Exhaust replacements

Bike aesthetic/mechanical/electrical modifications and general wrenching advice.
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Re: Exhaust replacements

Post by vcyclenut » Mon Oct 01, 2018 2:48 pm

Kwee wrote:
Sun Sep 30, 2018 12:58 am
vcyclenut wrote:
Sat Sep 29, 2018 11:04 pm
Kwee wrote:
Sat Sep 29, 2018 1:46 am
vcyclenut wrote:
Fri Sep 28, 2018 12:44 pm
agree, the bike is tuned so rich from the factory and there is still plenty of resistance to flow with the pre cat and cat that you could completely remove the canister and not hurt anything including low end power
Because of supercharger ? My VFR 800 was lean af.
because its tuned rich from the factory

was lean where? meaning what throttle position and rpm?
At low throttle position and WOT

On your dyno results, the AFR WOT at 3k-4k is lean too

you asked if we could cause damage to valves

no way your causing damge to valves at 3-4k rpm's there isn't enough load or time to generate the heat to cause any issue.

I have also learned to not chase these spike in air fuel when you first rip the throttle open on the dyno. If the air fuel shown was the actual true air fuel at that point the power curve would sag big time.

I am not 100% sure why the sensor reads these fluctuations when you first rip open the throttle but it does. This is another reason to start the 100% throttle run so early in this case 2500 rpm, this gives the air fuel time to stabalize when it gets to the rpm's im really concerned about 100% throttle

The internet and social media has gotten eveyone so paranoid about burning up valves and even though its in my best interest to promote this idea that a bike thats a little lean will burn up valves i dont beleive it to be true. I live on social media and web boards. I can count on one habd the number of posts ive seen in the last 10 years about someone burning an exhasut valve and i would bet that they were more related to not enough clearnance on the cams not being lean.

We dont use leaded fuel anymore and valve seats are hardened. I really think this worry stems from back in the day when the leaded fuel was key to keeping valve seats healthy. When we switched from leaded to unleaded fuel cars and bikes started burning up valves. Then hardened vlave seats were introduced and its pretty rare now to hear about burnt vlaves.

I know a guy who had an intake boot rip casuing that cylinder to be so lean it burnt a hole in his piston. The valves and seats were still fine.
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Re: Exhaust replacements

Post by Bengarzy » Fri Nov 30, 2018 6:04 pm

If the can only is changed it seems the valve and cat take away o lot of noise so not much is needed noise reduction wise, the Akrapovic can sounds just the same as the standard one and baffles not removable, don’t add it to your new bike.......disappointment looms and it’s not cheap.
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Re: Exhaust replacements

Post by Kwee » Fri Nov 30, 2018 7:12 pm

For information, with my new exhaust i don't feel any difference in torque in low end and mid range. This bike is run great. Next upgrade is gonna be air filter.
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