A few uncorking questions

I was out in the garage dreaming while the freezing rain was falling in Oregon! Me being a newbe and reading all of your input about uncorking I was looking at what was in store for me and I have a few questions. One question I have is how loud it will be? I would like to be able to rip up the street with pissing off then neighbors. I pulled the tip to see how load that would be and it fired right up and idled real easily. Just that item made a difference. What would be the best tip to buy that wouldn't be too loud? I think I want to keep my stock tip. Next question, where is the restrictor plate? Is it in the boot between the carb and the head? Does somebody have a link to a picture of what I need to carve out? Next question, I have a bike from California. I was looking at removing the smog pump but would like to know the best way to deal with the tubes coming out of the cylinder. Are the pressed in or a compression nut? Can they be cut off and capped with silver solder? Any good ideas for doing this?

JC :cry:

the "restrictor" you speak of, is a good-sized lump in the passageway of the rubber intake manifold , it can either be ground down, or an un-blocked version available from your Honda Parts man ... check Baja Designs for the smog block-off kit ...

Thanks, I will check with Baja designs. Does anybody have any feedback on how loud one of the Baja design Exhaust tips are?

You can get all the necessary uncorking parts at the Honda shop, or from Baja Designs website.

The boot between the carb and the cylinder is restricted with a rectangular piece of metal covered in rubber. I don't know how hard it is to grind out. I bought the HRC intake boot from Honda which is not restricted.

You can also get the HRC exhaust tip, which is a spark arrestor also, but has large, 40mm opening. It's louder than stock of course, but it's not annoying, it's a deep, non-penetrating tone.

The airbox also requires uncorking; peel out the rubber snorkel, and then on the back side of the airbox is a flat plastic plate, snapped in place. Remove that piece.

Then the carb must be rejetted, you can't run stock jetting if you uncork the bike, no way. Run the main jet rich, 175 is what is usually used, but for high altitudes it will be smaller, probably anywhere from a 150 to a 160.

Changing the main jet requires a change of needle position. For the stock needle, you should raise it (lower the clip) from the stock position to 4th groove from top with the stock needle, or use the B3E competition needle and set it in the middle (3rd position).

After doing all of that, the bike will be very fast and quick, night and day compared to stock.

Nice, that's good info. It seems if you buy the HRC insert and the Baja design baffle it get's up to $200 pretty quick.

Don't bother with the HRC tip. The performance gains over the drilled and snipped stocker is minimal for the hundred bucks. If you take a 1-7/8th to 2" hole saw to it, run a 68s pilot, 172 main, and the hrc intake, you can do all the mods for 20 bucks. The B53E needle isn't necessary either. In fact, many claim a rich condition with the hrc needle.

Here's a pic of the drilled and snipped tip. The SA is still intact.



I'm in the same boat.

Looking at the cost of the HRC baffle + the potential cost of then having to silence it further, might as well put that into full on aftermarket exhaust. I'm concerned that just drilling out the stock tip won't be enough, given the way the internal baffles line up, won't it be necessary to shim the stock tip out at least 1/2"? There is a .JPG file in the Yahoo xr650r files section showing how this is done. Looks like a fabrication PITA. There is very little other information available about this so it would seem most people don't bother. I have never been able to get a definative answer as to whether this is necessary though careful measuring suggests just drilling out the stock tip doesn't clear up the main constriction.

The other issue is fiddling and experimenting could seriously cut into ride time. The HRC tip was designed to flow a certain way. At least I would be able to rule out one potential trouble spot if I have runability issues after rejetting and doing the airbox mods.

BTW, if you haven't been to Erics (Haymaker) site you really should.

http://www.xr650r.us/ One stop shopping for everything you ever wanted to know about the BRP.

I think I just talked myself back into the HRC tip.

Maybe a piece of radiator hose with a 90 degree bend hose clamped to the end of the pipe would quiet it down.

As another sidenote, I'll be back in the Gorge with my piggie by march (currently snowbound in Truckee). If your in Portland, I know a lot of trails on the Or. and Wa. sides.


:cry: Glad to hear somebody else at the same point as me. Even better that you live in Oregon! I am looking at going with the conservative method. At 1st wanted to keep all of the stock stuff to be able to put back on but why? I have never heard anybody on one of these forums going back to stock. I am going to drill out the inner baffle so it ends up at 1 3/8" and then look at spacing the tip out. I will have the fab shop that we use at work burn out some Stainless spacers on the laser. They will always do freebie favors. If you are interested I will have them burn some extras. Couldn't a person grind away some of the internal baffle instead of the spacer? I have spent a lot of time on the Haymaker site, I think I have read through it more than once. What a great job he has done. What are you doing in Truckee? You don't happen to work for Slayden construction do you?

