BLSully
Been Around the Block
Alright folks. The magic bit was 2.0 slides. It's not perfect by any stretch but I'm going to wait to do fine-tuning til I have my air filters and fix a few other things on the bike (tires, chain/sprockets, steering head bearings), but then I'm going to ride the hell out of it and see what spots need to be "filled in", but without a doubt it's making more power now than it ever had on those CV carbs.
Instead of typing it all out again, I'm just going to post a link to my Google Document of running notes (and copy the content here for those who don't want to click off-site links)
https://docs.google.com/document/d/1YJNV7SK6QT4QijFAXL--f6dReBW3g5OP-XoRZzr4bwE/edit?usp=sharing
Configuration 1
Carb Setup
Pilot: 35
Main: 170
Needle Jet: P-6
Needle: 6F5 (middle clip)
Slide: 3.0
Air Jet: 2.0
Visual sync only
Running Notes
This configuration runs, but has essentially nothing in the 1/8-3/4 range. Idle is good, with a slight hang once the engine is fully warm.
Carb Setup Notes following are incremental changes from above
Configuration 2
Carb Setup
Needle: 6F5 (4th from top, 5th from top)
Running Notes
Idle seems to have suffered even though the only change was the needle position. Is it possible it’s feeding some fuel even at idle? Midrange is MUCH improved, however. I’d call it “rideable”, though still a bit flat. Definitely goes WAY lean if you crack the throttle too hard. A smooth application of throttle will pull it through the flat spots and top end is reasonable. Feel like 180 mains might not hurt. Constant rate riding in the ~3k range shows no signs of surge...chain has some snatch to it..needs to be replaced.
Configuration 3
Carb Setup
Needle: 6F5 (middle clip)
Needle Jet: Q-6 (What came with the carbs, used/ebay)
Running Notes
This is actually the best configuration so far in terms of power. Idle needs enrichment when cold, but will idle w/o enrichment pretty quickly ~45-50 degrees ambient. Throttle response is poor until it’s run a couple of minutes though.
I’ve been running the bike on this configuration a few days now and I feel like it has a slight surge at constant rate riding (30-50mph), but with the chain being in such terrible shape, I suppose it could be that as well. Sorta hard to tell what is chain snatch and what might be a tiny bit of surging.
After idling for 5 minutes, plugs are pretty black (not wet), but tip and electrode aren’t coated...so rich, but maybe not TOO rich? Leaning out idle air screws even 1/4 turn causes idle to hang ~3k, though so .... ????
I’m going to get the 2.0 slides in to see if that helps the midrange whenever they show up in the mail. I suspect the midrange and top-end is going to go pretty rich based on the fact that other configurations around the internet never use a needle jet in the Q range, let alone a Q-6, so might need to go back to the P-6 needle jets, or maybe just drop the needle? We shall see...
Configuration 4
Carb Setup
Needle: 6F5 (4th and 5th clip)
Needle Jet: P-6 159
“Wire” idle sync, then “$1.55 carb balancer” http://www.powerchutes.com/manometer.asp
Running Notes
(Excerpt from email)
Last night I changed the N/J back to the P-6. Left the needles on 4th clip. This combination idled well, but has a severe stumble at anything over 1/8 (maybe a hair less) throttle. Just faceplants. However, I rode it around the block a few times to warm up the motor and it /does/ low rpm steady state even better than the Q-6 combo. Any hint of surge is gone in the 2-3.5k range. Aside from the horribly stretched chain on there snatching a bit, riding along ~30-35mph in 3rd through 6th gear it was happy as could be.
Took it back to the house and went to full rich clip on the needle. This is a significant improvement. There's still a gigantic hole above 1/8th throttle, but can be coaxed through it, and once the engine is spinning, the throttle can be opened up and it still pulls well once the RPMs are up at full throttle. Guessing this is just the side effect of giant carb throat and little motor. Again I'm noticing the idle gets a bit "wet" sounding though when I pull the needles all the way up. The idle rpm drops by ~200 I'd guess, but the interesting thing is that even though it's barely ticking over fast enough to stay running, a small application of throttle brings instantaneous response. However, holding that small throttle opening, while it responds so nicely coming off idle, the rpms will slowly drop... I think that means it's going WAY rich just off idle? This problem goes away as I drop the needle, but then of course the mid-throttle positions tank. (Oh the joys of balancing the various circuits Honestly, I'm still having fun... It gives my mind something more interesting to work on than the daily grind)
Thankfully my 2.0 slides came in this morning (along with a couple other pilots and 6F4 needles). It looks like according to the Mikuni charts, the 6F4's taper begins significantly earlier in it's length, so that should help with the super lean lower midrange I'm thinking. Also the 2.0 slides should affect that a lot as well.
I don't want to munge my research by changing multiple things at once... what would be your recommendation on what to try first? Would going from the 6F5 to 6F4 needles or changing from the 3.0 to 2.0 slides make more sense based on what I've told you about the current condition of the tune? It seems to me the slide change more directly address the throttle position that is currently most problematic (1/8 to 1/2) with not enough air velocity/vacuum at moderate throttle openings.
Configuration 5
Carb Setup
Slide: 2.0
Running Notes
Well, that just about did it. There is power everywhere now. It /has/ developed a slight surge so I’m going to drop the needles one clip but I’m wondering if maybe I’ll need a shim as it’s so close I wonder if 1 clip will be too much.
