Will an exhaust alone enhance performance?

[timebombprod]

While I'm waiting for some new pilot plugs, I was wondering if an exhaust alone does increase power to the bike.

I am having to up my pilot jets from stock size to 45 and my mains are also a size up from stock, and I was wondering since more fuel is being added to go with the airflow would that mean theres any real gain in power? I'm not asking does it make my bike have heaps of a difference I'm just wondering is it a bit of a step up from stock.

Also is there enough of a power increase to make mods like pods (dont plan on it) or sticking a filter straight to the second half of the airbox worth it? I know jetting would need to be done but I'm wondering if its enough of a difference for somebody to say they would do it again.

My own answer is since more fuel is having to be added because of the exhaust that there is a little bit of extra power but I'd like to hear what others know. Maybe somebody had the chance to run a dyno testing this out.

[Rob S.]

As I recall, V&H did not recommend any carburetion changes when installing their "Street Megaphone" 4-into-1 exhaust system, just removal of the air box cover. And power increases, if any, were never as much as manufacturers' claims.

The back of the CB750 Four's tail pipes frequently rusted through because on short rides, they didn't get hot enough to burn off condensation that had accumulated. 4-into-1 pipes seemed to solve that problem, and were cheaper than four new pipes.

When I installed pods on my Kaw 900, it ran fine with no jetting changes. But the look, and sound, of both pipes and pods caught on very heavily in the '70's and '80's.

[rphillips]

My opinion, only bolting on the 4 into 1 nothing else, the reduction in wgt. will mean more than an increase in power (But will really make it sound faster). That being said, bolt on a good flowing & scavenging pipe will get more exhaust out, so increasing inlet air flow with correct fuel mixture will definitely increase power. If the pipe gets more exhaust out, you need more, power making, air/fuel mixture going in for max. power. Just my opinion. Dang it, I can no longer find my old V&H paperwork, but Rob, I think you are wrong. I'm pretty sure the paperwork that came in the box with my new V&H pipe, back then, they did recommend larger jets along with removing the air box lid.

[timebombprod]

As I recall, V&H did not recommend any carburetion changes when installing their "Street Megaphone" 4-into-1 exhaust system, just removal of the air box cover.

It's a mac revers cone only brand who supports an aftermarket exhaust for the 650. I'm not sure how the filter would stay one without the cover lol I made sure I'm not missing any pieces, I know other airboxes do have another piece but this one doesnt.

[timebombprod]

The air filter fitted on the second half of the airbox would he the direction I'd go if I wanted to modify the intake side but damn it runs so smooth i wouldn't want to jeopardize it.

[wymple]

I put a 4 into 1 on my GS1100 and the real difference was a 24 lb weight reduction. Beyond that it pulled redline easier with the factory pipes.

[metalfab]

Power is all about flow. If you increase the cubic inches of the air fuel mix you burn as your engine cycles through the air it consumes, you get more power. That and squeezing the air fuel mix a little harder for more of a reaction when it ignites is good too, but it is tough to increase the compression ratio. A 4 into 1 sound's great, and should add some power if everything else is correct.

[earlfor]

It's a mac revers cone only brand who supports an aftermarket exhaust for the 650. I'm not sure how the filter would stay one without the cover lol I made sure I'm not missing any pieces, I know other airboxes do have another piece but this one doesnt.

Mac specifies retaining the stock jetting for their street pipes. Bigger than stock jets will cause it to run rich and foul plugs. Removing the air box or filter will cause lean running and decel popping plus running hotter.

[timebombprod]

Alright cool, everything is stock except my mains I've never had an issue with them (that I atleast realised was the mains) but I do have the stock size still so I can definitely go back if needed.

It does have the competition baffle but since I have a stock airbox I dont think that matters much.

[Spyder]

More fuel, requires more air. If you are not increasing the air coming IN, then you do not have to increase the fuel. Doesn't really matter how much air is capable of going OUT. The engine is just a big air pump. Like a few others have stated, the biggest gain is the MASSIVE weight reduction you will get from a 4-1 setup.
If you were to consider changing the intake up, I highly recommend removing the filter box, and adding 1 big K&N to the end of the plenum box attached to your carbs. You will retain the proper air velocity (and even improve it), and raise the air flow. THIS setup, you will need to re-jet for. Individual pods are a major pain to tune for, and you will have to revisit your tuning more often.

[timebombprod]

If I go for the power gain the one big filter will definitely be the move

[GSXR7ED]

My opinion, only bolting on the 4 into 1 nothing else, the reduction in wgt. will mean more than an increase in power (But will really make it sound faster). That being said, bolt on a good flowing & scavenging pipe will get more exhaust out, so increasing inlet air flow with correct fuel mixture will definitely increase power. If the pipe gets more exhaust out, you need more, power making, air/fuel mixture going in for max. power. Just my opinion. Dang it, I can no longer find my old V&H paperwork, but Rob, I think you are wrong. I'm pretty sure the paperwork that came in the box with my new V&H pipe, back then, they did recommend larger jets along with removing the air box lid.

I increased the Main Jets from 112.5 to 117.5 and kept the original airbox. Some said to goto 120s but I stayed with the 117.5s and it worked out great while out in NM.



Pipes look great!



The "T" is a beautiful bike.



Ed

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