Working on an S&S 124HC crate motor. Thing is tuning in really weird. VE's are way off what I'm used to seeing. Bike has S&S 640 EZ start cams. Pulled a CCP test and a dynamic compression test. CCP came in at 145psi rear, 170psi front. Dynamic was 120 rear, 150 front. Leak down was at 3%front and 5%rear. I know the EZ start cams throw CCP off but is this far off front to rear normal? The numbers look to me like the cams are a tooth off. Any ideas?

 

Don't know if cams being a tooth off are the problem but with 25psi difference between cylinders, cam timing would be worth checking out and easy enough to do.

 

That was pretty much my thoughts. This engine has around 20 miles on it but it's had probably a dozen different peoples hands on it before it came to me. They've been trying to get this running for the last 9 months or so, whole nother story there, but it's now running and supposed to be with me just for a tune. Something isn't right here though. Just trying to make sure I don't have a mechanical issue somewhere before spending more time on the tune. Another note is that the IAT numbers are coming in really high. 90-100°c when engine is only at 80°. Almost feels like it's pulsing out the intake.

 

I don't mess with EZ start cams and by what I hear trying to get a reasonable compression test is difficult at best.. I would start with a New IAT sensor.. Reading 100*c at ambient temp is out of line.. I would start there..

 

20-25 psi difference is usually a cam 1 tooth off.
Scott

 

Maybe I am missing something . Someone purchases a new crate engine. It does not run right. Why the heck are you even messing with it. Left them fix it. 9 months someone got screwed screwed. S&S does not sell you a create motor then ignore you when it does not run right.
They would have it figured out in flash . The rest of this story may help a lot.

 

The guy that owns the bike had friends install it. The place he bought it from drilled the case so that external oil lines wouldn't be needed. Drilling the cases voids the warranty. They also installed a grudge box at the same time. Could never get it to stay running so they gave up and took it to Harley. After 6 months or so at Harley one of the corporate tech guys asked if they'd checked the speed sensor. Turns out with the grudge box there's a spacer that needs to go under the sensor. This wasn't installed so the sensor got chewed up and was shorting everything out. Fried the ecm and caused all these issues. Harley made the repairs for all that and got it running. It was then trailered to me for a tune and here we are.

 

Wow that's quite a history, all the more reason to check that sensor it shouldn't be putting out those temperatures You got to remember it's a potentiometer so it's very likely it got fried as well..

 

Good point will need to check that out.

 

Any way the ez starts could be causing the difference? I'd think they would still be equal with or without the ez starts though.