sns heads effect compression ratio?

[greenshovel0014]

I have an 83 fxsb. starting this thing has always ben a bitch. had rnr cycles rebuild the motor back in 97. they bumped it up to 11:5/1 compresion i think...... bike ran strong but always had quirky starting. This is a long story but I stuck a valve about 4 years ago.  funny thing was It would only stick when  i got it real hot. rear cylinder, thought it was coils and all kinds of other things. anyway i picked up a set of sns heads after an old timer told me i was sticking a valve. The bike would run fine until i got it hot the one cylinder shuts down. the sns heads ran strong and good  if i could get it started. I broke 4 teeth off the kicker gear .....replaced that had the hitachi motor twist itself off and break the inner primary mounting points. .....replaced all that  with new 1.4 kw starter all new gears. mounts. hit the button and nothing. replaced starter relay  multiple solenoids . little stupid spacers inside solenoids. starter fork  copper washer on inner primary  tried cut old primary cover. jammed a screwdriver into solenoid posts , i can get the starter motor to spin but not get the solenoid to engage as the starter motor spins. I jumped out the little post to the lower solenoid post and no go.yes new heavy duty cables clean ground, grounded starter. I cannot kick the bike over . I get it to the point where it starts to puke out the oil on the garage then i,m all done.  nothing has been changed to the bike since it used to start .    maybe a thick head gasket........ I gave up on it been sitting for 3 years riding an 07 which makes me sad.

[Hybredhog]

   11.5:1? is just to much for a street shovel, but you may be able to have the heads Machined for compression releases, or use the extra plug holes (if your S&S heads have them), for releases, if they're not being used for extra spark plugs. Another option is to change the cam to one with more overlap, and later intake closing, just need more details about the build, and whats a compression test tell you for poundage?...Jeff

[greenshovel0014]

you know Its been so long maybe it was 10.5/1 but  its high. only one spark plug. what range of psi should i be looking at when i  crank it over and it there a gauge i can purchase or make to fit in the spark plug threads? on the original build it has a sifton 107 cam was a low to  mid cam. bike has a dyna single fire dyna s? i think 2 5 ohm coils.  I had a shop try to fix it and they gave up but still charged me. back then ..2 years or so ago it would still kickstart  if it was in the mood. I even went as far as buying one of those manual solenoid plunger things but didnt use it because it would reqire the origional starter relay plus wiring from that gto an old style relay, plus it was plastic junk colored chrome. the hacksawblade trick doesnt work.(iused a battereycable as a jumper)  stock 80" bore. belt primary,stock. have some time on my hands now to work on it as i,m laid off and probably have to sell the dyna.

[Hybredhog]

   If its a kick only rig, if your over 180#compression, throw away your gym membership. But 190#- 200 should work with electric starters, much higher than that, compression releases are probably needed. A sifton 107 crusader ain't bad for what I sugested, and has plenty of overlap, and the intake closes at 54abdc. And If I were to sugest something that bled of more presure, it'd be an Andrew #6, with a bit more OL & closes at 56abdc. It has .510 lift, but S&S heads should handle that just fine, but clearancing checks should be done for valve to piston. I've had good luck with the spyke 4 speed starters, with a Heavy duty remote starter button without relay, making sure the bendix shaft turns freely into the prim cover.

[greenshovel0014]

Thanks jeff , iam hoping to get to the root of this problem  but I wont be changing cams.This is just a long frusrating problem. and gotta dive back in it  batterey is probably kaput by now.  would at least like to get it kickstarted. cases prbobly have 2 quarts in em by now.

[hotham]

The right cam makes all the difference.  I like a late closing intake.  This does wonders for starting.  I run a Leineweber , and yes they are a little hard on the valve train, with their fast ramps, but never a starting problem.

[greenshovel0014]

a new cam  huh? Andrews #6 any other suggestions? guess i will look in the drag book. the sifton only had 440 lift   which was mild.

[stroker800]

  I have never found a bike that could not be started if built correctly,,,timing and cam timing will make all the difference no matter how high the comp...I've have 1 that wouldn't start do to a terrible port and polish job...My shovel is a 4 3/4 stroke kicker only ,,,10-1 ratio dual plugged single fire ignition,,,2-3 kicks after prime..My engine builder has a drag bike 108" with 17:1 comp ,,starts welll off of a stock starter.
Dave