FJ2400 - Bonneville Land Speed Racer

[fj1289]

A follow on question then seems to be - will a single FJ pump flow enough for both engines at sustained WOT?  (My gut tells me it probably would - but I wouldn't want to try it without testing it first!)  That way - if one is enough, then you already have a spare!

[fj1289]

More I think about this one, the more i think gravity feed is the way to go. 

You are putting together a custom fuel system so you can spec LARGE fuel taps and lines to the carbs.   When you send the carbs to Randy for rebuild you can let him know the plan for gravity feed and he can supply the proper seats.   

On the first version of the dragbike I ran a 1447 engine on oxygenated fuel (requires more volume than non- oxygenated) and ran a gravity setup to the Lectron carbs.   Never had any fuel supply problems.   I did install a large Pingel tap and ran larger lines than stock.

[racerrad8]

Sorting out the wiring for the Bonneville bike and (I searched I swear) I gotta ask:  Do I NEED the fuel pump?

Yes, you need a fuel pump or two. The bigger question as Chris already mentioned, does the O.E. fuel pump have enough flow to supply two sets of carbs? Only the gallon per hour (GPH) can answer that question. Once you determine the GPH of the pump, we can probably figure out if you need one or two.

The gravity FJ's have a "gravity feed system". It starts at the tank & petcock and continues all the way to the needle & seats in the carbs. The fuel system is 10mm to make sure there is enough head pressure to adequately flow the required fuel for demand.

The fuel pump system runs on a 6 or 7mm fuel line, which is what you have. It has a small orifice petcock, a smaller tank opening, smaller hose along with a filter and smaller needle & seats in the carbs. The internal flow of the carbs is also reduced at the fuel tee and single inlet on the fuel pump models. While you can bypass the fuel pump in an emergency to get you home, for your application of sustained wide open throttle, you'll require pressurized fuel supply.

Onto the next topic, wiring. You only need a few wires for this application to run the engine and fuel pump. I wouldn't use any of the stock wiring harness other than maybe a few plugs.

See the attached wring diagram that has been used for close to 30 years powering the Legends racecar. I'm sure you have to have a rider tethered kill switch which can be easily wired into the power circuit after the ignition toggle switch.

If you have any question on the wiring, please let me know.

Randy - RPM

[racerrad8]

...Never had any fuel supply problems.   I did install a large Pingel tap and ran larger lines than stock.

Chris, think of the sustained WOT this has over the drag bike. The drag bike has probably 15 seconds max I would suspect. The land speed track is miles long, so it will be held at WOT for significantly longer duration of time.

I disagree, this application is going to require a fuel pump...or two.

Randy - RPM

[freakhousecustoms]

The reference to "potential problems" always sticks in my craw in this context, the idea of a pump is to eliminate them! Fuel blockages stop a lot more bikes than failed fuel pumps.

On any bike, when I'm home, I would never question a fuel pump.  But the things I've seen fail due to "Salt Gremlins" at Bonneville are innumerable, so for me - K.I.S.S. is my mantra:

Keep It Simple (because I'm) Stupid.

When I built The GloWorm, I had an old ZX6 fuel pump on the shelf.  Because the rear engine sat higher than the petcock, I had to use a pump.  I ran, and tested that sucker for weeks.  Then I decided to buy a brand new one as a back up.  That pump stopped working after 3 days.  I had purchased on Amazon, so the seller sent me another pump and I was allowed to keep the broken one.  After swapping to my original pump, I tore apart the broken pump, pushed some stuff, pulled some stuff and sprayed lubricant everywhere.  Slapped it back together and it ran!  When the 3rd pump showed up, I took IT all apart and did the same.  This is why I have THREE fuel pumps.

EVERYTHING to me is a potential problem when it comes to the remote-ness of The Salt Flats.  Everything that can go wrong, once your leave the Boat Ramp, will.

