qdemon

Hi Guys
I think this has probably been asked before I have a spare stock 257 which will need drilling / taping to fit the nipple.
thats not a problem but do you have to do anything else to it in order to use it on a QD25 ?

Thanks Bob.

BMAD01

Bob, A WT 771 would be a better carb. Why would you need to drill and tap? Just swap out the bottoms. They are all interchangeable. Brian

qdemon

Hi Brian
sure thing can swop out the bottom cover just didnt know if anything had to be done inside the carb ?

Bob.

PS. just read your thread on shipping the gas can personally I would not chance it I would get a cheap plasic one from
the gas station to use temp.

Scott Schneider

Agree, the 771 is a FAR SUPERIOR carb to the 257 in high rpm engines !

Slow Motion

" Bob, A WT 771 would be a better carb. Why would you need to drill and tap? Just swap out the bottoms. They are all interchangeable. Brian "

the point is weather a 257 or 771 ect. is mounted on a qd, you need to drill and tap the carb for a pulse fitting to join the crankcase pulse feed. there is no pulse feed into the cylinder through the intake to join with the carb. the fuel pump wont operate.

BMAD01

"the point is weather a 257 or 771 ect. is mounted on a qd, you need to drill and tap the carb for a pulse fitting to join the crankcase pulse feed. there is no pulse feed into the cylinder through the intake to join with the carb. the fuel pump wont operate. "
Slow, any Walbro WT carb will work on the Q/D. You need to have the pulse line coming in from the bottom cover.

Bob, just unscrew the bottom cover on your existing carb and let the cover hang by the pulse line. Unscrew the bottom cover on the 771 and screw on the one hanging from the motor. Done deal, no further mods needed. Needle settings are going to be different. Somewhere around 1 1/2-LOW, and 1 1/4-HIGH. I'm running @ 5120ft, so your definitely going to be different slightly. Good luck, Brian

Slow Motion

BMAD01 agree completely. we're both giving the same advice. for bob its a simple cover change.

kawasakikr1

My Feedback: (1)

I've got a 771 on a 28.5 zen and can't seem to get the mixture right, i'm running at sea level.
Please could you give me some good starting settings?

Scott Schneider

1 1/4L and @ 1 1/2H

771's are SUPER stable carbs, would make damn sure intake manifold gaskets are well sealed, pulse hole unobstructed and you don't have a leaking fuel barb ( If you rotated it ? )

kawasakikr1

My Feedback: (1)

Thanks Scott, I'll give those settings a try.
Looks like I had it way off at 1 1/2L and 1 1/8H