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I have just over 700 miles on my latest rebuild.. 96"er 11:1 with total Seal Rings, Hillside stage III heads w/compression releases, Cam 3Sun Mars EB2112A mid to upper rpm range, S&S G .031/74/105 Thunder-Jet, SE programmable ignition single fire, D&D FatCat...
I never took it over 4k yet but I think I have 2 issues here.. lean and to much timing...
1) I know my timing is a little too far advanced.. I actually thought I set it to a reserved setting of 30* max and I'm NOT using the VOES. The coil ohm readings are, primary 2.9 both front and rear and secondary 15.4k and plug wire are new, 6k ohms on the front and 2k on the rear wire..
Now when I first start it cold it takes about 30-60 second before it smoothly will idle like one cylinder is weak and am wondering if the front cylinder is causing that.. I say the front because the timing strap is very vague. Not as pronounced as the rear. The only thing I think could cause that would be the coil itself.. However ohm readings indicate not.. ???
2) Between 3000-3600 rpm getting on it it feels like the clutch is slipping a little but what I really think is there's a flat spot fuel wise. My Wego III says I'm around 14.1 so I think I'm going to increase the main jet from 74 to a 76 and maybe even decrease the size of the external air bleed for the main jet from a mikuni 160 to a 140 to allow the main to come in a little sooner...
Note: there is no pepper species on the plug porcelain indicating no detonation and I'll make 1 change at a time to see if it does indeed make a difference..
One thing I would like to add is that lean is mean but not to the point of destruction...
Last edited by 98hotrodfatboy; Oct 10, 2021 at 09:27 AM.
Today's gas doesn't do justice on color reading the plugs but the timing heat mark is accurate and your gambling. Since you are chickensh*t to open it up your on the low and main jet since the Thunderjet is helping with WOT.
2 theory's, add some fuel cooling the cylinder and rechecking the timing strap heat mark which is safe or pull some timing which brings the the strap heat mark back plus richen's afr's like we spoke of EFI tuning. Pulling timing looses power and adding fuel can do the same, I'm more of a safety guy with leaving some ponies on the table but after making long runs with new bikes year after year with a big cube, putting more gas in the tank hasn't been a big issue.
Make sure your give those bigger engines what they want, different breed.
Just me personally, I've never been able to get what I felt was a good read with NGKs, no matter how I did it. Always had more reliable readings with RN12YC. But please, let's all not get into a pizzing contest over plug brands
That said, yeah definitely looks lean on both and timed high, but only on one plug. (?) That's one inconsistency I always get with the BPRs. And, reading the ground strap (for me) was always best done on a warmed up engine, new plugs and then run 15-20 miles at consistent road speed. Running them for several days, more miles and especially with many cold starts seemed to always make the mark inconsistent or disappear totally. The "timing mark" on the ground strap is always bit of puzzle. That is, it's the heat of the combustion chamber created by the timing that makes the mark.
Depending on which module you're running without VOES and not going over 4k rpm, on curve setting 4 (30 total timing) - if it's D2ki it's never gotten much over 25 BTC at 4k and an Ultima would put you at full timing at 3k rpm. Timing affects AFR in relation to jetting. So I'd suggest bumping up the jetting while ignoring the Wego and get that looking better on the old plugs then do another ground strap read on new plugs and see where it's at. When you get that looking close, then do your Wego thing for the fine tune.
Like Hess said - they tend to pull better on the lean side.. until they don't.
Bagger was posting while I was still typing, but I 'think" he was saying the same thing as I was getting at....
Originally Posted by 1997bagger
Today's gas doesn't do justice on color reading the plugs but the timing heat mark is accurate and your gambling. Since you are chickensh*t to open it up your on the low and main jet since the Thunderjet is helping with WOT.
2 theory's, add some fuel cooling the cylinder and rechecking the timing strap heat mark which is safe or pull some timing which brings the the strap heat mark back plus richen's afr's like we spoke of EFI tuning. Pulling timing looses power and adding fuel can do the same, I'm more of a safety guy with leaving some ponies on the table but after making long runs with new bikes year after year with a big cube, putting more gas in the tank hasn't been a big issue.
Make sure your give those bigger engines what they want, different breed.
Yeah fully aware of today's fuels.. Did you ever tune with E85? I'm thinking about it.. The benefits of a cooler running motor with more timing really interest me.. Sure a tank of gas will only yield a 100 miles but I bet you could feel the difference..
I haven't taken it over 4k yet because what Johnjz said about the break-in.. He rebalanced the crank for me because of the vibes I was getting and couldn't keep a main seal in the motor.. All that is good now.
And Yeah you asked... Twice.. Jim.. lol.. 4" from the front exhaust port.
I did pull the timing 5*. And I fattened up the intermediate to a .032 but that might have been a mistake.. with the .031 I was 1 and 1/8 turns out.. probably should have left that alone.. But did up the main as well to a .076 but now it's raining... So no testing.. I did leave the air bleed alone..
