Jetting

Beamster · Post by **Beamster** » Sun Apr 21, 2013 12:49 pm

I've read a variety of post about rejetting for big bore and head changes but they related primarily to the main jet.
Did anyone have to get into fiddling with the slow or needle jets?

Throwback7R · Post by **Throwback7R** » Sun Apr 21, 2013 1:56 pm

Mine runs really good " with the bbk 61mm kit and large head with a drilled out main from 92 to # 57 DRill bit so that makes it roughly a 109.2 main jet the next size drill bit i could find would be a # 58 and that was too large.

I did not change anything else in the carb

tortoise · Post by **tortoise** » Sun Apr 21, 2013 3:38 pm

Related thread on main jet selection using a cylinder head temperature meter (spark plug sensor).

Beamster · Post by **Beamster** » Mon Apr 22, 2013 1:19 am

Throwback7R wrote:Mine runs really good " with the bbk 61mm kit and large head with a drilled out main from 92 to # 57 DRill bit so that makes it roughly a 109.2 main jet the next size drill bit i could find would be a # 58 and that was too large.

I did not change anything else in the carb

What Elevation might you be at?

lovemysan · Post by **lovemysan** » Tue Apr 23, 2013 1:36 am

161 kit, prima pipe. Running a 100 main jet. Could probly run a 95 or 98 as the oil gets black quick. I'm at 600 feet.

Throwback7R · Post by **Throwback7R** » Tue Apr 23, 2013 2:07 am

Beamster wrote:
Throwback7R wrote:Mine runs really good " with the bbk 61mm kit and large head with a drilled out main from 92 to # 57 DRill bit so that makes it roughly a 109.2 main jet the next size drill bit i could find would be a # 58 and that was too large.

I did not change anything else in the carb
What Elevation might you be at?

Near Chicago I believe around 630~650 ft above

Beamster · Post by **Beamster** » Tue Apr 23, 2013 2:20 am

Throwback7R wrote:
Near Chicago I believe around 630~650 ft above

Good information.
We're down by the salt water so a tad richer might fill the bill, but I'll start at 110 main, close to your estimate.

A company that supplies Honda jets has an on line program that just requires input of elevation, modifications from stock and they figure all jets and needle shimming and provide the appropriate parts.

Too had there isn't such a program for the Buddy.

Throwback7R · Post by **Throwback7R** » Tue Apr 23, 2013 2:33 am

all i did was some basic math .. 150/ 92

SO CC/ Jet size = new CC /x find x

So 150/92= 173/x
x is 106.1 I also did a prima pipe and they always say to go larger so i went to a 109.2 with the 2 $ drill bit

Beamster · Post by **Beamster** » Tue Apr 23, 2013 2:52 am

Throwback7R wrote:all i did was some basic math .. 150/ 92
SO CC/ Jet size = new CC /x find x
So 150/92= 173/x
x is 106.1 I also did a prima pipe and they always say to go larger so i went to a 109.2 with the 2 $ drill bit

Ok, so that would indicate that a 100 main would apply to a 58.5mm upgrade from a 125 Buddy.

Seems like a little fussing will ensue.

Throwback7R · Post by **Throwback7R** » Tue Apr 23, 2013 2:55 am

Just remember the needle on the carb does not have "Clips like other carbs. so you have to use shims and or the air/fuel mixture screw.

rick71454 · Post by **rick71454** » Thu May 02, 2013 6:15 pm

Hello BuddyLand:

I installed one of these 161CC BBK.
The stock main jet is 92.
I bought a another main jet and bored it out to be 104, since they did not have any larger than stock 92. My engine became a little sluggish at top speed.
I rebored the main jet to 112 and the engine is no longer sluggish at top speed.

Rick71454