Uncorking a XR200R

[Chuck.]

The sticky at the top of this forum discusses breathing improvements for the intake and exhaust on XR200s so I thought I would show one way to help uncork a XR200, also why I didn’t mod my airbox. I am not after more peak power, but I want more torque at the bottom for trail riding. Some history:

Currently I have two 200s; a MX chassis with an early XR200 engine and a modded 90 XR200R with a stock engine. The exhaust port on the XR200 engines is 1 3/16” in diameter but the Honda header has a 1” ID!! Powroll says the stock head pipe is too restrictive and I found on my other XRs that a larger head pipe really helped bottom end and throttle response. I ran across a dyno test of an 81 XR200R by one of the cycle magazines that showed a 20% increase in torque at 4000rpm and a 14% increase at 5000rpm with no change in peak power by pulling the baffle from the muffler. Those numbers are hard to ignore. So a test was in order, My riding buddy and I took both of my bikes to a hill climb with a consistent grade and good traction. By doing a standing start in second gear perpendicular to the fall line and making a hard right turn to the hill I insured a consistant starting speed. I used a GPS to record ground speed up the hill and then used the speeds to derive engine rpm. GPS speeds at the bottom of the hill for most runs were 5mph (1600rpm), two were 6mph. Notes were made on each climb, six runs were made with the XR. The stock XR struggled all the way up, would not accelerate and seemed on the verge of loosing speed and stalling, max speed 9mph (3000rpm), needed clutch fanning. Removed the little exhaust tip and it ran a bit better. Next removed the baffle and did a few runs; 12mph top speed (4000rpm), could loft front wheel by fanning the clutch. We also ran the Powroll piped bike up the hill several times and it just charged up the hill with ease, had to shut off and coast over the top. We also did some back to back comparisons on a trail section and it had much more grunt and acceleration when exiting turns in 3rd gear. So the XR200 engines respond by uncorking the exhaust, and the Powroll piped bike provided the best results.

Powroll pipes are no longer made for the XR200s so my next choice was a XRs Only stainless steel pipe. The next photo shows the difference in size between the stock pipe and the XRs Only pipe. The XRs Only pipe has 65% more cross sectional area than the stock pipe, the Powroll pipe is 95% bigger than stock (the Powroll pipe is 1 ½” OD).

Powroll says best power from the 200 engine is with their pipe and a 3” SuperTrapp muffler with 8 discs, and when I had that setup on the Powroll piped bike it ran great but I didn’tlike the noise so I installed the FMF Q. Powroll also says the best power and quiet setup is to use a Supertrapp ISD2 muffler w/ 8 discs (it has a 3” Supertrap inside). I didn’t have either handy so my next option was to try something a little different using what I had available.

This next picture shows the inlets of two mufflers; the small one is a XR200R muffler and the large one is from a 84-85 XR250R. Other than mid pipe size both mufflers appear to be identical; inserts and tips have the same part numbers and they have the same attachment points for the frame. This is because the 84 XR200/250 frame layout was used for the 86 and on 200s and influenced the 86-95 XR250, many 84-85 parts fit later 200s such as panels, air box, shocks, fenders, seat, tank, etc.

The 250 muffler has a 1 ½” inlet which will fit the Powroll pipe but is too large for the XRs Only pipe so I made up a 0.050 thick sleeve from a piece of automotive exhaust pipe adapter that I bought at the local auto parts store. The sleeve was a little too thick so I had to thin the gasket and bell the mid pipe connection, I should have used 0.040 sheet metal for the sleeve. Fit would have been better if the XRs Only header was ½” longer but it all bolted up nice with the help of a little bit of red RTV to help seal any leaks. Roman]

The XR250 muffler didn’t have a standoff for the side panel so I added two blobs of red RTV to the side panel to keep it away from the muffler

I did not remove the snorkel on the air box because it helps to keep water from running into the air box. This photo shows that water gets onto the top of the air box and the snorkel lip helps keep the water out of the air box. Also the snorkel extension inside the air box keeps water off the air filter. The filter shown is an UniFilter (which flows more air than the OEM), I have a K&N filter but it is so big that the snorkel must be removed for it to fit inside the airbox. Maybe next summer I’ll pull the snorkel.

