D-Tracker 150 (AKA KLX150) - TOO LOUD...

[wayanlam]

this is aimed at all of you ppl that have had the pleasure of playing about with some small 4st. single cylinder off-roaders. hoping that Kelly can help

so, Kelly, im hoping that your decades of messing about on bikes might help me figure out how to fix my little brothers bike.

he has a KLX 150 (actually he has the D-tracker 150, but same thing almost~). I don’t think it’s a bike that’s available in the states. it’s basically the little brother of the KLX 250, single cylinder, air cooled engine.


thats the 150 in the front right, and an orange 250 to the left.

so, we just started modding it a bit. last week we changed out the silencer and put in a full aftermarket exhaust. there is a noticeable power gain over the stock exhaust, pulling harder through the upper revs, but its friken loud! something i wanna try and remedy, will touch on that later.

anyhow, with the stock exhaust, the bike was already backfiring a little, but it was barely noticeable since it’s such a quiet exhaust. but now since we change it with the aftermarket exhaust, it is backfiring heaps, and its very noticeable now! mostly when we let go of the throttle when slowing down.

Until now we have not tried to remedy this issue in any way, mainly because we have had no time I guess. However, I just bought a new CR carb today and we might have the time to install it tonight. The original carb form the KLX150 is a vacuum carb, like ours on the ninjettes, not sure what size they are… theoretically they should be the same or a little bigger since its for 150cc, compared to our 125cc’s

Anyhow, I am hoping that we can tune the CR so that the air fuel mixture is richer, I think the bike is probably running lean so when when we let go of the throttle its really and that might be causing the backfires? Im no expert at this, so im just having some wild guesses here.

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Now for the issue of the exhaust being incredibly loud and raspy…. I am wondering if I should plug up the end with a piece of metal and drill out a smaller hole, kind of like the extra silencers that Area P make for their exhausts.

Any second thoughts on this? Could there be some other little tricks that we can try to muffle the sound a little? I think that once we get rid of the backfiring, it will already relieve us of some of the racket. However gunning the bike is a little heavy on the ears.

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thanks in advance for everyone who can lend a helping hand

cheers!

[kkim]

Wayan,

When I played with different exhausts on my crf150f, I went back to my stock pipe, but had backfiring which wasn't there before I switched exhausts. I found that I had not reinstalled the exhaust using the proper torque on the bolts on the exhaust pipe at the exhaust flange. I retorqued it and my backfiring went away. It seems air was leaking in at that juncture and leaning out the mixture. I suggest you first double check your exhaust installation for proper sealing from front to back to eliminate the backfiring.

As far as loudness, I went back to the stock OEM exhaust with the exhaust silencer removed, but spark arrestor still in place. Also, pull out any intake restrictor they may have on the stock airbox.

I have no clue where to start on rejetting your CR. You might want to to visit http://www.thumpertalk.com/forum/?f=410 and see if they have suggestions... or you could ask in that forum of the jetting specific forum on that site.

[ScraitT]

I have a similar setup to KKim on my 230. I pulled the exhaust baffle and intake baffle and bought the jet kit. Honda knows people want more sound and power, so they makes removing the baffles easy and they sell a jet kit you can buy. Quick simple and easy.

Even with the stock exhaust and baffle removed, the exhaust is incredibly loud to me. I haven't heard an after market pipe, but I could imagine it would be far too loud.

I'm not sure if Kawi has a similar setup to Honda or not with the removable baffles, but if not, I would definitely try to figure a way to quiet the bike up some. I'm not sure where you ride, but thats that quickest way to loose a riding area, sound. Street bikes get hassled and bad looks for being loud.....offroad bikes get their riding areas taken away in the blink of an eye for being loud.

[wayanlam]

here there are no laws here regarding sound limits i dont think. there are idiots riding around on 100cc scooters with basically straight pipes that are like 50 dB louder than my AreaP exhaust, lol

ill be getting the new CR carb today, and while playing with that, we will check that the seal is sitting well between the header and flange. i did tighten it really well, but maybe its set out of alignment somehow... we did start up the bike and paid close attention to see if there was any smoke or strange sounds coming out that might indicate a leak, but it seemed fine.

after we install the carb, i plan to experiment a little with a custom bit to insert in the end piece to reduce the airflow a little and hopefully it will reduce the volume.

ill post an update later on with what results we got,

[ScraitT]

There are sound laws everywhere, they just aren;t enforced in a lot of places. Here for example, the sound laws are never enforced.

But it isn;t the LAW that you have to worry about, it's the neighbors. I'm not sure where you plan to ride, but if people bikes are too loud that the neighbors start getting annoyed and begin to complain, say goodbye to that riding spot.

It's happened to virtually every riding spot in S Florida. I don't know of a single legal place to ride without driving for hours. I know there are illegal places to ride, but if you're caught, your bike is gone and it's just a stupid risk.

Good luck with the new carbs and tuning.

[wayanlam]

id honestly be surprised if there are laws here in bali against noise pollution, but yeah, maybe somewhere deep in some rule books there is something written about sound limits, if not for bikes, maybe for something else.

what is certain is that they don't enforce it here, lol

also the reality of things here is that no matter how much anyone were to complain, i doubt they could stop bikes from passing through any roads here. motorbikes are the primary means of transportation here.

http://www.youtube.com/watch?v=jTEcBwn50ps

not sure how to embed videos, but this is my 5~ish minute ride from my house to the office, lol

[ScraitT]

Oh ya, that's crazy and a bit different

I swear I looked at your location last night and saw Indiana
In the US you have a lot of problems with loud bikes (offroad). But over there since everyone owns bikes, I'm sure no one would even notice.