I've been working with my local shop to dyno tune my '78 XL. Have to say, am not real happy or impressed with the results. The bike:
Mostly stock 1978 XLH
S&S Super B with Thunderjet, and S&S and air cleaner
MAC dual shorty exhaust
Stock P cams
I don't know what is supposed to be typical for a 70s stage 1 Ironhead, but does 38HP sound about right to you guys? I was thinking it should be up in the low 50s or so, but maybe that is just wishful thinking.
What really through me was the A/F ratio plot. Down blow 3500, it was getting up above 15:1. That ain't good for old iron with no-quench hemi heads, is it?
I'll post the dyno chart when I can scan it. Not allowed to post in the AFR zone, they did not record the results the way that I had asked.
-JW
I think low to mid 50's is right where it should be. What was the AFR above 3500 rpm on the main jet? 15:1 on the intermediate jet, I think you need to go to a one size larger jet to richen it up a little. How many turns out is your idle mixture screw?
Linky to some IH dyno runs and discussion:
http://xlforum.net/forums/showthread.php?t=951664&page=2
Yeah Gup, that was basically what I was expecting to see. Not the case, so it looks like I have a lot of work to do. And the starting point is, find somebody that actually knows how to tune an Ironhead! I might know a guy down in San Jose, he loves Ironheads, but is a bit of a pain in the ass to deal with. As long as the results speak for themselves, probably worth the pain.
Dyno sheet attached, sorry for the lousy picture qualtiy. I doctored it the best I could, the orignal was quite pale.
I think the number one concern is how the torque starts off OK, then quickly falls past 3000. And thus, so too will the HP. Real lean below 3500, but OK after that. So where is the power going?
-JW
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On the one run it looks like the main jet is too rich, maybe go down one size or turn off the Thunderjet. Hows the engine health? Done a cranking compression test lately? What kind of baffles do the MAC mufflers have in them? You're a pretty savvy guy, I would think you could tune it yourself. The S&S Super B manual and Mikuni HS40 manual have some good tuning info in them.
*edit* Are you running E10 fuel like we have to use in the midwest?
Actually, I think I'm going to start with going back to a CV. Yes the Super B is stylish, but sure comes with some baggage. I'm not sure what baffles are in those MAC mufflers, they're not exactly quiet so likely not that restrictive. So the journey begins...
-JW
The pipes don't look bad on the dyno. No ~3000 rpm dip
++ on the CV much better for the street.
Best is a Mikuni VM39 with a branch kit.
(no butterfly and shaft in the way provides more flow)
And the slide gives you a Variable Venturi at the fuel discharge port for better atomization.
And Dual plugs....
No dip, but that steady downhill decline after 3000 is a problem. Even stock P cams ought to be holding torque out past 4500. Something is wrong, I just need to figure out what. Timing?
I love the look of the Super B, but a really hate how twitchy they are just off idle. As in, when downshifting, and reaching for the clutch level and you move the throttle ever so little, and the motor surges. Hate that. CVs don't do that at all, in fact one of their "drawbacks" that I find a positive feature is the damping effect from the slider. They don't respond to minor movement on the throttle due to that slight delay in response. Much better street behavior if you ask me.
What is really strange, is that the behavior of the bike out on the road does not really correspond to what the dyno chart is saying. It actually runs quite nice, does not seem short on power at all, and pulls fine up to 6K. I'm tempted to go somewhere else and get a baseline on it before changing anything just yet, and this time with SAE correction.
-JW
What gear was that run in?
4th.
-JW
Still trying to sort this Ironhead out. I bit the bullet, and bought a Daytona Twin Tec WEGO iii. Before taking it back in to the dyno shop, I want to make a few changes to it, and try to tune it a bit myself with the WEGO. The changes:
Out with the Super B, in with a CV40 (done)
Out with the MAC exhaust, in with an OEM set HD "performance" exhaust (ala Cycle Shack)
Out with 23T trans sprocket, in with 22T
I need to weld a oxy sensor bung to the front pipe, am guess a few inches from the port? There's not much option, either close to port or down past the bend. The pipe hugs the frame tube pretty tightly. Then send them out for ceramic coating. Will swap the sprocket this weekend.
