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Yamaha RMAX destruction and remodeling

Barkbeetle

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I’m a former pirate member and I’ve been posting stuff on the YamahaWolverineforum but jhama78 convinced me to rejoin here. There are some good builds and sagas being shared so I figured it is worth sharing my typical destruction of OEM engineering.

I like building stuff as much as I like driving them and when things like noise bothers me too much, it’s time to fix it. The RMAX has a lot of great features, the noise and cab heat are not part of it. In addition it is a bit short for some of the steep stuff I get on. My friend I got the rear end airborne on a steep crawling decent and had to roll out of it. It definitely got our attention. The plan starts with this front driveshaft I ordered 2 months ago!


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With the help of my friends lathe, we destroyed a perfectly good factory part.

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I have to order tubing and then weld it up as a new longer driveshaft for a destroyed RMAX!


Don’t proceed any further if you don’t want to see a naked RMAX!




Teardown has begun.

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These thing are not designed for maintenance, getting to the mechanical bits is a pain! I’m going to do something about that, the noise, the heat, tire clearance, wheelbase, and more. Let the real build begin.
 
The Flowmaster 70 series muffler showed up. It is the quietest one they make. It is about double the size of the stock one. Hopefully this will address the exhaust noise. I also got a stock RZR spark arrestor to stuff in the end of the tail pipe to stay legal. They fit very snug in 2.5” exhaust tubing. Several years ago I read on one of the engine tuner websites that the high rpm of CVT machines blows out the glass packing and chambered mufflers are the better way to go. A Flowmaster worked good on Old Timer so I think it will be fine here.

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I made good progress cutting and grinding today. Definitely no turning back now. It was surprisingly easy to cut the sides off. There is not very much weld holding them on.

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Looking at the stripped down machine makes it so tempting to build a single seat buggy but my daughter gave me the sad face and said NO. It would be so light, even with 15” more length, which would have been mandatory for the seat.

There is still more destruction to do but I am going to leave as much as I can for the steering and hopefully transfer it to the new steel before removing the rest of the current structure.




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Barkbeetle

Registered
Joined Sep 18, 2020
167 Posts
Discussion Starter · #12 · Sep 22, 2022

Accomplished another experiment I have wanted to do for awhile. Pull all the springs and see where the bottom is. Turns out there is approximately 5” of ground clearance when everything is tucked on stock tires.

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Spinal Surgery should start tomorrow because all the specialty tubing showed up earlier in the week.👍👍👍👍👍👍
 
Here is the update for this weekend’s work. Half of the steel I need is now in hand, getting steel in NM takes the better part of the day because the only place to get it is in Albuquerque. On Saturday I decided I should sort out the exhaust while I could still fire it up. Boy am I glad I did. As stated above, I came up with a solution for the 70 series big block muffler. Here is the result with the recycled Yamaha exhaust hangers and the RZR spark arrestor.

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With much anticipation, I fired it up expecting a low quiet exhaust note. Fail! What I got was loud and raspy so I proceeded to carefully cut it all up for try two. I went to the local parts store to see if I could find a turbo style muffler (combo of chambers and fiberglass matting). Our stores don’t stock much but I was able to get one for a Jeep Cherokee that would work. I proceeded to weld it up in the same location as the Flowmaster. Here is how It turned out.

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I tried putting the tip at an angle for a different look and started it up. The sound was better (not so raspy) but still too loud, especially when rev’d up. Try 2, FAIL. Out of curiosity, I held the Flowmaster over the tip and the sound dropped massively. The engine noise now dominated the sound in the garage. At least I know it is possible. With this information, I cut it all up again and re-installed the Flowmaster In the original location. I stared at it for quite awhile and did a lot of internet searching last night and came to the conclusion that I will be cutting it up again to install a 12” glass pack/resonator in the horizontal tubing run below the main muffler. I am confident this will eliminate the raspy sound and should quiet it down a moderate amount. Parts are ordered and I should be able to get back on it in two weeks. My hope is this will be quiet enough to balance the engine noise. If it is not quiet enough, I will add another glass pack downstream from the Flowmaster. Going back to my VW days, this might be a bare Supertrapp disk setup instead of the RZR spark arrestor, a Supertrapp with glass pack, or a basic welded glasspack. Here is the Flowmaster reinstalled as try three.


