Topic: Jet size gauge

[Scott S]

 Would this work to measure Keihin jets?

http://www.ebay.com/itm/Fuel-Air-Jet-Gauge-Tool-measure-hole-size-0-45-1-50mm-WEBER-SOLEX-DELLORTO-EMPI-/301429385413?hash=item462e9768c5&vxp=mtr

 Or, what size bits do I need to check stock 100 main and 38 pilot jets?

[70CB750]

Haha, hello from home town.

You would be beter off to get a whole set of drill bits on eebay and do the go-no-go routine to find the dimension.

[754]

Anyone know what size a Honda 105 is... Supposed to be..

[jonda500]

#100 Main jets are easy to check as they are exactly 1.00mm - just use the blunt end of a 1mm drill bit.

#38's are not so easy as a .38mm drill bit is going to be hard to find.

Watch out buying micro drill bits on feebay- I bought a set, borrowed a micrometer to check the size accuracy and they were way out - not one of them was less than .05 out and some were just multiples of the same size only longer or shorter! They were cheap and can drill tiny holes, but I still feel ripped off!

A #105 jet should be exactly 1.05mm.

[flybox1]

Honda jets marked #100, are exactly 1.00mm. 
They are not 'drilled with' 1.00mm drill bits and measure 1.00mm+

[jonda500]

Honda jets marked #100, are exactly 1.00mm.

My 1mm drill bit is a nice tight slide in fit when used like a feeler guage in my oem #100's, whereas it is a noticably less snug fit in my aftermarket #100's.

I only use the smooth end of the drill bit! - if you used a 1mm drill to drill a jet, I think the hole could end up slightly larger than 1mm. -maybe that's how cheap aftermarket jets are done...
John

[Bodi]

Drills do not make precision holes. You need to drill an undersized hole and ream to the final size for that. Good luck finding a reamers in jet hole sizes.
Precision small drills (precision drill rod diameters, they still can't make precision holes) are expensive because percentage tolerances become very small dimensional tolerances. Mic any small drill you want to use as a hole gauge.
Many of us have found aftermarket jets wanting. I don't know what causes the issues with them: even with ones where the metering hole diameter is as close to exact as I can measure, the jets perform differently to Keihin ones. The relief hole diameters and depths differ, the chamfers are different, maybe the surface finish inside the holes is different? Install a Keihin #120 replacing a Keihin #120 and the bike runs the same. Install a "Brand X" #120 and it runs differently.

[Don R]

Many holley jet sizes are drilled with the same hole size, the taper at the opening is used to adjust the flow. Bike jets could be that way too.