take some detailed photos for you.
Do you have any photos of your cap?
Do you have any photos of your cap?
According to partfilla you have the same pin. That would be awesome. Thanks Mailman. Glad to see you out riding on that beautiful machine of yours. Your one kick video pisses off the head of ranch security the weiner dog every time I watch it. Of course the volume is turned way up.
Ok I’ll go take some photos, be back in a few.
I'm thinking maybe a drill bit shank with the push on clips.
If the part # is 90249-03088-00 it's available on E-bay.
https://www.ebay.com/itm/YAMAHA-NOS...802011?hash=item3d8eeb7a5b:g:b4UAAOSwNe9dIg62
https://www.ebay.com/itm/YAMAHA-NOS...802011?hash=item3d8eeb7a5b:g:b4UAAOSwNe9dIg62
Ok in this photo,
#8 is a simple rolled pin that measures 3mm x 32mm long
#23 is a solid nail head pin that is 3mm x 29mm long with a groove at one end, held in place with an E Clip
#19 is a solid nail head pin that is 3mm x 23 mm long with a groove and an E Clip
Hope this helps,
Bob
#8 is a simple rolled pin that measures 3mm x 32mm long
#23 is a solid nail head pin that is 3mm x 29mm long with a groove at one end, held in place with an E Clip
#19 is a solid nail head pin that is 3mm x 23 mm long with a groove and an E Clip
Hope this helps,
Bob
Wow. Thanks for the photos. Brought back memories of my buddy's bikes. The 74 has the latch in the cap that grabs the pin that your latch pivots on. Same part number pin. Interesting.
Went and took some pictures myself and discovered the ebay gas cap won't work. On to Plan C I guess.
Went and took some pictures myself and discovered the ebay gas cap won't work. On to Plan C I guess.
Funny how they left the mount point for the early caps. The original latch and cap would work if the later mount point wasn't there.
DogBunny got me fixed up. He found a tank and cap on ebay that I had overlooked. He has the lock that this tank is missing. This gas tank thing has sure turned into a rabbit hole. More scrubbing and polishing.
Those (nail-looking) pins are easy enough to fabricate. I had to make one for "The Basketcase". I used a drill as a lathe (Stone Age Garage!) to reduce the size of a nail head, and a triangular file to cut the slot for the "e" clip, then trimmed it to length. It's neither perfect, nor pretty, but hasn't budged... 
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This is so true
CYCLE WORLD magazine June 1980
Yamaha 650 owners tell us their machines are motorcycles. “You remember motorcycles. They have a pulsating throb instead of an electric motor whir …. They’re narrower than your car …. You can actually adjust the valves without removing the camshaft. Just one camshaft? …. gas tanks with curves instead of bends …. a strange looking lever on the side you can kick to make it run …. something you’d feel uncomfortable wearing a suit and tie on …. They let you park it with the Harleys down at the tavern.”
CYCLE WORLD magazine June 1980
Yamaha 650 owners tell us their machines are motorcycles. “You remember motorcycles. They have a pulsating throb instead of an electric motor whir …. They’re narrower than your car …. You can actually adjust the valves without removing the camshaft. Just one camshaft? …. gas tanks with curves instead of bends …. a strange looking lever on the side you can kick to make it run …. something you’d feel uncomfortable wearing a suit and tie on …. They let you park it with the Harleys down at the tavern.”