The finished product

I'll go riding tomorrow and then report on how the new exhaust works.

Edited November 4, 2009 by chuck4788

[Chuck.]

Went back to the hillclimb that I did the previous tests on but the soil was a little softer today than last time. Lower speed during the turn into the hill and only acheived 12mph going up, the same speed as the previous best tests with a stock pipe and no baffles in the muffler. However the thing that limited speed was lack of traction not lack of engine power, the engine was much more responsive and would spin the rear wheel easily, much different than last time. Did some corner tests like last time and this combo exits corner with pull like my Powroll/FMF piped bike. This pipe/muffler combination is much much noisier than the stock pipe/stock muffler wo baffle, also a very differnt and annoying sound. Still a little lean with popping on decel but the bike starts easier than it ever has. I'll work on the noise issue this week, I have several option from using a stock insert to adding the OEM tip. I also have an insert that is just the end piece with no core.

Later

[Footy]

This is good stuff. Thumper racing use to make a slip-in insert with a turned down tip for the stock XR mufflers. When you find the right combo let us know all of the parts required. My 87 is still in progress. I have spent a year tinkering on this thing (in my spare time). Seems like one of my "primary" bikes (or the damn lawn mower) is always on the work bench and the little XR stays in the corner under an old blanket. It is 2/3's complete!

[Chuck.]

I wanted to reduce the amount of water getting on top of the air box so before installing the seat I added some duct tape inside the rear fender area. After a very wet ride I pulled the seat there was much less dirt deposited on the top of the air box than shown in my last post.

As mentioned in my last post the exhaust with the XRs Only header and the XR250 muffler is just way too loud and obnoxious without the insert. So I tried a couple of combinations to find a way of reducing the noise. Here is a pic of the stock insert used in the 200/250 mufflers.

I didn't want to use the stock insert because it really reduced power with the stock muffler and header so I cut the end plate off an insert, Honda welds these things in so many places that I had to band saw the insert just in front of the outlet end, then I drilled and ground the welds to remove the inner pipe from the end piece. This next pic shows the end piece on the right and the factory tip on the left.

I tried both pieces individually and together; Both seemed to provide the most sound reduction, I'll test the different combinations on the next ride.

[sdubfid]

Chuck, any updates on your exhaust testing and sound levels?

[Chuck.]

Some updates: This noise vs power vs weight seems to be an ongoing good news bad news saga and I haven't found the magic combination. The previous tests were done on a stock 90 XR200. Currently I'm using a stock exhaust on my stock 90 XR200 and a Supertrapp IDS2 muffler from a XR400 on my Powroll 218. The IDS2 was recommended by Powroll as second best to a 3" Supertrap for power. This muffler has a 1 3/4" inlet so I fabbed a 1 3/4" mid pipe. Still noisy so I made up an outlet reducer to reduce the outlet to 1 1/4" using 1 1/4" escutcheon plate, works good. I increased the disc count to 12 which helped top end. I also installed a Supertrap Quiet insert which really cut the noise level but I suspect it increased back pressure a bit because of an exhaust leak at the header to mid pipe connection. I also have CRF250X muffler which is suppose to be very quiet, and it almost fits my chassis but it is very heavy, so I'm kicking that can down the road a bit.

Main jet now 2 sizes larger at 115 and I'm considering a 118. The 115 created ragged off idle throttle response and some mid throttle richness which a triple taper needle from a XR250R helped. Bike now feels like a half kick starter and runs great but throttle response is not where I want it. I tried a BSR32 CV carb and it was much bettter at low speeds but too lean mid to top, then my fuel data logger quit working so I put the stock carb back on. When my air fuel data logger gets repaired I'll do some more tests.

