Fuel filter mod

I completed this mod on my 08 gen 2 today out of necessity. It's drag racing season again here and after 3 rounds I couldn't figure out why I was still 0.8s off my fastest time. The bike was getting to redline but just not quickly enough. Someone mentioned a Busa owner they knew who previously had the same problem, he ended up replacing the entire fuel pump assembly, and down came his ET's again. That's AUD$300-400 here, so I found this fuel filter mod thread. I also replaced the pre-filter sock & stock Mitsubishi UC-T30 motor with a Kemso motor & a Whites Racing Products washable filter. I used a Ryco Z200 inline filter with 15-20cm of Codan fuel injection hose on either side held on with 4 Tridon EFI hose clamps. All up it was about AUD$100. I decided to do a pre & post mod flow test (fuel lines already primed) with the injector rail disconnected and pointed down into a 1L measuring jug ;
Pre-mod... 10 key-turn primes... 420mL total.
Post-mod... 3 key-turn primes... 500mL and stopped there, I figured we already had a winner!
It's round 4 this Saturday, so I hope to have solved my problem. I'd cross my fingers...but it makes it a bit hard to launch.
 
chrisjp said:
a quick break down. i will do pics and description of two very different methods to this modification. one is easy in my opinion and i wish i had chose that route. the other is more difficult. the first method is the easiest and that is simply drilling a hole in the filter assembly to bypass the filter but it leaves the old clogged up filter in the assembly to flush out and clog up your new inline filter you will be putting in. so that means change the inline after a while to keep making sure gunk not clogging up new filter. 10$ per filter and 5 min of time...not that much of a hassle. the second method is considerably more time consuming and it was difficult to do...but it removed the old filter and reassembled the whole assembly. so no worries of the old stuff back washing into the new inline filter. the third method i thought of after all the work was the possibility of using purple pvc pipe adhesive. but am not positive if it is gas previous. if it adheres and holds up in gas...it would make the second method SOOOO much easier. so here we go with the first method. you will see some duplication of pics reference to the inline filter set up.
Click to expand...


So I followed your instructions to a t and when I restarted the bike i had to adjust the idle to keep it running not a huge deal but when I rev it up and let off if I get above 3k rpm the bike does when the revs come back down what could I have done wrong
 
Sounds like you still have a fuel restriction somewhere else. If it was me, I would be checking in -some- order of preference:
1. A fuel hose kink. It can kink if it's too long, AND if it's too short. Get right down there with your eyeballs and a torch as you lower the tank.
2. I replaced the pre-filter sock, instead of cleaning it up. And I do so every 12mths.
3. When I back-flushed the internal filter, it absolutely PUKED out thick coffee coloured sludge that would have otherwise have continued it's merry way on to my injector rail. I got myself some Nulon Pro Strength Fuel System Cleaner, and ran out the whole 500ml bottle in equal parts over the course of the next 3 tank fulls. But you'll need to look for a fuel system / injector cleaner with the words polyetheramine or PEA. Redline or Techron also have it.
4. I replaced the external fuel filter after that was done. And do so every 12mths.
Hope something here solves your issue.
 
chrisjp said:
here is a diagram of the orientation and some pics showing the angles you should be aiming for...i would start with a small hole...use very little pressure..you want to only just penetrate the chamber that the fuel filter resides in. the drill size .177 give or take a .01 so 11/64th to a 3/16th max a 16 bit is exactly .177.

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Click to expand...
 
Completed this on my gen1 without success.
Not sure if I drilled the hole at the wrong angle, but I was sure it was right at the time. I even checked by trying to blow into the inlet before and after the mod.
I’m having stumbling/surging under heavy load. Debating on just buying a new overpriced filter assembly.
Producing only 30ml during engine prime. New pump perhaps?
 
Last edited:
NiteRunnr said:
Completed this on my gen1 without success.
Not sure if I drilled the hole at the wrong angle, but I was sure it was right at the time. I even checked by trying to blow into the inlet before and after the mod.
I’m having stumbling/surging under heavy load. Debating on just buying a new overpriced filter assembly.
Producing only 30ml during engine prime. New pump perhaps?
Click to expand...
did you figure out the problem?
 
@chrisjp this post is still helping people. Thank you.

My 2005 sits way more than I'd like to admit and a couple years ago I had a big problem with rust in the tank (that I forgot to park full with Stabil) Chain, rust treatment, lots of flushing, etc. got the fuel pump going again.

Thought everything was fine but a couple months ago when I took it out there were problems. It would run good for a while and then almost die. It would idle but any throttle and it would cut off.

Figured the rust was still the culprit so... time for the fuel filter mod.

I took it apart and drilled the hole. Picked up those same parts at Advance Auto and put in my new filter. Routed it a little different (on the RH side) trying to make sure I didn't kink the hoses and it's all good with no leaks.

Started it up and wow. Had to back off the fast idle ("choke") lever for the first time in years.

I can feel it running better, both on the throttle and even at idle while moving the bike around.

