[ace.cafe]

I looked at your photo of the stock intake from your other thread. It appears that the manifold ID is quite a bit larger than the port, and it has a relief cut for the injector spray in the top.
What is that diameter, and might it be suitable for a gasket matching strategy?

Also, what size diameter are the throttle bodies?

I just feel that the port is just too small for the displacement. I really estimate that 32mm would be about right.
Maybe just try a very slight port roof raising, just a little, and see if it helps the port shriek?

Thoughts?

[Gremlinsteve]

Ready for assembly

[Gremlinsteve]

I feel like this weeks worth of work is really good results. Maybe a another head and a couple more aggressive grinds and I may exceed 200 cfm

[Gremlinsteve]

I also agree on raising the roof
I’m limited to stock t bodies for now though

[ace.cafe]

Cool!
Let's see how she goes.
 

I'm gonna guess 60hp at the rear wheel.
 

[Gremlinsteve]

I’m shooting for 70

[ace.cafe]

You'll need some rpms for that.
Let's see where it's at with what you have.

[Gremlinsteve]

Anyone interested in port work get with me
I’m game for doing more of these things

[ace.cafe]

Anyone interested in port work get with me
I’m game for doing more of these things

You're the first into the game, and you showed all your work and documentation, which is a very good presentation.

[Gremlinsteve]

Small fish I am

[Arschloch]

865cc is going to be massive engine, if you land up with let's say over 60hp at the wheel a dual disk front brake would be neat.

Good on RE that they replaced the cropped spoke hub on the rear with something similar as on the front wheel with straight ones. Nothing more annoying than snapped spokes.

[Gremlinsteve]

Well.  A quick update


I’m awaiting my cyl the be bored and then have the new liners installed
Machine shop I’m using will be done this week I hop

[Jared_Lee]

Question, it appears you've needed to do a lot of additional work to ports, valves, possibly new throttle body, etc. to get optimal performance from the 865. Was the kit not designed to be plug and play? What I mean is, is it understood by manufacturer and consumer that you cannot just bore out for the new cylinder sleeves, replace the pistons and then EFI tune for quality performance? I'm interested in exploring a big bore option, but this is well beyond my engineering knowledge and I don't have a shop I trust to blindly follow into this type of work.

So the real root inspiration for this - would the 750 kit require less additional work than the 865? What I'd ideally be after is a big bore kit, coupled with S&S cam, EFI tuner, open headers and cat S&S mufflers (at the end of the day, I do care about running my motorcycle with unrestricted emissions). That's it. Can this be accomplished effectively by just boring out for the 750 cylinder sleeves, replacing the pistons, replacing the cam and then tuning the EFI? A little adjustment beyond that aside, no other engineering to ports and valves and boring other parts of the engine to change characteristics and its performance.

Sorry if I'm derailing the thread from Steve's 865 project, but it seems to me that the best engineering eyes are on this thread and I'm hoping for a knowledgeable response. And please, to the others, I don't care what you would or wouldn't do or what other bike you could buy with the money, etc. Please save it.

[ace.cafe]

If I can be permitted to jump in about your question, the answer is yes, you can just do the barrel/piston, or you could do barrel/piston/cam, and an EFI tune to suit.
That can be done.

However, there are certain things to be expected from certain mods, in terms of engine behavior.
With a big bore kit and tune, the basic result will be much higher compression, resulting in higher torque/hp thru much of the rpm range, but the rpms for peak tq and peak hp will be somewhat lower than before. The overall rev range will be shifted downward due to bigger displacement being served by the same breathing capacity as before.
So yes, more tq and hp at the revs you can still reach, but lower max rpms than before. More of a puller than a revver.

Add a cam, and it can make up some of those lost rpms by providing more breathing time for the cylinder to fill, even if the head still is unmodified.

Add some port modification, and the revs and power curve can climb higher yet, due to more flow into the cylinder during the time allotted by the cam.

And each stage would need its own tune.

You can take it to whatever stage you want, but you should be aware of the effects you get at each stage. These are just basic descriptions given, but are intended to provide general expectations from certain mod stages.

Hope that helps.
Obviously, I don't intend to be the only responder to the question, and I look forward to hearing what others may have to say on the topic.

[NVDucati]

Question, it appears you've needed to do a lot of additional work to ports, valves, possibly new throttle body, etc. to get optimal performance from the 865. Was the kit not designed to be plug and play? What I mean is, is it understood by manufacturer and consumer that you cannot just bore out for the new cylinder sleeves, replace the pistons and then EFI tune for quality performance? I'm interested in exploring a big bore option, but this is well beyond my engineering knowledge and I don't have a shop I trust to blindly follow into this type of work. /SNIP/

This video (Reverly Cycles) gives a overview and more specifically speaks to you question at about 7 minutes in.
https://www.youtube.com/watch?v=N7nHqVu5npE