1977 stock carb question

[pa23driver]

i tore apart my carbs today for an excessively rich mixture. there was a bunch of shit in the bowls, floats levels were way off, idle mixtures were all effed up, good thing the PO assured me he did a good job rebuilding the carbs.

my bike is a 1977 650D (i checked the VIN and it is a 1977) and according to the carb guide i should have VM22/210 style pilot jets

after pulling everything apart i found the BS30/96 style pilot jets - size 42.5. my question is should i buy the rebuild kit for with the VM style pilots or the BS style pilots?

 

[grizld1]

You should by all means assume that the PO knows more than 5twins and I do! Seriously, check to see that you do in fact have D model carbs with correct float bowls. There's a round boss on the bottom of the float bowl. On bowls for 76-77 carbs, the boss is stamped with the letter "O." Rebuild kits don't usually include pilot and main jets and many parts are generic (meaning they don't fit our application). Usually, the only usable bits are gaskets and float valves.

 

[pa23driver]

Thanks grizld, i checked the float bowl and it does have the "o" stamped on it. the rebuild kit i was looking at is Mikesxs part# 48-1920

with this description: "Carb Rebuild Kit - Fits: XS650C/D (1976-77) Kit Contains: 8 Hole choke body Gasket, Float bowl Gasket 256, Float Valve assy. 2.0 with washer, Pilot Jet #27.5 VM22/210 type, #135 SmallRound Main Jet N102/221, Pilot air Screw and spring, Choke plunger and Washer for float bowl main jet access plug.
Made in Japan - 1 kit required per carb."

it sounds like everything is there, and proper - feel free to chime in on any experiences with said rebuild kit.
I'm still reading through the carb guide, but the guide is awesome, so i hope it didn't sound like i didn't trust the content - or trust the PO over you guys.

 

[5twins]

The pilots in that rebuild kit are the proper type (VM22/210) but the wrong size. So are the mains. For some reason, that kit has main and pilot sizes from the '78-'79 carb set. Your original pilots were #25s so the 27.5 may work if you've done some mods (pipes and pods). The 135 main is pretty big though considering your original was a 122.5. The 135 could be too big with minor mods. I tried a set of '77 carbs and the biggest I could go was 132.5. If you need all the other stuff in the kit, it may be worth buying. Total up the individual parts prices and see.

 

[pa23driver]

Thanks 5twins, i'll take a look at the prices of individual pieces. the only thing i need out of the kit is the correct pilots, but while i have everything apart it wouldn't be bad to replace what i can.

my main jet is stamped with a 30, does that mean anything? i'm gonna go ahead and assume that because the PO installed the wrong pilot jet, he also installed a wrong main.

 

[5twins]

Mains for these were in the 122.5 - 135 range. Maybe you've got a 130 and just can't see the "1" stamped in front of the "3". 130 mains and those 42.5 BS30/96 pilots were used in an earlier carb set ('72-'73). Maybe the P.O. installed the wrong rebuild kit.

The pilots can be confusing because externally, they look the same and the 2 types will interchange. The bowls they're used in however, are designed to use only the one type specified for that bowl. The other style will screw right in but won't flow correctly. It has to do with where the air is fed to the jet and what the jet flows. The BS30/96 type pilots have the air fed to the bottom of the jet. They flow a gas/air mix. That's why they're sized in the 40s. The VM22/210 style has the air delivered to the top, above the jet. The jet flows only fuel and the air is added after it. That's why they are sized in the 20s.

 

[5twins]

You probably should make sure your carbs are '77 units as well, or at least that the float bowls are the VM22/210 type. Here's how to tell by looking inside at how the pilots get their air delivered .....

 

[pa23driver]

i was wondering what was the deal with the size differences between the two variations of pilot jets.

i took a look again at the mains and on one and i could see a ghost of a "1" in front of the 30.

the funny thing is when i test rode the bike (prior to buying) it felt fine with plenty of power with the plugs only slightly rich running pods and sportster mufflers. yesterday i took the bike out for a spin after rebuilding the top end and swapping out the mufflers for commandos, made it around the block twice, then had to push the bike home. the tank was rusty, so i figured shit made it from the tank, past the inline fuel filters, into the carbs during the run and clogged the hi speed circuit. pulled the plugs and they were soaking wet.

after pulling the carbs apart its amazing the thing ran at all, the floats were well outside of the 1 mm tolerance, one idle mixture was set correctly with the other at around 3 turns, now the wrong pilots and mains.

i'll swap out the mains for the correct type, and buy a couple different sizes to dial it in

 

[pa23driver]

You probably should make sure your carbs are '77 units as well, or at least that the float bowls are the VM22/210 type. Here's how to tell by looking inside at how the pilots get their air delivered .....

just took a look at the bowls and they are the vm22/210 type

 

[5twins]

The 130 mains might be OK with pods and the Commando mufflers. You might want to try 132.5s eventually. I would try the proper VM22/210 pilots in the stock #25 size and one up, 27.5. If you go with the one up pilots and larger mains, you may need to lean the needle a step.

 

[pa23driver]

sounds good, thanks for the help 5twins, i'll give those sizes a shot