Fuel Injection Discussion, 2T And 4T

[feetupfun]

A couple of old saying that spring to mind regarding carbs vs EFI

1) If it ain't broke don't fix it

2) Fools rush in where wise men fear to tread

Honda have done a very good job of miniaturising EFI and getting rid of the wiring harness, but these small EFI units are not integrated with the ignition ECU to the same extent as car systems. It effectively became compulsory to fit a Lambda sensor and use closed loop fuelling on cars from 1993. 2T EFI is not yet closed loop, ie. it is already at least 11 years out of date, and when riders of 4RTs dispense with the Lambda sensor they pretty well retard the fuelling to a pre 1993 situation.

Honda have vast experience of EFI and sell the systems in very large numbers meaning development and tooling costs can be spread thinly. European manufacturers of much lower production volume and less developed 2T EFI systems are likely to face significant difficulties and high unit costs.

Honda have some of the highest manufacturing quality standards in the world and for their off road bike supply decent manuals. Compare this with the usual output from the Europeans.

Long term back up may also be an issue. EOBD (which trials bikes don't even have yet) is not as universally compatible as it should be. I know of at least one series of vehicles where a scanner is not available and the manufacturer never sold the diagnostics kit, they just leased it (quite expensive) to franchised dealers. Once the volume of those vehicles being brought to franchised dealers for servicing / repair dropped the dealers no longer bothered to lease the diagnostics.

Unless there is some sort of rigidly enforced OBD protocol for bikes soon there are likely to be numerous serviceability issues in future.

Read the text below the video, the link may not take you to this, 3 injectors at $500 each?

A quote I came across "Old technology.? You are not paying attention. New 2 strokes are super quiet, super efficient, no smoke, and I get 2 nm per gallon. My old yami 2 strokes were great motors and lasted nearly twenty seasons, but the technology in the new etecs can't be denied"

What use would closed loop control be on a trials bike anyway? Fine on a car or on a road bike, but on a trials bike, the motor would never be at a single condition long enough for it to go into closed loop mode

[dadof2]

#48

I have looked through the handbook regarding the Kokusan Denki system and the Kscan Kwrite pro stuff and it is similar to OBD II but looks nothing like as comprehensive.

What is the cost of the leads and kit and how hard were they to get hold of?

Initially (I have not checked recently) they were not readily available in UK.

[dadof2]

#49

Montesa (Honda) must think closed loop is some benefit, otherwise why fit it?

Depending on sensor type closed loop can respond pretty fast (0.5 to 0.2 of a second) and correctly on 4T, certainly is will detect any general drift in fuelling towards say a rich condition as caused by a clogging air filter and correct it. I have a Lambda output monitor in an LPG car and it responds pretty well instantaneously and that is with a basic 3 wire zirconia sensor.

Incidentally I suspect the high RPM misfiring on open class 4T MXers may be due to air filter clogging that is not corrected for due to lack of Lambda sensing

"The exhaust gas oxygen sensor (EGO or O2), or lambda sensor, is the key sensor in the engine fuel control " This quote is from leading diagnostics supplier.

I can envisage 2T close loop being more problematical because of the residual fuel and oil in the crankcase. As RPM and flow through the crankcase increase this stored oil and fuel will be blown into the combustion chamber and when burnt will cause the Lambda sensor to show a very rich fuelling condition when in fact the present fuel ratio will be near correct from the preprogrammed map. Some pretty cunning software will be needed to get round this.

[jkmr1]

K Scan software is very basic. Simple diagnostics and set up functions. K Write pro enables map upgrades. Cost was $500 sourced through the Australian importer. (spent more than that on getting the Keihin sorted on the JTG). I believe that generic leads are available now at a much lower cost.

[copemech]

I know a bit about FI, and carbs. I am also a basic K.I.S.S. type. In trials application I find no need for the added complexity of FI. A good carb just works, and in my mind the Dellorto is the best $15 carb on the planet. Prolly won more events than anything when you add it up.

Seems to me Ossa has done a lot of development to make things work in the 2T trials, although it has been a project of great proportion, reports are good on the running and many love them. I have not ridden one, but the vids look and sound right.

Question here in the Ossa, mapping options to taste? In the Monts, yes there are or were, not sure now.

I did a bit of test riding on the Monts a while back. They like to idle fast and such. Just to see how well the motor would chug along and recover, I clicked up to 4th or 5th and was rolling along at a decent clip. When the thing flamed out, it about threw me over the bars. It ain't no Bultaco!

In the 4T range, the CV carbs as used on the Beta seems to work well. The 250 is a really smooth and progressive bike. No need for FI here. Add those carbs can be tweaked a bit. Although I admit I have sometimes not had good luck at recovering an old rotton neglected and contaminated CV carb to work well.

