4-stroke Question

S

Skitspuce

Member

May 21, 2003

63

0

• Mar 21, 2004

• #1

I'm new to dirt bikes, but rode sport bikes for about 12 years, and I'm curious about something...
Why do 4 stroke MX bikes need top ends/valves every couple of seasons when a CBR600RR can last much longer with a similar redline (15K), compression, etc? It seems (not that I know what I'm talking about) that a MX engine is just 1/4 of a sportbike engine. Am I way off - was I taking crappy care of my street bikes?

 

elf

Member

Jun 7, 2003

695

0

• Mar 21, 2004

• #2

Most 4 strokes especially the 250fs get run at wide open throttle most of the time. Compared to your street bike which spends most of its time in the cruise mode. How long would your 600 last if you were racing every week? Dirt bikes have to work much harder than street bikes.

 

Y

Y2Z

~SPONSOR~

Apr 6, 2002

411

0

• Mar 21, 2004

• #3

from the second they are warmed up, they are pretty much pinned (for people who race, or people who just ride hard), it takes a hell of a beating like this.

 

S

Skitspuce

Member

May 21, 2003

63

0

• Mar 22, 2004

• Thread starter
• #4

Reasonable enough. Embarrased that I didn't think along those lines.

 

M

mxer842

~SPONSOR~

Nov 11, 2003

597

0

• Mar 22, 2004

• #5

also remember where these two machines are run...a street bike is run in the streets while our bikes are constantly getting roosted and run through the mud, even if you clean your air filter every 10minutes it is inevitable that a few pieces of grit will get in there and acclerate wear to some degree.