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XLIII
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10,078 Posts
Discussion Starter · #1 ·
One last option I think might deserve a look before we start tearing into my engine.
My low RPM numbers are as good as anybody elses, and it's just 3-3.5k and up WOT where I'm falling short. Tuner I use was taught to tune to 13.5 AFR w/ the SERT, and I'm wondering if going to 12.9-13.2 WOT would get me appreciable gains. Several tuners I've spoken with have said they tune that way, w/ 13.5 being what they shoot for in the cruising range and not less than 13.2 WOT. How much of a difference on a setup like mine, 95", 10:1 CR, Flat Tops, SE Perf Heads, 37G cam w/ 2* advance key and V&H Dresser Duals w/ Samson Rolled Thunder slip-ons? If it's just a couple HP, that's not my problem, but if significant gains could be there, we'll try that. Just don't want to waste any more of his time.

Thanks in Advance!
 

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Premium Member
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1,389 Posts
A half a point in AF ratio is not gonna move a power curve up or down by the amount you are off for the "typical" 37 build...a couple hp maybe. And fatter is not necessarily better....at high rpm the most power is made at the verge of detonation..... Where that is in terms of AF ratios and timing depends on the comp. ratio, chamber shape, rpm range, load..etc.
On my 292 cubic inch 6 cylinder motor in my Syclone...I was at about (depending on ambient temp..and humidity) 11.8 to 12.1 AF ratio and only 24-26 degress advance...under 20lbs of boost ! There is no majic number.
You've gotta check those cams just to eliminate them as the problem if nothing else. the bike should be tuned with the knock control off for best numbers...then switch it back on to see if it pulls timing out ...then adjust accordingly.
 

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Total Nutcase
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2,691 Posts
If you've got the sert, try richening the bike up in the higher RPM ranges. Most maps I've looked at are even richer then 13.2 in the upper throttle to WOT throttle settings... Try more like 12.2 or even as much as 11.8. Richen it up and do a data mode run with the knock sensors on and check for any knock sensor activity. I agree with Scyclone that a half point ain't gonna do much. If you don't see any knock sensor action, you might be able to pick up some power by advancing the timing a little in those areas that you richened up.

Give it a shot and see how it pulls. Worse comes to worse, you reload your original map. Ohh..one more thing.. I'm not a professional tuner. :harhar:
 

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Mega,

With the set up you have with the +2 key and the Rolled Thunders, you are not going to help yourself by lowering the AFR number into the range that is being suggested. The scavenge rate of those pipes combined with the advance timing on the cam tends to respond better to timing changes in general and front to rear timing offset in particular. The RPM range that you are describing is exactly where we tend to aggressively increase the timing slope and begin to offset the cylinder trim. The engine dynamics at this RPM range causes the v-twin to require a later closing valve event, but you have sacrificed that a bit with the cam key, so now the cylinder is having a tougher time filling. You have solved what would normally be a power stealing reversion at low engine speed, but you have to pay the piper a bit on the high side of the RPM cycle. So to squeeze a bit more out of her you need to work with timing and VE adjustments TOGETHER. Not that I know much about tuning either, but that's what someone told me..................;)

All the best
G
 

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XLIII
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10,078 Posts
Discussion Starter · #5 · (Edited)
GRock, Thanks for weighing in on this one!
I'm gonna be in Londonderry, NH the late afternoon of June 2 through the morning of June 5th. You do any tuning Fri Afternoons or Saturdays, if I don't get this straightened out before then? We tried adding timing up top and it just lost power. Here's the dyno and the map that's in it, plus the run w/ the V&H Basic slip-ons so you can see everything but the bike. Any suggestions as to different slip-ons that might work better? I thought I'd see gains by swapping out from the V&H basics, but I didn't. What I DID see was better numbers in 5th.
W/ the Basics, the torque and HP were both a few ft/lb and HP lower in 5th than 4th, but w/ the Samsons, both were about 4% higher, as should have been expected.
What does it tell us when those Basics made less Tq/HP in 5th than 4th, yet made more HP than the Samsons?
I'm about ready to throw a 31G in there straight up if everything is right and the cam in there is actually a 37G when we open it up Tue.
The main reason we're opening it up is that an old guy in FL thinks maybe the cam timing is off.
To look at the dyno curves, it also looks more like a good, healthy 21G run than any 37G runs I've been able to find. I'll never think any build is plug-and-play again.
Ever.

Samsons:



V&H Basics:



Link to map
 

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Premium Member
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GRock said:
Mega,

With the set up you have with the +2 key and the Rolled Thunders, you are not going to help yourself by lowering the AFR number into the range that is being suggested. The scavenge rate of those pipes combined with the advance timing on the cam tends to respond better to timing changes in general and front to rear timing offset in particular. The RPM range that you are describing is exactly where we tend to aggressively increase the timing slope and begin to offset the cylinder trim. The engine dynamics at this RPM range causes the v-twin to require a later closing valve event, but you have sacrificed that a bit with the cam key, so now the cylinder is having a tougher time filling. You have solved what would normally be a power stealing reversion at low engine speed, but you have to pay the piper a bit on the high side of the RPM cycle. So to squeeze a bit more out of her you need to work with timing and VE adjustments TOGETHER. Not that I know much about tuning either, but that's what someone told me..................;)

All the best
G
Good to see you haven't dissappeared alltogether my friend.
 

