Engine configuration ideas

[Dunc]

So, I have acquired a Long Rod conversion kit, 80mm Ross pistons, CR500 rods with gudgeon bushings fitted & crank pins with bearings. I've pulled down the 1978 engine I got last week to prepare for building it & ordering stuff as I go along. Plan is to re-sleeve barrels for the pistons, Smedspeed valves & a good tidy up of the ports. 34mm VM Mikuni carbs. Ignition/Charging will be either a Hugh's or Vape to suit. I have an adjustable cam sprocket for stock cam as well.

Do I 277 re-phase as I have a Shell cam from Heidens to fit already or leave it 360 & get a different cam?

 

[650Skull]

How Manny CC's ??

 

[Dunc]

Seven fiddy

 

[Signal]

Great project somethings for you to consider.
Ignition:
If you opt for a rephase you may be limited (for off the shelf items) to a Vape ignition as the last I was knew Hughs CDI did not have a rephased option. The 277 Vape is considerable more expensive than a standard Vape.
There are many more ignition options available for standard 360 timed bikes.
Cams
Grizld1 a very knowledgeable forum member who tried a similar design of of cam shaft to the Hieden 277 (as pictured on his website) removed the cam after it caused what he considered excessive vibration. He thought problem was caused by the two lugs that act as the sprocket boss.

There are more used performance ground cams for standard timed motors around and they do come up for sale from time to time.
A Webcam 59A is basically the same grind as a shell #1 if you see one for sale.

The adjustable sprocket is nice to have as you can get the cam set where you want it easily and you can compensate for a skimmed head or thinner gaskets if you need to.
Dont forget the springs the last lot of kibblewhite springs I bought were pretty pricey as well.

I have built one long rod XS 650/750 rephased. It goes very well.
The kit I used was from 650 central it uses KX 500 rods a bushing in the little end and special pistons. The cam was a Megacycle 250-30 which for a performance cam idled really nicely.
Please keep us informed of you progress.