Fuel Injection Discussion, 2T And 4T

[johnnyboxer]

FI is the future

I'd always opt for it, given the choice...........not only does it run better, but in general fuel consumption is less too

Carbs are old hat, with too many variables

[jrsunt]

Yes bike is standard other than the stickers. I have to say they are very economic, it'll do nearly 30miles of road work on 2.1l of fuel on soft tires being ridden like a k..b. I bet on road tires and road gearing it would be blo8dy great fun

[trialsrfun]

A few questions on EFI please now we have a place to ask them,

Are EFI units readily available or do they need to be made by the bike company.

What type of pump is used to pressurise the system.

Is there an atomizing injector which presumably on a two stroke would spray into the inlet tract.

Is a reed valve needed or fitted.

Hope the above provides answers not arguments???

[guys]

The throttle body on my 4RT is made by Keihan but the whole system was mainly developed by Honda in first instance for small engined motorcycles.

Most small engines have atomizing injectors for fast and complete combustion. One can barely see the holes in the injector of a 4RT.

Reed valves are necessary to prevent air blow back / maximum filling of the cylinder , just like a carburetor bike.

My previous 2008 4RT never mist a beat, I did mount the aluminium tank bottom to save some weight and prevent rust in the tank bottom.

Edited December 22, 2014 by guys

[0007]

In my opinion FI is a stop gap for 2 strokes, albeit a long one, face it, it's really just an electronic carb, it's not futuristic and it's definitely not high tech in 2014

If you want to see what today's 2 stroke tech is like look at Ski Doo and Evinrude outboards, I presume that neither of these are very popular in the UK so perhaps many are not familiar

Etec is outstanding, never is there fuel in the bottom end to dilute 2 stroke oils, no puddling and no contamination of bottom end and oil with whatever properties today's fuels have (Sulphur)

It has been in production in snowmobiles since I think 08 and today the give us

The best fuel economy

The best engine durability, up to 4 years warranty

The best 2 stroke oil consumption

The most power in a production 2 stroke @ 164 hp in an 800 twin, that's over 200hp per Litre

It does not require a battery

And we practically never see them fail

Nothing has a harder life than a snowmobile used in the mountains, trust me, if you haven't lived this life then you will have to take my word for it

D.I. Is the best thing to happen to 2 strokes since oil injection

Edited December 22, 2014 by 0007

[guys]

I know that some of you don't like the comparison to cars, and it's for a good reason, believe I know, but it's useful because cars had to comply much sooner on emission levels and such.

I saw what a carburetor looks like when they try to make it as "clean" as fuel injection and I can tell you it doesn't even come close to resemble the simple carbs that are on trials bikes. I think it had more vacuüm hoses and electric cables on it than my euh... vacuüm cleaner for instance.

And for those who like a bit more history and knowledge about Honda's "small engine" FI system:

http://world.honda.com/motorcycle-technology/pgm-fi/p4.html

Edited December 22, 2014 by guys

[ross brown]

In my opinion FI is a stop gap for 2 strokes, albeit a long one, face it, it's really just an electronic carb, it's not futuristic and it's definitely not high tech in 2014

The best fuel economy

The best engine durability, up to 4 years warranty

The best 2 stroke oil consumption

The most power in a production 2 stroke @ 164 hp in an 800 twin, that's over 200hp per Litre

It does not require a battery

D.I. Is the best thing to happen to 2 strokes since oil injection

Then I wonder why we don't see them around on bikes.

I recall Honda had a Dakar race prototype direct injection 2T of about 350cc a few years back. Is itemissions that remains the issue? Are a boat and a snow mobile are not subject to same strict air quality output.

[guys]

I'm pretty sure that motorsport commissions and manufacturers had a part in keeping stricter emission rules away from the sport, and so "saved" the carburetor from certain death and with it the two stroke, at least in Europe.

It's no coincidence that Honda, Beta, Sherco and even GasGas for a while, came out with a four stroke at around the same time there was talk about stricter emission norms. And I think cost was the main argument.

[0007]

Then I wonder why we don't see them around on bikes.

I recall Honda had a Dakar race prototype direct injection 2T of about 350cc a few years back. Is itemissions that remains the issue? Are a boat and a snow mobile are not subject to same strict air quality output.

Having worked for a major MC,SM, ATV, OB, etc manufacturer For over a decade I can tell you the answer to almost every question you will ever ask is "Money", the second most popular answer is patent infringement by the way

Aside from that Japanese manufacturers focus on making existing inexpensive products cheaper and better, unfortunately they are NOT creative inventors like the rest of the world, so a company like Honda which as far as I know owns Kei Hin will happily sell their EFI systems to all comers

In this case Bombardier chose to commit long term to the difficult answer to a difficult questions (Emissions), other manufacturers chose the easy answer which is 4 stroke

All manufacturers are subject to EPA but the ridiculous thing is a clean company like (insert brand) can sell their carbon credits to anyone they want so they can make dirty bikes

And don't forget Bombardier is a huge company and can amortize developement costs over a lot more units than a small manufacturer can

And yes marine and snowmobile are subject to EPA regulation (even weed whackers and chain saws) and marine is very very strict

[dadof2]

The Evinrude and Ski Doo direct injection engines are far from a new concept. This type fuelling was initially developed by the Germans in the 1930s, Used in the 1950s on lorries (with diesel as the fuel) and very nearly put into cars by Jaguar / orbital in the 1990s. A brief check suggests these DI engines are several thousand dollars more than their carburettored equivalents. Snowmobiles and watercraft may be driven hard but do they have to cope with abrasive dusts, etc that are found on trials. I do not know the cost nor reliability of the DI on snowmobiles but a typical GDI for a car costs 3 to 4 times as much as a Dellorto PHBL and lasts nowhere near as long.

