New and in need of help

Discussion in 'Sportster Models' started by cmoore, Nov 22, 2008.

  1. cmoore

    cmoore New Member

    When setting timing in correct positions am getting backfiring through intake and rocker box leaks, no excessive pressure in oil bag, also, when installing pistons, put pistion 'tangs' small lines on underside of piston towards primary belt side drive. Both manuals seem confusing on this point. Is this causing crankcase pressure to be wrong and causing oil leaks? Holes in gaskets and cyclinder line up. Doesn't seem to be a carb problem because simulated same problem with two different carbs. Static timing also set and no low rpm and backfires through intake but upper rpm revs okay. Could this be a valve problem?
    How do you set top dead center for setting the cam timing on 1975 Shovelhead because of two marks on the pinon gear of crankshaft?
  2. the draggin

    the draggin Active Member

    Man you're making this tuff, and what makes it harder is someone hooked off with my factory manuals. To find top dead center go to the primary side of the engine, right at the point where the cylinders coverge there is a bolt or plug, remove this plug, there are marks on the crank that you can see, I believe one is a 0 and the other is like two lines, you use these to set running timing of ignition, so they will give you a point of reference for TDC. Now take out the front spark plug and using a TDC idicator tool ( you can get this at your local bike shop they have them in catalog) or you can carefully use a 6 inch screw driver and observe the movement of the screw driver as you rotate the engine, when it reaches its highest point coming out of the spark plug hole you will be at TDC. Now, check in the hole at the base of the cylinders, make note of the mark it should be bysecting the hole at 12 and 6. Now go to the cam side and see where the pinion marks are. One should be at 12 o'clock the other might be at about 10 o'clock ( this is where it gets fuzzy). You can go to the Andrews performance web sight and get instructions for the setting up of cams and timing marks they are great at providing info. but it sounds as if you have the breather out of time for the internal pressure problem. The back fire sounds like a vacuum leak. I wold check to make sure intake o-rings are in properly, I have had them slip while tihtening the clamps and that would give you the backfire at low rpm and would seem to clear up on the upper rpm.