I bought a 2003 Z400. It has a Yosh muffler on it. It is oval in shape, but I really don't know enough about these bikes to know if I have a slip on muffler or a full system. The label on the muffler only says "Offroad" on it. I don't have the means to post pics right now, but I can say that the muffler is fastened to the head pipe by two springs rather than a clamp.

Can anyone tell whether I have a full system or just a slip on?

springs = full

Thanks alot. That's what I thought and jetted accordingly. I wanted to make sure though.

I have to admit that the Yosh muffler is LOUD. If I wanted to change the muffler, would I also have to buy a header or can I just get another muffler?

your yoshi should only be 96db's. i dont think thats too loud compared to some other exhausts. its got the spark arrester in?

You can buy the yoshimura quiet core insert..it quiets it down alot.

Yea if its loud its because the quiet core got taken out... cause with the quiet core in there its not half that bad...

they also need to be repacked every once in a while. the packing breaks down and it gets louder.

you most likely need packing. yoshi's are pretty quiet

i know a lot of people that have aftermarket slip-ons and never repack them. they dont beleive me when i tell them they need repacked every so often.

what can happen if you dont repack often?

Dont know the long term effect but the slip on yosh i had was installed 2 weeks after i bought the bike brand new... in 05.. we just repacked it in 08/09.... didnt seem to do anything exept where the clamp is its turning a goldish colour.. now my bro has it.. it sounds alot better being repacked

supposedly, if you dont repack it regularly(like atleast every 3-4 months depending on how much you ride) it will take away some power and it will definitely get louder. almost all the manufacturers claim you need to repack every 10-15 hours of use. thats just expensive. you should check out some of the web sites for yourself. http://hmfracing.com/atv www.yoshimura-rd.com/ www.fmfracing.com/ www.dubachracing.com/ here are just a few web sites to check out.

Ok, so the yosh isn't supposed to be that loud. I have an HMF on my Big Bear and the Yosh on my Z400 is a lot louder than the Big Bear 400. Maybe it does need to be repacked. What do you want to bet one of the screws gives me trouble? Is the yosh quiet core universal for all models of yosh pipes?

just re-pack it when the packing is down to about a 1/3 of the pipe or less. and if your pipe is carbon fiber and you run it without packing you can burn it up and it looks nasty.

yes. i think you can get them from advantage cycle or woodward for less than $20