Stay "tuned".
:hyst:
-JW
Since tuning 1 carb for two cylinders is a compromise, gonna weld bungs front & rear? Would be good to know you aren't too rich/lean on either cylinder.
Yes that is true, but at the end of the day, what can you do about it? From my experience, the rear plug always seems to be a tad darker on a well tuned V twin, so get the front one tuned to the "optimal" condition and don't worry about the rear?
-JW
At minimum weld a bung in the back pipe too. That way it's done already should you decide later. I may even have a spare 18mm bung. You should put the bung about 3-4 inches from the exhaust port if you can.
Overall your tuning options are pretty darn limited as you know. Maybe you should have bought an aftermarket EFI set up :-) :sick:
Next thing to put on your To-Do List: Figure out how to wire those iron heads for a block heater and kiss those cold running blues goodbye.
Well, in looking at the rear pipe, I don't see much chance of adding a bung and getting the sensor screwed into it, unless the bung is on the outside of the pipe. That wouldn't look so cool, right? Way too cramped on the backside. As far as where to mount it on the front, the Daytona book says "as close to the exhaust port as possible", which is quite easy to do on an Ironhead. Tons of room.
Limited tuning options? How many does an Ironhead need?
:SM:
I think the CV has enough adjustments for a clever guy (If I can find one!) to dial it in close enough for good enough.
Regarding the cold bloodedness, I think the solution there is tighten that choke cable backside nut so the knob stays put, and.... lots of spare spark plugs!
By the way, it seems that Daytona Twin Tec is now Daytona Sensors. ???
-JW
about 4" from the exhaust port is good for the sensors
try to get the outside of a bend
try to get both pipes
get plugs to blank them off when you are not tuning
once you have fished tuning you don/t have to live with the sensors
From the Daytona instructions:
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As it turns about, about 3 inches is as close as I can get it and have it somewhat not visible after it's removed, unless I put it on the front side of pipe. Which I'm not going to do. Will mount on the rear side of the front pipe pointed to the carb. And I can probably put a bung on the front side of the rear pipe, also pointed to the carb.
Seems like everything I touch, have to do a bunch of little things before doing the thing I'm trying to do. The bracket that came with these new exhaust pipes doesn't even remotely line up with the mounts on the pipes. So I need heat/bend it to fit the pipes. But alas, my damn oxygen tank regulator gauge is not working, so it's off to the welding supply...
-JW
there has been a lot of discussion over the years about optimal location for the sensors
generally pipe and bike manufacturers are oblivious to the requirements for gathering good data
sensor position being determined more by aesthetics and convenience
probably more important for fuel injection but applies equally to carb
for wide band sensors 3'' to 4" from the head is optimal
stay away from the inside radius
otherwise you are just going through the motions
Clean signal is what you want. Wideband sensor (bosch like Wego uses) wants to be close to the ex valve and can handle the heat.
Do the pipes have heat shields? If so put the bung wherever. A zit on the prom queen can be covered with make up :-)
Got the new pipes mounted, here is where I'll put the 02 sensor bungs:
[attach=0]
No shields on these pipes, so on the outside would not look so great. These will get ceramic coated after I get the bungs in place.
-JW
That looks like reasonable placement, but still might be a bitch on the back pipe. I might install the front one 90 degrees from where your arrow is. Tucked between frame and front of the engine. You can get angled bungs if that would help. Do you have the kit yet?
There is no room on the back, the pipe hugs the frame real tight. In fact, it has a flat spot pressed into the pipe to clear the down tube. I have the WEGO laying on the bench. Just swapped the trans sprocket today to a 22T. And now have to pull a link out of the chain, ran out of adjustment on the axle. Damn hot out there in the shop, yikes. I am kind of contempating dropping the heads off at RE Engineering and have him dual plug them. What the heck. What a better waste of money than throw it at an antique Ironhead, right?
