Those heads and your combination works fine. The '07's are about 10% down from 06-erlier because of the Primary drivetrain ratio. Your cranking compression is not high enough. A couple things. The CNC heads require the use 22444-02 piston kit. Any other combination piston will not work (unless oversize). Improper squish is probably the biggest issue if not checked and could also be cylinder to piston clearence. If cylinders and piston were purchased as "std." and not checked,I could almost guarantee they are not correct. I have seen pistons that will not fit in bottom of bore and be .005" barrelled in the center. This will increase drag at bottom of stroke and compression loss. The air / fuel ratio shown on your chart is pretty "wavy" and tuned to 13.0:1. Bring that up to 13.5-13.7, depending on sea level. With that low of cranking compression should increase, only a small amount. Sounds like it was just assembled and the major things as piston/cylinder clearence, ring end gap, squish and piston protrusion were not checked.

Alot of people wonder why some shops charge more than others and how cheap someshops are. Some of the times this is why. It takes extra time to check these, however if not done while assembling, it is too late now.

 

It's never too late i still own the bike, and a tool box if i have to we will tear it down and get it right..
I thought about taking my stock cylinders and having them bored to 107;that can be done right?
Then the cylinder will be straight.
in the mean time I would like to figure this out and see what i can do. this might be a learning process.
i just checked the compression pressure, so i have not talked to Bob Wood about that issue.

 

I heard back from the other guy a I sent this to. Here are his comments. For reasons of full disclosure, the comments below are from Mike Stegman of Latus Motors HD in Gladstone, OR. Mike is a very well known builder/tuner and was recently featured in American Iron magazine doing a 113" build.

I guess we would look at four things.
1. We've not had good luck with the 400 cams. I just believe it's not enough duration for a 103 motor (Bob will disagree).
2. A pipe change may be in order. The suggested D&D would be my preference. A pipe change would further compliment a cam change.
3. The cranking pressure does sound low for your combo. But I want to be cautious because gauges and technique can provide different results. FTR, we use a Snap-On Motorcycle gauge, white schrader valve (important), holding the throttle wide open, spark plugs out and with a good strong battery you should be seeing 195-210 lbs.
4. The fuel curve could be better. This leads one to believe the rest of the tune could also be better. Was each cylinder tuned seperately? Were the spark tables adjusted? Was Knock control turned off? What was the methodology?

In STD 5th gear numbers, we would expect to see 110-115tq/105-110hp with your current combo. You can see several 103 build dyno charts on this site to get a feel where these numbers come from. In SAE (likely 4th gear) numbers your not too far off, so most may be in the tune.

You can go to Latus Motors website and view the dyno library for other 103" builds. Hope this helps in some way. I would suggest trying to get a better tuner to take a crack it before you start tearing it down and swapping parts out.

 

I have the same basic build, and have not been on the dyno yet, but I can tell you this thing outpulls my last bike which was 102hp, and 115tq from a 95 incher. The 103 with the build you are describing should easily get to 115, 115. My LSR Blackhole 2 into one pipes will be in next week, and once installed will be going to the dyno shop to get some numbers and will post them for comparison. Harleypaw is running the same build, almost identical to mine except he is running the SE throttle body instead of a reworked one like mine and he is pulling 118/118, and actually had higher numbers but cut the tune back a bit to where the engine ran the smoothest.

I am tuning this setup myself with the DTT TCFI II tuner, only thing needed on the dyno is what the engine is doing , not used for tuning like the SERT. One explanation is a lousy tune, but that is not the only thing that could be impacting your numbers. Could be just bad numbers coming from the dyno?

There is nothing wrong with the HD CNC heads but it takes a bit of work to get the squish right, involving machining of the cylinder base if the piston is too low in the cylinder at TDC. Thinner head gaskets do help but getting the squish right is critical if you want optimum performance.

There is a real issue withthe injector sizing on the 07's they are rated at 3.91gm/sec, down from the 4.22gm/sec in the 06's. I went with a reworked HD throttle body to 50mm, with SE injectors rate at 4.89gm/sec. Running the smaller injectors with this type of build will require the injectors to operate above a 50% duty cycle or even higher, meaning the injector is firing fuel into the manifold for for the front cylinder during a time which the intake valve for the rear cylinders is open, meaning that there is fuel in the manifold at all times, causing alternating lean/rich conditions in each cylinder at times. This could explain the erratic fuel line. Is there a reading from the SERT that measures injector pulse? There is in the DTT System. If it is above 50%, you will definitely need to go up in injector size.

