Safari Tank Mod
Written by Highfive & 10cup
This project is called the "10cup Mod" since it was invented by a fellow WRR rider known as 10cup on ADV.
The procedure that follows is his. I have only helped to contribute improvements to it as a result of being the first person (besides 10cup) to complete the procedure. We collaborated thoroughly on lots of additional testing to refine the end result. Warning: this was a bold & daring modification which demanded accuracy & precision at every step. Do not attempt this modification, you probably can't do it. 10cup has years of experience working with fuel delivery systems during his Kart Racing days. So, he is obviously more comfortable working with this kind of stuff than the rest of you-uns. As for me, well....I'm just plum crazy!
As of the publishing of this article (Feb 2010), the Safari tank is the only large capacity tank available in the aftermarket for the WRR/X. The fit & finish is quite good, and it seems to perform very well exactly as it comes from the manufacturer. The purpose of this modification was simply to enhance the performance. An attempt at making a good product even better. Here is currently what's inside the Safari tank when you receive it:
It employs one medium capacity Mikuni vacuum pump to transfer (lift) fuel from each wing to the primary Yamaha fuel pump...necessary when the fuel level drops below the primary pump intake. A significant amount of fuel capacity within the "wings" sits below the primary fuel pump sump, and thus, it must be transferred up to it...to be useable.
The reasons that we have performed this mod are threefold: 1) To provide a secondary (backup) vacuum pump system 2) To enhance the fuel delivery rate to the primary fuel pump under highway speed conditions 3) To ensure maximum utilization of available fuel capacity within the tank.
This Mikuni vacuum pump is a simple, proven, & reliable design. It has been used in many fuel applications successfully for many years. Here's a close-up of this pump:
I made the black line with a Sharpie so I didn't forget which way to reassemble the cover, because I will be taking it apart to replace that brass nipple with a different fitting. We'll get into that later...
Here, you can see small directional arrows stamped into the casting on the inlet and outlet (intake & discharge). I added some black arrows of my own (with my Sharpie again) cause I'm getting old....and can barely see those stamped arrows. Its my self-imposed "Vacuum Pumps for Dummies" precaution.
This would be the air (vacuum) side of the pump. The fuel moves beneath that diaphram. Its a pretty simple system where a pair of rubber flappers open and close in synchronization....pulling fuel through a series of connected channels in the casting. Pretty failsafe when everything is working correctly.
However, as I've learned through my testing, if there is any leakage of fuel into the air side of the diaphram, the pump will stop working. Same thing happens if there is an air leak around the fuel inlet coupling (where the fuel supply hose connects). Neither scenario causes any damage to the pump. But, any such leaks must be eliminated for the pump to begin working properly.
This would probably not be a concern for most people. But if you've learned anything about me from reading my articles, then you'll understand where I'm coming from. THIS is something that could keep me awake at night.....and you know how I feel about getting a good night's sleep! So there you have it. No need for you to get all worked up about something that might cause me to lose some sleep....when I'm 500 miles in the remote....solo....without a support crew.
With one vacuum pump pulling fuel from both wings of the tank, as soon as one sucks any air, the system’s capacity drops off until it can’t pump at all due to the air being picked up. This would be known as "cavitation" and could potentially be an issue when running at highway speeds, on the last half gallon of fuel remaining in the tank. Probably not as much an issue if traveling at a slow pace on a trail, dirt road, or around town. Nobody really runs a little 'ol two-fiddy out on the Interstate anyway.....right? So, 'ol 10cup probably just had too much time on his hands when he concocted up this notion. And, you know how much I like to tinker. Well, it was just bound to happen....us coming together like Obi-wan Kenobi and Luke Skywalker.
Ok...maybe not. But is sure sounded like a fun project to me. So I just had to give it a go! You didn't really expect me to read the instructions with a brand new $450 tank, and actually follow them....did you? As sure as 10cup liveth, my new tank went from the shipping box to the work bench in the Mad Highfive laboratory....never to see my bike before I started drilling holes. Oops...I didn't meant to say that! Yet...
As the fuel level drops below the primary fuel pump, there does seem to be a greater accumulation of fuel in the left wing versus the right wing. This situation is most likely caused by the rather short kickstand on the WRR. The bike leans heavily to the left when on the side-stand. So, air could be sucked into the vacuum pump inlet as the right side is depleted earlier than the left side. Granted we're talking about the bottom of the barrel, here. But, 'ol 10cup wanted to be able to suck every last drop of useable fuel out of the tank. If him too, then me too....naturally. Cause I'm never one to be left behind....like the Krabill... he knows a lot about that. But forgive me, I digress (again).