-JW
Back in the day when I was campaigning a stroked 74" cast iron, gave it to the ex and then she left & snorted it, I went though a lot of trial & error. The CV was one of the best things I did (was probably one of the first "CI" with a CV ever), along with Baisley roller rocker. Pipe wise I got along with MAC drags with some mode baffle, and eventually duel plugged heads with an HI4 single fire, Cam wise I was using Sifton GX's. But I think the P's really wake up with 1-3/4 ex valve, and can work well with strokers too. As for an DTT O2 port, alls fair & it'll get you closer damn near anywhere you put it, as long as you KNOW the clamp area is not leaking. I used one on my Bonneville bike.
With the duel plugging, stock pistons don't leave much room, and can be problematic with it easy to burn though. You might be able to find a set of those old KB sloped pistons & then you probably wouldn't need the duel spark, but a single fire is almost a must.
Front cylinder runs leaner on a carbed H-D, use the front pipe for the O2 sensor.
Get or make a long bung for the sensor so just the tip is in the flow.
A short bung will have the sensor stuffed into the header pipe and obstruct the flow.
If those mufflers are straight through I don't think they will work well, the ones with the flap work good.
Really if you want to get it in it's happy place grab a EVO pipe and fit it.
(https://i.postimg.cc/Nf5CSsDG/Iron2-1.jpg)
[attach=0,msg1316284] Heres my old late '84 XLX. Yeah I tried one of those POS two throats, actually got it to work OK, the brackets weighed more than the carb. But the CV was hands down much better and more responsive . Sorry for the chitty pic, its all I have to remember that bike by is that plaque I made :cry:. Some day somebody is going to walk in with a basket case & I'll recognize it immediately.
My son's 1000cc Iron XL, with HD, P cams, Wiseco pistons, our heads, S&S E, Dyna 2000i, and a rare R&M 2/1 header he stole from me... :hyst: runs 65 hp, 63 ft/lbs.
The dyno chart posted looks like a plugged up exhaust system.
I use one of these, with a long piece of 3/8" copper tubing so it goes way up into the pipe by the head. No bung needed...
https://www.innovatemotorsports.com/xcart/product.php?productid=16141&cat=271&page=1
Indeed I have no idea what the deal is with the MAC exhaust that is on there. Since it's not very loud, I guess that implies that it's restrictive as well. We'll see how the HD/Cycle Shack pipes work out. Just picked them up yesterday from the ceramic coat shop. These were actually meant for a 80-85 sporty, so the provided bracket is not right for my '78. Need to do a little bit of fabrication to mount them.
-JW
A carbed bike can be VERY easily/quickly tuned.
Yes, they can be. Having a AFR sure helps I've found.
Baseline:
45 pilot, 160 main, N65C needle
Daytona WEGO III gave me:
Idle: 14.5
Part throttle: 14.7
Full throttle: 15.0
OK, very lean. Explains a lot about the behavior, i.e. coughing at off idle and no power. (38HP on the dyno with a Super B, now has a 40mm CV)
Jetting changed to:
48 pilot, 185 main, N65C needle
DTT WEGO III gave me:
Idle: 12.5 (readjusted to 13.2)
Part throttle: 13.1
Full throttle: 12.2
Running A HELL of a lot better. Pulls hard at WFO. It now has the 'surge on backing off throttle from WFO', which means still lean on the main jet I think. 12.2 on the meter would seem OK, but this is an Ironhead, with slow burn hemi combustion chamber. So it might want to dip into the 11s at WFO for best power. More tuning tomorrow, but so far much progress.
-JW
Having an AFR gauge on a carb'd bike is a game changer. Glad to see you got it straightened out. With an onboard AFR the only real need for a dyno is for the WOT hp & tq curves. Totally not needed for tuning a carb'd bike.
Yes, handy indeed. There's a bit of skill involved trying to interpret the AFR value jumping around, not sure I've mastered that yet but maybe after a little more time with it.
