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Discussion Starter #1 (Edited)
So, Ive got two FXDX bikes. One, a 99, the other an 04, carbed, and both have comparable mods.

The 99 has 37k miles, a Thunderheader, Big Sucker intake, stock pistons and SE 204 cams, and made 86 lb ft and 79 hp on the dyno.

The 04 has 56k miles, a Supertrapp 2-1 with closed end cap and 20 plates installed, Big Sucker intake, stock pistons, Mikuni HSR42 carb (50 AC pump nozzle, AC pump set to engage immediately and full travel, 98 needle with clip in middle, 17.5 pilot, 160 main jet) and, according to previous owner, SE 203 cams, which are close to SE 204s, from what I can tell by the specs.

The issue is that the 04 has noticeably less torque than the 99, so Ive been investigating why. First, I was thinking perhaps cam timing was off, so I did a compression test to see if there was a big difference in readings between the front and rear cylinder on the 04, as Ive been told youd see around 30 psi difference IF the cam timing was off a tooth. I also did both bikes, so that Id have a basis for comparison.
Firstly, 160psi is perfect for the 88ci motor from what can tell, with these cams installed and OEM headgaskets and pistons.
04 has 140 psi in both holes. 99 has 155psi in both holes. I dropped about half an oil cap full of oil into both holes on the 04, and the compression reading went to 150 psi.

So, if 160/100= 1.6, and bike should make 79 ish hp to the wheel and 79/100= .79 and 160- 140= 20/1.6= 12.5% loss which would theoretically be 10hp if the correlation between hp and compression is linear.
IS 140 psi enough to make this bike a slug in comparison to my other bike with 155 psi? I also was wondering if the crank case was filling with oil due to sumping and that was slowing it down, but I took it for a rip and then promptly pulled the plug from the bottom of the crank case, and only 1-2 oz of oil came out, so its not that.

Im going to perform a leakdown test tonight to see if the valves are sealing properly next. Im just wondering, the head gaskets are clearly stock, so Im sure adjustable pushrods were used in the cam install, and if theres major leakdown from the valves, could it be that the rods were adjusted too long and are preventing the valves from seating fully? If the rods were adjusted too short, could they be keeping the valves from opening fully, thus giving a false lower compression reading and also hindering performance? If either of the previous mentioned issues were present, wouldnt the valve train be noisy and perhaps have grenaded by now?
 

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The difference between 140 PSI and 155 PSI is significant and you would notice a difference in performance between two otherwise identical machines. Increasing the compression reading by adding a bit of oil to the cylinder is a strong indication that the rings are not sealing very well. A leakdown will help pinpoint where the compression loss is. If the pushrods were loose enough to not open the valves as you described, you would hear the clatter. If you hear air escaping back through the intake or exhaust during the leakdown you can back off the pushrod to determine if that's causing the valve to be off of the seat. Just be sure the cylinder is at TDC on compression and hasn't moved when you applied the air. I'd guess it's the rings based off of the info you provided so far.

One other thing I'd look for is the difference in gearing between the two machines. That could cause one to feel more sluggish.
 

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Ok take the low one apart and have a look. My guess glazed cylinders and it never broke in right. Probably means oil by the rings too.
 

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Discussion Starter #5
So I put the thing in fifth gear. I got the front cylinder close to the compression stroke. I put 5 PSI into the system and then I gently Rock The Wheel back and forth until there was no hissing out of the intake or the exhaust. I then had my girl hold the foot brake on the rear wheel so it could not rotate inject it to 100 PSI and with the main gauge reading 100 the other gauge was reading 97.5 PSI with no hissing out of anything not even into the oil crankcase. The exact same is the case for the other cylinder. So I do not know where my power is going.
 

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Discussion Starter #6 (Edited)
I pulled the cam cover to check cam timing. With the rear cam sprocket dot on the line on the cam chest, the front cams dot is at 9 oclock. Thing is, theres no dot on the crank sprocket, so the fucker must be on upside down, which could mean the cams are lined up but the crank is not, so tomorrow i will pull the sprockets off and see.
 

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Discussion Starter #9
I apologize, guys. I meant to say the front cam mark is at NINE oclock, with the rear cam sprocket mark on the line on the cam chest, and I edited it to reflect that. The mark on the pinion sprocket on the 04 very well could be under the washer. When I built a 99 for my girlfriend, the mark was on the tooth of the pinion sprocket, so I just expected the mark to be the same on this one, though Im aware they changed quite a few parts between 99 and 04.
 
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