Solution:
Add a second vacuum pump and dedicate one pump to each wing of the tank! That way, if one side depletes first, there will still be fuel delivered from the other side (separately) to the primary Yamaha fuel pump. That'll really make her good to the last drop under any riding condition!
First thing, remove the stock tank and empty all the fuel out safely. Of course, to do that you have to unhook the electrical plug and the fuel line disconnect.
I've learned these things are a lot easier to disconnect, if you have someone else hold the tank for you. That lets you get two hands in there instead of one. Got to be careful and don't force or break the fittings. Follow the instructions in the Yamanual, & all that. Don't just grab & pull them in frustration. There are tabs &/or buttons to push on these thingys prior to releasing.
Once the tank is off and we've finished removing the fuel, then carefully remove the primary Yamaha fuel pump noting how the pump is positioned. The fuel inlet on the primary fuel pump points toward the front of the bike when the tank is installed. Got to pay attention to that orientation, but for now, carefully set it aside.
All work will be done through the bottom of the new Safari tank once the primary Yamaha fuel pump is removed from the stock tank.
Now, gently remove the nut from the vacuum pump located at the lower rear of the Safari tank where the vacuum line hooks up. I know....its a repeat photo, but I like this one. The nut was located where I'm pointing the screwdriver. There is an O-ring on the inside of that fitting to seal against the tank wall. Hold onto the pump (inside the tank) when removing the nut. Carefully pull the vac-pump away from the tank wall and remove that O-ring before it falls off the fitting and gets lost somewhere inside the nice new big tank. Put the O-ring & nut in a safe place, then gently tug, pull, and manipulate the vacuum pump and both fuel lines out of the tank. These poly fuel lines are pretty stiff, so it took some bending and tugging. Had to be careful.
By the way, don't get confused by the different things you see in all these photos. You'll be looking at pics from two different installs (10cups & Highfive's). I am using a combination of photos from each of us to help show all the details. So, there will be different colored hoses and different orientations in the pics. Commercial over....let's continue:
Under the tank, above the engine, the vacuum line must be tee'd off close to the pick up point. The vacuum source will be this port on the throttle body. It is the same port that gets capped off in the AIS Removal mod., and shown here with the screwdriver.
We Tee'd the vacuum line with one leg running rearward for the #1 vacuum pump (per the original instructions), and one leg running forward for the #2 vacuum pump (new addition). Located the Tee close to the engine, not far away (i.e. close to the vacuum source). Then, made the two vacuum lines very similar in length...using as little hose as possible for each leg. This helped equalize the amount of suction in each line (& maximize pump performance). The original vacuum line from the AIS system can be used for this, or buy some new vacuum line from a local auto parts store. Just have to make sure its pretty small ID line with a thick wall for a tight fit, to minimize chances for any air leakage. Additional vacuum tees and elbows can also be purchased, as needed, from an auto parts store. I used my heat gun to warm up the hose prior to installing. This makes it slip onto the fittings much easier. I reckon a simple hair dryer could work effectively too.
The original #1 vac-pump’s duty does not change other than it is now only pulling fuel from one side of the tank, instead of both. We determined feeding the #1 pump from the left side of the tank was a better deal. This pump seems to get the most suction, and deliver the most fuel...so we directed it to pull from the side of the tank that is expected to have more fuel remaining in it.
Now, let's look closer at the fuel lines that will feed the vacuum pumps. This is how the fuel suction line came from the tank manufacturer:
The poly hose is stiff which helps keep it pointed into the wings of the tank. And, as you can see above, its just an open-end hose with a filter sock and large compression clamp. Not saying its bad....just thinking it can be made better in two areas: 1) weight the end of the hose to keep it down on the bottom of the tank 2) replace the compression clamp with something less likely to snag on the inside wall of the tank. With all the bouncing around from rough riding, spills, etc, we don't want that hose to move off the bottom of the tank and get hung up somewhere above the fuel level....and start sucking air...excuse me, "cavitating".
Therefore, some heavy "brass fuel pickups" were installed in each end to help prevent the fuel line from riding up out of the fuel level in rough conditions. Purchased from here: http://www.out2win.com/catalog/fueltanks.html
These things are are heavy and should keep the lines on the bottom. You can't tell, but I'm straining to hold my hand still for this photo....really.