My brother has been riding up on Hood off of Highway 216. You ever ride up there? I have been out riding for almost 20 years after getting married young. I just bought my pig and haven't had it in the dirt yet. My brithces are getting itchy! One of the reasons I waited so long to get back into riding was I didn't know anybody that rode. My brother got back into it so I made the plunge and now people are popping up everywhere I look. JC

I do know that the drilled and snipped stocker did not run near as good for me as the HRC tip. The internal baffles do not leave much clearance around the stock tip however the HRC extends inward past the baffles to make for less restriction. For the stocker to come close the solid end would need to be replaced with screens to allow it to breath. If they made an aftermarket exhaust out of light alum that had the same design as the stock unit with the HRC tip it would be the best of all worlds. At least this unit doesn't require any repacking since sound control is due to the chamber and the baffles.

Jcoyne,This fellow;


Seems to be running the stock exhaust tip yet has rejetted and removed the manifold/airbox restrictions. Don't see how it would run well with a potatoe in the tailpipe, maybe I've read it incorrectly. Maybe there is potential there to keep the stock tip. I broke down and ordered the HRC tip from Service Honda today. Roll it on, your making me feel a little better about that decission. I have all the other parts though its rather a moot point at the moment due to snow. I would have to drive about 6o miles to ride. This week is supposed to get quite warm so I'm hoping the areas I was riding around Reno will melt out. Reno has not received this much snow since 1916. Found this great snow cover map;


Make sure to scroll down to the good maps, though they haven't updated since friday.

Certainly you could modify the internal baffles of the canister though since you have access to a machine shop, 1/2-3/4" of spacing should improve flow dramatically. Bear in mind though I'm basing this all on logic, and measurements. Wish I had the time to experiment but I can't ride anywhere near home at the moment so one trip wasted would essentially pay for the HRC tip. I'm familiar with the area out 216 but have never ridden there, spent two years living in Government Camp, 15 in the Gorge. Know a lot of riders in the Hood River area but this is my first dirt bike in a long time too so I've been looking at this from a Mt. bike perspective. I'm very familiar with the area up forest service road 44 (goes between 35, and Dufur). Theres a million miles of clandestine trails up there friends of mine have built. Of course its all snowed in right now. Your in a good spot and could go east or west for riding. I hear the Tillamook state forest has loads of good riding. I'm kind of a long time desert dweller though and don't really care for mud :cry:

Roll it on, what about stuffing some packing in the can with the HRC tip? I'm definately going to try angling the tip down with some radiator hose or similar if its too loud.

Jcoyne, keep me posted how the mods go, I'll do the same.

The biggest reason to get the HRC tip is that you can always put the stock one back on. Hole-saws are for life!


I'm going to ride it once stock so I know the difference. I will keep you posted. I'm going to study the stock baffle a little more, you keep me posted on how loud your new tip is. I saw a picture on the Yahoo picture area of a guy who used part of a drain pipe that angled down. You might want to check that out. I do have a lot of options on where to go. You didn't answer what the hell you are doing in Truckee.

You should definately ride it stock to get a feel for the baseline. I was initially pretty impressed with the acceleration, but after a couple of rides I wanted more (though still haven't done the mods of course). The area I have been riding though has some fairly wide open straights, but also a bunch of tight twisty single track. I was pretty impressed at how quickly it could be redirected. A good thing, as a lot of the riding in the gorge is even tighter. I know of only one other 650r, most folks seem to opt for the wrf or ktm's. Initially I thought the I wanted something that I could use on the road so I went for the 650. I've installed the Baja Designs (easy install) kit and will probably plate it when I get back but after riding it for a while (all of my 170 miles experience), I don't see myself wasting too many miles on the road, particularly since my rear tire is probably 25% gone in those 170 miles ( I guess thats not bad really).

Why am I in Truckee? My girlfriend lives here....

I wouldn't put any packing inside the stock can at all since there is nothing set up in there to accept any muffler packing which is actually one reason I like the stock can. Nothing to mess with. Baja Designs sells a baffle that is designed to fit inside the HRC tip and it turns the exhaust down while dropping the DB's by a few making it pretty quiet. It is real easy to put it in an take it out with only a setscrew to remove. The HRC alone is right at the sound limit of 96-97 DB's and I have never been hassled by any rangers and I have been stopped several times to have them check bikes that I am with. I'm sure if you could just find a clean way to turn down the tip it would help also.

The biggest reason to get the HRC tip is that you can always put the stock one back on. Hole-saws are for life!

Ditto, works if you need to quickly pass a tech sound test and get back to the rig and re-install the HRC. I think someone said the HRC was at 96 db from an idle... :cry:

96db at idle doesn't sound right. At idle the HRC tip doesn't sound too loud. When you crack the throttle however that is where the volume is at. Even at a steady 3,000 or higher rpm it doesn't sound that loud. The real noise is when you are in a higher gear at low rpm and then lay on the throttle. It kind of has that "harley" sound to it. Sounds pretty cool!

I'm almost positive that TT member "InChanWeTrust" did a NETRA event up here and tested at 96db from an idle. The HRC exhaust tip is pretty loud guys. You don't really notice it being on the bike.

That is a good point TimBRP. I guess I havn't been behind the bike while running and your right, it doens't sound all that bad while sitting on the bike.

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