Great mod to replace a ridiculous fuel filter design. Do it.
 
seangt said:
@chrisjp this post is still helping people. Thank you.

My 2005 sits way more than I'd like to admit and a couple years ago I had a big problem with rust in the tank (that I forgot to park full with Stabil) Chain, rust treatment, lots of flushing, etc. got the fuel pump going again.

Thought everything was fine but a couple months ago when I took it out there were problems. It would run good for a while and then almost die. It would idle but any throttle and it would cut off.

Figured the rust was still the culprit so... time for the fuel filter mod.

I took it apart and drilled the hole. Picked up those same parts at Advance Auto and put in my new filter. Routed it a little different (on the RH side) trying to make sure I didn't kink the hoses and it's all good with no leaks.

Started it up and wow. Had to back off the fast idle ("choke") lever for the first time in years.

I can feel it running better, both on the throttle and even at idle while moving the bike around.

Great mod to replace a ridiculous fuel filter design. Do it.
Click to expand...
What did you do about the rust in your tank? KREEM?
 
Bigboy Busa2 said:
What did you do about the rust in your tank? KREEM?
Click to expand...
No, I was worried about stories I read with liner/coatings eventually peeling off. I'm sure there are some that work but I didn't want to risk it.
I took a couple feet of chain and shook it, turned it, shook it, turned it, took a break, and did that some more. Then I poured in a whole bunch of Evapo-Rust and let it sit. Turned it over and repeated a few times.

When I thought I had it all gone and treated/converted I tried to coat it with some thin oil and drained all that out.
Now I'm more careful about leaving it parked with a full tank and I use Stabil 360 Marine which has something to let of fumes inside the tank to protect where the fuel isn't touching.
 
chrisjp said:
a quick break down. i will do pics and description of two very different methods to this modification. one is easy in my opinion and i wish i had chose that route. the other is more difficult. the first method is the easiest and that is simply drilling a hole in the filter assembly to bypass the filter but it leaves the old clogged up filter in the assembly to flush out and clog up your new inline filter you will be putting in. so that means change the inline after a while to keep making sure gunk not clogging up new filter. 10$ per filter and 5 min of time...not that much of a hassle. the second method is considerably more time consuming and it was difficult to do...but it removed the old filter and reassembled the whole assembly. so no worries of the old stuff back washing into the new inline filter. the third method i thought of after all the work was the possibility of using purple pvc pipe adhesive. but am not positive if it is gas previous. if it adheres and holds up in gas...it would make the second method SOOOO much easier. so here we go with the first method. you will see some duplication of pics reference to the inline filter set up.
Click to expand...
Picked up a 2002 Busa back in Sept of 21. Never felt like much of a bike, and got fuel choked at 6,500 rpm. Finished the filter mod today, and went out for a test ride. IT IS A WHOLE NEW BIKE!!! Thank you for this bike saving guide.
 
@chrisjp one thing that I noticed about the mod is that now the fuel pressure regulator doesnt get filtered fuel. In all automotive and motorcycle fuel applications, FPR always gest clean fuel so its positioned after the filter. In this case, the FPR can get clogged and wont work properly anymore. Usually FPR has a tiny screen, nothing else to protect it. The filtering system in gen 1&2 is indeed stupid and expensive to replace but your way has flaws also. If someone wants to do things "the right way", the FPR should be also relocated behind the filter and then add a return line to the tank OR just buy new OEM fuel filter. I have one gen 1 on my hands and Im thinking options what to do with the 60k km driven fuel system...
 
Jusa101 said:
@chrisjp one thing that I noticed about the mod is that now the fuel pressure regulator doesnt get filtered fuel. In all automotive and motorcycle fuel applications, FPR always gest clean fuel so its positioned after the filter. In this case, the FPR can get clogged and wont work properly anymore. Usually FPR has a tiny screen, nothing else to protect it. The filtering system in gen 1&2 is indeed stupid and expensive to replace but your way has flaws also. If someone wants to do things "the right way", the FPR should be also relocated behind the filter and then add a return line to the tank OR just buy new OEM fuel filter. I have one gen 1 on my hands and Im thinking options what to do with the 60k km driven fuel system...
Click to expand...
The fuel going to the fuel rail is filtered with the external filter, its fine,, so many people have done it this way.
It started on the SV 650 boards
 
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I ordered a cheapo muffler for my gsxr from Ali-Express.
Tracking showed it landed in NJ 5 days later.
2 months later, and I still havn't gotten it.
After emailing them several times throughout the last month, with Zero response...F them.
I filed for a refund through Paypal last Friday.
If Paypal hears nothing by this Thursday, they will give me my money back.
I knew it was a gamble to start with, but I will pass on all things Ali-Express from now on.
 
Working on this mod if I can't get a decent pressure and flow. I love the teardowns since it helps understand the engineering, but has anyone found a Spec sheet for the OEM pumps yet? I've been looking all over for how many amps this thing draws at high demand and can't find it anywhere!
 
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