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Going back to OEM exhaust ?

10K views 28 replies 16 participants last post by  rawheadjim 
#1 ·
The reason I ask is I’m just really tired of the loud ass aftermarket exhaust. I’m wondering what effect it would have if I went back to my original stock exhaust and left everything else as it is.

The current set up is a two brothers full exhaust, a Chimera intake, Kitaco 164 BBK, Kitaco type 2 cam, stock head and valves, PCV with Wide Band Auto Tune. The fueling is pretty much dialed in as the auto tune only makes very small adjustments to the map each ride.

So here’s what I’m thinking about doing. Removing the two brothers exhaust and installing the stock exhaust. Removing the auto tune in module and AFR sensor. Going back to the original stock O2 sensor and only having the PCV for fueling. Knowing that just adding an exhaust does very little to help or hinder the motorcycle why wouldn’t this be a good idea? The way I am looking at it with the map I’m running right now changing the exhaust wouldn’t put me in any kind of jeopardy as far as AFR values are concerned or am I way off base here. A little help from the experts around here would be appreciated. I’m just sick of listening to that damn loud exhaust! And yes I know I might take a small hit in the horse power department but I can live with that as the bike is plenty strong as is.
 
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#2 ·
Sorry KC not an expert, consider with your map it is perfectly dialed in to your current components as a whole... Not familiar with your exhaust but stock is very restrictive and that in itself may imperfect your map. To what degree maybe not much maybe enough to make your bike run like shit... But would imagine some kinda difference, I could tell the difference going from yosh with loop to hindle with straight header, did have a tuning difference to adjust to...
 
#3 ·
We are in the same boat, except my boat is bigger. (Koso 170)

The exhaust on a stock motor gives a laughable increase of power. Now when you add CC's (BBK) the exhaust comes into play more than ever for the potential making of power. I say potential because not all exhausts will flow the needed gasses that a BBK puts out. Some of them are pretty damn small diameter.

The flow of gasses are directly related to noise, IMHO. I know with my Hindle with the DB killer in, it kills my top end. And if you put the stock exhaust back on you are likely to gain bottom and maybe mid, but loose a bunch up top. That head pipe is so tiny.

As of this writing you cannot have a quiet Grom and make power. Period.

Please prove me wrong, I would love to have a quieter Grom again....
 
#10 ·
........As of this writing you cannot have a quiet Grom and make power. Period.

Please prove me wrong, I would love to have a quieter Grom again....
I am not convinced that this is true at all. I think we may be somewhat limited by our commercially-available options: the stock exhaust which just might be a bit restrictive, vs. a lot of the more-common after-market exhausts which seem to regard being LOUD and *sounding* powerful as marketable attributes. (Many times I have read on this forum a report of someone who put an exhaust on their Grom and seemed convinced of more power simply because it was louder......hmmmm?)
 
#4 ·
I do believe there is a solution but I can’t get enough info to make a purchase. On WeBike they sell exhausts for our bikes that meet strict Japanese noise requirements. However from what I’ve been able to gather they still flow much better than the stock exhaust and in some cases as well as some American after markets. I just I haven’t been able to find enough information to help me make an informed purchase.
 
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#13 ·
I have a Takegawa Bomber and couldn't be happier with it. On stock bore it's pretty silent but with a nice sound. With a 4 valve setup it is louder but still quiet compared to most exhausts available, a Tyga on stock bore for example is louder than the Bomber / 4 valve setup.
You could also try running the stock can with a performance header. I think nd4 is running a DG header / stock can setup on his 164.
 
#5 · (Edited)
When I put the Hindle baffle on my 181cc, I maxed out at about 65mph (down from about 80mph), but accelerating up to 60mph felt almost the same. I couldn't imagine trying to run a bbk on a stock exhaust system. Try looking into if 2 Brothers makes a baffle for your muffler. There are also universal baffles you can try. Since you're running a stock head, you might not be losing too much top end running a baffled exhaust.
 
#6 ·
I’ve already called Two Brothers. No baffle available for the Tarmac exhaust.
 
#7 ·
I don't get how everyone says that their Hindle baffle makes such a dramatic difference. I've had mine in since day one and have gone over 75 down the highway... and it's still loud as hell.

