Uncorking 2007 XR650R


40 replies to this topic
  • jdubb75

Posted February 04, 2008 - 04:08 PM

#21

I found a few helpful pieces of info that might help clear up the issue of drilling the stock tip. This if from a post here on TT...

[COLOR="Red"]1) Drill (well, grind weld) at 1 1/4" and removed 4" long insert
2) Drilled to 2" and removed 1 1/4" insert
3) Same as 2 but with stand off baffle snipped off
4) Same as 3 but with 1 to 1 1/4" hole through remaining baffle and stainless mesh bolted over this hole (to retain S.A. function)[/COLOR]

...and this is from the FAQ's on the Pig Pen...
http://www.xr650r.us/xr650r_faq/#1a

[COLOR="red"]#4 Q: What can I do with the stock exhaust? That depends on where you are. It seems that the ED (Euro spec) bikes come with the HRC competition exhaust tip, either installed, or in a package with the bike. These have about a 1.5" opening and very little in terms of internal baffling, other than the stainless steel mesh for spark arrestor function. The NA bikes have an exhaust tip with a tiny 3/4" exit and 2" baffles that line up with plates welded in the pipe so that they can pass the 82dB federal noise regulation. If you have one of these, your choice is to either modify the one you have, or buy the HRC tip (part number 18317-MBN-640, approx $110 USD).

For a slight increase in flow (and sound level) a machinist can use a lathe to cut away the weld holding the spacer which in turn holds the 3/4" pipe. This leaves the 1 3/8" pipe as an exit, which is already bigger than the area for flow around the internal 2" baffles.

Taking things to the next level involves drilling out the whole 1 3/8" section with a 2" holesaw. This is what you will typically see recommended on most of the sites that describe the uncorking process. You can also remove the tip assy. and cut the last baffle off from it, leaving the spark arrestor intact. You get tremendous gains by doing this, a true "thumper" sound, without breaking the windows of houses and having little kids tremble in fear as you ride by.

Finally, if you are after full flow HRC-like closed course mode, you will need to add a 1 1/4" hole in the remaining 2" baffle and use four small screws to fit a 2" disc of stainless mesh (similar to what Honda uses) over this new hole to retain spark arrestor function. This may be too loud for most circumstances, but a 2" disc of stainless steel can be exchanged with the mesh to revert back to the previous step.[/COLOR]

It looks like I'm at #2. This must be what you were talking about abby. I'll be getting out the snips this weekend. I don't think I'll be drilling a hole in the end of the spark arrestor plate though.

Sorry for the confusion earlier!:busted:

  • abby

Posted February 04, 2008 - 04:09 PM

#22

Maybe I am miss-understanding you, bit I don't think so. I was confused about exactly the same thing when I looked into it.

You drilled the tip out from the OUTSIDE with a 2 inch hole saw and removed the small pipe that was there leaving a 2 inch hole in the end - but that is all you did, right?

On the other side of the exhaust tip, there are two baffle plates, one under the spark screen and the second one exposed. The second baffle plate (the one not covered by the screen, and the one that would be furthest down in the pipe) is the one I am talking about which I drilled to 1.25 inches. Most guys drill that out to 2 inches also, which leaves the spark screen intact but opens up the restriction. So there are two holes, not just the one you drilled.

Just drilling the end from the outside is still quiet. If you drill that inner baffle, it gets louder.

  • abby

Posted February 04, 2008 - 04:11 PM

#23

I found a few helpful pieces of info that might help clear up the issue of drilling the stock tip. This if from a post here on TT...

[COLOR="Red"]1) Drill (well, grind weld) at 1 1/4" and removed 4" long insert
2) Drilled to 2" and removed 1 1/4" insert
3) Same as 2 but with stand off baffle snipped off
4) Same as 3 but with 1 to 1 1/4" hole through remaining baffle and stainless mesh bolted over this hole (to retain S.A. function)[/COLOR]

...and this is from the FAQ's on the Pig Pen...
http://www.xr650r.us/xr650r_faq/#1a

[COLOR="red"]#4 Q: What can I do with the stock exhaust? That depends on where you are. It seems that the ED (Euro spec) bikes come with the HRC competition exhaust tip, either installed, or in a package with the bike. These have about a 1.5" opening and very little in terms of internal baffling, other than the stainless steel mesh for spark arrestor function. The NA bikes have an exhaust tip with a tiny 3/4" exit and 2" baffles that line up with plates welded in the pipe so that they can pass the 82dB federal noise regulation. If you have one of these, your choice is to either modify the one you have, or buy the HRC tip (part number 18317-MBN-640, approx $110 USD).

For a slight increase in flow (and sound level) a machinist can use a lathe to cut away the weld holding the spacer which in turn holds the 3/4" pipe. This leaves the 1 3/8" pipe as an exit, which is already bigger than the area for flow around the internal 2" baffles.

