Topic: Problem solved?

[Magilla]

Back in the spring I bought a stock 76 K6 CB750. It has always run rich.  I've cleaned the carbs and reset them but it still ran rich.   The jets said 105 and 40. But I could never lean it out.  Today I gave up and brought it to a mechanic.  He just called me to let me know that the jets were drilled out.  They were drilled to 110 and 48. Sheesh no wonder it ran rich.

[lucky]

Back in the spring I bought a stock 76 K6 CB750. It has always run rich.  I've cleaned the carbs and reset them but it still ran rich.   The jets said 105 and 40. But I could never lean it out.  Today I gave up and brought it to a mechanic.  He just called me to let me know that the jets were drilled out.  They were drilled to 110 and 48. Sheesh no wonder it ran rich.

Now there is a good mechanic!! He actually measured parts and looked at the details.

BTW...ANYONE that drills out a jet should remove the numbers from the drilled jet!
Also if you have a electric engraver finish the job and put on the drill size.

This just cost Magilla frustration time and money.

[Magilla]

It cost me a summer of riding too.

[Dimitri13]

Hot damn! That is one good mechanic. Since we're on the subject, how is one able to measure the jet size? I never really understood what the numbers meant.

[Frostyboy]

Hot damn! That is one good mechanic. Since we're on the subject, how is one able to measure the jet size? I never really understood what the numbers meant.

Back in the days when I worked on a dyno, it was a matter of go/no go with a set of drill bits. Increments of diameter increase varied depending on what set of drills you bought. Here's an example of a set on ebay.
http://www.ebay.com/itm/JET-DRILL-SET-WEBER-CARBURETORS-DELLORTO-WITH-PIN-VISE-/280932387076?pt=Motors_Car_Truck_Parts_Accessories&hash=item4168e00904&vxp=mtr

[dave500]

yeah its not unusual to find a 265 hemi with six different jets if its been dyno tuned properly with webers.

[Magilla]

The go, no go test with drill bits is exactly how this mechanic found the problem.  This guy only works on 69-78 CB750s and 550s.  Nothing else.  I'm guessing if your that specialized it helps you to figure out most problems even before you open things up.

[Magilla]

As it turns out the mechanic that fixed my problem is a member of this forum.  So I would like to give him the well deserved credit.  His login on this forum is workingguitar.

If your in the Mass/RI area and need a mechanic, you should look him up.

[lucky]

Hot damn! That is one good mechanic. Since we're on the subject, how is one able to measure the jet size? I never really understood what the numbers meant.

The jet sizes on Keihins are in mm's So a 110 main jet is 1.10 milli meters.
Multiply 1.10 X 25.4=.043 thousandths.

[lucky]

Good job workingguitar!

[scottly]

Hot damn! That is one good mechanic. Since we're on the subject, how is one able to measure the jet size? I never really understood what the numbers meant.

The jet sizes on Keihins are in mm's So a 110 main jet is 1.10 milli meters.
Multiply 1.10 X 25.4=.043 thousandths.

I think you need a new calculator, Lucky. According to mine, 1.10 X 25.4 = 27.94.
To convert from mm to inch, multiply the mm size by .03937.

[lucky]

Hot damn! That is one good mechanic. Since we're on the subject, how is one able to measure the jet size? I never really understood what the numbers meant.

The jet sizes on Keihins are in mm's So a 110 main jet is 1.10 milli meters.
Multiply 1.10 X 25.4=.043 thousandths.

I think you need a new calculator, Lucky. According to mine, 1.10 X 25.4 = 27.94.
To convert from mm to inch, multiply the mm size by .03937.

I actually just type in inches=mm into Google and it does the conversion for me and since my math is bad I count on them to give me the right answer.
Yes 25.4 =1mm (.03937 )

I should have stated it better.

[scottly]

I actually just type in inches=mm into Google and it does the conversion for me and since my math is bad I count on them to give me the right answer.
Yes 25.4 =1mm (.03937 )

I should have stated it better.

Wrong again. 25.4mm = 1 inch.

[lucky]

I actually just type in inches=mm into Google and it does the conversion for me and since my math is bad I count on them to give me the right answer.
Yes 25.4 =1mm (.03937 )

I should have stated it better.

Wrong again. 25.4mm = 1 inch.

Yes you are correct.

[lucky]

I should have said devide not multiply. The size of the hole is .043 thousandths.
I gave the correct size, I just did not state the equation properly.

I will be more careful in the future.

I just use the automatic calculator to make sure I get the right answer.

Now I have apologized twice.

[Magilla]

Anyway you do the math it still comes out to to much gas

[HondanutRider]

I should have said devide not multiply. The size of the hole is .043 thousandths.
I gave the correct size, I just did not state the equation properly.

I will be more careful in the future.

I just use the automatic calculator to make sure I get the right answer.

Now I have apologized twice.

Let's go for THREE! 

If as you say: "The jet sizes on Keihins are in mm's" - wouldn't that mean a 110 main jet was 110 mm in size?   You went on to say: "So a 110 main jet is 1.10 milli meters.?