I feel like the top end could probably be richer, maybe get the next few sizes of main jets and see if that changes anything in the top end.
Instead of typing it all out again, I'm just going to post a link to my Google Document of running notes (and copy the content here for those who don't want to click off-site links)
https://docs.google.com/document/d/1YJNV7SK6QT4QijFAXL--f6dReBW3g5OP-XoRZzr4bwE/edit?usp=sharing
Configuration 1
Carb Setup
Pilot: 35
Main: 170
Needle Jet: P-6
Needle: 6F5 (middle clip)
Slide: 3.0
Air Jet: 2.0
Visual sync only
Running Notes
This configuration runs, but has essentially nothing in the 1/8-3/4 range. Idle is good, with a slight hang once the engine is fully warm.
Carb Setup Notes following are incremental changes from above
Configuration 2
Carb Setup
Needle: 6F5 (4th from top, 5th from top)
Running Notes
Idle seems to have suffered even though the only change was the needle position. Is it possible it’s feeding some fuel even at idle? Midrange is MUCH improved, however. I’d call it “rideable”, though still a bit flat. Definitely goes WAY lean if you crack the throttle too hard. A smooth application of throttle will pull it through the flat spots and top end is reasonable. Feel like 180 mains might not hurt. Constant rate riding in the ~3k range shows no signs of surge...chain has some snatch to it..needs to be replaced.
Configuration 3
Carb Setup
Needle: 6F5 (middle clip)
Needle Jet: Q-6 (What came with the carbs, used/ebay)
Running Notes
This is actually the best configuration so far in terms of power. Idle needs enrichment when cold, but will idle w/o enrichment pretty quickly ~45-50 degrees ambient. Throttle response is poor until it’s run a couple of minutes though.
I’ve been running the bike on this configuration a few days now and I feel like it has a slight surge at constant rate riding (30-50mph), but with the chain being in such terrible shape, I suppose it could be that as well. Sorta hard to tell what is chain snatch and what might be a tiny bit of surging.
After idling for 5 minutes, plugs are pretty black (not wet), but tip and electrode aren’t coated...so rich, but maybe not TOO rich? Leaning out idle air screws even 1/4 turn causes idle to hang ~3k, though so .... ????
I’m going to get the 2.0 slides in to see if that helps the midrange whenever they show up in the mail. I suspect the midrange and top-end is going to go pretty rich based on the fact that other configurations around the internet never use a needle jet in the Q range, let alone a Q-6, so might need to go back to the P-6 needle jets, or maybe just drop the needle? We shall see...
Configuration 4
Carb Setup
Needle: 6F5 (4th and 5th clip)
Needle Jet: P-6 159
“Wire” idle sync, then “$1.55 carb balancer” http://www.powerchutes.com/manometer.asp
Running Notes
(Excerpt from email)
Last night I changed the N/J back to the P-6. Left the needles on 4th clip. This combination idled well, but has a severe stumble at anything over 1/8 (maybe a hair less) throttle. Just faceplants. However, I rode it around the block a few times to warm up the motor and it /does/ low rpm steady state even better than the Q-6 combo. Any hint of surge is gone in the 2-3.5k range. Aside from the horribly stretched chain on there snatching a bit, riding along ~30-35mph in 3rd through 6th gear it was happy as could be.
Took it back to the house and went to full rich clip on the needle. This is a significant improvement. There's still a gigantic hole above 1/8th throttle, but can be coaxed through it, and once the engine is spinning, the throttle can be opened up and it still pulls well once the RPMs are up at full throttle. Guessing this is just the side effect of giant carb throat and little motor. Again I'm noticing the idle gets a bit "wet" sounding though when I pull the needles all the way up. The idle rpm drops by ~200 I'd guess, but the interesting thing is that even though it's barely ticking over fast enough to stay running, a small application of throttle brings instantaneous response. However, holding that small throttle opening, while it responds so nicely coming off idle, the rpms will slowly drop... I think that means it's going WAY rich just off idle? This problem goes away as I drop the needle, but then of course the mid-throttle positions tank. (Oh the joys of balancing the various circuits Honestly, I'm still having fun... It gives my mind something more interesting to work on than the daily grind)
Thankfully my 2.0 slides came in this morning (along with a couple other pilots and 6F4 needles). It looks like according to the Mikuni charts, the 6F4's taper begins significantly earlier in it's length, so that should help with the super lean lower midrange I'm thinking. Also the 2.0 slides should affect that a lot as well.
I don't want to munge my research by changing multiple things at once... what would be your recommendation on what to try first? Would going from the 6F5 to 6F4 needles or changing from the 3.0 to 2.0 slides make more sense based on what I've told you about the current condition of the tune? It seems to me the slide change more directly address the throttle position that is currently most problematic (1/8 to 1/2) with not enough air velocity/vacuum at moderate throttle openings.
Configuration 5
Carb Setup
Slide: 2.0
Running Notes
Well, that just about did it. There is power everywhere now. It /has/ developed a slight surge so I’m going to drop the needles one clip but I’m wondering if maybe I’ll need a shim as it’s so close I wonder if 1 clip will be too much.
I feel like the top end could probably be richer, maybe get the next few sizes of main jets and see if that changes anything in the top end.