exhaust ? for the gurus

If I were to eliminate my duel exhaust system on my 700f and run a single short pipe with a baffle in it off the side with it coming out of a heat shield. would I lose alot of power or have to tune?

 

- Just a W.A.G. from experience says that if you eliminated your dual exhaust system and modified it as proposed, you absolutely will have to do some carburation work to adjust for the modifications in the exhaust. Whether or not you lose power is a function of how those changes effect exhaust flow. Up to a point, reducing restriction in the exhaust can help increase both power and torque. Without appropriate carburation changes, your air/fuel ratio might end up way off, and you could end up way lean (burned pistons), or way too rich (fouled plugs, etc.). YMMV Good luck.

 

Humm....Hard to say
It can be done if you can maintain the same air flow and compresure from the original set up. There were old thread about this.

 

I don't know the 2nd gen, however,

More than likely (talking out of my ass here) the bike is on the lean side already so the change you suggest may lean it out further and it is quite possible that you may loose power and with that super lean condition comes the danger of exhaust valve damage. Plan to do it properly with a high flow air filter and a tune so you can benefit from the mod or leave it stock. Remember that the engine is basically an air pump so the extract more power you need to move more air through it with the corresponding amout of fuel. Changing the exhaust is only part of the equation. So freeing up the exhaust while the intake is still restricted, makes no sense unless you just like the sound.

 

thanks for all the replies. I cant think of any other way to increse the airflow when the airbox in under the gas tank. unless the tuning is simple turning of the a/f screws

 

The air screws simply adjust the idle mixture (fine tuning). When in search of horse power gains, which is what I assume you are doing, you need to move more air which starts with removing restrictions in the system like small openings in the air box, restrictive paper filters, restrictive and heavy exhaust. Other common areas of concern are emission controls such as the PAIR system and flapper valves. Elimination of these makes the tuning process easier. Once the restrictions have been eliminated or reduced, a tuner will look to porting and valve lift and timing to further increase flow through the heads. With this all new set of parameters, the tuner must ensure that the carbs and ignition timing make the most of the modifictaions without exceeding safe limits which could damage the engine.

So even though the air box is under the tank, you can increase flow by reducing restrictions like the paper filter, the nozzle and or the flapper valve if it has one.

As I said before, I don't know the 2nd gen but the general principles apply regardless.

 

not so worried about power just wanted to clean up the bike. make the exhaust smaller and lower.

 

note this exhaust. I enjoy the look of this style 2009-12 Yamaha R1 RLS Exhaust

 

Yah that "Look" has become popular of late.

Well, be prepared to do some carb work if the beast isn't running well after the exhaust is modded because it will likely be running a bit lean. This can be a very time consuming ($$$$$$$$) process as jetting is kind of a trial and error thing especially when dealing with one off unique set ups like what you propose.

 

so even If I was to make one shorty or two one on each side with using stock baffles. just the smal shortening of the distance will require re jetting and a tune? or would compensation with a better air filter rather then an old paper one. and maybe opening the air box a little more cover it? and changing the a/f screws from 2 turns out to 3

 

Yep, even if.... (+1 with what Jethro said.) The relationship between the airbox, carburetors, intake ports, intake valves, pistons, exhaust valves and ports, header pipe exhaust and sound control system (muffler can, etc.) orchestrated :rockband: or directed :director: by the camshafts, makes for a complex relationship :grouphug:. While the front end parts are moving in and mixing fuel and air, the exhaust needs to be extracted as completely as possible, with significantly greater volume than the intake side.

Small changes can require significant tuning to ensure the best combination of usable power and ride-ability. Too lean, the bike can have a bad case of the stumbles, and as it is placed under load, you can burn (melt holes in) pistons, valves and seats, Too rich and and the bike can be sluggish :boozer:, and you can foul plugs, wash lubricant off the cylinder walls, or even fill the crankcase with unburnt fuel (plus fuel mileage will really suck).

Many motorcycle carburetors have 4 areas which can change how the motorcycle runs. The idle (or pilot) circuit typically covers from idle (duh!:der to about 3k rpms (or from about 0-1/4 throttle). Then the "mains" take over from the 3k 'till redline. Float level can also affect these two circuits too (too high - rich, etc.). The choke (or starter) circuit provides warm-up enrichment until the engine can run on the idle circuit, and the enrichment circuit adds extra fuel when the throttle is opened quickly - although many constant velocity carbs do not have an additional enrichment circuit - not sure about an '87, since my viffr is injected.

 

I just hate this high cans they are ugly and sound like shit. so what options do I have? slip ons?

 

Off the shelf? Nothing is available that I know of but I would stay vintage as far as looks are concerned. Something like this would be appropriate for the bike,

1985 RVF750 - Bing Images

 

Hey look, A dead horse!!

Actually, that plastic muffler is way too restrictive and would most likely melt.

I am planning on doing the same thing. So go ahead and do it! Just make sure you post pic's and keep us updated during your project. If it works for you, I will do it too. Oh hell, I'm still going to do it anyway. If I ever have the time (more like money) I will start.

My plan is to cut everything down to the collector, pipe the left side to the right side, tie them together, and then dump it through a car style exhaust resonator. If there is not enough back pressure, I will weld in a washer (baffle) or two. I saw a thread somewhere where someone has already done something like this.... looked good!