60mm Open Exhaust Systems
 

Is anyone running a 60mm straight exhaust system on anything?

I am looking at building a 748r with an 853 kit on it. I love the revvy nature & weight of the 748 so don't want to really go 996r route.

Would this engine require a 60mm exhaust to get the best out of it or would it be overkill for this setup?

I am not quite sure how much bhp I will be able to squeeze out of that engine yet but I want a really nice lightweight large bore system on it.

Has anyone ever had an exhaust built for them before? A friend had a full bore titanium system made for his R1 and it was a piece of art.

60mm would be over kill IMO
and very expensive.
best of with a full 50mm
and more available second hand

I've played about a lot with this, I have a 748 RS, 853 kit and every engine mod possible (really got carried away) 57mm full system worked best, 60mm was too much and the bottom end and mid range suffered.

On a 748R with 853 kit, flowed heads and de-restricted throttle bodies (the usual and most cost effective route) 54mm would be the biggest you could use. 50/54 half system works just as well though.

how much is a 853 kit for a 748 R and what are the power gains ?

853 kit on its own, i.e. not done as part of a service, is about £1200 fitted/set up, inc gaskets, dyno runs etc. etc. if you dont have an adjustable chip (FIM Ultimap) or power commander then you'll need one too.

IMO, 853R is a mega conversion, i love em! the peak horsepower figure is only up by 5-8 bhp usually, but the area under the graph is much better, more mid range, typically the power you get at 10k on the 748 you get at 8k on the 853 and it holds it until 10k, so when you change up you don't get so much of a power drop, it feels great to ride. The revy 748 but with more punch out of corners.

748 R is the best model for the conversion but you need to use high compression pistons, the 748 R pistons have large crowns and the valves are set back in the head to suit (748R has a larger cylinder head volume than the other 748 models) Increasing the bore size increases the compression ratio anyway but with flat top pistons you would lose out on a lot.

Something to think about. :D

More like something to save up for. Yum, Yum!!! :o

Hey Wilf

Who did your all your engine work and setup.

It sounds like you have done exactly what I am looking to do. Are you pleased with the results? Do you have any Dyno runs you can post / pics?

Just a guess, but probably in his lunch times at................................... ?Check the site on his thread!!! ;)

Beat me to it ;)

The other thing to watch for with the big pipes is that once you get much bigger than 54mm, you'll need the mag swingarm. it's longer so as to offer more clearance for the pipes. that'll dent the budget a little :o