plug reading at 600 miles

deadchef

deadchef

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at the beginning of the season i changed my plugs from the ngk iridiums to autolite 63's. also changed the jets from 45 pilot & 140 main to 42.5 pilot and 135 main. iridiums had obvious signs of running rich.

i have bs34's
canadian needles set on middle clip
uni's
emgo shorty mufflers
pamco
pma
good battery
high output coil
mix screw set at 3 turns out
timing good and advancer works appropriately
premium gas (although 10% ethanol- no choice around here :mad:)


the top plug is the left and bottom is the right.
4214636E_zps2dea4437.jpg


pics aren't the best. little pinkish color which i've heard is attributed by additives in gas but not sure. couple tiny tiny black flecks on porcelain. i don't drive the bike too hard and haven't really went on any longer rides than 50 miles. nothing on the freeway.

bike runs great. great response all around, no dead spots or sputter. doesn't really 'pop' on deceleration but 'bubs' a little. i'm typically getting around 39mpg which seems a little low.

thoughts? too lean? too rich? just right? start using rocket fuel? :shrug:
 
At 600mi I'd expect them to be darker than that. The black flecks indicate knocking. Adds up to too lean. Where are the rest of the plugs :)
 
what? you don't use an angle grinder to take out your plugs? lol

i think i'm going to up the pilot one size and check after another 500 miles.
 
The thing with the Canadian needles is there's really no documentation on where they were actually set from the factory. Set in their middle (#3) slot, they are 2mm shorter than the fixed originals which is a big difference. I would try them in the #2 slot with 45 pilots.

Your left plug looks a tad rich, the right darn near perfect. The difference may be due to mismatched float levels, all else being the same. You also made no mention as to whether you're using the Canadian needle jets along with the needles. You should be. Those two components are made to be run as a matched set.
 
5twins said:
Your left plug looks a tad rich, the right darn near perfect.
Click to expand...

They both look lean as hell considering they have 600 mi. The black flecks he describes are from knock. The plugs might look ok if they were new and he had just done a throttle chop, except for the specks. They should be a lot darker after 600 mi.

The 39 mpg I can't explain. Maybe a gas leak :)
 
Just fyi on the pinkish color. Gasoline is color-coded (dye additive) for identification. If memory serves:

Red - Auto 80-100 octane
Blue - Avgas, 100 LL (low lead)
Green - Avgas, 130 octane
Purple - Avgas, 145 octane (used on WW2 birds)
 
i'm wondering if i should even continue to dick around with the canadian needles/jets. i have perfectly fine stock ones that could go back in. i really want to up my mpg and i'm kinda stumped on why it would be so low, especially if the plugs indicate a lean condition. just an fyi, these carbs have been completely disassembled and cleaned, new diaphragms, new carb boots, new oem throttle shaft seals, floats are set properly, new manual petcock, new fuel lines. bike does run great right now, no hesitation whatsoever at any point and no smoke out the exhaust.
 
Heads up, here. The smoke ring at the base of the insulator won't tell you much that's useful on a plug that's been used in gentle mixed riding. The smoke ring is read to get an indication of MJ size after a full-throttle ignition chop. Lean fuel mixture is not the only cause of detonation. Since the dark flecks occur on both plugs I'd be inclined to have another look at timing--if in fact they're aluminum flecks, a conclusion I wouldn't jump to from a photo. Re. the difference in mixture, look for vacuum leaks and check float levels. Good luck.
 
Hi Deadchef, this is an interesting thread as I am in a similar boat contemplating ordering Canadian needles.

I have:

BS34 carbs completely rebuilt with new diaphragms
45 pilot Jet
137.5 main Jet
Floats set at 22mm
Mixture 2 3/4 out
Foam Unipod filters
Straight through pipes with inserted baffles
Boyer bransden ignition
PMA
New battery
Two teeth down on the rear sproicket to 31
Returning 49 MPG

The bike is running great apart from at WOT in the upper rev range where i get stuttering. If i go up main jets it gets worse. Back at 132.5 it is fine but runs lean and a little hot. The best compromise is with the 137.5. So, i was going to buy the Canadian needles to drop the needle to see if that will get rid of the stumble. Im wondering if float height needs to be increased / decreased according to main jet size?

I think yours isnt far away - 39 MPG is a little low but I suppose it will depend on riding style???
 
Needle position will have a big effect on gas mileage. It controls your midrange and that's where you spend most of your time running. Running too rich here can really kill the mileage. As I said, try the #2 needle slot, that should help. It might be too lean with stock mains and pilots but should be good with larger ones. You have to remember that when you increase the mains and pilots, they bleed over into the midrange and make it richer too. That's why an adjustable needle is so helpful when re-jetting carbs. You can compensate for this. The stock BS34s with their non-adjustable needles can usually be re-jetted without problems because the midrange was a tad too lean to begin with. The bleed-over from larger mains and pilots just makes it right.
 
5twins said:
Needle position will have a big effect on gas mileage. It controls your midrange and that's where you spend most of your time running. Running too rich here can really kill the mileage. As I said, try the #2 needle slot, that should help. It might be too lean with stock mains and pilots but should be good with larger ones. You have to remember that when you increase the mains and pilots, they bleed over into the midrange and make it richer too. That's why an adjustable needle is so helpful when re-jetting carbs. You can compensate for this. The stock BS34s with their non-adjustable needles can usually be re-jetted without problems because the midrange was a tad too lean to begin with. The bleed-over from larger mains and pilots just makes it right.
Click to expand...

sorry, i should know this. if i'm looking at the needle with the point of the needle pointing to the earth, the #2 slot is the second one up from the point, correct? that would make the needle higher up in the jet making it richer correct?

currently stock pilot and +1 size (135) on the mains and middle (#3) slot on the needle.

my plan is to go up a one size on the pilot (45), keep the (135) main and change the needle position to #2 (slightly richer).
 
No, you have it opposite. Etch this into your mind, in fact, download the pic and save it. Repeat after me, like a "mantra" .....

NeedleSlots.jpg


No, you don't want to lower the clip, that will raise the needle and make the midrange richer. That will hurt your fuel mileage even more. Place the clip in the #2 slot (from the top) along with larger mains AND pilots. Being 2mm shorter than the original needle, the Canadian one is too rich to be running in the #4 slot.
 
Deadchef, an old memory just percolated to the surface. Re: Your dark speckles on the plugs. Back in the day, we scheduled 500 and 1000 mile service inspection/tune-ups for all new sales. Part of the service included NEW plugs, per H*nda requirements. Why? During break-in and ring seating, tiny metal particles would often appear on plugs, and H*nda didn't want to chance customer dissatifaction from brand-new stumbling bikes. I would often save the old plugs for blasting later, but some stuttered anyway.
 

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