[KTM520EXC]

After following Chuck's thread, I thought I would try running up and down my street (1 time so as to keep my standing w/ the neighbors in tact) with and without the baffle. I don't know if this was a fair test because the little rectangle baffle plate underneath the exhaust was missing, Any rate, tried both attributes, baffle in, baffle plate missing, ran very good, much less noise due to the sound going directly to the ground vs. baffle out, baffle plate out, noticably louder.

I don't know if this was subjective and don't know if Chuck tried removing the rectangle baffle plate underneath the exhaust. I noticed a slight but noticable difference with the baffle out, but not to the point I would run this on the trails. I would think if you got the oversized header there would be even more of a difference.

BTW, looked on the parts diagram and Honda classified the rectangle baffle plate as obsolete, so I guess I have to go to evilbay to track one down.

[Chuck.]

If it is the small plate under the muffler near the end it is there to allow cleaning carbon buildup out of the muffler. I think the area behind it is before the spark arrestor so removing it would allow some gas to bypass the spark arrestor, not good.

I found the biggest difference in bottom end by removing the round insert but no change in top end and a lot more noise. Noise may be acceptable in competition but if too loud it can be tiring on a long ride.

[GEOF]

Hey great thread chuck. ?

[KTM520EXC]

OK, after researching the heck out of this, the general consensus is that 50% say, yes, removing the baffle is removing the spark arrestor, the other 50% say, no, the spark arrestor is built into the exhaust before the baffle and has no effect, other than being louder.

I can not find a schematic, or anything to support one way, or the other, so I guess one has to be conservative and speculate that the baffle is part of the spark arrestor system, as well as the exhaust carbon cleaner opening in the bottom, ie if it's not installed, then it is not spark arrested.

Being in California this is a must, so for me, I need to find the exhaust cleaner plate.

[Chuck.]

The spark arrester is a spinnier in front of the insert and any carbon particles settle out into the bottom of the muffler where they can be removed via the little cover on the rear bottom of the muffler. Removing the insert does not defeat the spark arrester but removal does increase noise. I and my riding friend also have some relatively quiet bikes and they are much less tiring to ride.

[KTM520EXC]

Well the carbon cleaning plate is at the very back of the muffler, so I would think that I would be OK then, because I can feel the baffle through the hole.

Again, went on line, can not see any specific breakdown of the muffler itself.

I just want to feel comfortable that sparks can not leach out that the carbon cleaning plate, because I don't want to be "that guy".

Thanks Again Chuck !!!

[KTM520EXC]

Has anyone tried the XR's only header pipe by chance ???

I am curious if they got a noticable increase in power across the board and did they have to rejet ???

Many Thanks in Advance !!!

[Chuck.]

I have used a XRsOnly header on a stock XR200 and a Powroll 218; nice pipe in SS that seems to flow better than a stock pipe. IMO based on comparison tests it adds about as much as an oversize piston and 0.5 increase in compression ratio. The pipe is about 3/8" shorter than a stock pipe and designed for XRsOnly muffler but with muffler inlet mods for diameter it will fit into a stock muffler. Powroll's ideal pipe is a stepped pipe like the XRsOnly pipe but my drag race tests didn't show a difference between it and the Powroll 1 1/2" pipe. Stock jetting is so rich that just a pipe won't require rejetting, I have not run bigger main jets with just exhaust and air bix changes. But I'm running 2 sizes bigger jets on my Powroll 218 and it is rich enough based on air fuel ratio analisys, but I have a restricted muffler for sound control; as a side note Powroll recommends 3 sizes bigger main jet for their full mods.

The good news is my 11:1 Powroll motor feels like a half kick starter with a warm engine, if the kicker is at the top. If the kicker is at half stroke (no compression release) it is very difficult to kick thru.

