Jet Bits

[5twins]

I've mentioned in the past that I custom grind 1/4" insert bits so they perfectly fit the jets. It's difficult, if not impossible, to find an off-the-shelf American screwdriver that fits well. This is probably due in part to the jets being metric and having metric sized screwdriver slots. In the past, I've always made do with insert bits I had on hand. These worked for the most part but I never really had any big enough to make a decent large round main bit. So, I went shopping for more suitable bits and managed to find just what I needed. For the large round mains, I found these quite large #14-16 sized bits .....

For the small round mains, I found these power bits. I liked the way they are necked down by the blade. This would allow them to be inserted down into the BS38 float bowl without having to grind the hex off the sides. I had to do this on bits I had previously used .....

For the pilot jets, you actually can get a metric bit that is very close to fitting. Again, a 2" long power bit style was chosen so it could reach down in and get at the BS34 pilot jets .....

For grinding the bits, I used my nice little HF portable 3" grinder. This is great for grinding little things. It has a fine grinding wheel on one side and a polishing wheel (great for knocking the grinding burrs off) on the other side .....

I managed to find a pack of reasonably priced metric bits for the pilots on Amazon .....

As I mentioned, they fit pretty good to begin with but a little grinding made them even better .....

The small round main bits needed to be narrowed slightly (to fit down into the BS38 bowl) and shortened a little bit .....

The large bits for the large round mains required the same treatment. They had to be narrowed slightly to match the jet width and shortened a little to get a good fit .....

And finally, here's some links. The 4mm bits for pilots on Amazon .....

https://www.amazon.com/dp/B07T3635CX?psc=1&ref=ppx_yo2_dt_b_product_details

..... and the larger bits on eBay .....

https://www.ebay.com/itm/332768329021?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m2749.l2649

https://www.ebay.com/itm/401572972334?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m2749.l2649

 

[gggGary]

chainsaw carb screwdrivers fit many jets...
But no fun in that I guess.

 

[5twins]

So, let's try these out. I had a couple pretty ratty float bowls from a junk set of carbs. One pilot was pretty crusty, the other not so much. Luckily, neither looked like it had ever been messed with. The screwdriver slots in both looked pristine .....

The main jet was another story, lol. It was really crusty and had been fooled with .....

To start, they were given a PB Blaster over night soak .....

Then, a suitable means of holding the bowl steady was rigged up, heat was applied, and one of my "new" bits was applied using a T-handle holder ......

And the results? ..... Success!! .....

 

[gggGary]

A light rap on the end of the driver with a hammer seems to be a good start to jet removal.