Taking things to the next level involves drilling out the whole 1 3/8" section with a 2" holesaw. This is what you will typically see recommended on most of the sites that describe the uncorking process. You can also remove the tip assy. and cut the last baffle off from it, leaving the spark arrestor intact. You get tremendous gains by doing this, a true "thumper" sound, without breaking the windows of houses and having little kids tremble in fear as you ride by.

Finally, if you are after full flow HRC-like closed course mode, you will need to add a 1 1/4" hole in the remaining 2" baffle and use four small screws to fit a 2" disc of stainless mesh (similar to what Honda uses) over this new hole to retain spark arrestor function. This may be too loud for most circumstances, but a 2" disc of stainless steel can be exchanged with the mesh to revert back to the previous step.[/COLOR]

It looks like I'm at #2. This must be what you were talking about abby. I'll be getting out the snips this weekend. I don't think I'll be drilling a hole in the end of the spark arrestor plate though.

Sorry for the confusion earlier!:busted:


Ah - you got it now! :worthy:

  • AEmedic

Posted February 04, 2008 - 04:18 PM

#24

Thank you guys for all the good info!

It sounds as if I will be happy with just drilling out the end with the 2" hole saw, and leaving the internal baffles alone.

It should open it up some but still be fairly quiet.

  • jdubb75

Posted February 04, 2008 - 05:09 PM

#25

Ah - you got it now! :busted:


...and learned something in the process too! Thanks abby.:worthy:

Just to get things straight. When you say you drilled the 1.25 inch hole was it in the baffle on the very end of the spark arrestor or the one that is attached to the spark arrestor by four legs?

  • abby

Posted February 04, 2008 - 08:11 PM

#26

...and learned something in the process too! Thanks abby.:busted:

Just to get things straight. When you say you drilled the 1.25 inch hole was it in the baffle on the very end of the spark arrestor or the one that is attached to the spark arrestor by four legs?


Yes, you are at step 2. I did not snip the standoff baffle off (step 3 above), I first tried drilling a 1.25 inch hole in it. That was the baffle on the very end opposite of the tip you already drilled out. It had a chirp to it, and that is when I gave in and bought the Q2 because I knew once I clipped that baffle completely off I'd be close to (or slightly over) 96 DB.

In step 3 you can clip off the second baffle and not have to mess with the spark screen. If you go to step 4 (approaching HRC tip flow), you will have to cover the hole you will drill in the remaining baffle with screen to still have a spark arrestor.

I realize now (it's been a while since I thought about this) I made an incorrect statement earlier when I said most guys drill the second baffle when in fact they are clipping it off. The recommendation that was made to me was to drill a hole smaller than 1.25 inches in step 4 to try to keep the noise down. But again, I never got that far.

I have a stock tip if you go to far and want to go back. I paid $40.00ish for it on ebay, but never used it. I also think I still have the one I drilled which has the first baffle and screen intact, so if you decide to go to step 4 and it's too loud, you can back up to step 3. PM me if you want to go that far, I am not 100 percent sure sitting here that I still have it. But I know I have the stock tip.

  • Thumpage

Posted February 04, 2008 - 09:23 PM

#27

Abby's pretty much summed up quite a bit on this. I will note that he has termed the steps a little different as he has added what i would call a 'half' step of drilling the end/exit baffle smaller than the traditional first step of 2". Here is an additional write up of what I had come up with in terms of 'stages' of modifying the stock tip. Look at this link starting at post #53 and get into more info & pics on Post #59. http://www.thumperta...ighlight=baffle[/url]

There is much more to read on this particular thread before and after I chimed in also. The bottom line is, just drilling the exit baffle is nowhere near the flow of an HRC tip but it is also not close in sound output either. You just have to sacrifice flow = power to keep things much quieter. The bike will also not really be able to use the full uncorked jetting specs with simply drilling the exit baffle. Abby has my fully modified tip.
I hope that will add some help to the mix of what has been posted here.

  • ej67ss

Posted February 05, 2008 - 11:54 PM

#28

I have a two 650r's one with stock exhaust and one with the pro circuit ti4. I put the hrc tip in and wow!! What a difference!!! The bike almost rips as good as the ti4 bike. But the problem I have with the stock exhaust is the power delivery. The ti4 is so much smoother and broader! You don't have that abrubt power any more just a smooth pull all the way to the top! I liked the ti4 so much I just bought another one but in stainless this time. I have not felt a difference between the ti4 and t4 as far as power goes just a lot cheaper. I would not drill the stock pipe just buy the hrc part. Goto service honda and type in the part number. That's where I got mine. I looked at both pieces and the stock tip has to be cut all up to even get close how well the hrc tip flows! And as far as sound goes shift it short and enjoy the torque lol..

