Pro Circuit Systems Questions

I bought my 08 YZ450F already fitted with a T-4 slip on muffler. What would be the weight difference between this muffler and the titanium equivalent Ti-4?

What would I gain, if anything, if I changed to a full Pro Circuit T-4 system including header?

I like how the bikes power is at the moment, but if I could gain some more bottom end or get the power to start even lower in the range would be good..

some say every 10 hours... i say every 50.

sick bike! if money isn't an issue a Ti System would look good on that set up.

Maybe some new grips too!

Repacking intervals depend on how hard you ride. Here is a good chart to give you an idea of how often you should be repacking:

repack.jpg

As for the weight difference between the T-4 and Ti-4, it is only a few ounces, you can barely notice it holding each one in your hands, and can't notice it at all on the bike. The Ti-4 isn't really known for its durability either, so I would stick with the T-4. I have had both and the Ti-4 disintegrated quickly, but I never had any issues with the T-4. Getting the header will give you some small gains, but whether or not it is worth the money is up to you.

Had a bit of a look at the muffler tonight. Took the end cap off and the steel mesh cone insert. What is the insert for? Any gains to be had from taking it out?

One concern I have is the removable end pipe outlet is a much smaller diameter to the muffler core. This looks to be restricting the flow. Is this the way the muffler is designed for optiumum performance or can it be improved?

A screen at the outlet end of the muffler would be a spark arrestor. There is normally no perceptible effect on performance with or without it. It might show up on a dyno, but not in the seat of your pants.

Cool ill leave the screen in.

Ive done some more investigating and have found I have the smallest diameter end pipe insert available for my muffler. (there are various optional sizes). Mine measures 1-3/8 inches diameter. The diameter of the inner core that runs the length of the muffler is around 1-3/4 inchs.

Does the smaller size restrict power and if I changed the end insert to the same 1-3/4 inch as the rest of the muffler how would the power be affected? I know it will be louder ofcourse.

Usually, the larger diameter end piece will slide the center of the power curve downward. It will also make it louder, as you've already guessed, and it may make the packing last a little longer.

Usually, the larger diameter end piece will slide the center of the power curve downward. It will also make it louder, as you've already guessed, and it may make the packing last a little longer.

So the larger diameter wont raise the HP in any part of the range? At the moment with the smaller end pipe, the exhaust gas would not flowing smoothly out. Its hitting the edges of the end pipe because it is not gradual but a straight step down in diameter if you know what I mean...

Ok. How often should it be changed? The bike hasnt been ridden much at all. Thought Id share a picture of it aswell.

129_2946.jpg

What kind of wheels are those?

What kind of wheels are those?

SM Pro there called.

A screen at the outlet end of the muffler would be a spark arrestor. There is normally no perceptible effect on performance with or without it. It might show up on a dyno, but not in the seat of your pants.

I would disagree on that. At least for my bike then. When I go on closed course race track you notice all '3' levels with the T-4. 1) with the sparky and silencer 2) Only Spark arrestor 3) Spark arrestor taken out. 1 and 2 have very small differences between power and the handling. But take it all out and the bike will rip!!! It will be louder though! So save it for closed course and don't be one of the idiots that was in a camp ground next to me revving the hell out of his bike at 6am with no spark arrestor or brains. :crazy:

and don't be one of the idiots that was in a camp ground next to me revving the hell out of his bike at 6am with no spark arrestor or brains. :crazy:

Let me guess, Hollister?

Let me guess, Hollister?

No unfortunately Stony Ford. :crazy: If it was Hollister it wouldn't piss me off as much because you kinda go there expecting those kind of people. The kind that think a proper warming up of your bike is to hit the rev limiter several times :eek:

T4 sparky's must be different than a DRD, then. On mine, you absolutely can't tell the difference.

I would disagree on that. At least for my bike then. When I go on closed course race track you notice all '3' levels with the T-4. 1) with the sparky and silencer 2) Only Spark arrestor 3) Spark arrestor taken out. 1 and 2 have very small differences between power and the handling. But take it all out and the bike will rip!!! It will be louder though! So save it for closed course and don't be one of the idiots that was in a camp ground next to me revving the hell out of his bike at 6am with no spark arrestor or brains. :crazy:

When you say 'silencer' do you mean the smaller end insert? What do you mean the bike wll 'rip' with it all out, what exactly is the differece? More power all round? Or mainly in specific area/s?

Im asking because I currently have the smallest/ quietest insert and may purchase a bigger one if the gains are what I am looking for.

When you say 'silencer' do you mean the smaller end insert? What do you mean the bike wll 'rip' with it all out, what exactly is the differece? More power all round? Or mainly in specific area/s?

Im asking because I currently have the smallest/ quietest insert and may purchase a bigger one if the gains are what I am looking for.

The silencer for the T-4 is the smaller insert inside the cap. Its also holds the spark arrestor in the pipe. I made a little doughnut so that it holds the spark arrestor in but I can now take the silencer out. (Still keeps it a relatively quite bike.)

I would say that taking everything out most certainly increases everything. I noticed more torque out of turns. The response feels much quicker. Also it seems to rev out just a tad farther. I have no dyno tests to prove this but I will admit it feels GREAT with it all out. Just stay closed coarse and don't leave the sparky out when your riding forest. Don't be one of those Hollister kids :crazy:

No unfortunately Stony Ford. :crazy: If it was Hollister it wouldn't piss me off as much because you kinda go there expecting those kind of people. The kind that think a proper warming up of your bike is to hit the rev limiter several times :eek:

Oh yea been there....its insane. I always yell "Rev it higher!" and they like that a lot:bonk:

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