10cup is apparently quite a bit stronger than me. He can hold it up with his fingertips. Ho-chi-momma!
10cup used stainless safety wire to secure these items, while I chose nylon cable ties. Both are definitely smoother and more slim profiled....making them less likely to snag on the tank wall. The theory is "if the line does move off the bottom (like in an upside down crash), we want the weighted line to fall back to the tank bottom when the bike is stood back upright". As evidenced below, I've already thrown in the towel. My tank is already upside down before its even got off the table!
10cup also felt the "ears" of the compression clamp can catch within the narrow sides of the tank preventing the hose from being fully inserted toward the front for anyone but a professional Aussie installer....really.
Next, remove the “Tee” on the intake side of the #1 vac-pump (original) and replacing it with a 90 degree elbow positioned to pull from the left wing, as previously mentioned.
Then it will eventually be reinstalled back into its original position inside the tank (being sure the lines are free & clear without any kinks in them). The vacuum pump can be rotated as needed to allow the vacuum pump pickups to be easily routed. This #1 vac-pump should be located in a horizontal position, the same as it was when you removed it from the tank. And the fuel supply line will be stuffed into the left wing (left side of the bike) all the way to the bottom front tip, similar to the original installation.
But we must wait to do this until after we have completed drilling a hole for the #2 pump. Yup, thats right. I said drill a hole into this pretty new tank....that is if we want to complete this nifty 10cup mod. And, it will be located directly above the hot engine when its all said and done. That's the daring part!
On the brighter side, consider that the tank already comes with three holes in it: one for the filler neck, one for the #1 vac-pump, & one gigantic hole for the primary fuel pump! So now, maybe you won't feel so nervous about me drilling a 4th hole into the purdy $450 tank. Just DON'T do it wrong, HF! We've only got one shot. And its a bit of a blindfolded shot at that. Hey, I warned you not to try this! You'd have to either be mighty comfortable with your hand-eye coordination skills to attempt this mod, or just plum crazy...eh?
For the second vacuum pump location, we must find a flat section near the front center of the tank that would also allow us to hook up the vacuum hose underneath (outside the tank...directly above the motor) without interference. There seems to be one such place slightly left of center that works nicely, and it looks like this:
Oh...gee whiz....I missed on the first attempt and drilled a hole in the wrong place. I thought 10cup said left side, not left of center....think we had a bad phone connection. So, just disregard the black spot on left side of the photo....over there. I'll photoshop that out of the picture and everything will be a-ok...really. The new hole drilled near the center of the photo above the primary fuel pump cavity is the one we're interested in right now. That other little black thingy is just for my stupid little turbo charger. No big deal....really.
Here are some shots with the #2 pump installed.
See, all photoshopped up it is....with a better match for the blue color. And, now you don't even know about the stupid little turbo charger project anymore.
In the next photo, I'm holding a mirror so you can see the connection underneath the pump. Note how its flush with the tank wall.
Each tank is probably a little bit different. I had to position this pump vertical and move it around a bit until I could find the flattest area in this same vicinity for drilling the mounting hole. Dead center seems to have a ridge, so that's no good. Mine is located left of center a bit (or right of center in this photo...looking down from the filler neck). Here is a couple of photos on 10cup's mount:
A couple of points regarding the new hole: 1) Don't drill it any larger than it needs to be...obviously (I forgot the size it took). Stepped up my bit size slowly until the fitting inserted correctly...not just the threads. There is a bushing area below the threads on the fitting. That portion is a little larger than the thread diameter. That's what pushes thru the hole in the tank wall. 2) Don't locate the hole any closer to the bottom fuel pump mounting flange than 1.75". I'm referring to the distance between that flat portion (in photo above) and the vacuum fitting. The magic distance is probably between 1.75" - 2.0". There are big bumps inside which cover those threaded brass inserts and the #2 vac-pump will hit them if the distance is too short, and the project will fail. Make the distance too long, and the project will also fail. There is a very narrow window of area where the hole must be drilled precisely to facilitate a flush, leak-free, mounting location. We must also insure that the new vacuum fitting (on the outside) does not interfere with the bike's frame rail when the tank is installed on the bike. Keep in mind that we need room to mount the vacuum line (on the outside of tank) to the #2 vac-pump fitting like this:
We also had to make sure the pump location inside the tank is far enough forward against the tank wall that it does not interfere with the primary fuel pump after it is reinstalled.