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With everything getting a little shorter each time, I had to get a little creative on the mounts and tubing. I ordered fresh tubing for the resonator install and this tubing will be useful for smaller bends. So, no frame stretcher tool for a few more weeks.
 
I am loosing track, but I think this is the fourth attempt at making this thing quiet. The combo of a resonator and the Flowmaster 70 series muffler has done the trick. The exhaust noise is lower than the engine noise and I held off welding the tip on until I get more of the rear completed. As a benefit, the flow is vastly superior than stock. I also bent the rear heat shield in preparation for an additional shield over the muffler.

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It was a successful weekend, I destroyed my RMAX by cutting it in half and then fixed it by welding it back together. The funny thing is that it looks longer now 🤔.

Before:

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After:

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Joking aside, the wheel base is just over 100” and the new driveshaft needs to be exactly 14.5” longer. I finally have all my steel too, so that won’t be a hang up for progress.
 
With the help of my very talented machinist/welder friend, I now have a new front driveshaft. It ended up with less than 0.005” runout, unbelievable! Without the stock one next to it, it would be hard to tell this one is a custom job.
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A little bit of this and that this weekend between house work. Getting the seat mounted was the biggest accomplishment. With it located I can determine cage height.

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I set the seat so when it is all the way back there is still clearance to the CVT. My goal is to be able to have the firewall stay on while working on the CVT. It’s going to be tight. I will not be routing the CVT intakes forward like stock. They will go somewhere behind the cab. Maybe a roof scoop for the intake. I am going to use a YXZ rear mounted radiator and mount the oil cooler in front of it. I didn’t like the way the stock lines ran and I was getting crap in the radiator from overgrown two tracks.


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I decided to use some expanded metal for the flat floor boards and I love it. Very grippy for my shoes and any crap that gets in there will fall down to the UHMW skid plates instead of acting like marbles under my feet. The boat sides and bottom will be 1/2” UHMW. The expanded metal stops where it meets the boat sides. In this picture you can see the new air intake extensions made from 3-1/2” aluminum tube. I have a small bead roller that works perfect for the retention beads. It sealed up but 3.75” tube might have worked a little better. The ID is basically the same but the plastic pipes are thicker. It is also exactly 14.5” long.

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Finally I made up a dead pedal for easy left foot braking and bracing in rough terrain.
 
Not a lot of progress over the last couple of weeks but important decisions and more small stuff. Once again I turning to my welding expert to help me extend the oil and coolant lines because I reverted to the stock radiator location. The cab configuration I want would not lend to good airflow at the back of the cab. Keeping everything in the stock location makes that a non-issue. The “transmission“ tunnel will be slightly more complicated though, with all the lines plus keeping the CVT intakes up there. I also ordered everything for the CVT ducts yesterday and I am going to use 4” brake cooling duct which is a good bit larger than the ID of the stock tubes. I did some searching on what the racers are using but came up dry. From pictures, it looks like they are using brake duct hose. It is flexible, light, and temperature rated.

Here are a few pictures of the extended lines. I un-bent/re-bent the oil lines to fit the new frame taper and they are a little rough but it gets the job done. The lines were Tig welded with stainless to DOM tubing that we bored slightly for a nice fillet weld. The coolant lines were easier because they were just a straight extension. All of them had to be carefully clocked to keep the bends and connections aligned.


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Lastly, I did a little cleanup on the subframe for the radiator and oil cooler to remove metal tabs I don’t need anymore.
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Making some good progress on the detail work that will make my wreck run again.

The roundly round racing 4” brake duct works perfect and with some 4” aluminum tube, a bead roller and some silicone 3.75” to 4” adapters, the CVT ducting is ready to go.