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Premium Member
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GRock said:
Mega,

With the set up you have with the +2 key and the Rolled Thunders, you are not going to help yourself by lowering the AFR number into the range that is being suggested. The scavenge rate of those pipes combined with the advance timing on the cam tends to respond better to timing changes in general and front to rear timing offset in particular. The RPM range that you are describing is exactly where we tend to aggressively increase the timing slope and begin to offset the cylinder trim. The engine dynamics at this RPM range causes the v-twin to require a later closing valve event, but you have sacrificed that a bit with the cam key, so now the cylinder is having a tougher time filling. You have solved what would normally be a power stealing reversion at low engine speed, but you have to pay the piper a bit on the high side of the RPM cycle. So to squeeze a bit more out of her you need to work with timing and VE adjustments TOGETHER. Not that I know much about tuning either, but that's what someone told me..................;)

All the best
G
A pleasure to see you post....nice to know you're watching so we dont get too far off center.
 

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Got Jet Fuel ?
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75 Posts
If your going to be in Londonderry NH, and your Having issue's with dialing in your bike. Go to R&R Cycles they are less than 5 minutes from londonderry in manchester. This is where the performance shops go to get their hi performance heads,intakes, and other goodies. These guys are also the ones who train a good portion of the dyno tuners around the country. :xhere:
 

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Aw shucks, guys, didn't know I was missed!

Anyway, Mega, you definitely have something happening there as you are around 10 points (at least) short on both graphs. AFR is very respectable, too. Our friend in FLA may be right on this one as not sure what else I would go to. If the cam timing is off that much it is quite possible that you are yanking the charge right thru the cylinder at higher velocity RPM range and not developing cylinder pressure. And the way the lines flatten out so early, you either have a key advance way over 2 degrees or possibly the wrong cam, or like FLA says, incorrect mechanical timing events. Seen that with valve float, too, but no reason to believe thats happening at those RPM ranges.

Also Mega, heliopilot gives good advice as Reggie and the crew at R&R are top notch. If he had done that build he would have never let it out of the shop until he found the problem. Good people!

And say HI to the old coot down south for me!!

All the best, guys, and have a great (and safe) riding season.
 

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XLIII
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10,078 Posts
Discussion Starter · #11 ·
Heck yes, you're missed!
Thanks for the advice, as always, and I'll post up when we get it figured out.
I'll tell the coot hey, too...
 

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XLIII
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10,078 Posts
Discussion Starter · #12 · (Edited)
Well, it's over there now, and I had a long talk w/ the tuner a few days ago and I don't think he went anywhere near as far on the timing as what GRock mentioned. Also looked at a discussion on another forum where the guy had a run a lot like mine w/ the AFR dialed in and timing (A LOT of advance) got him to where he should be.
We're also using a 95" Stage I Dyna map for the base, since the timing is a bit more advanced up top, and the injectors don't shut off during decel like on the Stage II maps we've used, so you don't get the jerk when you roll the throttle back on, and it sounds more Harley-esque during decel. I should know in a couple days how it went, and will post up w/ whatever we find, and maybe some questions if we get stumped. I had that map in there when I rode it over this morning, and the "butt dyno" said it was an improvement, so we'll see after he gets done tuning it.

P.S. If anybody has a copy of a map or even a screeenshot of the timing tables that GRock (or anybody else who tunes the same way w/ a SERT) has used on one of these builds, that would help us out a lot!
 

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XLIII
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10,078 Posts
Discussion Starter · #13 ·
Problem solved.
Looks like we'll be at 97TQ and 89 HP, with the low end and middle even fatter than it was.

Samson Rolled Thunders, while one of the premier performance slip-ons for built 95" Baggers w/ STOCK HEAD PIPES, over scavenge w/ the V&H Dresser Duals, just like an older fella' in FL told me after I discussed my problem w/ him and he called some other coots in his Rolodex for answers. V&H Ovals are now happily snuggled up 'neath my bags. 10:1 CR and cams make the Samsons sing a sweet Harley song, but the Ovals make a nice sound w/ the compression as well.

Anybody need some Miter-cut (slash down) Samson Rolled Thunder Slip-Ons for a late model Bagger? If you have stock headpipes, they're the hot ticket. Only 150 mi on them, perfect. Retail is $398.95, 20% off online vendors sell for $319.16 plus shipping. $275 plus shipping will buy them here before I try eBay. I'd rather somebody here get a deal. And no chance of factory defects like peeling chrome. Had that on my first set out of the box and was down an extra week waiting for replacements.

BTW, we got real aggressive on the timing and got squat for our troubles. W/ the duals, the mufflers were sucking the charge out of the cyl before it had a chance to light...
 

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XLIII
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10,078 Posts
Discussion Starter · #15 · (Edited)
BTW, all the great tuning tips were appreciated, and we learned some stuff along the way. If it hadn't been the mufflers, I'm sure the tuning advice would have come in handy. W/ the advance key shutting down the top end early, I really think it's right where it should be now.

Hint to everybody. Start with a Stage one map and import what you need. MUCH better behavior during decel, no surge or jerk during decel when the injectors come back online at 1800-2200 RPM since they never shut down and retard the timing like a Stage II map does, sounds like a Harley.

And thanks for the kind words, Deluxe. It's been driving me NUTS!
 

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XLIII
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10,078 Posts
Discussion Starter · #17 ·
Still in there. Costing me a few HP up top, but nice and fat on the bottom.
Kind of like a Weeble. :D
 

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Premium octane member
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Good to hear Mega. It is good knowledge for all of us to have. It just stinks it took you some extra time and money to figure it all out. You made up my mind for me on the duals. When my build is finally done its 2 into 1. So, are you going to have new sheets when you pick it up?
 

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XLIII
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10,078 Posts
Discussion Starter · #19 ·
But of course.
Should be able to con somebody into scanning them for me on Friday.
BTW, I've still got duals, just a bit more restrictive mufflers.
 

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Now that i think of it, Dirty Jim (the falling h-d stock guy) made some good numbers with his stock CVO 103 and the true dual/oval combo. He took the dyno down but I think It was at/around or over 100/100. Which is good for a cvo103 bike.
 
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