No spark! New Build

I don't know for sure what tells the ecm there is no compression...I would have to guess that the speed of crankshaft revolutions without plugs while trying to crank the bike will not allow it to fire.
 
That's right. I read something about the slowing of the crankshaft on startup indicates there is compression. I will also check compression today and make sure all valves are closing all the way. The instructions on the adjustable pushrods made me think that a valve could be open. When I pulled my previous pushrods with the cam on the base circle, I could turn the pushrods by hand. The new pushrods will not allow me to rotate them by hand after adjustment. Maybe this is how it's supposed to be, but I think that checking compression will give me that answer. I'll start back to the bike at around 10:00 after some yard chores.
 
I also checked the pro super tuner for fault codes and there werent any. That's a nice little feature that I didn't expect. I had some historic codes that I am thinking triggered when unplugged and replugged a few things. Throttle position sensor was one of the codes. I'll check for codes periodically today. I really don't want to remove the throttle body unless absolutely necessary. That thing is just a PIA! Dont' want to have to drain the tank again either.
 
Harry?
Did you clearance your rocker box covers for the valves to full open/close?
I didn't do it on my HQ 107" build...couldn't get it to start.
Called PhilM & Dalton, they both asked that question.
If the valves don't close, you get no compression...thus, no start.

If you didn't clearance the covers, no need checking compression.
Take the covers off and clearance.
 
BadPiggy,
Before I did the build, I specifically asked that question on the HQ forum. I got a resounding "no, we never had to do that". They just said to make sure that the valve has room on the lower rocker box covers, which they did. I don't get a tapping sound when I turn the engine over, so I will check compression first. The only problem that I have with removing the rocker box covers, is that I will not be able to torque them to spec after. I'm not good enough. haha. If I don't have compression, I'll pull em and clearance.
 
yep, 575s. I got no compression on the rear cylinder. I didn't bother to check the front. I double checked that the compression guage was working with my Air compressor. I lucked out and had an adapter for it that fit the spark plug hole. Are you sure that pushrod adjustment couldn't be the culprit? Like I said, the old pushrods spun around with my fingers when the cam was on the base circle. At least I am getting steered away from nightmare electrical stuff and in a direction where a wrench might solve my problems. haha Will check back after a while. Thanks for all the replies. I really do appreciate it.

harry
 
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