When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Top end big bore - compression not what it should be?
Engine Mechanical TopicsDiscussion for motor builds, cams, head work, stripped bolts and other engine related issues. The good and the bad. If it goes round and around or up and down, post it here.
I haven't been following but the OP has said the 570s feel soft on the bottom and the butt dyno doesn't feel like the 100/100 expected numbers have been achieved. Not experienced with the 570 cams but at 9.6 corrected and CCP at 202psi I wouldn't think the 570s would be soft on the bottom. That much compression could be a tuning challenge but could the motor be sumping causing the "soft" bottom?
I did 105ft.lbs, 93 at 2200 in a stage 2 103 with the stock staggered head pipes and Rush slip ons.
Wow, I know I'm only at 96" but there is no way I'm getting anywhere near 93lbs TQ at 2200rpm. Either my tuning / jetting / timing is way off or there's something seriously wrong with this build.
Youve been asked several times about the possibility of sumping but youve never acknowledged that youve checked it.
So, to check for sumping on a softail I take it on a ride and then when it's hot just pull the crank case drain plug and measure how much oil comes out?
I haven't been able to ride the bike the last few days. Bad weather and I've had the clutch and primary apart.
Thanks
So, to check for sumping on a softail I take it on a ride and then when it's hot just pull the crank case drain plug and measure how much oil comes out?
Tried today, but the crank case drain bolt would not budge, even with a braker bar. If I wrench on it any harder I feel like I will crack the case.... I don't feel like it's a sumping issue, as the performance does not ever change, it's not like I suddenly lose some power mid way through a ride. I've done 500 miles and it's never fluctuated.
My gut says its a combination of not yet having a proper tune on the dyno and the effect of having a cam that has too much exhaust duration.
Is #1 in the attachment the plug you have tried to remove?
If the motor is sumping it won't suddenly lose power; it will be sluggish, like dragging an anchor and it will heat up faster as well. You have been in the cam chest and could have mis-aligned the oil pump or botched up the scavenge port o-ring, or both.
Softails gravity drain oil from the tank to the sump when left siffing for a few days so you will need to take a ride and get the motor up to operating temps to check for sumping. Have you done that? If not, the plug may be easier to remove at operating temps; it shouldn't be that hard to remove.
JMHO but you need to know if the motor is sumping or not before you get the bike on a dyno, cam change or not. A good dyno operator should be able to tell if the motor is sumping and will not proceed with the tune if the motor is sumping.
Is #1 in the attachment the plug you have tried to remove?
If the motor is sumping it won't suddenly lose power; it will be sluggish, like dragging an anchor and it will heat up faster as well. You have been in the cam chest and could have mis-aligned the oil pump or botched up the scavenge port o-ring, or both.
Softails gravity drain oil from the tank to the sump when left siffing for a few days so you will need to take a ride and get the motor up to operating temps to check for sumping. Have you done that? If not, the plug may be easier to remove at operating temps; it shouldn't be that hard to remove.
JMHO but you need to know if the motor is sumping or not before you get the bike on a dyno, cam change or not. A good dyno operator should be able to tell if the motor is sumping and will not proceed with the tune if the motor is sumping.
OK, will do.
Yes #1 is the drain plug I was attempting to remove. Well not be able to get to it for another few days. Will report back.
Thanks
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Slideshow: The bar-and-shield logo shows up on far more than motorcycles, some of the company's most unexpected products have nothing to do with riding.
Slideshow: From the troubled AMF years to modern misfires, these bikes earned reputations for reliability issues, questionable engineering, or disappointing performance.
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Slideshow: The Swiss custom shop has taken a Harley Softail and stretched it into something so long and low that it looks closer to a rolling sculpture than a conventional motorcycle.
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Slideshow: A standard cruiser becomes an intricate metal canvas in the hands of a Swiss custom house known for pushing Harley-Davidson platforms far beyond their factory brief.
