FJ2400 - Bonneville Land Speed Racer

[freakhousecustoms]

...you can create the same (enough anyway) amount of slack you get by disconnecting the cables at the twist grip as you suggest, by just holding or jamming the butterflies wide open.
Didn't someone here post a number of times over the years, with photos, a quick and simple technique for this? It made it so easy. 

Yes!
This is exactly how I do it on all my bikes.
Usually the first thing I toss is my airbox tho... so I think that skews my vote, since the carbs just pop off with nothing behind them.

[freakhousecustoms]

I've never lost any bits and find it a really useful gadget.

See, should have changed my last name to "Murphy" decades ago.
IF it can be lost, I'll lose it.
Always at the WORST possible time.



I will say that - now that you all have educated me on it's intended use, it IS definitely a useful bit to have.

BUT - I still stand by the belief that your use is secondary.  Mama Yamaha definitely designed it for me... and now it's going to be a staple of my future double-engine builds!
Better stock up now, cuz when the "Dual Engine" craze catches on, that's going to be a hard part to come by!

[fj1289]

Cool build - lots of attention to detail.   I appreciate it, but still prefer form following function - like a functioning rear suspension.  Unless the salt is perfect, he'll be leaving a lot of speed on the table.   Or in a drag race scenario - unless it has a big wrinkle wall slick and bars, he's going to be very limited with how much power he can hook up on launch and even down track...

Looks like he runs SCTA - does he also run Bub/BMST?  Also looks like he runs the gas class vice fuel.  

Another thought - you ought to take the fairing with you - if all goes well in the A class - you can follow it up in the APS class!  

I typed this this morning - but must have missed when I hit "Post"  

[fj1289]

Pat - I never realized the ThunderAce had RSD forks - always assumed they were USD.   Gotta think finding anything for those bikes in the states is like finding hen's teeth in a pile of rocking horse poo ...

I know the front wheels are hard to find - they are the only rim with the R1 style brake rotors for use on R1 forks but still uses the mechanical speed drive for a swap to an older Yamaha. 

[freakhousecustoms]

Another thought - you ought to take the fairing with you - if all goes well in the A class - you can follow it up in the APS class!  

APS-AG-208.45-Campos, D-Harley-Davidson-1974
APS-AF-231.597-Campos, D-Harley-Davidson-1974

  Yeah, the APS records are way faster that I want to go 
I've seen what it takes to go 200mph on the Salt and, at this moment, it's not something within my budget... or my skills.


That said, the fairing IS coming with me, for photos & driving around West Wendover.  It's just not legal in the class I want to race in.
If - by some astronomical chance - I manage to get the A-AF record, I would then consider going for the A-AG record.

[Pat Conlon]

Pat - I never realized the ThunderAce had RSD forks - always assumed they were USD.   Gotta think finding anything for those bikes in the states is like finding hen's teeth in a pile of rocking horse poo ...

UK FleaBay is where you look....

[freakhousecustoms]

UK FleaBay is where you look....

Ha!  Shipping prices from Canada is usually a deal breaker for me!

(is there a "skinflint" emoji?) LOL!

[freakhousecustoms]

I was happy with how she rode on one engine, so I tossed the 2nd motor in.
Still cruising on just the rear engine (need to build the outboard bearing support/engine coupler), but she's a well balanced and smooth ride.
I was even able to make a u-turn and come back down the hill with very little fanfare.



Click pic for video:



"Look Jack!  I'm FLYING!!!!" 

[freakhousecustoms]

Engines coupled!
Now PLEASE note that this is just a mock-up.  I need to schedule time to get on a lathe and build the individual pieces square and true, but for now, I just needed to see WHAT I needed to make and figure out how I'll be making the needed parts for myself.

That said - Video #1 is rear-engine, driving the drivetrain.  Front-engine in neutral.

Click pic for video:

[freakhousecustoms]

Video #2:

Front-engine driving the drivetrain.
Rear-engine in Neutral.

If you watch this video, you'll see why I won't be trying to get both engines to sling the chain at the same time.

[freakhousecustoms]

Okie Dokie.
Here it is folks - my "How-It-Works" video where I (attempt to) explain the easiest way to build a dual-engine motorcycle.

Anyone with a level, a welder and a grinder can do it.  It really is as easy as it looks. 
You don't need CAD or lasers... a plumb bob might help... but honestly, there's nothing special about it.  Or me.



Click pic for video:

[fj1289]

Cool!

Will the final design incorporate an adjustable roller or slider pad mid run to take up slack?  Or do you tweak one or both engine angles to achieve the same?

[freakhousecustoms]

Whoops!  I still have a piece to figure out how to install.  My plan is to use a primary chain tensioner from a Harley, because that's what I just happened to have sitting on my shelf.  Don't ask me why I even have this part, as I've never even owned a Harley, but it's a nice piece that fits the bill.  Please note that what you're looking at are 630 chain and sprockets - again what I had laying about - the real engine coupler will use 530 chain and sprockets.



Once it's all said and done, I'll have a slot cut into the back plate where the tensioner can slide up and down to remove the slack - and I want to build a chain guide that the top of the chain will glide on simply to stop the chain from whipping up and down as well.

[RPM - Robert]

Pat, you do realise you can create the same (enough anyway) amount of slack you get by disconnecting the cables at the twist grip as you suggest, by just holding or jamming the butterflies wide open.
Didn't someone here post a number of times over the years, with photos, a quick and simple technique for this? It made it so easy.  

Rest the carbs on top of the motor roughly above where they will be fitted, wedge the throttles wide open and fit the cables with the now available slack, fit carbies to motor, job done.
Your method makes hard work of it, I'm sure Randy does it the way described above, ask him.

Noel

Noel is right on that. We hold them open. The only thing I would add is, if you are going to put something in there to hold them open make sure it is the plastic end of the screw driver or something similar. Don't ask me how but I have seen more than a few sets that had the butterflies damaged by something. Whether they were dropped or whatever the case may have been. Always better to be safe then sorry.

[Pat Conlon]

Pat, you do realise you can create the same (enough anyway) amount of slack you get by disconnecting the cables at the twist grip as you suggest, by just holding or jamming the butterflies wide open.
Didn't someone here post a number of times over the years, with photos, a quick and simple technique for this? It made it so easy.  

Rest the carbs on top of the motor roughly above where they will be fitted, wedge the throttles wide open and fit the cables with the now available slack, fit carbies to motor, job done.
Your method makes hard work of it, I'm sure Randy does it the way described above, ask him.

Noel

Noel is right on that. We hold them open. The only thing I would add is, if you are going to put something in there to hold them open make sure it is the plastic end of the screw driver or something similar. Don't ask me how but I have seen more than a few sets that had the butterflies damaged by something. Whether they were dropped or whatever the case may have been. Always better to be safe then sorry.

Yes, I've done it that way a few times...using a soft wood dowel to hold the throttle plate open....then futzing with the cable barrels on the linkage...I didn't like it. The bowls are full of fuel, turning the rack upside down. I too worried about bending the throttle plates.
For me, it's easier to just disconnect the cables at the throttle...
I use this time to lubricate the cables, clean and dry lube the throttle tube.
Regardless....
I think we all agree that carb removal with the splitter box is the easier softer way.....(don't we?)