What can be done to make my bike quieter?

[ARH]

I have a "74 WR250, set up to be street legal, passed the inspection to get my plate except for the exhaust noise. I admit it was a little loud but no louder than many other bikes I hear riding by. I got the muffler repacked, it is quieter, but still not sure if it is going to pass. Anyone have any ideas to quiet it more? I'm hoping I get a different guy out to check it this time, the first cop knew nothing about bikes, not sure he realized a 2 stroke is noisy up close but the sound dissipates as you back off a bit. They are supposed to check it at a certain distance with a DB meter, he just said "nope, too loud" when I fired it up with him about 6 ft. away, so I really didn't get a fair inspection. Anyway, I want to have it as quiet as possible so there is no way the next guy can fail to pass it.

 

[justintendo]

what is on the intake? alot of times the intake produces alot of noise as well..is there a way to put a turn down on the tip of the exhaust? a turn down pointing down can help alot

 

[ARH]

Everything is stock. It does sound like alot of the noise is coming from up front.

 

[justintendo]

is the header sealed really well onto the cylinder? i try to get this really clean and seal with orange rtv and nice tight springs. as for the turndown a pipe with a few slots cut lengthwise can be hose-clamped on temporarily for the sound check. i had a 71 400 years ago that was a real growler. the older 2 strokes werent much for being quiet..

 

[Bigbill]

The bike has the long straight pipe. It's loud. A turn down pipe plus lower the idle as low as you can go. Higher Rpm's = more noise, less rpm's = less noise.

 

[Jeff B]

A fair bit of noise can come from cylinder fins. Find black rubber fuel line and stuff it between the fins on the outside edges. You only need to dampen the vibrations. Put it on the sides not the front fins. Some bikes have a bridge between the fins but they still vibrate. May not fix the problem, but will help. Jeff

 

[suprize]

"He has the long straight pipe"...(pssst Bill, its "she" has the long straight pipe) and a loooong pony tail

try making some long rubber bands out of tyre tubes by cutting a few 1" wide squid rings off and wrapping them over the cylinder head, this can cut down the ding a de ding ding rattle that can lift noise meters off their frame as well . check the kick starter isn't rattling against the pipe. blobs of silicon in the fins can do the same as the fuel line trick above but is messy . good luck

 

[juicypips]

Ear plugs!

 

[Bigbill]

I fixed it now I'm politically correct sorry.

 

[justintendo]

i had forgot about suggesting the rubber fuel line trick. my 79 250 was missing half of its rubber so i pulled them all out and it was pretty loud. after cutting a bunch of 2 inch pieces and stuffing them in it helped alot.
still dont understand why they are giving you such a hard time, there are likely many louder bikes out there..

 

[2premo]

if you find a lot of noise from your pipe the WP endure models used a cover over the pipe to create a double wall pipe to dampen the exhaust noise

 

[suprize]

one must wonder about the whole "noise limits" thing...everytime a brace of hurley dudvidsons go past with straight pipes

 

[84scrambler]

Yes you need to find a wr pipe , my 79 wr is too quiet . you can buy header wrap from auto parts store and wrap the pipe temporary get the grayish black color it actually looks cool when done rite . Its probably the tinging coming from the main pipe (expansion chamber) that the main noise is coming from . Need to wrap that pipe.

 

[2premo]

one must wonder about the whole "noise limits" thing...everytime a brace of hurley dudvidsons go past with straight pipes

HAHAHAHA
loud FARM EQUIPMENT, hurley dudvidsons funny name
you are right about that, they call it attitude, well i call it stupid
when they tell you they have some special engine i remind them the bore and stroke is greater than my diesels
that's the point you lose them, but you hear them speeding away for a veeerrrrry long time

 

[dumpbear]

Hello Toni you need a wr pipe they have the spark arrestor built in and they have the end cap w/the rubber flapper they are a lot quieter than a cr pipe.If the pipe is like the one in your new print i don't think you will ever get that style quiet enough to be street legal in MI.I think i have a wr pipe like you need.
Tom

 

[ARH]

I got some help stuffing my exhaust, so that did make a big difference, but now I also notice some exhaust escaping at the connection to the header because it is so restricted (it was not doing this with the open pipe) so I'm going to seal that up better, rubber fuel line bits between the fins sounds like a great simple fix, I'm going to try all this stuff to shave off noise like some people try to shave pounds off their bikes. In the process of doing this all I was pestering the guys down at my local shop and they commented on the fact that my bike was really hard to start. They asked if I had done a compression test... no I didn't, runs fine... it is cold blooded and I just learned to kick with my left foot... anyway, turns out I only have about 100 PSI so I'll be needing to install a new piston. I have never done this before but I think I am going to be learning how to very soon. I knew it was eventually going to need to be done, the bike being a 2 stroke and all. I'm sure I'll have to consult the experts here on Cafe Husky if I get stuck. I really would like to get the paperwork for the plate in to be processed before I take the bike apart. The most annoying thing is all those other noisier bikes with plates riding past.

Hey Tom, leave me a PM message with details about that pipe you have.

 

[justintendo]

pretty easy, most important part is having a good machine shop to do the bore for you. write down the available sizes of piston for the bike, and take them the cylinder. they will tell you which piston to order. once they have the piston in hand they can do the final honing to insure the perfect piston/bore clearance..the bike is going to run much better after break in!

 

[jimspac]

We had strict noise requirements in the 70's at NETRA endures. 88db @ 50ft wide open in 2nd gear. To make the limit, you had to have a spark arrester silencer( the quieter the better), rubber plugs in the fins to quiet the rattling, lining the airbox to quiet the airflow, and a few that escape me at the moment.

Funny thing is that loud pipe HDs are tolerated somewhat better than us off-road hooligans were treated in the late 70's and early 80's.

Super Trapp was a good silencer back then and the version that will work on the 74 250WR is still available

 

[justintendo]

i worked outside sunday getting some things ready and heard so many loud bikes..all big twin style...i mean shake the windows on your house loud.
i even have a full muzzy on my zrx and keep my bike much quieter than that, especially in town here. a constant revving, coming to a stop, at a stop, in betwwen shifts. so annoying...i sort shift my bike in town and have had my friends ride it for me to hear it. surprised how quiet a big four is if you want it to be..

 

[ARH]

The crazy thing is, its not like I live in a quiet subdivision, I'm on a curvy road that runs next to a lake with no traffic lights or stops, so you can imagine how many bikes cruise up and down at all hours. On top of that, I'm two doors down from an auto garage that specializes in exotic imports and race cars, so there is always loud engine noise, not like anyone is going to complain or even notice my bike with all that going on.