How much compression can I run with an SE 203 cam, without needing
compression releases or having to deal with starter problems, detonation
or pinging? I have the 203 in the bike now,and will soon be adding S&S 95"
barrels,pistons and heads.
06 RoadKing easy cruising machine,not a race bike.

 

Anything over 9.5 is hard on the starter and related parts. I just redid a roadking with 203's and 9.7-1 without releases, 40k on build. Cracked the clutch hub teeth, added releases this time. Mike

 

The 203 is really designed for stock compression. By adding static compression, you will raise the CCP to the point where it will be hard starting and tough to tune. If you want to increase compression a bit, go with the 204.

 

203 has 36*intake closing and 204 has 34* intake closing so it would seem that the 203 would handle the higher compression better than the 204. I have used neither so could be wrong but based on intake closing which is the biggest factor in building ccp.

 

We sign off on that about 9.4.
If looking to get more from the cam, then headwork may be a viable option, or even change that cam out, to one of the many available bolt-in grinds that'll have MUCH more on tap that the 203. Something to think about.
Scott

 

when you say "S&S 95" kit & heads,are you doing S&S heads also? we`ve used S&S .570`s with great results.would really compliment build for a nice,very well behaved touring bike(203`s wont be your best choice,the S&S head/piston combo would be at the high end of compresion cams would tolorate)
kirby

 

If in fact, the purchase of the S&S components has not already been established, then you can take your OE cylinders to 98", re-work your existing cylinder head castings, and with the advent of either a Wood 6 or 7H, the power delivery will come off idle, and rip thru the entire rpm band.
More that that?? Install the 400 cam of his.
Scott

 

if you are just looking to install a cam 9.4 compression is ok anything higher you may need releases. espeacially with softtails they have a smaller battery then touring bikes .
i ran my build at 10.0 with no releases but kept battery charged with a good tune.
if you want to stay at 9.4 compression use a woods 6 with a 4degree advance or go with a T-Man 525 cam . bolt in with stock heads. will work fine .

 

Totally wrong.
The last thing you want to do with a 204 is increase comprssion. The extremely early exhaust closing raises static compression considerably. Any more added compression will result in pinging and be very tough to tune.

 

My dad had a 06 Ultra with 95" and 204 cams. We sent the heads off to Hillside and had them mill them to get 9.7 compression with a .030 head gasket and do a port cleanup along with a good valve job. I used a Head Quarters Protuner and SERT to tune it. The bike ran strong with no ping experienced once I got it tuned, it would pull almost as hard as my 95" Head Quarters Touring build. He road loaded and 2 up in 95 degree weather in mountains with no pinging. At one point while we were out west we had to fill up with middle of the road quality fuel with no pinging. Someone who understands how to get the timing and fuel right can tune it with no problem. I didn't manage the ping by killing it with fuel either because it would get 43 - 45 mpg if you kept no higher than 70 mph.