pistons
 

Having engine stripped. Should I fit Pistal pistons or keep original ones. Any Ideas.

Omega if you can afford them.......

what bike / year is it?

whatever you decide to do, check the weight of the new pistons against the stock ones.
I'm rebuilding a 996 engine with Omega items and they are almost 70g a piece lighter. This needs the crank rebalancing and adds more work and £'s to the job.
If you're looking at hi-compression items, IMO, it's a great mod. A little bit more everywhere. Watch for valve to piston clearance though.
The Pistal items are great bits of kit. JHP import them in the UK. Check the application with them and I doubt you'll have an issue.

Hi Wilf, Its a 996R 2001 with 8000 miles on the clock. what do you think.

Omega's

Hi

Nelly has covered the main points, piston weight is very important and i would recommend a full balance (but it is loads more labour). Also setting squish clearance and piston to valve clearance's is vital. If you do need to change the squish by then you need to re-time the cams.

Hi comp pistons can be a bolt on item but its pretty rare that none of the above needs to be done.

Can't say i remember fitting them without re-timing, balancing etc. its usually done as a package.

Pistal pistons are very good, Call John at JHP who will certainly have fitted these to the 996R/998S motor so he will know the weight and clearance details.

If you are looking for a cheap upgrade 'while its apart', hi comp pistons may not be it. Be prepared to get the whole lot done so you dont get caught with a big bill you weren't expecting.

Having said that, it is a VERY good mod, the 996R motor is ideal for it and is much sharper after the upgrade. dialed in cams, balanced bottom end, squish set and hi comp pistons make for a fantastic motor indeed!

High Comp. DP on my 916. I believe these are the ones to go for if you want to cut down on costs and not have to strip crank out.

Same weight as originals and so no need to strip to crank and re-balance, good bhp gain, but only use high octane fuel afterwards, worth having squish's done at the same time and cam timing checked or better still vernier gear to 'dial in cams'.

I went on to fit SP heads as well so cannot say exactly what the gain was in figures but it felt much, much better, foolish for not dynoing but knew heads were to be fitted a few weeks later so dynoed then.

Also as a matter of interest I found the best overall chip was the 062 Senna a couple of bhp down at the very top end compared to 'custom' chip, but a full 8 bhp up in the midrange and not as much noticeable flat spot low down.

So there's my experience for what it is worth.






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