YOSHIMURA 4-1 Help

[anthonygs1000]

Baffling

I went through the same issues. my dad an I took a piece of muffler pipe 1 ¾ “ and cut it to what we though was
The right length then we put it on the drill press and drilled a bunch of holes (for the exhaust to pass and muffler pipe was thick enough to weld to) we then went to our buddy at a local machine shop and had him cut us two pieces of 1/8 ” steel on his laser in a circle to fit the diameter of the inside of the can .then we drilled both pieces in the middle that he cut and used our die grinder to open the caps to our preferred size. we then welded the two ends to the muffler pipe and mounted tabs where the existing holes were in the can (to mount the new baffle to the can ) we used new fiberglass baffling material and bolted it in the thing sounds great and has held together for the last two years. the total cost was under 20 bucks

[76FJ55]

I made a trip to STL this weekend short trip but had enough time to find my old Yosh pipe still stored under the stairs where I left it. If you're still looking for baffle I have one. Don't know if I'll here back from you before I get back on the road to head back to Tulsa so I'll throw it in the car. Let me know if you need it.

[maro]

I made a trip to STL this weekend short trip but had enough time to find my old Yosh pipe still stored under the stairs where I left it. If you're still looking for baffle I have one. Don't know if I'll here back from you before I get back on the road to head back to Tulsa so I'll throw it in the car. Let me know if you need it.

thanks for grabbing this. I'm really curious to see it and to know the dimensions.

Duaneage and I (mostly Duane ) spent all day yesterday fabricating a new baffle for my Yosh. I WILL BE CREATING A DIY for this as it worked out nicely and we used only 3 parts from Lowes. no welding was necessary. some grinding, drilling and some muscle was all that was needed.

I have a bunch of photos, but here is a quick shot for now with some captions of the parts


FYI- Bike pictured is duanes Yamaha, not my GS...it just happend to get into the shot.

[76FJ55]

It will be interesting to see how that baffle works for you. It looks extremely restrictive to me, but I guess the berformance results will tell. I will try to get mine pulled out of the pipe but it may not be till tomorrow. I'll have to figure out how to post photos when I get it pulled. I'll also get you all the dimensions for you when I get it pulled. I'm anxious to see how yours performs. What are you using for packing material, and how much did it weigh when you where done building it.

[maro]

It will be interesting to see how that baffle works for you. It looks extremely restrictive to me, but I guess the berformance results will tell. I will try to get mine pulled out of the pipe but it may not be till tomorrow. I'll have to figure out how to post photos when I get it pulled. I'll also get you all the dimensions for you when I get it pulled. I'm anxious to see how yours performs. What are you using for packing material, and how much did it weigh when you where done building it.

I forgot to mention that I had NO BAFFLE in the can to begin with . $hit was LOUD!!!

I rode about 35 miles to Duanes house with no baffle, mostly highway. I then rode home with the new baffle and noticed no real difference other that it was quetier. I'm used to riding a 650, so I'm still getting used to the amount of punch the 1100 has in comparrison, and that might fog my perception of restriction... however, the bike pulled like it did before..so....

It actually has a really nice growl when I opened up the throttle. We packed it with steel wool. To be honest though, I will be putting in stock carbs in (I am now running 33's with veloctiy stacks) and maybe a stock airbox over the winter, So I will be re-jetting when that happens. If I do notice a difference upon further testing and riding, I will remove that end cap that is pictured to allow more air flow. I'm thinking it weighed in at around 6 - 10lbs. I'm not racing this thing so the extra weight is not an issue.

looking forward to your pics. If it looks to be the same size, I might just buy that from you just to have the proper baffle..in case I need it. thanks man!

[duaneage]

I took it up to 8K in second, didn't seem restrictive to me. That thing is a monster.

All those holes easily add up to the exit diameter of 1 inch. The flow from the back was really strong at idle. Josh could not even hear it riding behind me, that's a great improvement.

The absolute most important thing is to get it quiet so he can register it and drive without being ticketed. In a rural area you can get away with anything but in Philly, revenue rules the day and a ticket for loud pipes can be expensive.

We can always make holes bigger. Or start all over again with a new pipe. A quick way to do the holes on the center section would be to grind 1/4 inch slots every inch so there is a 1/4 by 1/2 notch along the pipe. As long as the amount of airflow exceeds the output by enough it should work. Pressure is low and airflow is high at that end of the muffler. Forward motion of the bike actually helps evacuate the pipe, and with the 1100 E there is a great deal of forward motion.

[isleoman]

Maro/Duaneage,

Good first shot to get you going.

On my Yosh baffle I would say there is substantially more perforations (breathability). They are more like what Duaneage suggested ie. notches that look pulled apart. Almost like they start with a pipe that is 2 inches short of the desired length, notch around circumfirence, then pulled apart or twisted to form the slots. The edges of the slots form a small lip on the inside of the baffle that looks like they are designed to direct some of the exhaust into the fiberglass packing as it travels the length of the baffle.