I replaced the "'88 sporty" N65C needed with an N72S, as it was stumbling a bit when I'd give it the wick at lower RPMs. My suspicion was that having both the "rich" needle and an accelerator pump, it was getting too much juice. The N72S did clear that up, but found that it was reading high 14s/low 15s at steady cruise. I put the N65C back in, cruise went back to around 13.6, but the low RPM acceleration stumble returned. I think the next step is back to the N72S, and start shimming it to get the cruise AFR to 14.0 or lower.
Turbo, a question. What will oil do to the measurement? I noticed after a few hard pulls it was now puffing some white smoke, and back home to the garage, stinks like oil. I think I see a top end in my winter plans...
-JW
I think you are on the right track with shimming that needle. As fo the effect of oil on the AFR reading, not sure as I have never had to tune in that condition. I bet the guys that run dyno's day in and day out could answer that question.
As a responsible dyno operator I would never strap down a bike that was smoking.
Chances are real good that it would eat itself up.
I have not yet blown one up and a smoker would reduce those odds dramatically!
Indeed, not going to waste any more time tuning it until I get the oil control taken care of. No big deal, riding season is starting to wind down anyway.
-JW
will be running leaner if there is oil in the fuel mix
since the quantity of fuel is fixed but the overall volume of the fuel mix is increased with the addition of oil
JW before you get out the wrenches, make sure the oil is not contaminated with fuel.
That will make them smoke and cause tuning headaches.
When I saw the bike on Sunday as JW was on his way home it was just smoking out the rear cylinder at idle. Not sure if JW saw more oil use after or before that. Nothing like tearing down the bike for it's 500 mile rebuild :dgust:
The O2 bung is on the front cylinder so I suppose if any oil is skewing the AFR it's getting to the front through the intake.
Yes, disappointing. I was at a stoplight and saw some clouds getting blown up in front of me, looked back and could see it puffing out the rear pipe, could not tell if any from the front though. Before that last tuning ride, where I was doing quite a bit of WFO pulls up to redline in 3rd, it was fine. So clearly something went "tink" in the rear cylinder. I personally had actually not had the bottom end apart on this bike, our pal Surfer Bill rebuilt this some 20 years ago. No idea of the pedigree of parts used. And here I was all worried how to keep myself off the streets and out of trouble over the winter. LOL!
Did some surfing last night, does not seem to be a whole lot of options for ironhead pistions these days. Tons of those Superior/Dixie slugs on ebay, but am not considering those. Twin Power has some moly coated cast pistons, am leaning that way. S&S and Wiseco both have forged 10:1, but they look heavy as hell and I don't like the noise of forged anyway. J&P has "KB 9:1 Hypereutectic", but when I looked at the KB website, it says 8.2:1. I'd actually go the KB route if they really are 9:1, but am skeptical. Will give them a call.
And since it's apart....
Now would be the time to dual plug it. Ironheads are kind of funky to get that right side plug in. This outfit does an interesting job, not so sure I want to notch the rocker boxes though. Wonder if this could be done with a 5/8" "peanut" plug and avoid the notch?
[attach=0] [attach=1]
-JW
Crazy idea, but have you considered that it might not be piston or ring related? A leak down test will tell all.
Yes, entirely possible. The only symptom currently is some mild smoke out the rear pipe. No unusual noises, and runs quite well. Just from my own past experiences with oil consumption, if it wasn't the pistons/rings, it was a valve stem seal that got knocked loose. Which can't be the case here, as Ironheads don't have valve stem seals, at least from the factory. And the guy that rebuilt these heads didn't install them either. (says he doesn't believe in it) At any rate, the heads have to come off. Will take it from there.
-JW
I dual plugged mine with a 10mm plug straight down from the top.
(https://i.postimg.cc/mDD9vCTj/dual2plugs.jpg)
(https://i.postimg.cc/bJBnprJh/dual-Plugs.jpg)
Used a CNC, calculated the electrode position and matched it on the left.
You don't have a pic of what the combustion chamber looks like, do ya?
Last set I had done, they went in straight from the side, between the pushrod tubes. Seemed to work OK.