[freakhousecustoms]

Haha, I love the irony of you saying if Yamaha decreed a fuel pump was needed, then so be it, when you're building a bike with two engines. 

:-D

Thank you!  Believe me, the irony of many of my questions does not escape me.

The #1 reason I chose the FJ1200 platform - and the one that keeps on impressing me - is the simplicity of the design.  But at the same time, IMO, it's is the pinnacle of air/oil-cooled engines.  The absolute biggest BANG for the Buck you can find.   That said, I'm keeping as much as I can bone-stock within my custom frame.  Over the last few weeks, I've moved to a new train of thought:  Make the bike so that the next owner can roll into a Yamaha dealership and any mechanic, worth his Salt, will be able to work on it, after the initial shock wears off. 

(see what I did there?  With the Salt?) 

As I am working out the wiring, I'm pretty sure there are less wires in ONE FJ1200 harness than TWO GS1100E harnesses.  It is an absolute delight working with the FJ.  It's almost like Mama Yamaha knew mad scientists would stumble across the FJ decades after they were sold.

[freakhousecustoms]

And a big belt sander! Most useful fabrication tool in my shop. Don't have a mill or lathe.

I too love your, Can do, just do it approach.

Oh, I constantly wander over to the belt sander section at Harbor Freight.  The things I could do if I had one!!!
I'm trawling FB Marketplace and Craigslist daily for a mill or lathe... but I honestly don't know if I have the space to have either.

I have plans to do a video that focuses on how much I do with so little, to hopefully inspire more folks that they Can Do it, if they Just Do It!

[freakhousecustoms]

A follow on question then seems to be - will a single FJ pump flow enough for both engines at sustained WOT?  (My gut tells me it probably would - but I wouldn't want to try it without testing it first!)  That way - if one is enough, then you already have a spare!

I've got plenty of room to mount both.  If they are needed, and following my KISS mantra, just as easy to keep the motors on independent systems.  The only thing they will share is the same battery. 

Now, there's another approach in the works here.  Since I plan to ride this bike all over the Front Range and up and over a few Passes, Kenosha, Guanella, Loveland, etc., I don't need to be running both engines all the time.  So I am designing the shift linkage to work both transmissions, but also allow a disconnect to run one of them in Neutral so I can ride around town with one engine off.

You've heard of "Street/Strip"?  This is "Street/Salt". 

[freakhousecustoms]

More I think about this one, the more i think gravity feed is the way to go. 

You are putting together a custom fuel system so you can spec LARGE fuel taps and lines to the carbs.   When you send the carbs to Randy for rebuild you can let him know the plan for gravity feed and he can supply the proper seats.   

On the first version of the dragbike I ran a 1447 engine on oxygenated fuel (requires more volume than non- oxygenated) and ran a gravity setup to the Lectron carbs.   Never had any fuel supply problems.   I did install a large Pingel tap and ran larger lines than stock.

Exactly my thinking!  I'm making my own gas tank and - to be perfectly honest - I'm shocked at how small the fuel inlet is on the stock carbs.  I'll try to get a pic of the GS1100 Mikuni's vs the FJ's.  Seems like the bottle neck would be at the carbs themselves, but - taking that out of the equation, I can run a high flow petcock (or two).  Larger fuel lines to the carbs, all that jazz.  But, if we are talking stock to maybe mild engines, do I even need THAT much flow.

This is all awesome Sunday morning conversation for me.  Nothing is set in stone, and I have plenty of time to experiment with different approaches.  Keep the ideas comin'!!!

[freakhousecustoms]

The fuel pump system runs on a 6 or 7mm fuel line, which is what you have. It has a small orifice petcock, a smaller tank opening, smaller hose along with a filter and smaller needle & seats in the carbs. The internal flow of the carbs is also reduced at the fuel tee and single inlet on the fuel pump models. While you can bypass the fuel pump in an emergency to get you home, for your application of sustained wide open throttle, you'll require pressurized fuel supply.