The location of this second vacuum pump is the most critical step. Checked and rechecked, because once you drill through the tank that’s it. Got to get it right the first time!
What makes it so hard, is that you can't see through the tank wall (at least not on the blue colored tank...which we both have). So, there is a bit of educated guessing going on to spot that location precisely. Sounds like real fine fun, don't it?
Had to make sure not to forget to install the O-ring on the fitting against the inside tank wall. And be sure to use a flat washer on the outside wall beneath the retaining nut. I also applied some Yamabond 4 sealant beneath the flat washer as an added measure against potential leakage. Tighten it snug & firm, but don't overtighten the fitting to the tank wall. That might force it to pull away from the vac-pump itself....causing a leak around the fitting into the diaphram. I'll show you more how this fitting is inserted into the pump a little later.
Once the pump was fitted, we needed to determine the proper length of fuel supply hose. We both ended up cutting about 2" - 3" off the fuel line that will run to the right wing of the tank (connected to the inlet on the new #2 vac-pump), as the original length was now too long. Took our jolly good time figuring this out, and to make sure we didn't get the line too short). Can use a 90 degree elbow inside there, if we feel that will help locate the fuel supply hose properly.
The last thing to do is install the primary Yamaha fuel pump. We must attach some discharge line from the each vacuum pump outlet and tie it to the fuel pump like this.
Make sure the ends of the discharge line are below the lip on the bottom of the primary fuel pump. There is a sump area down there, and we want the discharge from the vac-pumps to spill directly into that sump....not fall outside of it.
Next, stuff it all up into the tank carefully sorting out the lines so they don't get tangled or kinked. Make certain the primary fuel pump inlet is facing toward the front of the bike....in the correct orientation for the hose connection to feed the fuel injection system. Then, bolt it down making sure we have not kinked or crimped the nice big rubber gasket at the the bottom of the fuel pump. Otherwise, Ugh...we've got em leak!
Here is how my finished package looks inside the tank:
Put the tank back on the bike, connected the fuel line, put in some fuel, and check thoroughly for any leaks. No leaks found, so I hooked up the electrical plug and gave it a test. Had to BE CERTAIN the vacuum lines were hooked to both the front vacuum pump and the rear vacuum pump, respectively, and then bolted the tank in place. I snaked my rear vacuum line (to the #1 vac-pump) inside the frame rail like this.
I did use a 90 degree elbow to make the turn without kinking my line. So, both of my vacuum lines have elbows in them after the Tee. I believe 10cup is using an elbow on the rear but not the front connection.
I'm going to talk about hose material selection in a minute. But just a note here. By using a translucent discharge hose like the yellow colored fuel line in my photo, I am able to see fuel being pumped through them when the engine is running. This is how I determine if my vacuum pumps are feeding the primary fuel pump. It allows me to fill the tank with enough gas to cover the primary fuel pump to get the bike up & running, yet keep the level low enough to watch my vac-pump lines working.
If you can't see through the hose, then you have to watch the discharge end of the lines at the base of the primary fuel pump as they dump into the sump. That could be hard to see, depending upon where I located them during the install. And, I'd have to keep the fuel level below my primary fuel pump to be sure. The whole point is "I had to make certain BOTH vacuum pumps (#1 & #2) are feeding the primary fuel pump from the wings of the tank.
Didn't want to be fooled by just one pump working (like #1 pumping while #2 is not). That could result in running out of fuel while still having some extra capacity remaining in one side of the tank. In that case, I'd had been better off never performing this mod in the first place.
VERY SPECIAL NOTE: These dual vacuum pump system may need help getting "primed" the first time they run. If one is running but the other isn't, simply remove the vacuum line from the working side and plug it (cap it). This will force all the vacuum pressure into the other pump (only) and give it more than enough boost to prime the empty lines and get running. After that, both pumps should work just fine on the amount of vacuum generated at the fuel injection manifold. I had to do this procedure to prime my #2 pump. I simply removed the seat, pulled off the vacuum line and capped it, then restarted my bike. The #2 pump was primed and running before I could even get around to the front of the bike and have another looksee into the tank. After that, it was All Systems Go!
