Skimmed Alive.....

[sonofpat1969]

Ok. with my recently resurrected mechanical curiosity and an engine minus its casings sitting in a lock up, I am beginning to hatch a bit of a plan....

I got the spare engine for 16 pounds (yep one six) off ebay, its minus its alternator and clutch casings, and has a large chip of metal missing from the block, just at the bottom of a cylinder head bolt (more cosmetic than terminal if it will continue to stand the torque from the head bolt).

The owner seemed a decent bloke, and claims it has only done about 15000 miles before letting water into the rear cylinder... both ccts are apparently still in working order. So maybe warped head or if my luck really has started to shine a blown head gasket.... the rest of the engine seems fairly sound bar what appears to be a rather unsympathetic removal leading to some bumps and scrapes, exhaust studs missing etc.

So thoughts so far....

As Henry the viii would say "off with the heads"

Have a look at the condition, and consider a simple tune up and try them on my storm (well if it blows up at least I will still have some spare engine bits.)

From reading the posts on here the most effective or reliable tune appears to come from increasing the compression, so off to machine shop for a head skim.... but how much.?

Some looking on the superhawk forum appears to indicate approx 0.4 mm, and some Google research appears to hold this theory if enough squish band is left (.8?), but that's after only very brief research and calculating. So more Googleing and maybe a trip to the library needed. Also thinking of squishing some plastercine between piston crown and head to measure existing squish... then with head full of figures and heart full of hope its off to the machine shop.... then fit to bike, fit race cans, aftermarket filter and maybe airbox mod (although it looks as though messing with airbox returns varying results) and then re-jet and pay for dyno test to see if I have improved (or otherwise) the power of my bike.

Well that's the plan, it may well change but in essence I am hoping for a fairly modest power increase, for relatively modest (?) Outlay, thinking that the dyno will prob be the most expensive part.. and something I will be able to put back to standard should I wish...
Any comment or thoughts welcome.

[benny hedges]

you will find solder is easier to measure than plasticine. thats what ive always used anyway

regarding water in the cylinder.... depends how bad the ingress was.... if it was just a bit, fine... if it was a lot it could have hydraulic'd the cylinder and bent the rod etc... seen it done in car engines.
hopefully not!

good luck anyway

[tony.mon]

The americans call this "decking", so if you're searching t'internet that might help.

One trick is to build the heads up with only the inner valve spring in place.
Then you can time it properly and physically push the valve down onto the piston crown and measure the valve/piston clearance to make sure it's enough.

How much is enough? Mmmmmmm.....not sure.

Why not just fit high comp pistons?

If you deck the cylinders it effectively lengthens the cam chain, so it will throw the cam timing out.
You'll need to slot the sprockets, and set the cams at the same centre lobe positions, using a dti.

[sonofpat1969]

Bloody hell.... wrote reply then lost it cause battery went on notsosmart phone.
Interesting reading, had not considered the cam chain effectively lengthening, makes sense tho, erm..
deeper you dig bigger the hole looks. I wonder if I would just have to slot one cam on each head 'cause of the chain staying the same length between the cams.? I need to blow the dust off that library card and do some more reading/thinking/looking....
I chose skim over pistons cause it felt a bit more DIY... and more reversible and possibly cheaper.. now not so sure... ? But its for fun more than anything else. thanks for advice..... thoughts always welcome.Will post any development or disaster.lol.

Sent from my Desire HD using Tapatalk

[tony.mon]

Why not start with a head polish and gasflow?
Plenty of fun, and you get shiny secret bits in your engine that only you know are there......

But it's a lot easier (and probably the same money by the time you factor in machining costs) to fit high comp's as opposed to decking.
And you could consider a 1mm overbore, too, if you want to have the bores remachined and oversize pistons made (JE do a lovely personal service, special coatings, one-off's etc.

Or all of the above, of course......

[sonofpat1969]

Sun and family, put a temporary stop to play at the moment....can only just justify the occasional just popping out on the bike moment.... but still thinking... when I get a bit of spare time will have a proper look at the heads... bit of a polish and tune sounds tempting for sure... high comp pistons also... but if the heads (or at least one) need a skim anyways then I'm still tempted to look at that as an option.... need to consider whether I would be upto adjusting the cams... would be very tempting to get a bit carried away. I already have a bit of an ebay addiction and shinking garage space not to mention a partner with decreasing patience...lol.

Sent from my Desire HD using Tapatalk

[tony.mon]

Or at least one?
Neither need doing, but whatever you to one you should also do to the other, you'll get vibration and uneven temp issues otherwise.
Normally skimming the head on an engine is because the head is warped, this is usually only on IL4's, and won't be a problem on the Storm heads.

[sonofpat1969]

I have spare engine (well most of ) part of my eBay addiction... which the last owner claimed took water in on the rear cylinder... was thinking about altering those heads and then putting them on my bike. Which was the other reason I first started thinking about head skimming... oh for endless time, and money!!

Sent from my Desire HD using Tapatalk