CC compression ratio question
Thread Starter
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Intermediate
Joined: Jul 2019
Posts: 39
Likes: 5
From: Sante Fe New Mexico
Awesome, you da man. That is exactly what i was looking for. Many thanks for your help.
Road Captain
Joined: Mar 2020
Posts: 654
Likes: 356
From: Sierra foothills
Find out what cams you have and if installed properly. What tuning device you might have. Are pistons flat top or domed. Otherwise it's all just guessing
Might all have been solvable by a good tune
Thread Starter
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Intermediate
Joined: Jul 2019
Posts: 39
Likes: 5
From: Sante Fe New Mexico
I couldnt find the usb, but its your standard usb that you plug into a computer. This is the envelope it was in.
HDF Community Team
Joined: Jun 2006
Posts: 12,774
Likes: 2,606
From: san antonio
I agree with 98HRFB and should have made the suggestion in my post #5. A compression test is in order; let's see what actual CCP and come up with a plan from there. CCP could be 200psi+ and if so, a cam change and retune should solve the problem. Removing material from the head chambers is just not a good idea.
Thread Starter
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Intermediate
Joined: Jul 2019
Posts: 39
Likes: 5
From: Sante Fe New Mexico
You do not want to remove material from the quench/squish area. Increasing effective head gasket thickness beyond. 040 will likely cause more pinging due to inefficient combustion. ..
Find out what cams you have and if installed properly. What tuning device you might have. Are pistons flat top or domed. Otherwise it's all just guessing
Might all have been solvable by a good tune
Find out what cams you have and if installed properly. What tuning device you might have. Are pistons flat top or domed. Otherwise it's all just guessing
Might all have been solvable by a good tune
Thread Starter
|
Intermediate
Joined: Jul 2019
Posts: 39
Likes: 5
From: Sante Fe New Mexico
Go back to post #5. The quench area is the area outside the red line which, if I understand, is the area the OP is considering removing material. It has been pointed out twice now that removing material from that area will reduce compression but most likely will not eliminate ping, possibly make it worse. 10 to12 ccs being removed from that chamber volume inside the red line is a lot. Dropping the valves would increase volume some but not 10-12 ccs.
I agree with 98HRFB and should have made the suggestion in my post #5. A compression test is in order; let's see what actual CCP and come up with a plan from there. CCP could be 200psi+ and if so, a cam change and retune should solve the problem. Removing material from the head chambers is just not a good idea.
I agree with 98HRFB and should have made the suggestion in my post #5. A compression test is in order; let's see what actual CCP and come up with a plan from there. CCP could be 200psi+ and if so, a cam change and retune should solve the problem. Removing material from the head chambers is just not a good idea.
Road Master
Joined: Mar 2013
Posts: 817
Likes: 380
From: Central Ohio
Continuing the shape of the chamber into the quench area shouldn't be a problem, just makes it closer to a hemi. If all you did was open up the flat surface and increased the piston to head dimension that might be a problem.
Road Master
Joined: Mar 2013
Posts: 817
Likes: 380
From: Central Ohio
More than likely the manufacturer marks are on the other end. But you should be able to tell if they're aftermarket based on the lobes. Maybe just pull up a pushrod cover to see if it has adjustable pushrods
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Road Captain
Joined: Mar 2020
Posts: 654
Likes: 356
From: Sierra foothills
Start with compression test. With compression releases disabled.
See if it has adjustable pushrods. If so, pulling cam plate with cams is probably easier than pulling heads. If not, you'll also have to pull rockers too.
I didn't see any envelope. Was there any writing on it?
A stock Harley with stock tune is going to ping on 87 fuel. Especially if air cleaner, exhaust were changed. Talk to some tuners. See if they can tune for 87 octane.
I have a friend who lives north of you near Angel Fire. Over 8000ft. elev. Spends winter at the beach. He has no issues with ping. But his bike has been dyno tuned and he uses premium
Kind of hard to modify an engine around an unknown tune
See if it has adjustable pushrods. If so, pulling cam plate with cams is probably easier than pulling heads. If not, you'll also have to pull rockers too.
I didn't see any envelope. Was there any writing on it?
A stock Harley with stock tune is going to ping on 87 fuel. Especially if air cleaner, exhaust were changed. Talk to some tuners. See if they can tune for 87 octane.
I have a friend who lives north of you near Angel Fire. Over 8000ft. elev. Spends winter at the beach. He has no issues with ping. But his bike has been dyno tuned and he uses premium
Kind of hard to modify an engine around an unknown tune
Last edited by tdrglide; Oct 13, 2022 at 04:44 PM.
HDF Community Team
Joined: Jun 2006
Posts: 12,774
Likes: 2,606
From: san antonio
There may be enough of the ID exposed on the front cam to see it but it can be hiddent behind the rear cam chain sprocket and the sprocket will have to come off ot see the cam nose.
