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Update:
I weighed a JE with rings and one circlip fitted vs a std one with rings and a circlip fitted, for comparison purposes.
Std Honda: 425.2 grams
JE high comp: 412.5 grams

So not a lot of a weight saving with the JE forged pistons, and the Honda one was still wearing some carbon deposits.

But of course this means that there's no need to rebalance the crank.

interesting... i would have thought the forged pistons would be much lighter vs the cast stockers. i guess even a small reduction in weight is better than added weight.

see im always way to into the task at hand when working on my bikes, that its hard for me to even stop and take pictures to post. so thanks tony!

interesting... i would have thought the forged pistons would be much lighter vs the cast stockers. i guess even a small reduction in weight is better than added weight.

Not always. Don't forget that the energy that flows back and forth between the crank and piston is a reciprocating mass. The same with lightening flywheels. Any change to the reciprocating mass is going to alter the speed of travel, in this case the piston. What people forget is the relationship between piston position in the cylinder as the spark ignites the charge, not to mention the relationship beween camshaft and timing of valves. http://www.vtr1000.org/phpBB3/viewtopic ... 31&t=33343

I'm sure there is reason for JE having that specific weight. Maybe something to do with the relationship between piston and valve timing to bring compression into a certain range/dynamic range. Ignition timing and valve timing needs to be taken into consideration

(:-})

Pinned!!!! So to be done mod to mine

Would be jnterested to know what you guys think on cams.......

Cams are good if you can get them

What do you suggest?

Sir-knob-head wrote:What do you suggest?

Praying for many many years .
If you find them ,buy them regardless of cost (up to £800)

Or get some ground...
The base circles can be ground down 1mm which gives you 1mm more lift, and a bit of dwell, too.

You lose the surface hardening- can't easily be redone because they can distort.
But they'll last a year or two of hard use, more if you aren't using your bike for too many miles.

And I got some done for £125 a set....took bloody weeks, as I was at the back of the queue.

It can be done.

nice build i have to say.. get it onto a dyno to see the figures

tony.mon wrote:Or get some ground...
The base circles can be ground down 1mm which gives you 1mm more lift, and a bit of dwell, too.

You lose the surface hardening- can't easily be redone because they can distort.
But they'll last a year or two of hard use, more if you aren't using your bike for too many miles.

And I got some done for £125 a set....took bloody weeks, as I was at the back of the queue.

It can be done.

mine reground cams were hardened again, it is possible.

Who did yours tony.mon?

Two quick things to add to this thread..........

The cam change is to regain the top end you loose with the piston change.
The reason you loose top end with the higher compression pistons is that the increase in cyl pressure inhibits the engines ability to rev.
This is the reason for the increase in overlap.

So if you are never going to use the upper revs (7K and above) cams will not really make much difference, in fact you will loose a little bottom end with them.



Also be careful with your rebuild....... the engine in this thread broke a rod shortly after the last post about it...... just an FYI that might be important.
Why it happened, I can't tell you as I never saw the engine in person.

8541Hawk: from what I remember, Lloydie did swap for JE pistons and got pretty good top end gain with oem cams, apart from other problems like loosing mid range or high oil consumption. It is posted in dyno charts (Amcq46 - 1st post).

Yep I gained top end with Pistons and ported heads ,full system ,
Lost midrange ,

Green line .

I guess I need to add more qualifiers to my posts for you guys......

Yes of course you will get gains in the top end when you up the compression ratio.

You should have power gains everywhere, though if you want the engine to breath at the top of the rev range with higher compression, you need to change the cams.

If you are not going for top end, then the stock cams should work pretty good for you though you might need to play with the timing a bit for max power.