Idle circuit running lean after mods Need advice

[DiverRay]

My question is did you do any "bump" of the compression on the engine? Read the beginning of LarryM's post about float levels. Now understand that high octane fuel burns MUCH SLOWER that low octane. The gas you have in the tank is fine for an 11:1 compression engine. These bikes are closer to 8.5:1, and the gas will not burn in a cycle. Drain the tank, put in regular grade gas, and see what happens before you go through a lot of work. As I stated earlier, if you CAN buy ethanol free gas, that is the best thing you can run in these bikes.

[gtem]

Besides carbs (and putting pod filters always opens up a big old can of worms with CVs it seems), I was chasing an idle/pilot circuit "carb" issue that ended up being me accidentally running resistor type plugs in concert with resistor type wires. Once I swapped in non-resistor plugs (or I could have swapped wires/caps) things improved immensely.

Have you tried out a Gunson Colortune to check the color of ignition at idle? Could help point you in the right direction, just a thought. You have my sympathy, several times I've spend *months* chasing issues on Mikuni BS CV type carbs, but just as many times a rebuild goes as planned and they work perfectly. I've certainly learned a lot. It's also been enough to convince me to keep a single carb Harley around for when I feel like just going for a ride instead of pulling my hair out

[Fairlyodd45]

My question is did you do any "bump" of the compression on the engine? Read the beginning of LarryM's post about float levels. Now understand that high octane fuel burns MUCH SLOWER that low octane. The gas you have in the tank is fine for an 11:1 compression engine. These bikes are closer to 8.5:1, and the gas will not burn in a cycle. Drain the tank, put in regular grade gas, and see what happens before you go through a lot of work. As I stated earlier, if you CAN buy ethanol free gas, that is the best thing you can run in these bikes.

The engine is bored 30 over so yes by quite a bit that's why I'm running the avgas mixture because 92 doesn't cut it and no Ethanol free fuel isn't available in my area.

[Fairlyodd45]

Besides carbs (and putting pod filters always opens up a big old can of worms with CVs it seems), I was chasing an idle/pilot circuit "carb" issue that ended up being me accidentally running resistor type plugs in concert with resistor type wires. Once I swapped in non-resistor plugs (or I could have swapped wires/caps) things improved immensely.

Have you tried out a Gunson Colortune to check the color of ignition at idle? Could help point you in the right direction, just a thought. You have my sympathy, several times I've spend *months* chasing issues on Mikuni BS CV type carbs, but just as many times a rebuild goes as planned and they work perfectly. I've certainly learned a lot. It's also been enough to convince me to keep a single carb Harley around for when I feel like just going for a ride instead of pulling my hair out

I'm running Dynatek coils with solid core wires and NGK Iridium plugs. This isn't my first rodeo with this particular model and I've had issues with these carbs before and ended up swapping them out with a set of BM34s from my KZ1000 project and they worked flawlessly. I do have a color tune and I am going to check the mixture again. I'd rather tune her on a dyno but the colortune will have to do for now.

[Larrym]

I've considered setting up a jig such as this to check the fuel level in the bowls, but normally if the level is too high you would end up with fuel seeping out of the vent tees which in this case isn't happening.

Ummm.....NoPe! (◕_ゝ ◕)

I mean as far as fuel seeping outta the vent tees or even thru the carb bowl to body gasket so as to drip/run down the outside of the float bowlz. (≖ ‸ ≖ )

Just lookey at the photos posted earlier. (ʘ‿ʘ)ノ

EG: Level is too high in #3 and so's the fuel just splatters in/over thu the needle jet/emulsion tube hole when engine is running. (╯°□°)

Imma sure you set the float heights correctly. But the point is that SO.... DID... I... and the fuel levels were at the levels shown in the photos. AND the engine ran similarly/like THIS-

Only other thought I gots whiles we's all spitballin' here till you actually TEST the IRL fuel levels in the carb bowlz and see fOaR yurself where they be? (O_o)

You sure you bought/installed the right TYPE of Idle jet(s)?




Wut do the ones actually installed in the bike lookey like? The one on the right or the one on the left? ( ͝° ͜ʖ͡°)

[Fairlyodd45]

Yep going to put something together this evening to do just that. Been working on replacing the entire braking system from front to back with all new calipers, slotted rotors, and braided lines and that has been one hell of a chore. Yes I am very sure I purchased the correct pilot jets for my set of BS34-II 2H7-00 and yes I did compare them to the stock pilot jets that were in the carbs to make sure the orifices were in the correct position. My bike sounds similar with the coughing and sputtering at idle when cold but she really takes off when the engine reaches running temperature and the idle sticks at 1500 to 2000 RPMs sure makes it interesting when you are trying to downshift and stop believe me, so she's parked until I get this issue sorted out because the bike is unsafe the drive in this condition. I'll let you know what's what when I get the jig set up and test the carbs. Thanks again.

[Larrym]

Fingers crossed fOaR ya...

[Fairlyodd45]

Fingers crossed fOaR ya...

