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2019 700 SE Tac Black
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Discussion Starter #1 (Edited)
Evening chaps 👍

As per the title , how relevant is back pressure in the exhaust to available or useable power/torque?
To cut a long story short I’ve been messing with the exhaust to see if an improvement is hiding and waiting to be released.
To start with I fitted an ehs tuner and 2r tip at the same time , obviously felt a bit perkier and louder ( noise often appears to be speed , but often isn’t ) Now , having seen the catalytic converter glowing red through my new open mouthed 2r tip ,
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it set me thinking ( dangerous and usually expensive 😆)
The cat is a massive heat soak and radiator of heat , all of which are deemed as a negative.
so I set about the hideous job of removing it whilst leaving the exhaust intact/uncut.
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So having beat and drilled it till I came out victorious, I excitedly refitted it and fired it up 🙈
Rudely loud is an understatement, it quite simply sounded hideous , very harsh sounding , and on overrun it would get to a certain point and then make a Nasty sounding farting / fluttering noise.
it also felt much flatter and less responsive too.
So I have now essentially ruined my brand new ( more or less ) factory exhaust which in the Uk the rrp to replace is £1000 😮
In a word Bollocks!!
This was just before a 4 day trip on the quad and a solution was needed.
As expected nothing was available on e bay as a replacement , even aftermarket options are shipped in to the uk and would take weeks so not an option.
I then thought 🤔Kodiak 700 is very similar, a quick search on e bay and bugger me dry and sideways there it was !! a brand new take off , kodiak exhaust , exactly the same part number as mine complete with spark arrester assembly/tip , which all in new would cost just under £1200 , I shit you not, £1200 😆 I bought it for £60 😋winner !!
So on it went with my 2R tip and all was well, sort of.
Having spent a fair bit of time riding with the tip , it ultimately irritates when cruising and makes it impossible to be stealthy.
I cut a stainless disc the same size as the gasket and then removed the centre with a 1 1/2” hole , basically a reducer.
This cut the noise down to a more acceptable level , though still loud.

Moving on a few months I started thinking again and chopped up the amazingly convoluted / engineered spark arrester tip assembly and fitted just the “basket” part before refitting the 2r tip
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This made the noise less harsh but a little deeper , and seems to feel a bit perkier midrange , after a bit more riding I decided it too was irritating.

I now have the new factory spark arrester and standard tip from the kodiak exhaust fitted and it’s refreshingly quiet 🤫, from the butt dyno I would say I have lost a little something but not massively so.
Now my thinking is ..... what about my original gutted and catalyst free exhaust , but with fact spark arrester/ tip fitted ?
No heat soak , or restriction in the can , but the tip assembly will tone it down as it’s a restriction for flow and pointing down at the tip too.
Any thoughts or experiences here peeps?
Or am i just being a tit 😆
 

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Grizzled
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3,619 Posts
I bought it for £60 😋winner !!
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I'm curious about what you've posted so tagging along for the read.

I do find it funny that so many muck around with a 2R tip, only to find most seem to go back to the OEM tip because they can't handle to increased noise for all day long rides or multi-day rides... myself included. I even went with a HMF Swamp with quiet core and just wanted the quieter exhaust back even though the HMF wasn't substantially louder.

As a FYI, I've always understood having some exhaust back pressure is preferred for properly tuning. But that is only what I've read as I don't have practical experience here.
 

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2019 700 SE Tac Black
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72 Posts
Discussion Starter #3
I’m never lucky generally in life , if I fell in a box of tits I’d come out sucking my thumb 🙁 so when I actually managed to simply buy it , not win it , I was like a dog with 2 dicks 😊

Generally forced induction assisted engines benefit from increased flow and less restriction but with n/a being fussy about length and diameter changes in the system , and for me no facility to properly tune or test changes ( no dyno based options for a small/niche market like quads ) over here it’s generally guesswork or suck it and see.
Off at a slight tangent , One thing I have noted about the ehs tuner is that for the 2019>models , the settings are the same for a standard exhaust or standard exhaust with tip , yet strangely for the 2016-2018 models with the 708 motor but identical exhaust to mine , they state settings for standard exhaust and then different settings for standard exhaust with tip 🤔 what’s all that about then.
I Guess what I’m after is a freer flowing exhaust for power and heat reduction without it being offensively loud.
I may try my gutted can with standard tip and see how that sounds /feels.
 
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Grizzled
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and for me no facility to properly tune or test changes ( no dyno based options for a small/niche market like quads ) over here it’s generally guesswork or suck it and see.
Search for a Koso BA004068 Air/Fuel Ratio Meter and buy/install it. All the guess work will be over and one could argue, even better than a dyno as it can be a permanent item on your Grizzly. It will allow you to monitor and make slight changes to your fueling so you are burning at the proper ratio all while under load in your conditions... a dyno can't match that. Dynos are extremely effective and get very close but an active AFR meter can be even better something @RockTaco convinced me of and he was right.

Keep in mind also, for EHS, they are pretty close to sea level where all of his tuning is done. The tuning really does change when it comes to increased elevation and I knew that going into the Bullet Box purchase. I pretty much had to decrease all 3 throttle settings as I was running too rich from the EHS settings. Again, that is specific to where I live and ride and will not impact everyone the same way. I haven't started messing with delaying when the 3 throttle settings start adding fuel yet, but probably will soon.
 
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2019 700 SE Tac Black
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Discussion Starter #5
That’s good advice buddy thank you.
I had thought of getting a lambda threaded boss welded into the exhaust , having run aem and motec wideband monitors in various cars over the years for use on the dyno or road mapping it was a very valuable tool.
I guess I had not thought I would need something like that on something as basic as a 700 single 🤭

I gathered from watching some videos that tuning cvt driven quads was a bit more involved than being able to repeatable fourth gear pulls in a car for example.
Food for thought thanks 👍
 

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As your messing with air flow, basically exhaust side only, try removing the filter cover for more air in during your tests. I live at 7000 ft. and ride routinely to 13,200 ft. and my 660 was rich in stock configuration, so I tried opening the air box which helped, then added a 2" tip.
I don't think its too loud, here is a video, the first part is the camera mounted on the winch fairlead, but after 3 minutes (scroll ahead?) the camera is on the helmet.
Maybe old with gradual hearing loose isn't so bad.
And one time I gutted a cat for a 460 ford engine, it was stopped up and being replaced the next day, and with just the hollow can and muffle back in place it was down at least 50% on power using the butt dyno.
 
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