This is a very technical mod, but it works very well and offers absolute maximum range, plus additional flow rate capacity for high speed runs. We are not suggesting anyone else attempt it. Just sharing our story so you can be jealous that we did...and it works....real good...for us. But then, who are we...?
Now, a brief discussion about hose material selection. I assume the poly hoses that come with the initial installation should work fine, as is. Although the poly is a bit stiff to bend for the vac-pump discharge line that ties to the primary fuel pump. I found it more convenient to use a softer fuel line to replace that portion, but its not absolutely necessary.
I did make what I feel is an important discovery during my testing procedures. I was having problems getting the vacuum pumps to work in the open air (not submerged) AFTER removing and re-installing the original poly lines. What it boiled down to was an air leak around the inlet coupling. The hard poly tubes may be sealed tight when they arrive on the original installation. But once removed and reinstalled, I could NOT get an airtight seal. This leakage around the tube connection caused the vac-pumps to not work.
As soon as I switched to a new, softer, tight-sealing fuel line, the vac-pumps began working like a champ immediately! I don't want to admit how long it took....and how many hairs I pulled out...before I figured this out. So, just take my word for it. To properly perform the 10cup Mod, I benefited greatly from changing out all the fuel lines to a different material. Here's the stuff I finally used for the suction (inlet feed) lines:
Its a softer (initially) poly hose 1/4" ID with the reinforced spiral fiber. I've purchased it at both my local hardware store and a farm & ranch supply called Atwoods. I'm sure its just about everywhere you find plumbing supplies. Again, I warm it a bit with my heat gun, then attach to my fittings and zip-ty very tightly while its still soft. Definitely worth securing the joints with something firm (safety wire would be even better). Just don't want to use a big squeeze clamp that could snag on the inside of the tank wall.
This particular fiber lined hose is reasonably stiff....at least stiff enough to feed into the tank wings adequately. However, after it sits in gasoline for a while, it turns very stiff. So, it will form to the position it is placed it within the tank and put into use....then stay there after it hardens. Just don't plan on ever re-using it once removed. I'll start over with some fresh hose in that case.
Regarding the discharge (outlet) hose for the vac-pumps, I've already discussed that above (where I used a softer, more pliable, translucent hose). That ensured I can see the fuel pumping thru the lines....to verify my vac-pumps are primed and working.
The final thing to discuss in this article, is the special vacuum pump fitting required for attaching these pumps to the Safari tank wall. The original #1 pump comes already installed in the tank, so it has the correct fitting (obviously). The additional pump (#2 duplicate) is available from Just Gas Tanks, but so far, it has not included the special fitting already installed in the pump. They sold that fitting to me separately, and I had to figure out how to install it like this: (Maestro....cue the music please)
Wow...didnt' that look easy? Well, its not. Not by a long shot! The fit is so tight and the seal requirement so precise, and the pump lid casting so fragile.....ITS VERY DIFFICULT TO DO CORRECTLY. Any imperfection, I've learned (the hard way) makes the little Mikuni vacuum pump run weakly (at best) or nada (at worst). And the margin for error is tiny. I've destroyed at least one of the vac-pumps already.....at least one. And some people actually think I kind of know what I'm doing...sometimes. Kind of.
Now you know why I call it the "Mad Highfive Laboratory". This little beauty caused me to go in & out of my tank with all the pump gear at least 6 times....at least. So, in lieu of my zealous R&D, I'm going to wait for a pump that has this fitting already installed in it correctly....should I attempt this again. Rumors allege that Just Gas Tanks is currently working on securing these spare pumps with the fittings already installed. Figures.....story of my life.
Hopefully, they will sort it out. In the meantime, I've gotten quite good at doing it. Send your little spare #2 pump and fitting to me, and I'll be glad to insert it for oh...let's say $450 a shot (plus tax & freight)....guaranteed. As far as the rest of the 10cup Mod, well,you'd have to finish that yourself. I'm done with mine....FINALLY.
HF
Disclaimer……
Any use of this information is at your sole risk. Neither the writer nor anyone associated with this web site can be held responsible for your work, or your decision to modify your bike in any way. You assume all risk associated with attempting to perform changes to your motorcycle &/or tank(s) based upon any information provided by this article. The procedures described herein were performed by the authors at and for their own pleasure (or lack of...really). It was shared for your reading pleasure and is really not a recommended procedure for anyone else to really attempt. Really....Really....REALLY! Ok...got it? I warned you. Really....I did!