I just replaced stock can with CF SP Engineering Moto GP stubby slip on can and the engine seems to be getting hotter than it used to ? It is cool outside temp. wise but the engine still seems to be getting real warm when in slow moving traffic. It just seems to be more so than before. It runs fine all through the rev range but has the free flowing exhaust caused a leaner mixture creating more engine heat ? Just curious if anyone else has noticed this after replacing the stock can ? I have not removed the spark plugs to see what they look like but will soon...

Don C.

Not sure about the effect of a different but in general leaner engine does mean hotter cylinders, you need to be careful because this can result in detonation and piston damage (if it is very lean).

Yes for sure I will pop a plug this weekend and have a look at it...Thanks for your input tigerclaw !

I doubt very much that just changing the muffler will have that effect on engine/water temp. For a change of muffler you usually need to go up a size or two with main jets from standard, but these only effect the high rpm range.

These bikes can run very hot, particularly in traffic and at low speed when there's little cooling airflow. You should only be worried if the temp gauge gets in the red, or doesn't cool down when you get up to a steady speed.

Yeah, these bikes run reallllll hot in traffic, especially with the weather getting hot here in sydney, my bike steadily climbs to the red. but once you get moving, it'll fall right back down.

Not familiar with the "red" zone as my NC30 has temperature markings but my bike's temp stabilizes at 90 degrees when stuck in traffic or slow running because the fan cuts in. Once road speed increases the temp falls quickly to the normal 80 degrees. Can confirm Cammo's comment, I run an after market end can with no jetting changes and see no change in engine temperature although I do not ride everywhere at max rpm.

Perhaps a K model bike with stock 110s in it might become leaner with one of those terrible motogp style cans which are just like an open pipe.

but what magg and cammo have said about it not usually being an issue is most likely true.

Thanks for input guys. Yes it does stabilize at 90 or so and never got into red. Once I get moving it does cool down. It may have been just me since I hadn't ridden it in a few weeks after fracturing my back on my MX bike
With season here coming to a close soon I will look more closely at any re-jetting if necessary but I think I'll be ok. It still has a rich smell to exhaust, and mpg still same, and I am an old school guy who tends to go with my insticts and they say it's not leaned out too much to the point of needing jet adjustment for now...Thanks for all the help,

Don C.