CV Carbs to TBI Plans and Hardware Kit

[FJ1100mjk]

Now how to stuff the fuel rail under the gas tank, and where does everything else go/fit?

"system will work on most types of CV carbureted motorcycles"

http://www.roadstercycle.com/CV%20to%20TBI%20plans.htm

http://www.roadstercycle.com/yamaha_vmax_fuel_injector_cv_car.htm

Costs more than my FJ is worth. I'll stick with the carbs!

[movenon]

Now how to stuff the fuel rail under the gas tank, and where does everything else go/fit?

"system will work on most types of CV carbureted motorcycles"

http://www.roadstercycle.com/CV%20to%20TBI%20plans.htm

http://www.roadstercycle.com/yamaha_vmax_fuel_injector_cv_car.htm

Costs more than my FJ is worth. I'll stick with the carbs!

Interesting information.  Yes there is more to the conversion that meets the eye.  BUT with new FJ carbs from Yamaha at 1000.00 which is/will drive the used parts and carbs up in price,  in the near future (as in now).  A conversion cost of 1000-1500 isn't all that bad.  And its my personal belief the cost will get lower for those that are handy.  

With the talent that is out there an FI/throttle body conversion for the FJ is inevitable.  In fact there will probably be more than one in the end.  Randy has been working on one for a year or more.  From just listening to what Randy had to say about the performance increase it sounds to me like another big plus.

IMO it is worth learning about and watching.  TNX for the links ! As always the FJ is evolving.

On the question where is everything going to fit... I guess the first step is get rid of that bloody air box. 
George

[FJ1100mjk]

No problem.

Stumbled upon it through someone listing the home website of the guy's business in a local Craigslist ad. Thought others here might find it interesting too.

I saw the earlier posts about RPM's efforts, but I thought Randy said it was basically a hobby project (my words not his), and it wouldn't make it to the buying public. Skunkworks no doubt.

[movenon]

No problem.

Stumbled upon it through someone listing the home website of the guy's business in a local Craigslist ad. Thought others here might find it interesting too.

I saw the earlier posts about RPM's efforts, but I thought Randy said it was basically a hobby project (my words not his), and it wouldn't make it to the buying public. Skunkworks no doubt.

Don't get me wrong please. I am no authority on it. Just another old fart in the garage.. I for one like all the information on the subject that I can get.  I am old but not to old to learn.  I think the information is cool (isn't that an old term) and to the benefit of all.  To me that's one of the benefits of the forum.  I am a fan of "open source" and expanding the knowledge base for those that are interested. 
George

[racerrad8]

I saw the earlier posts about RPM's efforts, but I thought Randy said it was basically a hobby project (my words not his), and it wouldn't make it to the buying public. Skunkworks no doubt.

That is the goal to be able to offer a pretty much plug & play RPM EFI system...

But, I am still quite a way from that goal at this time, but that is the goal.

That is a pretty interesting idea of what has been done, he definitely was thinking outside of the box.

Randy - RPM

[Pat Conlon]

Do I understand this right?

The injector sprays in front of the throttle plate? Won't the partially open plate disrupt the spray pattern?

How about when you're zinging along, in the 8,000 rpm kookaloo zone and you snap shut the throttle...now with the fuel spray on the other side of the (closed) throttle plate, won't this cause a lean condition?

[Country Joe]

Pat,
You have answered your question already. When you snap the throttle plates shut, you have just shut off all the air except for what is needed to idle. At the same time the throttle position sensor is telling the fuel computer to cut back fuel to only what is needed for a closed throttle setting. I did some messing around in the mid to late 90s with GM TBI on the truck engines. Very simple operation, a pain in the rear to get one tuned just right until Autotune came along. This is a pretty slick approach to fuel injection for CV carbed bikes.

[fj1289]

Looked at this setup a couple years ago.   Very clever idea and setup.   But I dont like the compromises it takes to execute - primarily the fact the injector sprays almost directly at a 45 degree "wedge" to redirect the flow from straight down - to down the intake tract.   Maybe it works fine with no discern able issues; maybe it creates distribution issues -- I don't really know, but know I don't like the idea.

