Tech question

[menace]

Ok i know this is probably a stupid question or whatever... BUT as im brand new to biking im just curious about somthing...

Do most motobikes run carbs or have I missread something?

If they do i dont get why? It seems pretty old technology and i dont know too many car tuners that still fiddle withcarbs, its mostly electronic injection and such. This makes it easier to map and even have a few diferent maps for different conditions/needs/wants. Its just plug and play...

Anyway im just curious... And probably wrong...

[pete376403]

More and more bikes are running injection, but usually rhe bigger, more expensive ones.
Carbs, although old technology, are pretty refined and they do work well. Factories build bike to sell and they don't really care too much about people who want to change them from stock, ie mess around with fuel maps and so on.
Consider also the economies of scale - cars sell by the 100's of thousands, if not millions. Also they sell for a lot more than bikes, so 1, they amortise the cost of developing expensive electronics over a lot more units and 2, as a percentage of the total cost of the vehicle, the injection cost is a smaller part.
FWIW, the first mass marketed injection system on a bike (GpZ1100) was based on a Nissan (Bluebird IIRC) system. U+It was pretty crude and tended to fry its electronics. The preferred fix was to replace it with carbs.

[Motu]

Most bikes have carbs,but fuel injection is making inroads on top of the line models.Like you say it's a bit of a puzzle - fuel injection is used for two reasons...emissions and costs - it is waaaaayyy cheaper to make fuel injection components,a carburettor is horendously comnplicated to make and difficult to spell correctly.It goes out of tune,wears out and needs adjustments.The odds are stacked completly against carbs - but they are still used....I guess the old technology is in place and working well,why change.

[riffer]

Yeah, its funny.

I can remember as a kid when my dad and I pulled apart and rebuilt the motor in mum's Herald 13/60 and he was trying to explain the difference in the motors between the car motor and the one in his GS550.

He was telling me how tehnology most often appeared in motor cycles first and told me how cars would one day commonly have things like electronic ignition and overhead camshafts.

Seems its almost like motorcycle technology is only advancing on the top-of-the-line models mostly now and its kind of stagnated on the cheaper models.

Still, as you said Pete, economies of scale and all that.

[Motu]

But all they have to do is transplant the car system to bikes - all the development work is done,Bosch controls everything about how it's done.The only hard part with multis is multiple throttle bodies and air flow meters,but that's been done on cars as well.You don't need special bike injectors,TPS,CTS,MAF,MAP whatever,all this stuff is cheap - it's the suppliers,I guess Mikuni says we'll supply job lot number x for $$,doing the same for an injection system would involve more components to source,price and supply - just comes down to costs.

[James Deuce]

One of the big factors in getting fuel injection to work on a bike is the fact that the "feel" of the throttle is vital. A slight off idle hesitation is no more than a possibly undetectable glitch in a 1.5 tonne car, where that hesitation could result in an accident for a 200kg bike. Triumph's (Hinckley - the new Triumph) first 600 had fuel injection and it suffered from inconsistent fuelling at part throttle settings, which is what most people use most of the time in real life.

The expensive late model bikes get a lot of R&D these days, but it is trickling down product ranges for the Japanese manufacturers.

[Motu]

From what I've seen (and hey,I could be very wrong) bike systems are basicly incomplete - not closed loop and usualy missing idle control because of multiple throttle bodies,in a single induction impulses play havoc with airflow meters.If you try and control idle speed with spark advance and injector pulses only - poor low speed and off idle control problems are almost gauranteed.The top end of the market and they cut corners because it's ''too hard'' duh.

[menace]

Ok guys thanx for that. It clears out a few things... Im not saying carbs are a bad thing because there are a lot of cars that still run them (think ported rotaries... ) But for variety and ease of tuning EFI is soooo much easier... IMO... Granted the intial cost might be steep but once it comes to modifing i dont know...

[Motu]

Well,electronic engine control will keep the engine in tune for a hell of a long time compared to points and a carb,but if you want to modify then the carb is an easier option.Money no object,then a tuneable engine manement is the way to go.I was down at Possums a few years ago and they had a WRX on the 4x4 dyno they were tuning with the so called Possum Link - fuel and ign could be altered all the way,performance gains without touching anything else were huge - but you could buy another car for the cost of that sort of set up.

[menace]

Well,electronic engine control will keep the engine in tune for a hell of a long time compared to points and a carb,but if you want to modify then the carb is an easier option.Money no object,then a tuneable engine manement is the way to go.I was down at Possums a few years ago and they had a WRX on the 4x4 dyno they were tuning with the so called Possum Link - fuel and ign could be altered all the way,performance gains without touching anything else were huge - but you could buy another car for the cost of that sort of set up.

Tehehe no offence but the the link system are not the greatest. IF i was going to dish out money for a CPU it would probably be a motec ok so they cost around 3 grand BUT the thing is you can use the comp again and again... (as in plug them into your new toy after your finished with one... )

Now motec is prety much top of the line... But if ur after something as almost as good you get haltech and get someone who can tune them and ur set to go go GO>..

[dangerous]

I have had injected bikes for over 8yrs (CX500 Turbo 1982 and a Moto Guzzi 1100 sport 1997) and think that its the best thing since sliced bread. The CX was fultless started from cold and always ideled at the push of the button were as thw Guzzi being Itiallian was a bitch when cold and often stalled when hot and had a slower responce but this is still faster than a carb to respond.
I recently brought a 03 VTR storm and it fells so slow to respond in comparision and you have to do the bloody warm up thing with the choke etc. Give me a ECU and injecters anyday

ps: I rechiped the Guzzi so easy and it ment more power and better mapping.and to ulter the mixture (which I never had to do) you plug in a diognostic puter and diled up +3% rich and un plug

[menace]

Ok can someone explain why carbs would be more "responsice" than an equalent injector setup? :spudwhat:

[dangerous]

Ok can someone explain why carbs would be more "responsice" than an equalent injector setup? :spudwhat:

"responsive" would that be?..... Well they'r not. A carb can prodcce more power that an inj however they are not as economical or set up as well.

eg: a carb can not adjust mixtures by its self when it comes to altitude, air temp were as a inj will so inj is suited in all terains were as carbs can only be set up for one type of condition. make any sence?

Inj is almost instent were carbs have mechanical parts which take time to open which means a lag between 'action and responce'

[Aleph]

I do not know the answer but is it anything to do with the fact that on a bike everything is going to get wet and temperature variations will be much greater than in cars.

[pete376403]

Injection can be "too" responsive. Some of the early setups are more like an on/off switch. When you have a high power/lightweight vehicle (ie a 600 or better sports bike) this can make riding round town very jerky. With a carb, when the butterfly opens the air speed change is almost instant, but the heavier fuel takes a little time to get going (hence accelerator pumps and so on) but the power increase becomes a little more controllable.
Could this be why the new setups use two butterflies, one before and one after the injector?