Well, if anything I would think the 103 might have an easier time running at 2000rpm in 6th gear, and mileage probably wouldn't be that much worse given a good tune. The 103 has a bit more displacement but it also has more compression, and the latter will help mileage.

The tune is important as well as riding style, and it probably wasn't too reasonable of me to compare my mileage with yours considering there are quite a few variables involved. I just think ~35mpg is lower than most achieve. A local friend with the 103/255 combo was getting in that range until I did some tweaking to his PCV map, and his mileage is now well into the 40's.

I don't doubt that it does run cooler, but I'm just surprised at the level of difference. I don't have much to compare mine to except the stock setup, and it is about the same. It's also true that the 103 will run hotter than a 96 for a variety of reasons, and the bigger engine indeed has a reputation for that.

I presume you also have a different tune which may run a bit more efficient in the cruise range. I just can't think of a reason why 255's would achieve lower mileage than anything else given a good tune, and my experience with them has been good in this respect.

Well, that really doesn't sound like 255s at all. If anything, the feel in 6th gear is one of the first things people usually cite as a big improvement. I find that I can go all the way down to 55mph in 6th, which is about 2100 rpm, although I normally don't go below 60mph.

Could you post both charts? It would be interesting to take a look at them.

You're right and you did a good job of clarifying your points. Thanks for the input. With some of your complaints I can't help wondering if you might have had a tuning issue or crankcase sumping with your first build. Sumping will increase heat as well as stifle performance and mileage. There are some checks you can make for that, but it's obviously too late for that now. Installing the cams one tooth off their correct positions will cause problems too, and this happens more often than you might think, even with experienced builders.

 

I really appreciate all your input guys. I've for sure learned a thing or too. In my car hot rod days, I've over cammed more than once, causing me to chase other parts to compensate.

Right now, I'm leaning a little toward the SE-204's. For one thing, I spend most of my time in the 2,000-3,200 RPM range and hardly ever hit higher than 4,000 RPM's but when I hit the throttle, I want the bike to be trying to pull me off of it. My thoughts are (since I don't have actual data to compare to), better safe than sorry. I think the 204's performance will be ending very soon after my normal high RPM's while the 255's performance will be coming in just before my cruising range. I'm probably safe either way but feel better erring on the bottom end torque side.

Is there a better way to make this decision?

 

Your turn "boogaloodude" LOL!
(I love 255 cam threads! LOL!)

 

255's will pull strong to 4500.

mikebaby

 

I like the orange color.

 

http://i988.photobucket.com/albums/a...21120001-1.jpg

my dyno run with 255 cams

 

Now you've confused me, let me highlight what you've said and what HD say:

SE204 - midrange with peak HP around 5800 revs

SE255 - ultimate low end, great for heavy bikes or for the person who routinely shifts below 4500 revs. Peak power is still made over 5000

Do you want to reconsider?

 

I'm always ready to reconsider. If I have it backwards, I need to straighten that out so that I don't make a big and costly mistake. Is that the way it is?

 

You can debate all you want.....They flat out run out of steam after about 4200 rpm...done gone they are done working! I have had them in a 96 and now in a 103 and I hate em! As soon as they can be gone, they will. Much better choices out there unless you drive under said rpm levels. I would try 204's before wasting $$ on 255's.
And run to redline? No way........

 

Now come on, that cant be right......they fall right off after 4k??......lol Just like mine.....if you NEVER rev it up then dont worry about it, but if you do, run! run away and get something else.....