Exhaust

Hi, total n00b, so take it easy!!
Got my 250x 3 weeks ago - 1 year old & 2500 miles, stock UK bike, in black, as new condition.
After riding for around 3 to 5 miles, motor appears warmed-up & hungry for revs. Then exhaust seems to get quite a bit louder. I assume EXUP opens up fully when hot, & this is perfectly normal on this type of FI bike. Anyone know if this is correct, or is there a baffle/exhaust/cat problem?? No error codes, can't see any leaks, starting is OK, power seems OK.
Maybe I'm just paranoid??

BTW: these bikes are very rare here in UK - got canned in MCN review; why, I don't know....

mash100 wrote:

Hi, total n00b, so take it easy!!
Got my 250x 3 weeks ago - 1 year old & 2500 miles, stock UK bike, in black, as new condition.
After riding for around 3 to 5 miles, motor appears warmed-up & hungry for revs. Then exhaust seems to get quite a bit louder. I assume EXUP opens up fully when hot, & this is perfectly normal on this type of FI bike. Anyone know if this is correct, or is there a baffle/exhaust/cat problem?? No error codes, can't see any leaks, starting is OK, power seems OK.
Maybe I'm just paranoid??

BTW: these bikes are very rare here in UK - got canned in MCN review; why, I don't know....

Yes, the little WR is getting quite loud unter circumstances. Did not fully understand the systematic, but I guess it is related to opening up the airbox flap. I am quite sure your bike is totally ok, since I had a similar experience and I am not the only onw. Maybe related to homologation issues and throttling. It is not related to FI, but it may be related to running a 250 high rev 4 stroke engine with 31HP legally. According to current legislation this is no longer possible without applying several tricks as like adaptive airbox and related fuel maps.
BTW it is not the EXUP system producing this sound, since Exup is opened up most of the time and will be closed only within some short rev band. EXUP is much more related to improving low end torque.
Compared to my XT660 Tenere (FI, also), the WR appears substantially louder at most revs. Both bikes being 100% stock.

Thanks for fast reply!!
So maybe its the air intake flap that only fully opens when motor is hot? I guess that make sense, as air/fuel flow would then be greater through the cylinder & then exhaust. Would that mean that in cold weather (like now), you would notice bike becoming louder after a few miles?

mash100 wrote:

Thanks for fast reply!!
So maybe its the air intake flap that only fully opens when motor is hot? I guess that make sense, as air/fuel flow would then be greater through the cylinder & then exhaust. Would that mean that in cold weather (like now), you would notice bike becoming louder after a few miles?

Well if it is _only_ related to temperature, it sounds more like valve noises increasing when getting hot. In my case it is related to several things as like throttle, revs, maybe temperature, whatever...
This engine is reported to give kind of hard and metallic noises, so again, if you are familiar with other single cylinder bikes it might sound new for your ears as it did for me (previously riding KTM).

The only thing I can really notice about how the bike runs as the engine warm up is when the fuel injection's automatic enrichener (like the automatic choke on a carburetor) turns off.
When this happens, throttle response gets better.

Even though I warm the engine for a few minutes before taking off, it still needs a mile or two out on the road to turn it off, with the hottest days being a possible exception.

YZEtc wrote:

The only thing I can really notice about how the bike runs as the engine warm up is when the fuel injection's automatic enrichener (like the automatic choke on a carburetor) turns off.
When this happens, throttle response gets better.

Even though I warm the engine for a few minutes before taking off, it still needs a mile or two out on the road to turn it off, with the hottest days being a possible exception.

That's pretty much my experience too regarding throttle response, only at the same time, the exhaust note seems to get louder, a bit like when your ears 'pop' on takeoff in a plane. Not THAT much louder, but certainly noticeable.
Flatboarder's comment about air intake sounds about right though. I will try to check tommorrow, after this cr*ppy rain has cleared....