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've learned a lot of lessons the hard way on this project, one of them being the down-side to centrifugal compression release cams. Like you said, inability to get accurate CCP complicates diagnostics.
Glad to hear your high temps haven't taken out pistons. With Harley killing the rear cylinder at well below 300 degrees to keep it cool, I worry about longevity. Once I get this sorted out, if the rear is still running very high 200's+, I'll probably install a set of fans to help keep things cooler, just to improve the chances of getting more miles from the build.
Mind you those temps were at idle and not running down the road. I'm sure I was cooler down the road.. but never checked that...
I've learned a lot of lessons the hard way on this project, one of them being the down-side to centrifugal compression release cams. Like you said, inability to get accurate CCP complicates diagnostics.
You can get accurate CCP measurements with EZ start cams. Unplug the injector on the cylinder to be tested, remove spark plug from cylinder to be tested and insert compression gauge, leave spark plug in other cylinder, start the motor and let it run for second. Boom, accurate compression reading on the gauge.
EDIT: Read the OP again and noted that Z says he followed the above outlined procedure and got a reading of 130psi. Don't know what he should have gotten but do know that 130psi is too low. If the procedure was followed correctly and the gauge is accurate, the readings should also be accurate. I am thinking a do-over on the compression test is in order with perhaps a different tester or verification that the gauge being used is accurate.
Oh and, to your question about how it runs: It runs great as far as I can tell, but I've been very gentle with it so far, as I'm breaking it in per the S & S instructions. That said, once the temp on that rear cylinder starts climbing, I start getting what I believe is valve train noise.
Noise after warm up indicates an oiling issue. Kirby's suggestion to check oiling jets is good. You might also check rear lifters, pushrods, etc... to make sure your getting good lubrication to the rear.
Checking piston oilers is worth doing as part of the process of elimination and high rear cylinder temp could be an oiling issue but noise usually points to other issues, not oil related. If a noise is due to lack of lubrication, disaster usually follows rather quickly. I am still thinking timing may be the reason for the higher temps as well as responsible for the OPs previous and similar problem.
Thanks DJI, as always I appreciate you giving consideration to this.
With the same factory timing in both cylinders, and with one cylinder running 100 degrees hotter than the other, physics points more strongly to an oiling issue than to a timing one, though I absolutely agree that my timing needs to be addressed.
Thanks DJI, as always I appreciate you giving consideration to this.
With the same factory timing in both cylinders, and with one cylinder running 100 degrees hotter than the other, physics points more strongly to an oiling issue than to a timing one, though I absolutely agree that my timing needs to be addressed.
Posted some thoughts in your other thread but thinking you might want to consider tossing the PCIII USB for the PCV; I believe it is available for your application. With the ignition module the system does allow AFR and timing adjustment by cylinder.
the PC3 also allows for timing adjustments on HD models, same as the PC5.
the PC5 has some advantages over the 3, but they would not be related to the OP's issues.
m
the PC3 also allows for timing adjustments on HD models, same as the PC5. the PC5 has some advantages over the 3, but they would not be related to the OP's issues.
m
Not my area of expertise but reading about both, seems to me the PCV with the ignition module might be more user friendly for the OP but WTFDIK. Still think the OPs issue is timing though.
the PC3 has the same ignition control built into it as the pcv, think of it this way, all powercommanders are " four channel" devices. for hd, 2 channels are used for fueling and 2 for timing, therefore 4 channels total.
on the jap 4 cylinders, they need all 4 channels for injectors, so the ignition module is an additional add on unit. some of the jap twin units have timing in them also.(PCV).
for the jap and euro bikes with 8 injectors the offer something called the secondary fuel module, that talks to the base PC to gain control of all 8 injectors. DJ Can network.
the pcv has the Multi-Function hub built into it, allowing other functions like nitrous, boost mapping etc, to be enabled in the unit, the pc3 does not have this, that was why for the older bikes the multi-function hub was an additional unit, that wired up to the pc3 to make things work. just for the record, this is how my Busa w/nitro is set up, and it does work very well.
And I also think the OP is having timing issues, so we are on the same page there!
m
My ThunderHeader head pipe is at the welders getting the stainless O2 bungs welded in for my Innovate Motorsports data logging setup, so I should have mixture data sometime this weekend.
I'm not sure how common this difference in head pipe discoloration is, but to my inexperienced mind, it's just evidence that the rear cylinder is running much hotter than the front.
While this is being done I'll be trying to track down timing tables for a similar build.