Tim Hodge exhaust mod

Take a look at this mod they're doing to the muffler on the Nighthawk cb750:

nighthawk750.com

Select "Modifications" on the left then:
Select "Tim Hodge Exhaust mod" on the left

I did this on my California '95 Nighthawk and it was freakin' amazing. My powerband evened out with a noticeable increase in low end torque. My mileage improved about 3-4 mpg (or about 15 miles to a tank of gas). The mod did not noticeably increase the sound level, but it did give it a deeper growl on acceleration.

The ass-end of my (again California) '86 Vf500f has the same 4 rivets as my Hawk so, assuming the construction of the mufflers is the same...I'm thinkin' seriously about the doing the exact same mod to my vf. Well, I'm not just thinking about it, I'm gonna do it tomorrow.

All you need is a drill and a riveter. The best part of this mod is that it's easy, free, and easily reversible if you don't like it.

Tip: I used aluminum rivets. They're a LOT easier to drill out if you want to increase or decrease the intensity of your mod later.

What do you guys think? You're the pros. I've only had this bike for a month now so any input you have is welcome and greatly appreciated.

BTW-They have a lot of real useful how-tos on that board that are well worth looking at.

 

that page brings back a lot of old memories...:smile:
i started to do this mod on my nighthawk and decided to try it out w/o the baffles before going ahead and drilling them out. i decided that i liked the sound w/o the baffles and that ultimately it was a waste of time to drill them out, reinstall, test out, drill, reinstall, test out...
honestly when you think about how an exhaust system works as a whole, your not going to get any performance out of drilling a few holes out of the baffles.(with a factory system with such small factory primaries coming off the header) you are just going to create added turbulence inside that small pipe that connects the different chambers in the mufflers. anything noticed by this mod is most probably just a placebo effect of the louder better degree.
i read a little bit further into this and people were actually talking about how many holes they could drill before rejetting was needed...:crazy:
eventually i went with a vance and hynes 4 into 1. which there was an actual performance gain with, and the factory jetting was still fine.

relating this back to vfr's, i would give it a try with out the baffle in place as being a v4 instead of inline4 its much more likely to sound great with out them in place. i just cleaned the back out a little and sprayed some high temp black exhaust paint in there and it looked hardly noticeable...

 

Was advised by my mechanic not to remove the baffles. I'm looking for better anyway, not louder. This mod seemed far more controllable and had more potential for performance. Honestly when you think about how an exhaust system works as a whole, lowering the back pressure in a restricted exhaust system seems like a pretty good idea.

Having driven motorbikes since 1970, and my Nighthawk for the last five years, I strongly doubt that my impressions on improved performance were due to any "placebo effect". I learned a long time ago the difference between loud and better. My gas mileage increase over the last two months was measured and real.

As California is a bit touchy about exhaust modifications (they're talking about emission/noise tests for bikes now, just like cars!) it's nice that this mod is not detectable w/o dismantling the exhaust.

Thank you for your thoughts, Candy. I appreciate your time and opinion.

 

Well I tried the same mod on my vf500f and it didn't work...the muffler is designed differently and after removing the four rivets in the back, I was unable to get the funnel assembly out. There appears that there's something else holding the whole thing together. On my Nighthawk it just pretty much fell apart at that point.

But, it was good that I removed the muffler from the header pipe. Found some corrosion behind the muffler that I wasn't aware of before, so the exercise wasn't a complete waste of time...

 

when i did my nighthawk one side came out relatively easy. the second side was a bitch, to say the least. being 2 years older my nighthawk probably was a little more coroded then yours. that 86 vf500 of yours, being old enough to consume alcohol, is probably gonna need added heat and or pb blast/wd40.

 

looks like crap and cheap, like you got drunk as hell and made a mess of your exhuast...........

 

yeah because you saw it right

 

Thanks for the help, Candy. I haven't replaced the rivets yet so I'll soak it in pb-blast today and try again tomorrow with a little heat (say good-bye to my fingerprints-Ha!).

 

lol nice good luck brotha.
i remember when i did mine the left one popped right out but the right one i had vice grips on it and i was pulling so hard i bent the small pipe inside up a little, where the vice grips were attached, before it finally popped out.