The cam you have is excellent and is specifically designed by Bob Woods to work with the CNC heads. Few heads will handle the .650 lift without quite a bit of additional work. I am a firm believer in the capabilities of Woods cams! The right ones in the right build are torque monsters, as you indicated in your initial post.

Bottom line is that if you are happy with the way it runs, and you have no pings or flat spots, try tweaking one thing at a time to see what the results are, unless you are really into a wholesale teardown and rebuild.

 

I agree with this. While, when "properly setup", those heads/pistons will make good power... they are some of the most difficult to get the squish set right. If the shop just assembled whatever cam outa the boxes... didn't check (and fix, if necessary) thedeck height, then that explains the lower than expected CCP.

I certainly would not discount Mike Stegman's comments either. It might be worth rechecking the CCP and possibly with another guage.

Guy ~ do you have any idea what your CCP is, since your build is very similar?

TG ~ keep the positive attitude & we'll get ya squared away!

 

CCP Front and Rear on my build = 195, and that is with the thick gaskets, didnt want to go above that for cranking purposes, even with compression releases.

 

Hey Dalton - Thanks for the info. I'll be curious to see how your build comes out on the dyno. No doubt it sounds strong. I was a little surprised to read Mike was not having luck with the 400's. I am also a believer in Woods cams. To many monster dyno charts out there to not think his stuff works.

Did you have to trim your cylinders to zero the deck out?

 

I've been learning how to use my SERT [-01B version] in data mode to try to optimize the tune...and without knowing what % to crank in for parasitic driveline losses, for my money the numbers are meaningless insofar as crankshaft HP goes. Knowing the bike's weight and integrating the RPM to derive acceleration allows the program to calculate what rearwheel HP is getting put to the pavement. On my 88 with 203 cams and SE2 pipes w/cut baffles it's 70.8HP and 83.9TQ, both at 4432 RPM which was where I shut her down being as this was just a proof-of-concept run. The second run to the rev limiter in 3rd gear [setting the 'gear' variable to '3'] produced 68.0HP@5846 and 63.8lb-ft@5294. But that's with "0.1%" entered for drivetrain losses. If I plug in a more realistic 10%, the numbers jump to 76.0HP/5867RPM and 70.3lb-ft/4861RPM...that seems like an awful high RPM for the torque peak. But I don't have enough open road around here to run her all the way to the rev limiter in 5th on a Saturday afternoon.

Which begs the rhetorical question what am I really measuring, anyway? Do I want to know rearwheel HP, which I understand is what is measured on a chassis dyno, or do I want to know crankshaft HP before parasitic losses are subtracted? I personally only know one way to get a true measurement of crankshaft HP, and it involves taking the engine out fo the bike...although I'm sure by now someone has quantified the parasitic losses pretty closely...but as soon as you start plugging in correction factors it gets interesting--if you're measuring, say, 100HP at the rear wheel, and thee next guy has entered a bigger number for parasitic loss correction factor, you're gonna think your bike sucks by comparison...

If anyone out there has good numbers for parasitic losses in a stone-stock '01 FXSTBi driveline, please email me at lurch@britewerkz.com

Many thanks,
Lurch

 

So I re-read the SERT manual and did a short pull in 5th, shut her down at 4000. Manual says to plug in 15%-20% for a driveline-loss figure, says use 15% for lower MPHs and 20% for higher MPHs...after plugging in 20%, the magic thinking box comes up with 78.1HP/3959RPM and 105.0TQ/3688RPM. That is about the rpm I would expect to see a TQ peak at with 203 cams in an 88.

Leave out the 'aerodynamic correction' built into the program, and it really tilts the curve. Makes sense since aero drag increases as the square of RPM. 105.0 seems like a pretty impressive TQ, but everyone I've let ride the bike has commented on how unnaturally torquey the bike felt to them.

Now to tune, log data, repeat as needed...but the final test will come at the track...