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I also got started on a precision CAD gas tank. This thing ended up crazy and it will be the most complex tank I have ever built. I went to my friends house again and now I want a fixture table. My 4x8x3/4 steel table seems inadequate. The fixture table made tacking the tank together way easier.


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One of the complex fixture setups
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In addition to the cardboard model, I did a quick Solidworks model to get the volume. The new tank is 9.3 gal versus 9.2 gal stock. I’m happy about that. It’s going to be fun welding this thing together and I still have to cut out the two biggest pieces. The diagonal side and top.
 
Didn’t work on the wreck nearly as much as I had hoped but I had fun attempting to weld my tank up and seeing how bad my tig welding is compared to the pro. The pro machined and welded the pump flange down. Clearly I am more of a grinder than a welder but all my welds held up for an overnight leak test. With the pass, I got the EFI fittings and fuel line hooked up. I decide against AN stuff because it is 2x the price ($100ish versus $50ish) and puts a lot more weight on the plastic pump outlet. The Dorman 90 fitting is much closer to the stock setup and is a fraction of the weight. We designed the tank to use the stock o-ring and hold down plate. I still need to order some M6 studs and glue them in but the tank is basically done. I still need to build a cage over the pump assembly and the seat will have to go up about an inch to make sure a passenger g out doesn’t smash something important.


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The brass vent at the front of the tank is a combo roll over valve/vent and has a heat melt plastic piece that prevents an explosion in the event of a fire. I learned about that feature the hard way on the last tank I built for Oldtmr when we used it as a heat sink for the thin fitting.
 
NICE!

I've had thoughts of doing something similar to a Pioneer 1000. Mostly because I'm white, but I'm not "$4ok for a four door RZR" white :laughing:
 
Awesome! I've wondered how many mufflers I'd need to string together to make the noise from my KRX more tolerable. I wonder if there's any way I could fit this assembly in mine...
 
One thing to watch for. It the glass pack sheads packing it will clog up the supertrapp. Had this happen on an ecotec buggy. Started loosing top end, buy the time we figured it out it wouldn't rev over 3000. Couldn't see any sign that the supertrapp was full of packing either.


Sure was quite though :homer:
 
One thing to watch for. It the glass pack sheads packing it will clog up the supertrapp. Had this happen on an ecotec buggy. Started loosing top end, buy the time we figured it out it wouldn't rev over 3000. Couldn't see any sign that the supertrapp was full of packing either.


Sure was quite though :homer:
Yup, I had the packing clog the spark arrestor on my RZR. Gotta keep an eye on anything with glass in it. Without the resonator the Flowmaster was loud and raspy but with the resonator it has a deep low tone that is pleasant. Big difference with and without a 6” tailpipe too.
 
Slightly off topic.....

Do you still have the ratrod SxS you built? That thing is/was :smokin:
Thanks! Sold it in 2020 to fund more concrete for my driveway as part of my garage extension and remodel. I definitely miss the look but not any of the parts that said Polaris. The guy that bought it was in southern NM but I haven’t heard of any sightings. I’m going to try and make this look ratty too, but different. The look should start to take shape in the next month as I start on the main cage.
 
There actually is a turbo kit for the RMAX. Not in my current plan, but you never know….

I did a quick Google after I posted that and the kit I saw was around $8k....... Seems insane to me that it could really cost that much.

I really wish they would have done a ~100" wb from the factory. I was just watching a video of the rmaxx vs the general vs whatever version of can am and the rmaxx looked like it was just way to short and top heavy with 4 guys in it. It's nice that it's not a full limo like the others, but 90" is just too short imo.
 
loved your ratrod sxs build the last time, and stoked you're back with another build! thank you for sharing
 
If people are wondering what’s going on, I got a little distracted with my new truck.

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I’ll be back on the RMAX soon with mixed work on truck as I get it ready for Alaska this summer. I’ll start a build thread on the truck in the Chevy…I mean Ford section😝. 7.3 gasser with the proper amount of doors.
 
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