is this realistically going to make alot of difference?

 

All the biger pistons (*) I had make big difference. It is also good to by asided with an FCR...



* 102mm JE 10:5 compression
* 104mm Egu-motoren.de 11:1 compression

 

The more cc's the merrier! :blob6::toothy8:

 

...and the higher compression will help too.

 

That is alright as long as the electric boot keeps working.

 

And the starters on these bikes aren't exactly keen in the first place
Grind, squeak, grind, squeak BROOMBA...

 

Quite right. I had an XBR500 running a high comp Wiseco big bore kit. It was interesting kick starting when the starter fried itself - but at least that was an option. There is no way it would bump start though so a 720cc high comp Dommie had better have a good starter motor unless it's an early kickstart model.

 

There's also another issue to consider. The stock cranckshaft rod is designed for low compression. Using 11:1 compression ratio and no extra cooling, you're pushing things past their normal usage limit.

 

I use hi compression pistons since 2006 with no problems.
The NX650 and xr650l (actually same engine) rod is quite durable and has no need to be upgraded.

Since 2008 I admit that I use an oil cooler from egu-motoren.

Anyways I ll give also my experience.

I have used the bike as stock for almost 4 years. The first year os usage was the very first and ONLY year that I did found myself at service (oil change) with just 1lt of oil in the engine instead of almost 2. It was all burned since with no modifications I did pushed a lot the bike to its limits and hi rpm in Greek summer time. YEt there was no issue in the engine

Since I upgraded the engine I had no needs to overpast 5500 rpm as so many times as stock. All the power was handy. I can assure you that I do 7000-10.000km every year, all of them in spring, autumm ans specially summer in Greece, where temperature rises well above 34C. Never had problems with oil. I also use oil deepstick and check everything.

Now i change oil every 4000km instead of manual's 3200


I can understand your worries but this engine is TOO reliable.
Last time with 11:1 compression I have forgotten to fill in plus 500ml oil for the oil cooler. Yet the bike was some 8C hoter but I never exceeded 90C in full summer time...

The only problem with 11:1 is to have a mechanic who really knows to setup the carb so there is no pinging. Otherwise 10:5 compression is impossible to ping even with a less precise tuneup of the carb.

If I ll ever install a bigger piston (108mm) I will avoid 11:1 and go for 10:5 or 10:1.


Good evening

 

Bonsoir, j'aurais voulu avoir des renseignements concernant l'origine de ces pistons de différentes tailles. Merci d'avance.