Has anyone else ran in to this problem?

[Guest]

I have several examples in my parts box.
These are from two sets of jets pulled from stock GS Mikuni carbs.
If I had drilled them over-sized, I mark them so as to not be confused in future repairs.
Although these don't appear to be tampered with, they are incredibly different!

For reference, I use index drill bits or numbered drill bits to measure them.
Torch tip cleaners are also labeled as to decimal sizes, BTW.



Hopefully, you can see the Mikuni markings clearly...



One set measures .043" and the other measures in at .055"




Just something to think about when doing jet changes. Always check!


Daniel

[duaneage]

I'm thinking the smaller holed one is corroded.

[49er]

My money is on the larger one being drilled..............you can see the marks on its flange where it's been held in a vise while it was drilled.

I never trust jet markings for this reason..............they sometimes make marking errors at the factory too. Most are drilled though. I have done so in the past, often soldering the holes once I have gone too big and then re-drilling to the previous size.

Jets are that cheap and readily available now, that its no longer worth the shagging around with drills. But they are still an excellent means of establishing a jets exact size.

[hampshirehog]

It's not uncommon at all over here.

[AJ]

I've drilled many jets, especially pilot jets, which were made way too lean in the 1980s and 1990s. Never had to hold them in a vice to drill them.

If I had drilled them over-sized, I mark them so as to not be confused in future repairs.

Never thought of marking them. What do you do, Dan? A scratch or maybe a small punch mark?

[7981GS]

I've drilled many jets, especially pilot jets, which were made way too lean in the 1980s and 1990s. Never had to hold them in a vice to drill them.


Never thought of marking them. What do you do, Dan? A scratch or maybe a small punch mark?

Just take a file and run it over the stamped numbers rendering them illegible.
A red light goes off and you KNOW to check (measure) them.
I have been doing the same with Holley, GM and Ford carb jets forever.

Daniel

[Zafe]

I drilled out my #80 mains with a dremel and a 3/32" bit if i remember correctly, Did the trick for now, Will most likeley be purchasing the appropriate jets down the line.

[AJ]

Just take a file and run it over the stamped numbers rendering them illegible.
A red light goes off and you KNOW to check (measure) them.
I have been doing the same with Holley, GM and Ford carb jets forever.

Daniel

Good idea!

[1948man]

115 mains on my Gl measured 160