I did start it and it was a little hard starting.. I think I was close to flooding it (too many pumps on the accelerator pump).. Head temps got up 200* and fine tuned the intermediate. I am at 1.5 turns out and honestly this is the best it's idled since the rebuild.. We'lll see what the future brings.. Maybe I'll even take it up to 6k.. I did put a Barnett Carbon fiber clutch pack in it so it should handle the power no problem.. Just need to wait for better weather...
I have just over 700 miles on my latest rebuild.. 96"er 11:1 with total Seal Rings, Hillside stage III heads w/compression releases, Cam 3Sun Mars EB2112A mid to upper rpm range, S&S G .031/74/105 Thunder-Jet, SE programmable ignition single fire, D&D FatCat...
I never took it over 4k yet but I think I have 2 issues here.. lean and to much timing...
1) I know my timing is a little too far advanced.. I actually thought I set it to a reserved setting of 30* max and I'm NOT using the VOES. The coil ohm readings are, primary 2.9 both front and rear and secondary 15.4k and plug wire are new, 6k ohms on the front and 2k on the rear wire..
Now when I first start it cold it takes about 30-60 second before it smoothly will idle like one cylinder is weak and am wondering if the front cylinder is causing that.. I say the front because the timing strap is very vague. Not as pronounced as the rear. The only thing I think could cause that would be the coil itself.. However ohm readings indicate not.. ???
2) Between 3000-3600 rpm getting on it it feels like the clutch is slipping a little but what I really think is there's a flat spot fuel wise. My Wego III says I'm around 14.1 so I think I'm going to increase the main jet from 74 to a 76 and maybe even decrease the size of the external air bleed for the main jet from a mikuni 160 to a 140 to allow the main to come in a little sooner...
Note: there is no pepper species on the plug porcelain indicating no detonation and I'll make 1 change at a time to see if it does indeed make a difference..
One thing I would like to add is that lean is mean but not to the point of destruction...
Originally Posted by t150vej
Depending on which module you're running without VOES and not going over 4k rpm, on curve setting 4 (30 total timing) - if it's D2ki it's never gotten much over 25 BTC at 4k and an Ultima would put you at full timing at 3k rpm. Timing affects AFR in relation to jetting. So I'd suggest bumping up the jetting while ignoring the Wego and get that looking better on the old plugs then do another ground strap read on new plugs and see where it's at. When you get that looking close, then do your Wego thing for the fine tuning
That simply is not true..
And just so you know Dynatek made the SE ignition module for the MOCO with the same adjustable curves..
I did start it and it was a little hard starting.. I think I was close to flooding it (too many pumps on the accelerator pump).. Head temps got up 200* and fine tuned the intermediate. I am at 1.5 turns out and honestly this is the best it's idled since the rebuild.. We'lll see what the future brings.. Maybe I'll even take it up to 6k.. I did put a Barnett Carbon fiber clutch pack in it so it should handle the power no problem.. Just need to wait for better weather...
Peer pressure lol.
I know nothing about E85, young tech at work runs it in a EFI forced induction Mustang on the street but he mentioned fuel rate is ramped up. He said E85 will allow more cylinder pressure and can turn up the ratio on the supercharger.
Bigger cubes can handle 12.5 -12.8 idle, cruise and WOT without noticing any sluggish street manors, they can eat fuel. Tried to go up to 13.8 at a idle, about spit the carb off the engine, gave it what it wanted to make it happy but some of it was reversion thru the 3" Dragula slowing down leaning the cylinder, watched it on the Wego.
Just be careful thinking about squeezing every inch of power out of it, bigger cubes can use a different set of rules
Thanks, never had an issue running 13.8-14.1... for cruise and 13.2-13.8 on moderate to heavy acceleration..
The E85 thing would only be an experiment.. I do know my starting point would be the current timing and the jetting would go up from .031/.076 to .040/.098. I've been told it's a 30% increase for starters with a target AFR of 9.13:1 which is the equivalent of 13.8:1 gasoline.. But like I said just an experiment.. if it would be permanent I would have to get 6 gl tanks at the minimum...
I know nothing about E85, young tech at work runs it in a EFI forced induction Mustang on the street but he mentioned fuel rate is ramped up. He said E85 will allow more cylinder pressure and can turn up the ratio on the supercharger.
Bigger cubes can handle 12.5 -12.8 idle, cruise and WOT without noticing any sluggish street manors, they can eat fuel. Tried to go up to 13.8 at a idle, about spit the carb off the engine, gave it what it wanted to make it happy but some of it was reversion thru the 3" Dragula slowing down leaning the cylinder, watched it on the Wego.
Just be careful thinking about squeezing every inch of power out of it, bigger cubes can use a different set of rules
I reread this today and must say that it's Absolutely true..
With the bigger intermediate .032 the sweet spot is at 13.2..
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Plugs do tell a story..
