no hole pilot jet or jet with holes ?

[spitfire]

hi,

i have a 79 (sf) 650 special with 38 carbs. the pilot jets have no bleed holes and have 275 stamped on them. i was just wondering if these were the right pilot jets as i have seen similar ones with bleed holes

why do some jets have no holes and others bleed holes and does it make any difference

thanks in advance

 

[inxs]

- these 2 pics basically give you the pilot jet run down

- the 275 will be 27.5

 

[KentMoney]

what about the pilot jets that have NO bleed holes? will they work in BS34s off my '81 XS650?

 

[5twins]

No, BS34 pilot jets need the bleed holes and must be the BS30/96 series.

 

[KentMoney]

ok, thanks 5twins. my local yamaha dealer only had the 47.5 size in the non-bleed type. I guess I'll have to order from Mikes :/ 650 central doesn't have 50 either, and I need both.

 

[5twins]

You need the bleed holes because the pilot draws it's fuel and air from the side, not through the top of the jet like on most carbs. That rubber plug over your pilot stops flow through the top of the jet. A no-hole pilot wouldn't work at all in the BS34s because there would be no way for the fuel and air to get into it. You may be able to get them from Dennis Kirk for about the same price and they would be genuine Mikuni jets to boot, not those crap knock-offs Mike's sells.

 

[angus67]

if 34's dont get fuel from the center, then why did xsjohn enlarge that 42.5 to a 46?

 

[5twins]

You're not understanding how the BS30/96 pilots function in the BS34 carbs. Fuel and air enter the jet from the side through the bleed holes and exit through the metering orifice at the bottom. That metering orifice was what John was altering.

 

[KentMoney]

welp, I managed to find some genuine mikuni 47.5 pilots on amazon for pretty darn cheap. came out to $9 for a pair including shipping. I am having difficulty finding mikuni 50's for the BS30/96 style carbs however, did they even make them?

 

[5twins]

https://www.denniskirk.com/mikuni/oem-pilot-jet.p176030.prd/176030.sku

 

[KentMoney]

ah, you're right! I looked at that but I was looking at the bottom portion of the list where they only list the x.5 increments. but I see it now! Thanks

 

[oldskoolcarbs]

http://www.z1enterprises.com/catalog.aspx?pid=KPCF2

 

[oldskoolcarbs]

You're not understanding how the BS30/96 pilots function in the BS34 carbs. Fuel and air enter the jet from the side through the bleed holes and exit through the metering orifice at the bottom. That metering orifice was what John was altering.

the air mixes on the other side(the outlet side) of the pilot.. i may have misinterpreted this.. all the kz1000s i work on have plugs over the pilots and have solid pilots/no bleed holes.. i have seen some diagrams showing some carbs pull air mid way in the pilots but i have never seen this.. i am looking at a set of 1981 xs650 now? there is not a hole between the threads for the pilot and the seating surface