Update: After setting the carbs up on the jig you suggested I found that #2 and #3 floats where set at the proper height, but the tabs that controlled the float drop where not set correctly thus allowing the floats to drop farther down into the bowl than they were intended to from the factory. This caused the needle to jam in the seat and not allow the fuel to be shut off properly thus over filling the bowls and dumping raw fuel into the cylinders and that is what was causing the popping sound I spoke of during idle. The odd thing is I had no fuel leaking from the vents which is usually the first indication of flooding. I also noticed that after pulling the plugs #1 and #4 were firing normally without any signs of a lean mixture. However #2 and #3 plugs were washed out with absolutely no color to them at all they looked like I just pulled them out of the box! That's some bad mojo. I checked compression on both cylinders hoping that I hadn't washed out my rings and they both check out with a strong 155 PSI evenly. I checked valve clearances and everything is within specs on the low side of the scale which is right were they should be. I've since received my 6 Sigma Stage 3 jetting kit and have installed it according to their directions and I will be mounting up the carbs soon. I have some ignition tweaking to do before I head off have her dialed in on the dyno. I'll report back the results. Thanks for all of your help !

[Larrym]

The odd thing is I had no fuel leaking from the vents which is usually the first indication of flooding.

Yup. ( •_•)

The needle jet/emulsion tube hole(s) AND the Idle air needle adjustment screw hole(s) are physically located BELOW where the Vent Tee lines actually open IRL. Ain't seen gas run uphill much in my life where there's a place fOaR it to leak out down hill. (◕‿◕)

LOTS of fuel can dump thru these openings. Apparently, enuf so's the fuel never makes it up-n-over the Vent lines outlet. (☉_☉)

But folks mostily ferget, mostily, that those new and beautiful brass vent TEES mean the overflowing fuel situation means the gas can and does get dumped into the adjacent carb which SHARES that vent tee. Thats ANOTHER needle jet/emulsion tube hole and ANOTHER Idle air needle adjustment screw hole fOaR the fuel to splatter out of. (≖ ︿ ≖ )

However #2 and #3 plugs were washed out with absolutely no color to them at all they looked like I just pulled them out of the box! That's some bad mojo. I checked compression on both cylinders hoping that I hadn't washed out my rings and they both check out with a strong 155 PSI evenly.

SOOooooo happy fOaR you that you caught this and didn't just continue to run/ride in that condition. (ʘ‿ʘ)ノ

When similar situation happened to me I immediately recognized the danger(s) of that much fuel washing out the mostily perfect build-up of deposits on the piston rings and..... ruined engine. I STOPPED riding till it was fixed and ran right. ヾ(oﾟДﾟ)ﾉ


Congrats on dealing wit this scenario properly and in a timely manner. (~‾⌣‾)~

Yur in the minority on this one according to the history documented on this forum. Most get sucked down the rabbit hole of desperately replacing OTHER components/systems which AIN'T the source of the problem so's they NEVER get the bike to run like a super bike.... ¯\_(⊙_ʖ⊙)_/¯

[Fairlyodd45]

The odd thing is I had no fuel leaking from the vents which is usually the first indication of flooding.

Yup. ( •_•)

The needle jet/emulsion tube hole(s) AND the Idle air needle adjustment screw hole(s) are physically located BELOW where the Vent Tee lines actually open IRL. Ain't seen gas run uphill much in my life where there's a place fOaR it to leak out down hill. (◕‿◕)

LOTS of fuel can dump thru these openings. Apparently, enuf so's the fuel never makes it up-n-over the Vent lines outlet. (☉_☉)

But folks mostily ferget, mostily, that those new and beautiful brass vent TEES mean the overflowing fuel situation means the gas can and does get dumped into the adjacent carb which SHARES that vent tee. Thats ANOTHER needle jet/emulsion tube hole and ANOTHER Idle air needle adjustment screw hole fOaR the fuel to splatter out of. (≖ ︿ ≖ )

However #2 and #3 plugs were washed out with absolutely no color to them at all they looked like I just pulled them out of the box! That's some bad mojo. I checked compression on both cylinders hoping that I hadn't washed out my rings and they both check out with a strong 155 PSI evenly.

SOOooooo happy fOaR you that you caught this and didn't just continue to run/ride in that condition. (ʘ‿ʘ)ノ

When similar situation happened to me I immediately recognized the danger(s) of that much fuel washing out the mostily perfect build-up of deposits on the piston rings and..... ruined engine. I STOPPED riding till it was fixed and ran right. ヾ(oﾟДﾟ)ﾉ


Congrats on dealing wit this scenario properly and in a timely manner. (~‾⌣‾)~

Yur in the minority on this one according to the history documented on this forum. Most get sucked down the rabbit hole of desperately replacing OTHER components/systems which AIN'T the source of the problem so's they NEVER get the bike to run like a super bike.... ¯\_(⊙_ʖ⊙)_/¯

I installed the 6 Sigma Stage 3 Jetting Kit and adjusted those pesky float tabs on #2 and #3. After some fine tuning the bike runs amazing. I'm going to be sending her off to the dyno shortly. Thanks for all of your help.