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Discussion Starter #141
Kibblewhite Diamond cut stainless valves, along with springs, seals and Titanium retainers. Very pretty.

102889

102891
 

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Discussion Starter #142
Found a donor bike for a couple hundred dollars, with some nice controls and other parts. cleaned up the controls and got a nice set out it.

102976
 

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Discussion Starter #143
are you having it made or are u making it yourself?
sounds like you are having it made because if you were going to build and weld yourself, you would already know what you are capable of.

steel is easier to weld, can be welded to frame to simplify mounting, more reliable ground (?).
but steel requires coating/painting/anodizing to prevent rust.

alumium is lighter...
i made it myself. came out good, but will still need the seams to be welded. ended up using steel, .015".
 

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Discussion Starter #144
this is a slow build... but, i'm learning a ton. trying to get the top end done, which has involved degreeing the camshaft, removing material from the head to allow for the higher lobes to work and several other "critical" clearances checked. To that end, i need some instruction, if you were... here's the problem...

Bike: 1980 CB750F Supersport.

I'm installing a new camshaft which is much higher lobed than the stock camshafts (Webcam Grind #110, part 55-491). I'm new to this precision measurement stuff, but here's what i have;

Valve lift: .395" (10.03mm) on both Exhaust and Intake.
Starting at 20 degrees BTDC @ 0" lash, using a dial indicator i measure .388" of travel on the exhaust side and at 20 degree ATDC @ 0" lash i measure.326" of travel on the intake side.
Starting at 0 degrees TDC @ 0" lash, i measure .312" of travel on the exhaust side and .245" of travel on the intake side.

here's where i'm stuck. in my head i'm thinking if the valve lift is .395", at all measurements it looks like i could hit the piston. Thus, i know i'm missing something.

Is there some calculation that is used to determine the correct P-V clearance? everything online just tells me the measurement is my clearance and don't actually tell me the calculation (if there is one). if i use the measurements i got, they look very large compared to the recommend .080" on the Exhaust side and .050" on the intake side.

any help is appreciated.
 

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You bought an aftermarket cam that was suppose to work in this motor did you not?

One would hope they did not sell you something that would slam your poppet valves into your pistons or each other, but then again, stranger things have happened.
... unless you also milled the head significantly in which case you are in :alien: uncharted territory for sure.
 

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Why don't you just assemble it bring it up on TDC and pour some wax or something in there to make a casting, then take it apart and you will see how close everything is when it's cold.
 

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You should follow your cam builders recommendations.
They should have info on whether the cam requires extra work on the pistons, valves or head.
Even then, you have to check yourself. And not just p to v clearance but also V to V clearance. There are no calculators really because every engine is slightly different. Even head/base gasket compressed thickness varies.
Throw into that that you had material removed from the head (whatever that means) no one is gonna be able to tell you if your setup is safe. You'll HAVE to measure ESPECIALLY if you are going oversized valves.
 

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Discussion Starter #148 (Edited)
V-V is .060 on intake, .063 on exhaust, at 0 lash. i did remove material, as shown in this picture.

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Nothing major, but enough to allow the cams to rotate freely. haven't touched the pistons yet and i didn't do the plasticene/wax as it's not as accurate as i want, which is why i used a dial indicator. and yes, these cams are made to order by Webcams thru Dynoman Performance. So, i'm sure they're the right fit.

Gasket thickness (compressed) is 1.10 mm/,043". Just trying to learn here, and given i know the valve lift, i know the travel at 20 degrees before/after TDC (after all head changes have been made, and i know the compressed thickness of the gasket, there should be some way to calculate true P-V clearance. Just not seeing it right now.
 

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You haven't even touched on the valve angle,
that's going to complicate your calculations considerably if you aren't designing this thing with the assistance of a very sophisticated CAD computer and software.
 

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Discussion Starter #152
Dynoman will be the ones to ask... don't u think?
I did. Cams, valves, lifters, guides and shims were all aligned to the piston (Wiseco pistons custom made) and sold as a set. Dynoman indicated clearances were needed to be checked as these bikes have different head castings, but angles should be good to go. "not our first rodeo," they told me. i just tended to trust that.

I did, however, I think i've figure it out. what i am missing is the measure of spring deflection to adjust for the additional travel allowed for the lower tension on the checking springs. what i found recommended was to subtract .040" from the travel measure to get true PV clearance. does anyone have any better recommendations?
 

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I dont think anyone knows exactly what you are talking about...
You should write a book though.
Reinventing the wheel- engine building for people that know more than the people that know.
Make sure you include pictures... for dummies like me
 

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I think what he is thinking about is the coil springs becoming coil bound before the cam lobes are finished pushing the poppet valve open.

What is this thing a dragster?
 

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Design inspiration based on something seen on internet or magazine somewhere,
not from countless runs down the drag strip and rebuilding the same engine over and over again.

"Dynoman indicated clearances were needed to be checked as these bikes have different head castings"
He's telling you to check it not attempt to learn the geometry.
try bee's wax it smells nicer then paraffin.
 

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... and next time buy a Laverda triple or something interesting like that to spend rude amounts of money on. That would be way more cool to see inside.
 

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Discussion Starter #158
I dont think anyone knows exactly what you are talking about...
You should write a book though.
Reinventing the wheel- engine building for people that know more than the people that know.
Make sure you include pictures... for dummies like me
Wow, nice to see you all are just as salty as ever. Always great reading your replies. However, "people that know" were once as ignorant as i seem to be...but hey, don't really care if i've insulted anyone. Like I said, just trying to learn.

I'll include pictures for ya next time...

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Alternatively you could possibly use a borescope or fibre optic endoscope to visually inspect inside the assembled engine, but that would prove very expensive if you don't have somebody in the optics related industry.
 
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