[attach=0]
-JW
Didn't realize you hadn't gone through the engine on this one. It was only smoking on rear when I saw it. Scope and leak test it? Call Ron (panman) about KB options? Pretty sure a few dudes around here might have ideas, AWS Racing? ( I think off top my head for Sporties).
IMO dual plugging it is a waste of time and money. Unless you want to kick it up a few notches. You have stock cam and low compression, it won't benefit much. Oh wait, "Harley riders are happily getting screwed". :-) never mind.
The only thing I touched were the heads. Did not tear it down past the cylinders. So who knows what was used or how assembled. Kind of odd that it started smoking after some hard and high rpm pulls. Piston pin C clip come loose? Dunno, leak down would be fun, but at the end of the day, it has to come apart to fix.
The thing I see dual plugs bring to the party is aversion to detonation with the crappy gas we have these days. Mountains of evidence that hemi heads, with zero quench and big mountains on top of the pistons, don't produce a lot of ping-abating swirl. Stock Ironhead, at 9:1 C/R, is not off the chart, but higher than stock Evos, Sporty Evos, and Shovelheads.
What can I say? I don't own a boat. What other black hole am I going to throw money into?
:SM:
-JW
Your daughters education? :-D
9:1 is not high compression and depending on the cam, likely lower. Did the R60 ping? It's got open hemi heads and at least 9:1 ... yes aluminum vs iron. How many miles you gonna put on this? 200 a year? :-D
I forget, what was the oil control issue with the other Ironhead, seals? Same head dude, same problem??
Quote from: JW113 on November 07, 2019, 07:46:29 PM
The only thing I touched were the heads. Did not tear it down past the cylinders. So who knows what was used or how assembled. Kind of odd that it started smoking after some hard and high rpm pulls. Piston pin C clip come loose? Dunno, leak down would be fun, but at the end of the day, it has to come apart to fix.
The thing I see dual plugs bring to the party is aversion to detonation with the crappy gas we have these days. Mountains of evidence that hemi heads, with zero quench and big mountains on top of the pistons, don't produce a lot of ping-abating swirl. Stock Ironhead, at 9:1 C/R, is not off the chart, but higher than stock Evos, Sporty Evos, and Shovelheads.
What can I say? I don't own a boat. What other black hole am I going to throw money into?
:SM:
-JW
I think there will be some gains had by dual plugging that ironhead. Even at 9:1 o lower, that is a huge chamber with a lump in the middle. The placement of the plugs would ideally be on opposite sides of the mountain instead of on it's ridgeline. Still, two sparks has to help. Too bad dyno tuning was not a thing back in the ironhead and shovel days. I bet tuners and aftermarket would have developed all sots of stuff that actually increased the power output of these old designs.
JW
My 'new to me' 1978/79 has dual plugs similar to the pic you posted except instead of removing two fins they bored a hole just large enough for the spark plug. The bike is stashed in a corner of the garage with a workbench built up to the left side and the right side is up against the wall, and a hinged drop down parts holding counter is against the front, can't get it out for a good pic. I also keep it covered so I won't get distracted from what I am supposed to be doing while I'm out there. I haven't done anything with it so far except store it until I finish my other projects. [attach=0]
I can't get the photo to load on here, they centered the spark plug through the top horizontal fin between the push rods with a half moon cut out of the outside vertical fin and the second horizontal fin. Neat installation.
Sure, airheads are hemi also, but as you said, made of aluminum, hung out in the breeze for better cooling, and it is not uncommon to dual plug those either. Ala my R100/S. And the pistons are narrow dome, similar to shovelhead pistons.
The problem with the Chopster was the crappy mechanic.
:SM:
It was 4-5/8 stroke, and the dumass didn't go the extra mile to make sure the pistons were not playing tag at the bottom of the stroke. So, collapsed piston skirts. Doh! But it sure ran like a scalded dog.
drifter, I think I know what you mean, and I was thinking the same thing. Cut the hole in the "corner" formed by top horizontal fin and right side vertical fin. I have an old rusty head laying around somewhere, might use that to experiment on a bit.
-JW
JW113
I've been playing with the pics, maybe I can get it to work now, self taught, might get lucky.
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