Okay, I'll buy into your numbers. But not mentioned is the bucks you put out for the bang.

Will you give us the cost of the finished engine work? Parts, labor and dial in? I am curious.

 

Uhm... mikstr... You must be doing something wrong... I haven't gotten around to sticking my pistons in there, and I'm pushing 118+ at the rearwheel... I might be completely wrong, but getting them in there and setting it all up accordingly should net me at least 5+ hp... Shouldn't it?

My homemade port & polish of the heads can't be that good... You should be getting more than me...

 

Come on Tweety. You just like throwing flies in the ointment, don't you? haha Agitator!

You may be able to use dyno results more to verify HP improvements if you use the same dyno, but comparing different engine build numbers from different dynos will likely yield unreliable results.

 

Well... Agreed, on the unreliable results on comparing dyno's...

But considering that mikstr is as far as I know using a professional dyno that should be calibrated, and numbers should be compensated for whatever, and I'm using my own dyno, built and "calibrated" by me, and it from all I can tell is reading a couple of hp lower than most dyno's, I just think he should be getting more out of that build...

One of these days I'll have mine put on the EC997 dyno that the local shop have... That should be fun...

 

Or it could be disappointing.

 

Your thinking is right in line with mine. However, I know the chap who did the work knows his stuff (as I stated in a earlier thread, he built the engines for the Honda Canada Superbike effort a few years back) and is very well respected.

I have been thinking about this matter since the other night and my thoughts are as follows:
- engine is still not broken in and there is surely more to come (could be a mind game but during the short ride I took the other night, in which I spent 60 km continuously pinning it and rolling off, it seemed to pull better towards the end, but that could be just wishful thinking too...)
- I have read that tire condition affects dyno readings greatly (thanks Google) and the tire used was brand new (known to generate low readings as it slips more), I expect a well-worn tire will help boost the numbers also
- the tech told me the engine was remarkably fresh and well aged despite the mileage, so perhaps some of the gains I was counting on from the refreshment part of the build were not as great as expected
- the gains, since last time it was strapped onto the same dyno, were just over 8 hp and just under 6 lb-ft; granted, the BMC filter, modded airbox lid and stick coils were not yet in at that time. Despite this, my tech seems to think that the gains I got (from the parts I added) are more than respectable (and actually more than he thought I would get)...

Either way, this is the end of the road for the actual engine mods (to go further would cost serious $$$$$). I could easily get more top-end from fitting shorter intake runners and having the intake cams retarded (am currently running them slightly advanced from Yosh specs - retarding would increase overlap and hence top-end), but that would come at a loss in low end and mid-range, going against my main objective of building a mid-range powerhouse. The torque peak is now lower than it was previously (down by 250 rpm), which inevitably affects top-end and consequently peak numbers. Unfortunately, with winter now setteld in, all theories will be on hold until a few months from now, at which time I'll be able to get better insight into all of this.

Am I happy with the results? Not quite. That doesn't mean I won't be later on, however, once the full break-in is complete and I have had sufficient saddle time to adequately assess what is going on.

It's going to be a long winter......

 

It sounds like you are right in there with the expected output for your mods.
Stage 1 cams are good for about 120 HP, if everything else is done right.

You could tighten up the squish clearance - stock JE pistons have about .050", with the head gaskets, which is only about .005 tighter than stock. .040" would be a tight, conservative number. But if you deck the block by .010" and the head too, you'll be high on compression.

Your engine will seal up with runtime and give higher numbers. The best thing you can do is stop worrying about the numbers and enjoy the riding. The thing's going to run great!

 

Thanks Randy. The heads have already been decked by 0.015" a few summers back when the cams were installed initially. Interesting note: the tech had to put aluminum washers under the spark plugs as the pistons were coming into contact with the ground electrode at TDC. He told me that the squish and valve clearances were ok, however.

 

I have been looking around and doing some "comparison shopping" with dyno charts for other bikes (Dynojet results, as this was the dyno used in my case) and noted while the hp I acheived is perhaps not overly impressive, the torque is quite robust. In fact, I have looked up results of various RC51s, Ducs, Aprilias and the like and have come across very few that have as much torque (and this despite many being quite heavily modded). The low rpm at which the torque peak arrives holds back the ultimate bhp numbers it seems. I expect that a proper break-in, low friction rear wheel bearings and a cleaned air filter will land me very close to 80 lb-ft (and 125 bhp) with a honkin' mid-range. In other words, it`ll be an impressive real-world mill, meaning I will have met my objectives. I could most certainly replace the long intake runners with short ones, have the intake cams retarded by a couple of degrees (to increase overlap, and hence high-rpm breathing) and subsequently move the torque peak up by a few hundred rpm, which would "artificially" inflate the peak hp numbers. This, however, would come at a cost in low-end and mid-range (the "raison d'être" for having a big twin), all for the sake of impressing the gallery, so to speak. All this to say I am looking forward to next spring.....

 

You're not even going to worry about it, once you ride it.

When I finally got my RC51 mapped, it made just over 70 ft-lbs peak and 130 HP. The rear tire is a racing slick and 20-30mm taller than a stock tire. I believe, in an apples-apples comparison, it would be closer to 75 ft-lbs, and smewhere near 135 HP, since those seem to be a good standard numbers, with JE pistons and some port work. The tuner spent the time and mapped the part throttle regions cell-by-cell, so it is very well mapped everywhere.

The bike weighs 408 lbs, with all fluids and a 2/3 fuel load. I'm 190 lbs, suited up. When I'm on the track, where I can use all of the available power, there are times when I don't even ride it wide open. It just launches forward whenever I want it. It is a fantastic motorcycle. You can expect yours to have similar performance. So sleep well and look forward to spring!

 

Mikstr, you've got a nice ride there so don't sweat the dyno results...just ride her and have fun. If you ever decide to flow the heads then at that time you can shave them some for more compression and more power, but in the meantime ride it like you stole it!
RC