Regarding carb vs FI, 4t and 2T are quite different. On 2T a carb can give very satisfactory performance over the rev range encountered on typical trials engine. Achieving this on a 4T is much more difficult, fit a big bore carb for high revs and the bike will run crap at idle and just above particularly if the throttle is opened sharply. As I think Guys mentioned (and I did with regard to a Suzuki jeep) attempts to make carbs work well on 4T have resulted in twin chokes, injector pumps, compensation devises and pipes all over the place, way different from a simple Dellorto PBHL.

The reed valve on a 2T gives a degree of variable valve timing (VVT) To achieve this on 4T needs a lot of complexity and is not practically achievable within the size, weight and cost constraints of a trials bike, that is possibly why the 4RT has a high tickover.

EFI clearly has advantages over Carbs regarding emissions,performance and to a lesser extent consumption. But against this EFI has much higher initial cost and complexity. To make EFI work well it needs a MAF sensor. This is fine on cars were there is plenty of room and electrical power. As far as I know neither the 4RT, Ossa or Vertigo has a MAF sensor, relying instead on more compact but less effective pressure sensing. The more you compromise EFI to make it fit a trials bike and reduce costs the less any potential advantage over a carb.

007 states "DI is the best thing to happen to 2T since oil injection" Well look what happened to oil injection, nearly everybody blanked it off and used premix. Will people do the same with EFI, pull it off and replace with a carb?

Honda (Montesa) have a good reputation for quality and reliability but if their EFI parts go wrong they are expensive. Historically, electronics of European manufacture have been much less reliable than those made in Japan.

[baldilocks]

Yes dadof2 but to repeat an earlier question how many people who have owned a 4rt or ossa have had to replace a component of the fi system? This isnt a question for you unless you have owned one of these bikes

[guys]

. As far as I know neither the 4RT, Ossa or Vertigo has a MAF sensor, relying instead on more compact but less effective pressure sensing. The more you compromise EFI to make it fit a trials bike and reduce costs the less any potential advantage over a carb.

The road legal version, as it's delivered in Europe at least, has an Lambda sensor and thus a regulated catalytic converter, isn't that enough?

Of course almost everybody bins both items, along with all the restrictions , the moment they unpack the bike, because it will be used in "race" version.

Just like no one uses the unregulated catalytic converter that comes with a GasGas.

You still haven't convinced me of a technical reason for not converting to FI, two or four stroke other than costs and/or the lack of legislation.

[0007]

Without quoting Dadof2

It's really a generational thing with modern fuel systems, it's progress and some don't accept it well and I bet they ride twin shock bikes anyway, it's like evolution, there are no more dinosaurs or Dodo birds, they didn't make it

No normal person I can imagine would purposely remove EFI to put a carb on a bike to "improve it" anymore than he would pull EFI off his vehicle and install a carb, this would be a guy who has no computer, no cel phone, no internet or cable TV, probably heats his house with firewood

He doesn't get evolution and he never will

The same conversation could be and probably was had about points and CDI but now there are mechanics who don't even know what points are, I have met them and I have not looked but I don't think there is a points conversion kit for anything, if there was it would be on the Internet and the guy who wants it would not be able to find it

I can only think of 2 major brands that have done DI on a 2 stroke, one is BRP, anyone name the other without the help of Google ? and I'm not talking about small low volume exotic race bikes

[guys]

Hear hear.

I've got both, a 2015 4RT and a 1975 Sherpa, and if I had even more money and even less sence (if that's possible) I'd probably also be the owner of a nice heavy pré 65 plonker.

There used to be a saying on this side of the canal among motorcyclists in the early 80's: I own a BMW because I like to ride, and a triumph because I like to tinker

[sniffy]

Just to throw a spanner in the works, or should that be a bit of grit in the carb. The sporting trials car boys have been running their previously petrol engined cars on gas for several years now, this uses a regulator in place of the carb/s and it has a real advantage when going up, down and across steep sections since there are no floats to worry about, there are no issues of flooding or sticking floats. If you think it may never get to bikes take a look at some of the new outboard engines coming to market that run on gas (the small ones even run on camping gas style canisters that you just screw in place). Did anyone think we would ever see electric kids trials bikes or even E1 motor racing, the world moves on?

Check this out. http://www.lehruk.com/

Edited December 22, 2014 by sniffy