K&L Jet Controversy

[petejw]

just had my carbies apart
the pilot jet was 40,
with no holes in the side,
i think the standard was 42.5.
its always been running rich at idle,
so i drilled 3 complete tiny holes in the side of the jets,
finally im getting a color other than black on the plugs,
still might make the holes a little bigger, but has made a
difference,
anyone else tried drilling the sides of the pilot jets,

[prometheus578]

"That T.C.! All bark and no bite."

I understand the choke lever thing. Nope... not broken off; completely different design. Unlike most levers... just where the lever starts to point upward, this thing sweeps forward into a large triangular tab, that I imagine one just slips their finger behind it, and flips it outward to activate. Seems to me that it was rusted-over chrome. Aftermarket chrome dress-up gadget? I need to steal my son's camera again.

[mro]

petejw

anyone else tried drilling the sides of the pilot jets

Some how I think your the first.

No mean feat to pop a few holes in the jet and actually have the bike run better.



mro

[prometheus578]

Drillin' for a thrillin'

PeteJW, The holes are emulsion holes, to allow air to mix with the fuel before delivery. No holes means rich mixture. Yes, drilling them would then lean it out a little. I'm of the opinion that the "no holes jets" are incorrect. But, they might be correct for Australia... having to do with fluid flow. The fuel mist would flow and spiral in a counter-clockwise fashion as you're in the southern hemisphere. Hhmmm...?

[Dan Hodges]

Re: "The results are in... and it doesn't look good!"

Originally posted by prometheus578
Incredible... Just stinkin' incredible!
Just got back from Yamaha to pick up my "confirming" pilot jet. Yamaha had discontinued the pilot jets for the E,F,SF,G,LG,and LH, so there was no way I could order one of those to see what it looks like.
What I did order was a pilot jet for an SG,H, and SH. The old part number was superceded years ago and the new number was 4G0-14142-42-AO. I was not ready for what they gave me.
I'm handed an N151.067 series pilot jet. (small bore, no side holes)
I had not expected this at all. This clears nothing up!
Until someone can find an application guide from a carb manufacturer...
Or... people here need to check their machines and see just what's in them. Obviously, they must be stock. No high speed air filter systems or custom exhausts. No evidence that a previous owner stuck his claws in there and changed anything.
I have an "E", 2-"F"'s, an "SF", and I think an "H" in the shed. I will pop the bowls tonight and report what I find.

This may or may not help,but I bought my 81 SH new and only I have touched it and mine had/has #42.5 pilots with no side holes and no plugs on top.I have one set of new pilots that I've had for about 5 years and the bag is numbered 4GO-14142-42-AO.I also have a set of #45 & 47.5 pilots from Yamaha that are of same configeration ,i.e. no side holes.I have a new rack of carbs for an 80 standard and they have #42.5 pilots that are capped with rubber plugs and the pilots have side holes,but I do not recall how many holes.It is my understanding that carbs that were equipped with capped pilots that feed from the mains had pilots with side holes and those that were not capped (81 SH),did not have the pilots with side holes.

[prometheus578]

"Since when is St. Louis in the Southern Hemisphere?"

Outstanding, Dan... This is just the kind o' info I'm looking for. Original owner with original carbs. I really didn't think these bikes used the no holer. (Note how I don't admit that I was wrong... I just state that I didn't know!) Ok... so now I know that the '81 SH used the N151.067 jet.(no holes) I can only imagine that Petejw's '81 Xs1100RH (Aus) is the same model as your '81 SH.
Now for JOHN from 23 Dec.,

On the 80-81 carbs, the pilot jets have a direct feed from the bowl, vs the main jet feed for the pilot jets of the 78-79's. The older carbs will have a screw or a plug covering the access to the pilot jet. The newer carbs will not have anything covering the access to the pilots,

John, my '80 "G" uses the newer BS34-III carbs, but DID have the rubber plug over the pilot jet hole. Is it possable that SOME '80's like the "G" used the rubber plug, but maybe the SG and later didn't?
My 'puter here is too slow and can't open the Yamaha online site, so I'll have to wait till Tuesday and use the 'puter at work to check the Yamaha Schematics to check about rubber plug re: models.

[petejw]

I had 2 push my luck,
i made the holes bigger
and now it runs/off idle like it did
b4 without the holes, like a dog,
guess im going to have 2 fill them in and redrill them
the way i did the first time.
my pilots were all 40's,
and were running rich, even with the pod filters.

[xs650mike]

What Mikuni jet sizes mean...

Saw this posted on the XS650 list and thought I'd pass it on, a cross reference for Mikuni and Dynojet.
http://roadstarclinic.com/content/view/61/96/

[pggg]

Yeah but mikuni and dynojet have got it all wrong because a 1.5mm drill bit won't slide thru a 145 mikuni.

[Dan Hodges]

All holes are not created equal

Originally posted by pggg
Yeah but mikuni and dynojet have got it all wrong because a 1.5mm drill bit won't slide thru a 145 mikuni.

Mikuni jet's are numbered according to their fuel flow,accordingly a 145 Mikuni jet will flow 145cc's per minute but a 1.45 mm bit will not go in it.Holley carburetor jet's are also measured this way and even though some are of the exact same drill size,they do not flow equally.Dyno Jet jet's are measured differently and the number stamped on them has nothing to do with their fuel flow.

[xs650mike]

Originally posted by pggg
Yeah but mikuni and dynojet have got it all wrong because a 1.5mm drill bit won't slide thru a 145 mikuni.

The chart explains this pggg, Mikuni measures there jets by rate of flow.