Hope this helps

Edited September 7, 2012 by chuck4788

[KTM520EXC]

OK, so I want to point out I was "wrong". You "can not" touch the baffle through the carbon clear out plate. Whether or not, it impacts the spark arrestor system is still undetermined. It gives me a reasonable amount of flow and the sound is "quiet", however I do not know at what cost at this point.

Edited September 7, 2012 by KTM520EXC

[KTM520EXC]

I have used a XRsOnly header on a stock XR200 and a Powroll 218; nice pipe in SS that seems to flow better than a stock pipe. IMO based on comparison tests it adds about as much as an oversize piston and 0.5 increase in compression ratio. The pipe is about 3/8" shorter than a stock pipe and designed for XRsOnly muffler but with muffler inlet mods for diameter it will fit into a stock muffler. Powroll's ideal pipe is a stepped pipe like the XRsOnly pipe but my drag race tests didn't show a difference between it and the Powroll 1 1/2" pipe. Stock jetting is so rich that just a pipe won't require rejetting, I have not run bigger main jets with just exhaust and air bix changes. But I'm running 2 sizes bigger jets on my Powroll 218 and it is rich enough based on air fuel ratio analisys, but I have a restricted muffler for sound control; as a side note Powroll recommends 3 sizes bigger main jet for their full mods. The good news is my 11:1 Powroll motor feels like a half kick starter with a warm engine, if the kicker is at the top. If the kicker is at half stroke (no compression release) it is very difficult to kick thru. Hope this helps

So with the 3/8th's shortage on the XR's only pipe, what inlet mods do you need to fit the muffler, or do they come with instructions from XR's only ??? Many Thanks in Advance Chuck !!!

[KTM520EXC]

It appears "clean out plate" must be installed in order to be spark arrestor compliant.

https://www.thumpertalk.com/topic/950171-pictures-of-exhaust-95-xr600/

[Chuck.]

So with the 3/8th's shortage on the XR's only pipe, what inlet mods do you need to fit the muffler, or do they come with instructions from XR's only ??? Many Thanks in Advance Chuck !!!

The stock header slips 1 1/2" into the muffler so the shorter length hasn't been a problem for me, but the diameter has been. Honda uses a sleeve gasket to seal the connection between the header to the muffler, and the gasket can be trimmed or removed to accommodate a larger header. Review the pics in post #1, the gasket fits onto the muffler and on the header like the shim ring shown in the third pic that was used to adapt a XR250 muffler. The second picture shows the inlet to two mufflers; on the left is a XR250 muffler with the sleeve gasket, on the right is a XR200 muffler without the sleeve. Here are some diameters.

Stock header outlet 1.13"OD

XRsOnly header outlet 1.375"OD

Stock muffler inlet is 1.3"ID with out the sleeve

Several ways to adapt the XRsOnly to a stock muffler; a muffler shop can expand the inlet to suit the XRsOnly header, make an adapter to suit a shortened XRsOnly header, or adapt the end of a stock header to the XRsOnly pipe.

And red RTV can be your friend.

[KTM520EXC]

If going to something other than a stock muffler i.e., ISD2, or some type of supertrapp set up, what does one do for a mid pipe ??? Thx !!!

[Chuck.]

I've built several mid pipes to adapt other mufflers to the header, it is basically a 'S' bend. Two problems: Finding mufflers with mounts for the XR200 frame, you'll need to adapt and/or use a muffler with adjustable universal mount. Second problem is finding mandrel bends in 18 gauge (0.049" wall) tubing rather than the common 16 gauge (0.065" wall). For my IDS2 muffler and XRsOnly header a header shop resized a piece of tubing for a no clamp slip fit sleeve for the header, no leaks and easy on/off. I then welded it to the S bend and added the mid pipe frame mount.

XR200 header outlet ODs:

Stock 1.13"

XRsOnly 1 3/8"

Powroll 1 1/2"

Some muffler inlet sizes:

Stock 1.13"

XR250 1 1/2"

XR400 1 3/4"