J&P Community

  Can anyone tell me how to set the static timing on a 1981 Sportster?I put the dynas in it and just cant get it set right.Sounds great idling but just dont have any power.Also will you actually loose compression when seatin rings or do I have a problem there also,I put new rings in and only put on about 25 miles but checked compression and is lower than when I first put them in.... 

 framer1994

The attached link is the installation instructions for this unit. Instructions. When you talk about a loss in compression what is the % lost of the number of PSI on each cylinder? A number of things can cause a loss in compression. Here are some examples. Major loss-Poor Cam timing, Bad rings, Excessive Piston-cylinder wall clearance, ect.

Another common problem people fail to do when checking compression on a motorcycle that is fully assembled is to hold the throttle fully open to ensure adequate air is entering the motor. When you first checked compression of the motorcycle was the carb/intake on the motorcycle and were you holding the throttle all the way open?

If you checked it initially without the carb/air cleaner on and got one reading, then checked it after with everything installed and not opening the throttle that could explain a decrease in compression.

 I have timed and timed and retimed bike,pulled dyna-s out out points and old coil back on static timed it and runs like a completely different bike.Think I just got a bad coil with the dyna kit or somethin??With it in any rpms and it falls on the front wheel,with point the front wheel just about wont stay on the ground.............Has been like this the whole time I have had it in..

I checked the instructions dtodd (J&P staff) provided to you - I was supprised that it included the specs for testing your coil - small job and then you will know if you got a "monday morning" one.

Hope this helps 

PS: 25 miles is a little short for breaking in a set of rings (assumption you honed the cylinders first).

My local indy tells me that S&S had been recommeding to run a new engine easy for 50 miles, change the oil and cut the filter apart (look for bad stuff), run it for 500 miles varying the throtle position (keep it under 3200) then do another oil change & cut the filter.  Run it for 3000 miles varying throtle but no full throtle, change oil & cut filter.

then drive it like you stole it

Framer,

    What is the new coil's impedance?..........Regular rings should be seated in 6-700 miles. Chrome rings can take up to 1,500 + miles to seat............I H is right, in that you should not go wide open untill the rings are seated, and compression is up to par (no more than 1/2 to 2/3 throttle as you get some miles on it, and don't punch it), and don't hold at steady speed for more than a couple miles. Did you check the cyls. for out-of-round? Did you hone the cyls.? Did you check ring end gap? Did you mic for piston and ring size? How were the valves, seats, and guides?..................You should not see a drop in comp. If so, you may have already blown the break-in procedure and ruined the ring to cyls. seal with the way it sounds like you're running it. Most ring kits come with break-in recommendations.

framer1994

If you have a poor compression issue like stated above you could be chasing problems. What was your loss in compression? Also you mentioned you thought you had a coil issue. What coil are you running with the ignition.

   i bought the dyna-s point replacement form here so what ever coil comes with part number 380-623.As far as they way I rode it I wnet p the street and opened her up once so I really dont think that was a issue and I went with steel ring cause I think chrome one take too long to seat if they do.I have had problems with this bike ever since I got it and thought it was ignition related but found that was 25 psi different on cylinders(chrome rings didnt seat).Ran good round town but when got some rpms on highway it just wanst there so now I put points back in and runs alot better than the dyna junk I wasted many hours and hard earned money on...Just cant figure out if it wasnt timed right or just a weak ignition problem.I had static timed the dyna a million times and a million ways and it just never got better...

Framer,

  I have installed the Dyna S in a few bikes and never had a problem. Take a compression check again (dry), then squirt some oil in the cyls., and check again. Let us know what the readings are to further analize your problem.

 well maybe I got the one in a thousand that is bad I dont know but I have had nothing but problems with it since I put it in.I can never get the timing right.I am going to put some miles on it before I do another compression test as I prolly on have 30 miles on it with the new rings.The cylinders were bought as a matched set with pistons from weisco so if they are out of round already then shame on weisco,the bike didnt have more than 1500 miles on it when I tore the top end off cause the chrome rings didnt set completely in the front clinder.When I mentioned the loss of psi this time I didnt wot it when check and bike was completely together.when I check it upon building I didnt have intake carb exhaust or any of that on it so that prolly explains the difference, I just think I got a junk ignition.The coil ohms out low so I know something is going on with it just a shame I wasted almost over a year with the techs here and at dynatec telling me to set timing and that never seemed to help......