KC if you put the stock exhaust on, I'd be interested in the results... can't lie I've thought about it before myself. I have the stock 17 exhaust in my basement, guess it's just welding on a bung and letting auto tune do it's thing.
 
#8 ·
That would be my try as well put on stock exhaust and bung let auto-tune do its job,,, plus less work.

Philly the db killer is only good at idle or no throttle lol, other than that TRUE its like its not there, plus Like Solid is saying it is a power robber my top end sucked with it in as well, took that shit right out will sell to any body for $20.00
 
#9 ·
I can relate to the OP’s situation. I also found the after-market exhaust (in my case, it was a Hindle w/dB killer) far too loud for my tastes. I enjoyed the bike a lot less from the added noise of that exhaust. More on point, however, — and do note that this was with a stock displacement engine — I found NO perceptible increase in power from adding the Hindle (along with intake mods and a fuel controller). So, I went back to the stock exhaust.

I really question the oft-cited narrative that one has to install an after-market exhaust in order to see power gains (at least at stock displacements). Where is the data that establishes this as a “fact?” If the stock exhaust was really all that restrictive, then it seems to me that one would expect to see significant power gains from installing a less-restrictive exhaust, but this does not seem to be the case for the most part. I think most of the after-market exhausts are designed to be loud because a lot of the more rambunctious young riders simply LIKE making their motorcycles loud.

I have no idea what the outcome might be from trying the stock exhaust with a larger displacement engine, but I don’t think it will hurt to try. I also think some of the quieter Japanese-certified Webike offerings might be worth considering. At the final outcome, you want the bike to be fun for you to ride.
 
#15 ·
There is a placebo effect the manufacturers count on for sales. Of this I am convinced.
 
#11 ·
a good aftermarket exhaust is usually a tuned exhaust. a bigger company like yoshi and two brothers has R&D behind them with many hours and prototypes to determine the best gains for given applications and desires, hence why those full exhaust systems cost $400 plus also providing better parts/quality and fitment.

with that being said my stock exhaust performs better than my FMF full exhaust PRIOR to 6k. the FMF outperforms the stock exhaust once past 6k. this is based off my two 2014 groms both have 14t, K&N, and power commander. I switch every other day between them and am reporting what I experience. (over 25,000 miles between both groms)

I am a heavyweight (+200lbs) my stock exhaust grom struggles to hit 60 sitting upright. FMF bike will hit 65 sitting up, redline tucked at 9800 rpm.
 
#12 ·
I take it you have the DB killer installed on the tarmac? I have never ran with mine in but I might try installing a screen spark arrestor so dampen the noise a touch. I usually ride with ear buds in but I think im getting hearing loss in my right ear lol.
 
#14 ·
OG grom here. A long time ago I had a DG header (no cat, larger ID than stock) and the stock can. It was pretty quiet for sure. I could never get decent top speed. I remember when I finally changed it I immediately had a very solid increase in top speed. Being quiet just didn't let it flow. Also the stock can weighed twice as much as my whole exhaust does now.

I ride with ear plugs, which I'd recommend to anyone regardless of exhaust. Check out Ear Peace. They are adjustable on noise reduction.
 
#19 ·
You could do like me and keep the stock exhaust can and run an aftermaket larger header (this is where most of the stock exhaust restriction is). I run a DG header and stock exhaust can on my grom with pretty good success..... the stock header though was WAY WAY to restrictive for even a mild 164cc bbk.
 
#21 ·
Would you be willing to send me a couple of pictures of that exhaust set up ? And, is it significantly quieter than the average aftermarket full exhaust ?
 
#23 ·
I just swapped back to the stock exhaust this morning as well. Had the Two Brothers Tarmac Carbon installed. Sounded great and mean, but just too loud after a month or so. I must be getting old. Stock exhaust just makes my ears feel better. I need to clean up the Two Bros and possibly sell it.
 
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#24 ·
I’m running the Tarmac as well too damn loud. Are you running any other mods such is a big bore kit?
 
#29 ·
I'm with you as well. I'm old now and need to avoid hearing loss, and ride mainly in local neighborhoods where I live in the suburbs. I wouldn't mind an exhaust that sounds better, but not louder, only if it didn't require other mods to run efficiently. The idea of spending a lot on a Grom to make it a little faster doesn't appeal to me, I bought this bike to go slow and quiet! I would have spent more on a full size bike if speed was my goal.
 
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