Pod Filters with stock exhaust pipes cut off muffler. Will I need to rejet?

[theblackassassin]

Hey Guys. New to the forum here just looking to get some help with some simple things

I just started tearing down my 1980 Yamaha XS650.
I am looking to put pod filters on instead of the stock airbox.
I also was looking to cut off the stock mufflers for now and basically have the pipes shoot straight down until I can afford to get a exhaust fabricated.

My question is will I have to have my carbs re jetted for such a simple modification?

If so what size jet should I be looking at?

Any opinions on cutting the stock exhaust would be great as well..

I am going to be doing a Hughs Hand Built PMA on this bike with a PamcoPete Ignition
Just to give you a heads up for what is in store for the future.

Thanks Guys
Johnny

 

[pahako]

Yes, definitely rejet for these mods. I would start with #140 main jet (which is 3 sizes up from stock), and #45 pilot jet (1 size up from stock). You may need to replace the rubber plugs that go over the pilot jets also. They need to have a good seal, and the originals are usually in bad shape due to age.

 

[theblackassassin]

Thanks for the response man. Really appreciate the quick response. The carbs as far I am concerned were just re done 3 months ago. Just bought the bike a month ago so when I get to pulling them off I will check on that seal.
How do you feel about my idea of cutting the stock exhaust and just running the headers and cutting them before the bend.
You think that would be foolish?
One guy I was talking to at work was saying I may not have back pressure because I would be removing the muffler and baffles and said air could go back up into the exhaust and the bike would not run right. But I feel like I see a lot of people with straight pipes and isn't that in theory the same thing? Maybe I am just dreaming too big lol.
I was thinking about cutting them at the same point at where Cassio Silva has on his bobber hard tail. That's the only reference I can find worth googling and finding easy enough.

Let me know what ya think about that.

Thanks again for the jet info

 

[weekendrider]

You might be happier in the long run if you just ride it as is through the summer.
Learn what needs to be done to get running well in the present state. Do your mods one at a time over the next winter.

 

[theblackassassin]

@weekendrider
I totally agree with you those were my original intentions when I got the bike to ride it as is this summer...
BUT..... I was riding it last week and I got stranded... The alternator died out on me.. Funny thing is I checked the charging system when I bought it and everything was great at the time. I had to push the sucker 2 miles to this cycle shop and they were nice enough to charge up my battery at no fee so I could ride it home.
As soon as I got home is when I made the decision to just start pulling it apart.
That being said.. I didn't want to put any money into her right away but now it's my little project on my 1 day off every week.

 

[TheBooger]

longer open pipes or pipes with extra bends will have more back pressure that just cutting stock pipes. there are plenty of things you can do on the cheap to add a little backpressure if you want but it still may not be the best option. the easiest way would be to weld a flat washer to the end of a bolt like a lollipop and put it 2 or 3 inches form the end of the pipe.

 

[pahako]

A lot of guys run with just headers. If you like it loud, it should run ok for you. I have straight pipes with a short drag style baffle you can buy at most motorcycle parts stores.

 

[Nine_Iron]

I agree with the comment above...ride it for a while first and see. I installed pod filters and punched out the center baffles of my mufflers (they were rusted and falling out anyway) which made it straight through, so I took the advice of others on here and went up a notch or two with my jets....bike runs good mostly but my spark plugs are always totally black and my mileage is just so-so. It still runs close to 300 degrees F on warm days too even running rich.

 

[CDNTX650]

so it doesnt run mostly good then....Rich like that will cause more wear than anything...why not jet it properly instead of guessing.

 

[scabber]

Seem like a waste. By 1980 Yamaha had there act together. With stock every thing 55 or 60 MPG. Then they put on the Pods not worth a shit in rain and fuckup a well designed muffler system. For What disrupted air flow Bigger jets lousy gas mileage and a noisy bike that can be annoying even to you. Ride it enjoy it fuck it up later.

 

[5twins]

Yes, saw those pipes off ..... but I would go higher, like just after the 1st bend, leave 6" at most of pipe sticking out of the head. Hey, go big or stay home, right? Don't bother re-jetting, you won't need any of that, lol. It'll run at least as good as a Honda 350 (on one cylinder). Maybe a 160 firing on both is you're lucky. When you kill this bike (which won't take long) then you can buy that Honda, join a Honda forum, and be out of our hair.

 

[hotdog]

I was going to write a list of reasons why you shoudnt - but I cant be bothered......as long as it looks cool.

Yes, saw those pipes off ..... but I would go higher, like just after the 1st bend, leave 6" at most of pipe sticking out of the head. Hey, go big or stay home, right? Don't bother re-jetting, you won't need any of that, lol. It'll run at least as good as a Honda 350 (on one cylinder). Maybe a 160 firing on both is you're lucky. When you kill this bike (which won't take long) then you can buy that Honda, join a Honda forum, and be out of our hair.

 

[weekendrider]

@5twins ICO...BAH

 

[scabber]

By the way welcome to the site. Chicago I would go stealth you don't need one that sounds like a ride by. A couple of backfires Down on bad street can bring the shit down on you man. Be cool.