  • philipstjohn

Posted February 06, 2008 - 05:48 AM

#29

The previous owner drilled the stock tip out with the normal 2 inch method with my bike. I then clipped off the second baffle just past the spark arrester/first baffle. Instead of drilling out that first baffle at the end of the SA section, then replacing it with a screen mesh, can't you just drill small holes in the baffle to create more flow? Has anyone tried this?

  • hondacrf150f1

Posted February 06, 2008 - 08:08 AM

#30

here's a visual for you guys, hrc tip on the left, stock drilled out tip on the right.

Posted Image

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  • philipstjohn

Posted February 06, 2008 - 08:30 AM

#31

Is the end of the HRC tip solid or screened?

  • cb60130

Posted February 06, 2008 - 08:42 AM

#32

The end of the hrc tip is solid....but it fits in the muffler further than the stock tip...past the internal baffle plates....resulting in much better flow.

  • hondacrf150f1

Posted February 06, 2008 - 09:28 AM

#33

The end of the hrc tip is solid....but it fits in the muffler further than the stock tip...past the internal baffle plates....resulting in much better flow.


yup:applause:

  • TrailRiderXRL

Posted March 06, 2008 - 12:48 PM

#34

Posted Image

So.... Is it much louder when cutting off the end plate that is held on by the 4 legs? Is there much difference in flow?

:thumbsup:

  • jdubb75

Posted March 06, 2008 - 01:20 PM

#35

Posted Image

So.... Is it much louder when cutting off the end plate that is held on by the 4 legs? Is there much difference in flow?

:thumbsup:


I cut the end baffle off mine and took a 2" holesaw to the exit restrictor and don't think it's too loud. It's louder than stock, but it's not obnoxious at all. It has a nice deep tone to it. Note that I just cut the end baffle off. I did not drill the remaining baffle.

According to the Pig Pen FAQ's there is an improvement in airflow by snipping off the baffle attached by four legs. My bike seems a lot happier drilled & snipped.

http://www.xr650r.us/xr650r_faq/#4a

I am looking for a used HRC tip to try as well to see if I can tell any difference in performance.

  • porterdog

Posted March 06, 2008 - 07:54 PM

#36

Some numbers to ponder...


abby, I tried to give you gas for this post but the system wouldn't let me for some reason. My comment was to read, "Sweet freakin' post. Real data!"

So- nice post, and thanks.

  • Thumpage

Posted March 08, 2008 - 02:31 AM

#37

abby, I tried to give you gas for this post but the system wouldn't let me for some reason. My comment was to read, "Sweet freakin' post. Real data!"

So- nice post, and thanks.


I agree.

Abby, you have taken the time to reference and add good info and data for those inquiring. Gas for you. Thumbs up.

  • AEmedic

Posted April 05, 2008 - 04:42 PM

#38

Well, I finally got to the business of uncorking...
I really had to fight with the screw in the throttle link arm, it was really tight and I nearly completely striped it, but I found a better bit for the screwdriver and it finally came free.
I am off to Home Depot for the hole saw, I thought I had...
When I get back I can finish her up.

  • jdubb75

Posted April 05, 2008 - 06:18 PM

#39

Well, I finally got to the business of uncorking...
I really had to fight with the screw in the throttle link arm, it was really tight and I nearly completely striped it, but I found a better bit for the screwdriver and it finally came free.
I am off to Home Depot for the hole saw, I thought I had...
When I get back I can finish her up.


You said earlier in this thread you were just going to drill and not snip. I drilled mine first and then snipped off the stand off baffle a couple weeks later. Snipping off the baffle didn't really do much for adding to the sound, but it did help performance. I have since purchased a HRC tip to try and it is quite a bit louder. Not bothersome to me while I'm riding with my helmet on and sitting in front of the exhaust, but I don't think I'd like following me in the trails for a few hours. I did notice a slight bit of a seat of the pants performance gain with the HRC tip over the drilled & snipped tip, but you pay a price in the sound department. I am still running the HRC tip and kept the modded tip to swap out in case I run any sanctioned events where sound level is tested. By the looks of things I'd still have to keep my fingers crossed to meet the 96 db requirements according to abby's data.

BTW -- abby I tried to give you gas for setting me straight earlier and posting the db data but it wouldn't let me for some reason. I'll have to get you back on another post. Thanks again!!!

  • AEmedic

Posted April 05, 2008 - 07:03 PM

#40

Yep, not snipping yet, I am going to run it with just the end drilled out.
BTW, someone had mentioned that the needle on the 07s only had 2 slots. That is what I found on my 07 as well. Good thing I ordered the comp needle set.





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