1010cc cafe racer

That was quick shipping from The Netherlands to SA! I guess you're happy with the adapter for external oil filter? And nice oil cooler too!
What do you think of the improved suction filter/ strainer? It was not available when I oredered from Heiden, so I got the slightly beefed up oroginal type.
Do you think it is worthwhile getting the new cylindrical type that you now got?
 
Hi
This is the first package with the oil temp guage, sump filter, bent kickstart and 1 piece clutch pushrod. Took about 3 weeks.
The next package, with the external oil cooler, is still on its way!
Waiting for Hugh's hydraulic clutch and some beading for the tank, and then it's full steam ahead.

Frame is at the powder coaters..

Losing sleep :)
 
Hi
This is the first package with the oil temp guage, sump filter, bent kickstart and 1 piece clutch pushrod. Took about 3 weeks.
The next package, with the external oil cooler, is still on its way!
Waiting for Hugh's hydraulic clutch and some beading for the tank, and then it's full steam ahead.

Frame is at the powder coaters..

Losing sleep :)

All the stuff looks great though
 
I'm going to debunk some myths , and possibly start a pissin match but some truth is needed here .
The ports are , in their stock form , intake and exhaust , too large even for an 800 cc
Even at and especially past 800cc the engine speeds decrease due to increased stroke so huge ports are not necessary but large valve lifts are . When using large valve lift in the XS eventually there is valve to valve to valve interference . That is the intake and exhaust crash into each other during overlap . A common fix is is to sink the exhaust valve while actually improving throat velocity through the port . Retainer to guide/seal clearances become a point of concern also .
There are three common valve setups installed in the big engines . The first is the stock valves of course . Then the XV (Virago) valves . Then a variety of vendors supply bubble gum valves before you find out that you get what you pay for . With the stock valves the interference across overlap would only happen with a near insane amount of overlap and a lobe center under 103 degrees . With the oversize XS valves interference can happen with even a moderate cam if the springs don't do their job . With after market valves and even a Shel #1 , 2mm intake and 1.5 exhaust will nearly touch .
If All that head work ended up on another engine and your head is stock a number of things will happen . You won't have the overlap required to bleed off cranking compression the chamber will be smaller because no one took the time to match it to the larger bore , and come on , when has the XS electric leg been anything but ballast ?

Enough of my anecdotal experience .
bore x bore x .7854 x stroke .
then the head gasket and clearance volume @ approx 5.5cc per mm at 84mm bore and 5.6 @ 85mm bore .
then the near 63 cc chamber volume unmodified
then what ever the cylinder swept volume is
once you have all that it's just the ratio between the maximum and minimum volume
@ 81.5mm with a 1mm head gasket and clearance compression is 7.2:1 with flat top piston and goes up from there as the piston dome volume increases .
I'll leave it to the user to develop the numbers and math for their particular dimensions .
Add to this math that uses the stock 74 mm stroke and then close the intake valve early and with the additional stroke and bore only a moderate dome will yield 10:1 easily Close the intake early and cranking pressures will climb well past 210 psi and starting becomes a problem .

My thoughts on a cure .
delay intake closing a bit .
retard the cam a degree or two
close the lobe centers a bit like 102 or 104
thicker head and or base gasket
retard the ignition a few more degrees
take a hard look at the electric leg and replace the important bits with permanent magnet guts
or how about little bit of each .

Now the know it alls and keyboard warriors can come in and pick at my spelling , punctuation , and grammar .While you're at it argue every point . If I'm wrong or got senile I'll not only fix it but admit it . If I'm right you just found the reason I'm not around a whole lot . Honestly I'm trying to help or I'm still a dick . take your pick

~kop
 
Wow Kop.
I've read your post many times now, and I'm really unsure how to respond.
I suppose I started the pissing contest by shouting 1180, which still remains to be proved, or disproved.

I totally get what you say about decreased revs available to a bigger motor, and I understand that my exhaust valves are bigger than standard (no one on this forum found it necessary to answer my simple question about that), but I rode the bike into the shop where the rebuild is taking place.

I don't think I have any problem with valves hitting each other, but there is definitely scarring where a valve has been touching a piston.

The cam I have is apparently not standard, with lobes that appear to allow for quick closing.

At this stage my technical ability is being stretched. :)

Please explain 'bleeding off cranking compression'
I was under the impression that all compression was a good thing ( while running anyway ).
As regarding the pissing contest, I think I started this whole thread badly.
I should have let the learned gentlemen here do the math for me.

What is clear is the bore.
87.5 xt500 pistons.
Stroke has been measured but by myself with a tape measure with the barrels and pistons removed. Just wobbly conrods, and I think that's where I made a booboo.
As you may have seen in my pics, there is certainly a stroked crank in there somewhere :)
Just not gonna commit myself to exactly what it is until the barrels go back on, which is taking a lot more time than first thought.

What interests me(amongst many things) in your post, is about the clearance volume and chamber volume.

How are engines measured for pissing purposes?
Is standard a 653 swept volume? Or does that include all of the above?
Does the intake valve not open at bdc?

As regarding cures..
We intend putting a thin gasket each side of the spacer plate, and I naively put decompression buttons into the head(according to some)

The Probe ignition will certainly help with spark timing.

Can't disagree with any of your cures, but I'm not ready to get someone to cut me a new cam just yet.

A long hard look at the electric leg sounds interesting.
Where would one start?

Thank you, Kop, for your informed input :)
 
'bleeding off cranking compression' delaying intake closing effectively reduces pre-combustion cylinder pressure
Valve Timing Is Checked With Zero Valve Lash
@ 0.050 Inches Of Valve Lift.

Intake
Opens 13° Before TDC


Intake
Closes 47°After BDC

Exhaust
Opens 48° Before BDC

Exhaust
Closes 12° After TDC

If you were to close the intake later , say 64° then compression would not start until then .


87.5 ? with out a "big block" 87 mm is the usual limit . Measured with a tape ? oh well the numbers for 87.5 are

87.5×87.5×.7854×74×2 or 889 cc
6cc per mm of stroke
unmodified chamber @ 63cc

so @ zero deck and guessing at one mm gasket
444.5 + 63 + 6 + 513.5
513.5 / 69 = 7.44 :1 with no dome

come on now it isn't that hard ...

~kop
 

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