Putting a S.E. 103 together. How much "down" in the cylinder is too much for cr 575 cams ? Supposed to be @ 10.3:1 compression.
Take all your info and run it through the Big Boyz compression calculator. You'll need to know your head CC's, deck height, piston info (incl valve relief), bore and stroke (select 103 cu in the calculator).
If you have set your pistons to zero deck height you need to know your valve lift at TDC and the valve pocket depth of your pistons from manufacturer specs. Best thing would be a clay check.
Armin.
Randy, Hyperformance has a youtube video how to check P to V clearance. It is a better method than clay. The clay method can bend valves. When I have everything here it is easy to check with the barrel on top of the head with trock to open the valves and clay on the domes then just shove them in.
Quote from: Pop-pop2 on April 06, 2019, 03:56:37 PM
Putting a S.E. 103 together. How much "down" in the cylinder is too much for cr 575 cams ? Supposed to be @ 10.3:1 compression.
Several calculators out there to help.
We have several of the Craig Walters versions.
:oops: Ok, my bad. :bf: After seeing the replies, my question should have been. How far can the "piston" be down in the cylinder ?
Flush with the top is best. You can use a thinner head gasket to offset a few thousanths down the hole. If you have the heads off, why not machine them to zero deck?
:agree:
Already sent them off an got them back. Didn't know to measure them when I took it apart.
I never had to worry about that with diesels, so I didn't measure it. Putting it back together with. 030" head gaskets. Heads are ported, forged pistons. Trying to do it right, just don't know if pistons .007" below the deck is going to be a problem.
Zero Deck height with a .030 head gasket gives you an optimal quench area....
I would be sending the cylinders back and have the .007" trimmed off if it were mine.
Quote from: PoorUB on April 08, 2019, 06:23:46 PM
I would be sending the cylinders back and have the .007" trimmed off if it were mine.
I agree.
Piston to valve is so basic and simple to do , you need nothing but a basic caliper and masking tape.
Remove valve springs set head on cylinder with No gasket.
Take the Valve and push it down until it makes contact with piston . Take your tape and put it on valve where the seal is at do this on the other valve as well
Remove head measure with caliper . It will get you as close as you need . Add in HG thickness + 60 for intake and 80 for ex and minus from your TDC lift and your done.
Clay does not work unless you have a solid lifter .
Poor UB and JR could you elaborate as to why you would have them decked the .007" ?
I have my suspicions, but I would like to hear your reasonings.
TIA
Quote from: Pop-pop2 on April 08, 2019, 04:21:54 PM
Already sent them off an got them back. Didn't know to measure them when I took it apart.
I never had to worry about that with diesels, so I didn't measure it. Putting it back together with. 030" head gaskets. Heads are ported, forged pistons. Trying to do it right, just don't know if pistons .007" below the deck is going to be a problem.
0.037" will be fine on a street ridden motor.
Quote from: Pop-pop2 on April 09, 2019, 06:54:21 PM
Poor UB and JR could you elaborate as to why you would have them decked the .007" ?
I have my suspicions, but I would like to hear your reasonings.
TIA
Compression will be lower than set at 0, squish's will be increased, chances of pinging are greater . Look up your specs on Bigboyz calculator.. pretty good difference from 0 to .007
It will run at .007, no doubt , but I'm ocd on everything I do
What did the head porter set the cc's to?
Are the pistons flat top or dome?
Are they both.007? Between.005-.007 is about average I believe.Most people would have them done to equal the compression between the cylinders.Get an optimum squish gives you the best fire in the combustion chamber. JMO. Coff 06
I agree with all of the above, including that it will run fine for a street engine. On the other hand You have it apart, just time and a few dollars in shipping will make it right. It would bug me to have it apart this far and not do it. You will be loosing about .15 of the compression ratio, 3-4 PSI of cranking compression, so not a huge deal,also the squish will be .037", where tighter is better, to a point.
Your call, only you can decide how much money you want to spend, and how exact you want the final result to be. My last go round I left the heads on, slapped in cams, exhaust and tune and called it good.
Heads are 94.8 cc ('03 Screamin Eagle heads), dome pistons, both are .007" below deck.
My concern is pinging. Why make it more difficult to tune than necessary. Am I out in left field on this one ???
Quote from: Pop-pop2 on April 10, 2019, 08:08:49 AM
Heads are 94.8 cc ('03 Screamin Eagle heads), dome pistons, both are .007" below deck.
My concern is pinging. Why make it more difficult to tune than necessary. Am I out in left field on this one ???
We need some clarification:
What year bike? 2003 RK? Didn't think Cycle Rama made a cr575 for 99-06 touring bikes.
What pistons do you have?
I ask, because the 103 CVO pistons from Arias (22444-02) were only 5cc domes, and brought the CVO 103 engines to 9.5:1 with a .040 HG, and 9.7:1 with a .030 HG.
'03 cvo road king. Keith Black - KB660C + .010 pistons. Cycle-Rama gear drive cr575 cams, .030 head gaskets.
Quote from: Pop-pop2 on April 10, 2019, 01:06:23 PM
'03 cvo road king. Keith Black - KB660C + .010 pistons. Cycle-Rama gear drive cr575 cams, .030 head gaskets.
Those should be 10.7 cc domes, putting you at ~10.25:1, 9.6 corrected, and should crank about 200 PSI. Good area for a street bike with a good tune.
Ok, back to the. 007" below deck question. Should this be corrected ? Will this make it more difficult to tune ? Have TTS for tuner.
I'm with PoorUB. It makes sense to take advantage of the fact the barrels are available to be machined before assembly. I don't think I could ignore the opportunity to fine tune that part of the assembly. You haven't said if both decks are the same. I would confirm what both barrels need and have them tuned up. It will also clean up the surfaces if done properly.
If you decide you do want to leave them you have other options. For example, a .027 Cometic head gasket (available) will cut the squish a little more down to .034. If the engine has base gaskets instead of o-rings, they can be adjusted with the right thickness size base gasket. As said, checking the valve pocket clearance will be important no matter which way you go.
added later;
The TTS tuner (if done on a dyno properly) will tune each cylinder on it's own merit so the tune should be OK. Any off balance in compression will have to be kept in mind if doing a compression check at some time in the future so it doesn't get interpreted as an engine defect. Check it after assembly and break in and record it so you know. It shouldn't IMO cause a vibration from off balance cylinders that can be felt but it will likely have a very slight effect on the toque and power.
It will tune just fine, it will run just fine. You might give up a couple HP.
That huge hemi combustion chamber has no quench area with that piston, so that .007" is not a big enough issue to worry about.
I think @ 10.25, with a 35° close cam, you're gonna need a decent tune.
Thank you all very much.
P.S. Yes, it does have manual compression releases.
Pop you got a good tuning device, if you get it dynoed by a competent tuner that likes TTS they will get it running right for you, would you post a sheet if you go that way?
Yes, but it may be awhile, I go in for surgery in May.
All the best mate.