Vfr 700 and 750 Owners, Can You Measure this Exhaust Part for me?

If you have the stock mufflers can you please measure the inner diameter of the exhaust outlet hole? This hole here. Thanks.

 

I'll try and measure it next weekend when I can get to the bike again.

 

Stock mufflers, what are they?

On a serious note, since my bike does not have the original exhaust I can't help. I wish I could!

 

Well, since these bikes are so old anyone with stock pipes like myself are kind of stuck with them.

I removed that center section in the photo to make it louder and it sounds great. I'd now like to add a little section of tubing to the endcap to make it look more stock. More finished looking. Maybe I'm being too anal about wanting it the same diameter as stock. I'm thinking if it's the same diameter hole, I'll have the same back pressure as stock.

Are the only alternatives to the stock muffler slip-ones?

 

I've got a yosh 4-1 that I haven't put on yet. Going to see how the stock sounds first and whether I like it or not. If you are looking at some aftermarket or just other options there's a plentiful post about it here: http://vfrworld.com/forums/1st-2nd-generation-1983-1989/35876-aftermarket-exhaust-87-vfr-700-a.html

Looks like we're getting a foot of snow or so up here so no riding this weekend but if you definitely want that diameter I'll run over and measure it this weekend.

 

I measure 26mm on my stock 87 vfr700f pipes. Do you have a picture of what ever you did to your pipes? Or maybe some sound?

 

Thanks for the info.

I do have a video, but it's not that great. I made it to highlight my engine knocking. If you ignore the knocking, you can hear the exhaust. It sounds quieter in the video than in real life. Maybe a tad too loud at idle and cruising speed, that's why I want to reduce the opening in the endcap and see how it sounds. Make it look nicer, too.
VFR700 1986 knocking sound - YouTube

I need to make a new video with my replacemnt engine to highlight the sound of the exhaust.

I've got a lot of pictures of the muffler when I removed the endcap. First I drilled out the welds holding the endcap on, then once I saw how it was designed, I shortened the cans about an inch to get rid of the big holes I drilled in it. Then I decided to cut out the center of the endcap which bypasses the mufflers internal chambers and let's it come right out the end.

If you wanted to do something similar, I would skip removing the endcap and just use an angle grinder on the endcap to remove the center section. Mask and paint and your done.

Doing this mod did not effect the power or carbs. It still runs strong throughout the rpm range. Just louder.

BTW, since the inner chambers were bypassed, I ended up shorting my mufflers again (with no change in sound). I think they are about 5.5" total shorter than stock. Stubby look. I don't have any pics of them yet.

 

Great! Thanks for the info!

 

Thanks for the pics of this job you have done to the mufflers as I need to do some work to mine as something is rattling in both of them.
I probably wont open up the outlets like you have just need to work on the internals.

 

The muffler is divided into 4 chambers as can be seen by the spotwelds. Honestly, I don't know how you would get any loose object out of it. Try and figure out which chamber it is in.

If it's in the back 2, you can drill out the spotwelds holding the endcap on and slide it out. That will give you access to the rear chamber and you can run a magnet on a wire into the next chamber. If it's in the front 2 chambers (or any of them) you might could drill a hole on the bottom front of the chamber and hope you can shake it out. Then weld up the hole or plug it in some way.

You might have to take the mufflers off and shake them out. Pull the front two pipes off first then you can slide the mufflers off. I had to hammer mine off and then rubber mallet them back on. It's tricky.

 

The mufflers are off as the bike is getting a rebuild
tried the shake option but with no luck, can the baffle tubes come loose?
Or should I be looking at some replacements like SITO mufflers?

 

The baffles that divide the muffler into sections are spot welded into place. So no, it doesn't come apart easily.

You could drill a small hole in the bottom to let what's rattling out and then fill the hole with a stainless screw.

I've never heard of SITO mufflers. What are they?

I was thinking of replacing my mufflers just to improve the looks. A basic slip-on can be made to work.

Or you could make a 4-2-1 style by cutting one pipe after the 2-1 section and wrap it around to the other side.

I keep hearing that the 4-2-1 designs create a flat spot in the middle of the power band which is not good. One guy who did that added a crossover pipe in the same location as the factory cross over pipe and it cured the flat spot.

I personally think the twin cans sound better than the single, but twin polished stainless steel slip-on's cost twice as much.

I might wrap my existing mufflers with a thin sheet of polished stainless steel. That way I can keep my nice sound, I can greatly improve the looks and it's way cheaper.

 

With my old 2nd Gen I purchased a mint 4-1 Yosh pipe. No matter what I tried it wouldn't fit. I couldn't get it onto the header pipes enough to clear the rear shock linkage.

I then bought a pair of Kerkers and they barely fit on....but when they did they sounded great.

Jason that's some fine work you did to those stock Cans.....I hated the exhaust sound from the stock pipes.

 

the stock sound sounds like a pissed off sewing machine.....

 

I have yet to upset a sewing machine.

 

you really lucked out if you got ahold of a decent 4-2-1 Yoshimura system...I'd say that's the best 4-2-1 system that was available for these bikes. As for stock, I don't even know if it's worth going out of your way to figure out what stock sounds like, it ain't great.

 

Sounds great to me.

 

Here is a new video of my modified stock exhaust.

My phone doesn't really capture the shear volume when revved. In person it's much louder. I need to make a video of me riding towards and away from the camera. Maybe I'll do that later.

VFR700 1986 Revving - YouTube