Topic: 750: How would you build the engine with these parts?

[Garage_guy_chris]

Well i have collected a bunch of different go-fast goodies and i cant decide what to build so Im asking the forums help. Pick your parts from my list, quick explanation as to why and if you think i need a supporting mod like stronger rods or HD cam chain please suggest away. 

All this will be added to a completely rebuilt bottom end with new bearings.

What i am trying to achieve is:
- a reliable engine that will go 30,000+ miles without having to worry about stuff
- a fun well rounded machine that will cruise at 120kmh or 75mph all day and be a hoot in the twisties
- good power band throughout rev range
- wont be a pain in the butt to setup and tune and keep that way (igniton and carbs)
- easy to start electrically and kick

Here are the available "option" parts

Pistons:
- Wiseco K811 kit 811cc 10.25:1 compression
- Cruzin image 836cc flat-top kit works out to 9.5:1 compression

Head:
- 70-71 style head fairly fresh rebuild with all OEM parts and tower bolts heli-coiled
- 72-74 style head with manley stainless valves, springs, retainers, and tower bolts heli-coiled

Camshaft:
- Kenny Harman "D" grind
- F2 stock cam
- Mid K stock cam


Other:
- machined flywheel with Elec start delete
- Kibble white studs (are getting used no matter what)

[HondaMan]

My votes:
First choice: 811cc kit with mild K cam in stock position, or perhaps the F2 cam, but advance it 3-5 degrees with a slotted sprocket. Polish the valves, use the K1 head (it was likely hand-ported by Honda techs), bronze valve guides from APE, stock springs, lose the lock-down bolts on the rocker shafts. This will give you the best shot at both 30k miles and a dry engine, in my experience.

Or:
The low-compression 836cc pistons with either of the above cams, the fancy valves with STOCK valve springs, and again the K1 head. Get an extra head gasket: you may find it weeping oil in about 20k miles, requiring a new one.

For both versions: use APE HD studs for a drier engine, so you can torque the head to 20 ft-lbs. in the end. Be sure to mill the head flat, and not too smooth (i.e., don't polish the tiny milling grooves away from the mating surfaces - they help seal it).

[RJ CB450]

Assuming both use same crank still, reliable to me is lower compression and the lower torque curve camshaft.  Head, that stuff doesnt to me make too much of a difference since I dont follow 750s to know the difference in model design.  Maybe lower final drive a bit to keep cruising rpms down a bit?

Overall, the parts themselves have little say if same in quality.  Proper assembly is what will make the difference.

Lower compression means easier start as well.

[Jerry Rxman Griffin aka MuthaF'er]

811 with the higher compression (still mild mid-range as far as compression)

Head with Manley valves and stronger springs as long as it's good and F2 cam which likes stronger springs

Stock rods will be fine

APE studs ditto

Tsubaki Camilla cam chain - they are cheap, it is new and stronger. Why not while you're in there?!

Reliability should only depend on how you ride it. I used my 811 kit with Manley stuff and Yoshimura Daytona cam for 30,000 HARD miles. It was getting loose as the stock studs were stretching. It'd do 10,000 rpm quite often and the stronger springs prevented me from floating another valve thus not destroying the engine again.

[Garage_guy_chris]

I totally forgot about the studs i have the kibblewhite studs sitting here ready to go in too.   Good suggestion on the Tsubaki Camila chain (BF05M-94) i was thinking a heavier chain might be a good idea.
 

[Old Scrambler]

Stay on the mild side of things for reliability and long-distance. I would add the latest cam-chain and tensioner system from Cycle-X. Depending on the age and mileage of your motor, you may want to add the Cycle-X primary tensioner up-grade..........and have a bottle of BLUE lock-tite handy.

[Garage_guy_chris]

Ive been thinking about the engine a fair bit and im leaning towards the mild variant to favour reliability. But... a part if me wants to build a juiced up hi-po mill. 
Hypothetically if i was to put together:
- 10.25 : 1 811cc wiseco's
- 72 - 74 built manley head
- kenny harman D grind cam
- kibblewhite studs
- tsubaki hd cam chain

What sorta lifespan and issues could be expected from such an engine?

[trueblue]

How long is a piece of string?
Too many variables involved, number one being how you ride it. If you wring its neck everywhere you go then it isn't going to last anywhere near as long as if you ride gentle and only wind it up high in the rev range every so often.

[HondaMan]

Stay on the mild side of things for reliability and long-distance. I would add the latest cam-chain and tensioner system from Cycle-X. Depending on the age and mileage of your motor, you may want to add the Cycle-X primary tensioner up-grade..........and have a bottle of BLUE lock-tite handy.

This brings up a point I am also interested in: has anyone run the new CycleX cam chain tensioner for any length of time?

[Jerry Rxman Griffin aka MuthaF'er]

Sounds like my engine. I put 30,000 hard miles on it WITH stock studs. The stock studs were my weak link as they were stretched when I took it apart. Had some lightly tightened stud nuts and some loose ones. Leaking and lower compression.

My guess is if you do it right it'll last as long as you want it to. Doesn't sound like you're going to be racing much so you should be fine.

+1 on what Hondaman asks. These things are basically 'field tested' for the most part. 

[ekpent]

A friend of mine had the Wiseco 811 with a stock cam and it ran very well and was easy to dial in the carbs. He rode it hard and never had any engine issues. You will definitely appreciate that little bump in compression. A hypo cam may change your torque curve and you may sacrifice some low-midrange grunt where most of your riding is.

[SkullCrusher]

Don't be afraid of compression. I built a motor with the cycle x 850cc 10.5:1 pistons and it starts fine...one kick usually. Also running cycle x race valves in a completely rebuilt head with bronze guides and re cut seats with a mild port and polish, cycle x cx3 cam, cycle x cam chain tensioner with stock chain...don't see how a chain that's been bathed in oil it's entire life is gonna fail...anyway the starter pushes it easily and you can stomp - start it pretty easily