Pistons

M

Monkeybrain

Guest
I am having a 95" build prepared by BigBoyzCycles in Maine, rebored cylinders, ported heads.

Now there is the question of compression and pistons.

Initially I am not touching the cams, that will have to wait until next year, but besides this I was going for a mild compression increase anyway, say 9.5:1.

I am sticking with stock gasket sets, again a cometic will be done when I change the cams.

What I have liitle understanding of is pistons-flat tops, short skirts....sounds like the wife 10 years ago.

the builder is going to have his own recommendation but I need a bit of input to know where I stand. Is wiesco worth the 30% premium, are the SE pistons OK?

Little help anyone????
 
Re: Pistons

I cannot comment on Twin cam packages...

however I am currently running 10:1 Wiseco 3 5/8 flat tops in my evo motor. they seem pretty quiet. i do have to have compression releases in the heads to save the starter though.

The bread knife runs dished wiseco's in her sporty 1200 conversion and again they go pretty well.

despite being forged both engines run pretty quietly.

One of my friend is running a pretty hot 95 TC with head work, larger inlet valve etc, high compression pistons, cams etc etc and he really needs the compression releases.

If i could offer some advice. decide what you want with your engine and how far you will go and bite the bullet and have it all done, it will be cheaper in the long run rather than having 2-3 strip downs etc etc

IMHO any way

SH
 
Re: Pistons

Monkeybrain said:
I am sticking with stock gasket sets, again a cometic will be done when I change the cams.
Click to expand...
No expert on pistons, try panman in HTT or Preachers for that, he designs them.
What I don't understand is why not put .030 cometic head gaskets in for proper squish band, i.e. proper burn of AF mixture when you are doing the B.B.?

No point in R&R'ing the heads twice when you can do it once, just cut out the pushrods and use adjustables when doing the cams later and leave the heads alone.
 
Re: Pistons

higher compression = more mid range power

downside is how good is your petrol

had 30 thou shaved off the heads of my evo to boost compression, made a hell of a difference bike is a lot stronger mid range

a increase in compression over stock by 1/2 a point will give more power with no downside

whilst motor is apart change the cams and get the full benefit of the 95" kit
 
Re: Pistons

You really have to decide on which cams you'll be using before you do anything to the heads or head gasket for that matter.
Even piston choice is cam dependent, some pistons are not suitable for some cams, and flat tops need relieved for some combo's, but not all.

Decide on which cams you'll either use now, (or later) then you can go from there.

Read: http://www.mikuni.com/fs-performance_guide.html (cam basics section)
 
Re: Pistons

a footnote

the twincam really is a 1550 in 1450 clothes
point being all they did was sleeve it down to 1450 for after market reason's of selling the engine twice:mad:
so the heads and cams are allready set for a 1550.
 
Re: Pistons

I was aware of that 1550 origins thing and so wasn't worried about doing the cams straight away.

In an ideal world I'd be wheeling the bike over to the states and getting Performance Machine or the like to take the bike to 98" and stick a 5 speed in. My world isn't perfect and so its what I can afford to do that gets done.

A trip to the NE USA meant it was a good opportunity to get the head work done at $300, I've also done some Ebaying and got hold of black barrels and heads from stateside and they have been shipped direct to BBCycles so the work will be done when I arrive.

I also have a PC III waiting for me.

If you read the 'trouble with the law' thread you'll remeber I need to get a new exhaust, went for this in the end
radikal.jpg


they've cost $1200, thats still ?400 better than the UK price of ?1200.


All of this means the cam chest must wait, maybe only till the autumn though, I've got a Shar Pei dog and we have our fingers crossed that she's knocked up, one puppy litter = holiday in Florida and an S&S geared cam kit.

When you read how the Americans go about the performance mods on their bikes its a full on single job affair, with airline baggage allowances and UK prices I can only do what I can afford and I'd rather do it now, cos I'm impatient.

PHUK IT, it's only money.
 
Re: Pistons

Any man who hopes his dog has been well and truly shagged because it means bike upgrades is very welcome in this club!!! :D :D :D :D :D :D

I salute your twisted canine logic!
 
Re: Pistons

kiwidave said:
Any man who hopes his dog has been well and truly shagged because it means bike upgrades is very welcome in this club!!!

I salute your twisted canine logic!
Click to expand...

Hmmmmmmmmm...:D :D
 
Re: Pistons

S.T.Chapman said:
a footnote

the twincam really is a 1550 in 1450 clothes
point being all they did was sleeve it down to 1450 for after market reason's of selling the engine twice:mad:
so the heads and cams are allready set for a 1550.
Click to expand...
Simon is correct & incorrect, yes 1550 in 1450, no to the cams.
The Cams are set up to pass emissions & noise regulations, the fact that they give you any power at all is a by-product.
With a V-Twin the more air you can get to move in & out = more power. Head work & bigger bore helps a lot, the cams do the measuring.
Mb`s financial reasoning cannot be faulted, we have all been there:(
The cams will have to be done to make it work though.
 
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