K&B 61.... tuning problems
10-23-2009, 04:54 PM
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K&B 61.... tuning problems
I have the K&B 61 with the Perry pump and carburator.... I have not figured out how to tune the high end needle .... There is a brass wheel about 1 inch in dia. and then another finger adjustmen on top of the flat circle adjustment... do you adjust both? As for the pump, I have tried to run the engine with the pump and without... is it ok to bipass the pump?
10-23-2009, 05:10 PM
#2
RE: K&B 61.... tuning problems
I think the carb is different with the pump than without. Check if you have the right combination. MECOA has K&B now, contact them for advice and info. I just replaced my Perry carb on my old .61 with a K&B carb from an old .40. Had to remove the carb spigot insert to allow the bigger carb to fit. Runs great now! But, I like Perry carbs, and will likely replace the o rings and put it back on just for originalness. Good luck.
V/r, Richard
V/r, Richard
10-23-2009, 05:31 PM
#3
RE: K&B 61.... tuning problems
There was a special Perry carb for the pump
Instructions http://www.perrypumps.com/VP-30%20and%20VP-40.pdf
http://www.perrypumps.com/Carburetor.pdf
Instructions http://www.perrypumps.com/VP-30%20and%20VP-40.pdf
http://www.perrypumps.com/Carburetor.pdf
10-23-2009, 06:15 PM
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RE: K&B 61.... tuning problems
Richard, tune the HS needle to peak then tune the LS with the little eccentric at the top of the LS disc. A little adjustment does a whole lot of changing, that's why they put the eccentric there so the adjustment is not so sudden. In other words make really small changes to the LS disc.
10-23-2009, 08:25 PM
#6
RE: K&B 61.... tuning problems
Is it a Perry pump built into the rear case or is it the external one. If it is the built in one it has to be used with the matching carb; the external can be bypassed.
10-23-2009, 08:32 PM
#7
RE: K&B 61.... tuning problems
My Perry carb for the un-pumped .61 does not have the little excentric screw referred to by Hobbsy. Rather, it is like the drawings of the carb in the Perry attachment referred to by W8YE. Other K&B carbs I have (not Perry) have an excentric screw for idle disc micro adjustment. I don't have nor have I seen the pump varient carb. The "O" rings in the idle disc adjustment metering barrel can dry out or take a set and leak or not hold the idle disc in position. I recently changed out the Perry on my .61 for a later K&B carb (with the bent needle), because the idle disc would drift as the engine was running. As Hobbsy said this disc is very sensitive to its' effect on running, a few thousandths of movement can make all the difference. I hope to replace the "O" rings on the original Perry carb and restore the engine as originally fitted out.
Since both W8YE and Hobbsy are in this discussion, may I ask both of you about the ASP 1.08 redhead that I understand Hobbsy got from W8YE. I have a previously owned one that I have yet to run. I also have an ASP .91 that does not like nitro much at all. I understand that head shims make it more tolerant of notro, but I don't expect to run more than 5%. I can not find the shims. Any suggestions for making or finding them? Also what prop and rpm do the .91 and the 1.08 like? Thank you very much.
V/r, Dick Smith
Since both W8YE and Hobbsy are in this discussion, may I ask both of you about the ASP 1.08 redhead that I understand Hobbsy got from W8YE. I have a previously owned one that I have yet to run. I also have an ASP .91 that does not like nitro much at all. I understand that head shims make it more tolerant of notro, but I don't expect to run more than 5%. I can not find the shims. Any suggestions for making or finding them? Also what prop and rpm do the .91 and the 1.08 like? Thank you very much.
V/r, Dick Smith
10-24-2009, 09:05 AM
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RE: K&B 61.... tuning problems
ORIGINAL: TFF
Is it a Perry pump built into the rear case or is it the external one. If it is the built in one it has to be used with the matching carb; the external can be bypassed.
Is it a Perry pump built into the rear case or is it the external one. If it is the built in one it has to be used with the matching carb; the external can be bypassed.
10-24-2009, 09:28 AM
#11
RE: K&B 61.... tuning problems
You can bypass the backplate pump...just use a loop of fuel line and connect the inlet to the outlet.
Keep an eye on those old backplate pumps. Sometimes they work well..but with 25-30 years of age, they can leak, or pump bubbles, or the check valves can go bad.
If you have a "Pump Carb" however, it will not work w/o the pump. There is no venturi in the pump carb, so it will not draw fuel well, if at all...it acts more like a throttle body (it's a "pressure carb" )
The throttle bore of a K&B .61's pump carb is .375" and is straight through...no venturi constriction.
A V30 pump is virtually the same as the old backplate pump.
Edit: The pump carbs are all Perry's
I don't recall ever seeing or hearing about a special "pump" carb made by K&B...FWIW
Keep an eye on those old backplate pumps. Sometimes they work well..but with 25-30 years of age, they can leak, or pump bubbles, or the check valves can go bad.
If you have a "Pump Carb" however, it will not work w/o the pump. There is no venturi in the pump carb, so it will not draw fuel well, if at all...it acts more like a throttle body (it's a "pressure carb" )
The throttle bore of a K&B .61's pump carb is .375" and is straight through...no venturi constriction.
A V30 pump is virtually the same as the old backplate pump.
Edit: The pump carbs are all Perry's
I don't recall ever seeing or hearing about a special "pump" carb made by K&B...FWIW