And THAT is all the reason I need.  If a pressurized fuel supply is needed, then a pressurized fuel system will be used.
For now, (right now... plans can change like the CO weather ) I'll weld in mounts for the two fuel pumps.  The complete stock wiring harness will be used - even though I could definitely cut out half of it, as you said - because I love this whole "plug and play" thing I have going on right now.  I honestly haven't even tried to memorize the wiring colors yet, because THIS plug only plugs into THAT plug.  Oh!  Another side-project with this bike is to be able to yank all the wiring out separately for each engine, with the ability to run everything on the bench, off the bike.

Did I mention how much FUN it is learning a new platform? 
 

[freakhousecustoms]

Chris, think of the sustained WOT this has over the drag bike. The drag bike has probably 15 seconds max I would suspect. The land speed track is miles long, so it will be held at WOT for significantly longer duration of time.

I disagree, this application is going to require a fuel pump...or two.

While I've been doing the 1 mile run up, then covering the measured mile for the last 4 years, I think - in going for the Big Boy record - I'm going to need the 2 mile run up and then the measured mile to get up to 189mph.  UNLESS the Salt is like it was in 2017... man, that was a GLORIOUS year.  While I never like to take a pessimistic approach, I have to assume the Salt with be wet and slippery, so it's either going to be a full 3 miles or, if needed, there's the Big Boy course with a 5 mile run up.


The reason I'm in love with the FJ platform is the high horsepower in a simple package.  I have the utmost faith that the 2 motors, in stock form, are all the power I need.  I feel like it's going to come down to chassis tuning and the Rider... << me being the most unreliable factor LOL!  As referenced in a previous post, I've tried to eliminate as many variables as I can, which is why I don't simply run 2 Busa motors.  I don't want to add water-cooling - and all it's components - the list of potential failures. 

I do not mind running 2 fuel pumps.  And my 3 spare pumps are EASILY wired in place if needed and are a band-style clamp mount, so they could (dont' tell tech) be zip-tied into place.

Thank you both for your learned advice.  As I said in one of my first videos, the more I dig into the FJ's, the more I DIG this bike!!!

[Pat Conlon]

Invest in quality pumps....don't buy cheap Chinese pumps with a "lifetime warranty"....ask me how I know...

[freakhousecustoms]

Invest in quality pumps....don't buy cheap Chinese pumps with a "lifetime warranty"....ask me how I know...

Oh yes, sir!
True-er words were never spoken.

I have faith in these 2 OEM, 30+ year old pumps.
And my back ups are 1 OEM 2000 Kawasaki ZX6 pump and 2 of the same cheap Chinese pumps - completely disassembled, lubed and re-assembled.

[Pat Conlon]

FYI We have some fuel pump alternatives listed in our File Section.
http://www.fjowners.com/index.php?topic=3683.0
Specifically look at the Airtex pumps (from Napa) what the race cars use
With easy access to a manual petcock for fuel shut off, you have a wider selection of candidates.
One large pump or two smaller ones? That's the question..

[freakhousecustoms]

With easy access to a manual petcock for fuel shut off, you have a wider selection of candidates.
One large pump or two smaller ones? That's the question..

For this build it's going to be 2.
Scroll up (or back one page now?) for my reasons.

Oh yeah... and since I run Fuel class, there are rules with which I need to abide.

2. E. FUEL SHUTOFF AND ENGINE KILL SWITCH
Motorcycles shall be equipped with a positive ignition off switch to terminate engine power. The riders shall be able to use the switch without their hands leaving the handlebars.
Gasoline class motorcycles shall have a fuel shut-off located within easy reach of the rider. Fuel class motorcycles shall have a positive fuel shut-off activated without the riders hand leaving the handlebars.

But I'm old hat at working my build into that rule.

Basically, it's just a cable that's hooked to the petcock that pulls it OFF when I push a lever.