temporarily restricted exhaust.....

[maraach]

Ok,

As a bit of a background, i run a 2000 model zx9r with a full Yoshi rs3 system (bike has also been rejetted to suit this system). A few weeks ago i started riding to work. This meant I was starting my bike early in the morning. As such, i figured it was the perfect time to try out the "DB noise limiter" which i had previously brought to fit my yoshi exhaust (yoshi genuine part - see http://cbrworld.net/forums/thread/263711.aspx).

I figured as it's a 12km trip each way per day, that if i kept the revs low, i wouldnt be causing all that much harm to the bike (apart from it running a little rich). Plus i figured seeing it was a yoshi product it would likely be fully compatible with the exhaust and wouldnt put it into dangerous territory.

I installed the part, and apart from being a little harder to start there seemed to be no obvious impact to the bike.

However, as always, at the least convenient time (half way across the harbour bridge) my bike decided to give me trouble. The first thing i noticed was that the power was dropping (dramatically). So much so, that about a minute later the bike stalled. The only thing i could think of was either i had

* run out of fuel
* it had something to do with the insert

As the insert was way too hot to touch. I decided to try the fuel tap to reserve. I still couldnt get the bike to start properly. As i was now sitting in the middle of a lane in the middle of the harbour bridge, i panicked, ingored the burning of my glove / hand and pulled the insert out. After this the bike started first go, and off i went.

To this moment im not sure if it was the insert / lack of petrol. I filled up at the next service station and was extremely surprised to find it needed 15.5l of petrol (which i had used in 148km's). Usually i fill up at 150km's odd and use about 10l.

However, since this time, the bike just hasn't felt right. Now im not sure if its just my imagination or if something isnt right. It just feels like it isnt as responsive or powerful as it was originally. I can notice noteable flat spots which i never really felt before, and comparing to a 2000 model zx6r... well as it stands until the high revs start kicking in the 6 feels a lot more "zippy" (in want of a better word). Previous to this the 9 was noteably the most powerful of the two.

My normal mechanic is on holidays until after new years so i havent been able to drop it by.... and in saying that.. i would feel weird dropping in and saying "hey, my bike seems to be feeling weird.. even though there arent any exact problems i can tell you about".

I was just wondering if anyone could shed any light on the problem? Or whether its likely just my imagination. Having never actually run out of petrol before im not sure what it would feel like. Also i cant understand how the db killer could cause me to use more fuel, or is that just coincidental and more an indiciation of heavy traffic riding? I only used the insert for about 60km's of riding in the end (over 4 trips). The longest taking about 35 minutes.

Oh and if it makes any difference, i was told (after the fact) by my wife that she had seen a flame shoot from my exhaust once or twice after i had fitted the low volume insert. I dont know if that is bad exactly or not, but flame from exhaust doesnt particularly sound good. Unburnt fuel is the best i could think of.

Thanks for the time spent reading this guys, any advice appreciated.

[photomike666]

Plugs............... Running rich will use more fuel, not burn it correctly and foul the plugs. Clean/replace the pulgs and all will be well again.

[maraach]

thanks for the super quick response photomike.

I see your point with fouling the pligs. It could happen that quickly though? Would have thought it would have to have some longer exposure than that?

However i have to admit hearing "plugs" was a lot better response than i feared may come....

[Stereo]

can happen quite quickly.... One of my previous bikes used to foul the plugs when using the wrong fuel in a few seconds flat...

[maraach]

Thanks for the info guys, i will check it out.

[IsleofNinja]

Yeah plugs are one of the first places to look re sudden lack of power / hard starting.

The DB insert should not have any real bearing unless your right up it in the higher end of the rev range.
If anything you may pick up a little bottom end torque with the insert fitted.

**On yours with the full Yoshi system it should give the average Gumby a scare in low / midrange (till the big dial touches 7000 that is!! )

NB; Fuel pumps have a habit of crapping themselves in summer {if plugs ok}.

[maraach]

hmmmm im too scared to put it back in to try again after my last venture... I must admit though i originally had the same view as you, that it couldn't cause that much harm.

I dont believe i went anywhere near the high end of the rev range, though there is a chance i did get up around the 7k mark at one stage (which coincidentally may have been just before the problem started...)

[IsleofNinja]

I meant 7K on the Gumby - Round about when the "hyperdrive" (as prototyped on the Millenium Falcon) cuts in



Any joy with the 9 yet?