Unleashing the YOSHIMURA 77 on an RT !

[cjackg]

When I first installed a new Yoshimura R-77 pipe on my 2012 RT, I was very disappointed in the sound. The quality of this muffler is superb in every respect but it sounded almost as quiet as the OEM RT muffler even though half the size, much lighter, and much prettier! I was not looking for a super loud muffler but I do like to hear that Rotax working out.

When I looked closely at the Yosh I could see there was an Insert-tube inside to reduce the exhaust opening, evidently to ensure meeting noise level requirements. Inquiries to Yoshimura resulted in no options as they insist the Insert is required to meet US specs. More searching for help showed me a YouTube video of a guy removing the Insert!

After listening to the RT sewing machine noise some more I decided to gamble and remove the Insert for a test. At this point I should warn you that the Insert is fastened to the muffler with only one bolt, but that the head of the bolt is spot-welded in place. A little work with a Dremel solves that problem... See the pics below showing the Yosh with the insert, and then opened up!

When I started up the RT with the Yosh insert removed, the sound was amazing.... a growling Rumble unlike a high revving engine that only got better with more rpms. This is the 4th different muffler used on my RT and is by far has the best sound I have heard yet from an RT.

Answers to the first questions... Yes, some Yoshimura 77s may be shipped without the Insert tube as seen in some pictures; Yes, the Yosh may require repacking of the muffler after some period of time; You can buy the Yosh from a number of sources varying from eBay to Amazon or from a dealer; Yes it comes complete & ready to install on an RT, using flange bolts not clamps. And did I say, It sounds great !!

 

[Spacetrucker]

Unleashing the Yoshimura 77 on an rt

When I first installed a new Yoshimura R-77 pipe on my 2012 RT, I was very disappointed in the sound. The quality of this muffler is superb in every respect but it sounded almost as quiet as the OEM RT muffler even though half the size, much lighter, and much prettier! I was not looking for a super loud muffler but I do like to hear that Rotax working out.

When I looked closely at the Yosh I could see there was an Insert-tube inside to reduce the exhaust opening, evidently to ensure meeting noise level requirements. Inquiries to Yoshimura resulted in no options as they insist the Insert is required to meet US specs. More searching for help showed me a YouTube video of a guy removing the Insert!

After listening to the RT sewing machine noise some more I decided to gamble and remove the Insert for a test. At this point I should warn you that the Insert is fastened to the muffler with only one bolt, but that bolt is spot-welded in place. A little work with a Dremel solves that problem... See the pics below showing the Yosh with the insert, and then opened up!

When I started up the RT with the Yosh insert removed, the sound was amazing... a growling Rumble unlike a high revving engine that only got better with more rpms. This is the 4th different muffler used on my RT and is by far has the best sound I have heard yet from an RT.

Answers to the first questions... Yes, some Yoshimura 77s may be shipped without the Insert tube as seen in some pictures; Yes, the Yosh may require repacking of the muffler after some period of time; You can buy the Yosh from a number of sources varying from eBay to Amazon or from a dealer; Yes it comes complete & ready to install on an RT. And did I say, It sounds great !!

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Yes you need repacking around 15,000 miles if you run hard. But if you just drive around town the at 7,000 t0 9,000 repacking needs to be. I would send back to the in Calif have them do it. they have a new type of packing that will alst a lot longer the next time at 25,000 miles past your last repcking . that is what we did and now has better sound and hourse power to and fuel milage to. nice pipe they have.......:yes:

 

[mcaccamise]

Looks goood glad you like the sound enjoy.
Mike

 

[scooterexpress]

i've had the yosh on for quite awhile now and ev1 says it sounds real good as it's not overwhelming while riding.but i'm considering going with straight line pipes no baffles what so ever give more rumble haven't looked into it yet but really considering it.anyone out there ever look into doing this?

 

[Jbiancolli]

Spacetrucker. When you removed the insert did you have to plug the bolt hole in the can?

 

[cjackg]

Spacetrucker. When you removed the insert did you have to plug the bolt hole in the can?

I used a short bolt to fill/cover the hole... but dont think it is critical at all.

 

[Jbiancolli]

How do you break the spot weld? I have a dremel but it is rarely used

 

[cjackg]

How do you break the spot weld? I have a dremel but it is rarely used

I used a small cutting disk on a Dremel, very carefully after nearly stripping the bolt head with an allen wrench.

Here is the Yosh Insert after removed but If that's too loud you can modify the Insert as shown below to shorten it and remove the tapered end.
I have run mine with all the approaches but like it best fully removed.

 

[napper39]

i have the spx muffler from esi that is wide open and had to put a socket in the end to qoite it dowen but it sounds like nass car on a good day,grate muffler an less money than all the rest.you need to call esi to get one they no longer show it but they still say they still show they still have them.

 

[spydercowboy]

I used a short bolt to fill/cover the hole... but dont think it is critical at all.

With opening it up so there is less restriction, are you having any backfiring on deceleration?

 

[cjackg]

With opening it up so there is less restriction, are you having any backfiring on deceleration?

None at all, even with the Insert tube removed.

 

[Spacetrucker]

No I did not plug it. But you can with hi temp sealant let dry for a day and all is good.

 

[Spacetrucker]

I use a flat head drive and taped I'd around . Will come off ok do not grind it off will mark it up.

 

[Chupaca]

Good looking..!!

Glad you found the cure, hate to see such a fine unit on your pile of disappointments..!! :roflblack::roflblack:

 

[scooterexpress]

With opening it up so there is less restriction, are you having any backfiring on deceleration?

at first there was no back firing but now after 12kmi it backfires going up and coming down not all the time but most even though it does it i like it.

 

[cjackg]

at first there was no back firing but now after 12kmi it backfires going up and coming down not all the time but most even though it does it i like it.

Have you ever had it repacked? Are you running with the Insert tube or without ?

After 12k miles it may be due.... I understand YOSHIMURA offers service for repacking and I heard they have new material they use now that lasts much longer.

 

[spydercowboy]

at first there was no back firing but now after 12kmi it backfires going up and coming down not all the time but most even though it does it i like it.

Guess that means it was on the hairy edge of running too lean and now that you have some miles on it and burned it out more it is running lean. Makes sense to me. I was actually surprised the computer could adjust enough in the first place.