Second - you are limited to the size carb you already have  - 36mm in our case (too small for a modified engine in my opinion).  Although the FJR TBs aren't really much bigger, they do at least place the butterflies up stream in the larger throats of the TBs so the smaller end of the TB (toward the cylinder head) is unobstructed and should flow more air.   

Also a 19 #/hr injector seems small - you'll start hitting an 85% duty cycle around 160 HP or so -- probably a bit too close for comfort with a 1349 with a little work done to it.

Being lean when the throttle is closed is no problem since the engine isn't at a high load - even if you're at 9,000+ RPM.   

And one thing to remember about a "plug-n-play" fuel injection system -- it means install it, set it up as directed (or as done by the tuner/shop), and go out and enjoy it.  BUT don't start fu€#ing around with settings you don't thoroughly understand ALL the ramifications of.  An ECU that allows the end user to alter settings opens up a whole new level and number of ways to make a great running bike into a temperamental, moody, poor running or even broken POS despite the best intentions.  Once again, not downing the idea - I think it is part of the future of keeping these bikes on the road, but I have had more than a couple headaches, WTFs, and self-inflicted "break downs" along the the way.

Funny thing is, I really am a carb guy at heart.  But after having my FCRs stolen, it was just too hard justifying that kind of money again - especially with the difficulty of finding them.  And I didn't care for the sticky slide action of the RS carbs I had used too.  Besides, a good challenge is hard to turn down.

Oh, and I should probably also make clear, the broken rod/hole in the crank case I suffered was in no way the result of the EFI system.  It was the result of me beating the ever living hell out of the bike on a nearly daily basis trying to think of ways to get the EFI to act up, hiccup, stumble, or in any way behave in a manner that would be unacceptable of a "plug-n-play" system.  It also probably didn't help that the engine came out of a stretched and lowered FJ with a strut and sidewinder pipe....

[JPaganel]

Do I understand this right?

The injector sprays in front of the throttle plate? Won't the partially open plate disrupt the spray pattern?

There is no problem with spraying fuel in front of the throttle plate. That's how Rochester TBI works, it was used by GM in millions of cars and trucks for about 15 years.



I wonder if a setup can be developed with a single TB and some rubber intake runners...

[Pat Conlon]

TBI's had provisions for a idle circuit...they were designed to address these issues.
This retrofit on the Mikuni CV's does not. The carb's idle circuit is non-op.

Call me skeptical.

[fj1289]

Few ways to deal with the idle.  You can either drill out the hole (or make one!) in the throttle plate to let enough air through for idle, or you can just turn up the throttle stop.  if the fuel is finely enough vaporized, it will find its way through also.  Then again, with appropriate EFI TBs, you are injecting down stream of the throttle plates anyway.  And that is in addition to a fast idle scheme (as used with the FJR TBs) or IACs (Idle Air Control valves). 

A lot of the super precise/complex/injector timing stuff really only matters if you are trying to meet ultar stringent emissions restrictions or strict fuel economy mins.  Most engines (especially FJs!) truely dont need, nor could you even discern the difference, with things like sequential injection or staged injectors.  IF they are well setup will at least match the performance of a WELL SETUP set of carbs (the vast majority are not -- not talking about just tweaking fuel circuits in the carbs but also the air circuits and acceleration circuits), and still have the ability to get better fuel mileage at cruise settings.

 

[Pat Conlon]

Ok, thanks for the explanation Chris

I do defer to your expertise!

  Saving my money for the RPM system, even if it's a year or two down the road.
I've had my bike for 30 years now, so waiting a couple of years more for a fuel injection system is doable.

Cheers

[Burns]

This thread exemplifies the "Zen in the Art of Motorcycles" tradition and is a modern example of a very old multi-national culture whose archetype is The Motorcyclist.

Love to buy you all a beer sometime.