I think you can quite down the exhaust more. With the design and number of holes you have now I don't think enough of the exhaust/sound/decibels can escape into the fiberglass packing. I'm thinking the majority just shoots out the back still. I think you need slots or small scoops, and as you form the slots you need to form a lip on the inside of the baffle that help to direct some of the exhaust into the packing.

Just my observations. Again great first attempt.

[maro]

Maro/Duaneage,

With the design and number of holes you have now I don't think enough of the exhaust/sound/decibels can escape into the fiberglass packing. I'm thinking the majority just shoots out the back still. I think you need slots or small scoops, and as you form the slots you need to form a lip on the inside of the baffle that help to direct some of the exhaust into the packing.

Just my observations. Again great first attempt.

Thanks brother. Definitely a pilot baffle. I'll need to ride more (been too cold to ride since I rode home from Duane's) but the sound..sounded....NICE. My 650 doesn't make a peep. it's dangerous in the city. The 1100 seems to have a growl now, but not obnoxious.

Here's my question. would " I don't think enough of the exhaust/sound/decibels can escape into the fiberglass packing" have anything to do with performance, or is this just a sound issue. because it still pulled like a train....?

[isleoman]

Maro,

Not really my area of expertise but I suspect that the baffle set up you have now will give better mid range with a slight loss of top end but thats just a guess. I don't it would cause you to have any problems with being too lean, may help in that area.

[duaneage]

maro has work to do on the carbs still. Once that issue is resolved we can step to finalizing the baffle design. Worse comes to it he can invest 10 dollars in more pipe and we can experiment with different baffles. pop rivets are cheap. It's nice not to worry about messing up some classic rare expensive piece of unobtanium while having some fun at the same time. I say, carry one on a trip, pull over, swap it out and try another.

[duaneage]

I punched 20 of the holes out to 1/4". No noticeable noise increase. I also replaced the rear progresso can with a steel electrical baffle for a 3 inch round junction box. It was an immaculate fit in the rear of the pipe, took a little tap to seat, no rattle. I secured it with three pop rivets, I will add a fourth for security. I'm heading to Lowes to get SKU numbers and local prices for this, I've gotten a few requests from people that want to know how it's made.

Sure cheaper than used baffles on Ebay.

[Big T]

Bump

Duane,

I went to Lowe's today and bought the parts based on what I see in the photos

I also bought a 3/4" floor flange because it seemed closer to the header ID

So, I found

Header ID - 3.38"

1" flange OD - 3.76"

3/4" flange OD - 3.42"

3 1/2" round ceiling box OD - 3.35"

So, did you grind .4" off the 1" flange to fit it at the back?

I don't want to drop to the 3/4" nipple as the volume decreases 45%

[duaneage]

Bump

Duane,

I went to Lowe's today and bought the parts based on what I see in the photos

I also bought a 3/4" floor flange because it seemed closer to the header ID

So, I found

Header ID - 3.38"

1" flange OD - 3.76"

3/4" flange OD - 3.42"

3 1/2" round ceiling box OD - 3.35"

So, did you grind .4" off the 1" flange to fit it at the back?

I don't want to drop to the 3/4" nipple as the volume decreases 45%

I had an additional 1 inch worth of threads added to one end of the pipe for it to fit. lowes threaded it some more for free.

I started grinding the flange down and test fitted it as it got close. When the flange went deep enough for all 12 inches of pipe to fit with 1/4" showing out the back It was done. Then I drilled the intake holes on the ground flange. This is critical since you want a tight fit that won;t rattle yet you don't want to force the flange in adn damage the pipe.

The electrical box was a ceiling fan mount plate, it was a perfect fit and had 1/2 of material to attach to the pipe with pop rivets.

[Big T]

So you're talking about the inner flange?

What about the rear one?

THe ID shown is at the rear of my pipe, so both 1" flanges are too big?

[duaneage]

That's the beauty. The rear flange fits right over the back with a small lip, maybe 1/8" all around. The electrical box has two holes that line up perfectly with the flange, allowing the other two to be marked and drilled precisely. The electrical flange needs to have a 2 inch hole cut in the center, I used a jig saw with a scrollable metal blade to carve it out.
Alternatively you could cut the rear baffle a bit to fit inside the pipe but we liked the look it had. And it is easy to remove.

The pipe and forward baffle is inserted into the pipe snug. The rear is threaded on until it comes to rest against the muffler. The pipe should be flush with the rear of the flange if about 1/4" of pipe is protruding.

I leveled the 4 screws with the ground for appearance and then drilled a few holes for rivets to hold it. I used stainless steel M6x20mm bolts and nuts for the hardware to attach the flange to the electrical box, didn't want rust lines down the back. Use aluminum or stainless steel rivets if possible.

I packed it with a single bale of #3 steel wool loosely spread around the pipe. It seems to be holding up well. It doesn't catch fire or blow out the back.