All point being, if I could run, program, map, and diagnose a simple FI system on a trials bile that worked well, and on a simple laptof set that did not require a mass purchase of junk to do it, I may be more inclined to buy into a system that worked well. Till then, I will stick to the $15 option! Will work until I do not!

[nigel dabster]

#36 I see you are picking holes again rather than making a positive contribution.

My experience of Ossa is not limited to just one bike, I just quoted this example because I knew it from new and regularly rode with and discussed it with the owner and knew some of its history after he disposed of it. I know of several other Ossaa that have had starting and running problems and mechanical reliability issues. I have also seen John Crinson win (although he fived my not too hard section) on one, but his success has not been sufficient to outweigh the perception of unreliability that has been created by other Ossas failures. The owner of the bike I gave as an example described it as a "heap of shyte". A bit harsh perhaps but it sums up his experience and frustration at the amount of down time the bike suffered.

Evidence of distrust of EFI. If I posted this my posts would be a mile longer than they are. I know of plenty of people who distrust EFI and are well fed up with the repair bills they get from it, these mistrusting people range from farmers, to car owners and motorcyclists. Try convincing a tractor owner who has just had to fork out £2500 for new injectors or a car owner that £550 for a single injector is reasonable and you will soon experience dislike and distrust of EFI.

http://www.pistonheads.com/gassing/topic.asp?h=0&t=625641&i=0

I made a comment if it doesnt agree with yours it may or may not be regarded as positive, you cannot and should not start a topic and want everyone to agree with you or question the validity of what you state, whether you THINK it is fact or not? My main point and I repeat it in case you didnt read my original comment and as you have said many times about others reading your comments, out of all the things that would put me off an ossa the fi is the last thing.

Your posts are too long and not realated enough to trials.

[baldilocks]

I think we can probably work out when dodof is on nights though

[dadof2]

ND I do not mind anyone disagreeing with me or having a different point of view but at times you make statements that are just not true such as saying I do not own a Gasgas or accuse me of not knowing anything about them when you have no means of knowing whether I do or not. The FACT is I own 2 GGs and have worked on or helped diagnose problems on several more recently.

If someone does have a different point of view I ask that they put forward a reasoned argument, not just say I am wrong.

I and anyone else is fully entitled to post what they like on this forum no matter how tenuous its link to the topic. It is up to the site owner and moderators to manage the site as they wish, not have unofficial self appointed "moderators" say what should or should not be posted.

Am I really on nights?

[dadof2]

http://www.trialscentral.com/forums/topic/53920-carb-leaking-fuel/

"Think of this! When you land off a large rock the weight of the floats push quite rapidly down inside the float bowl. This is known as gravity. The extended movement of the floats downwards tends to do two things. It moves the floats way down inside the float bowl allowing more gas than needed and it also causes some of the excess gas to be pushed up into the jets and into the engine"

The text quoted is taken from #9 of the link above it. Do the floats actually do this, anyone any thoughts?

[copemech]

http://www.trialscentral.com/forums/topic/53920-carb-leaking-fuel/

"Think of this! When you land off a large rock the weight of the floats push quite rapidly down inside the float bowl. This is known as gravity. The extended movement of the floats downwards tends to do two things. It moves the floats way down inside the float bowl allowing more gas than needed and it also causes some of the excess gas to be pushed up into the jets and into the engine"

The text quoted is taken from #9 of the link above it. Do the floats actually do this, anyone any thoughts?

Floats have no weight! That is why they float! Whomever has written this is a blithering idiot!

I shall jump out of my truck holding a helium balloon just to demonstrate. You see what happened, nothing! The mass of the balloon, even though accelerated rapidly with a downward motion does not have enough mass to gain momentum through the air enough to disrupt its stability.

And if you believe I am jumping out the truck to prove it, you too are an idiot!

[copemech]

Do not think an O2 sensor will work in a 2T due to oil contamination, nor would a mass airflow sensor.

All the same, good fueling may be done using basic inputs and proper mapping for the motor as in the Montesa. Throttle position, manifold pressure,temp,baro, rpm are all that is required with a given fuel pressure. Closed loop does nothing for performance. Maintaining stoich is not ideal!

They work, but on a Mont with no battery you gotta keep things spinning fast enough to keep the capacitor charged for electrical power or they flame out because of no battery!

[b40rt]

Floats have no weight! That is why they float! Whomever has written this is a blithering idiot!

I shall jump out of my truck holding a helium balloon just to demonstrate. You see what happened, nothing! The mass of the balloon, even though accelerated rapidly with a downward motion does not have enough mass to gain momentum through the air enough to disrupt its stability.

And if you believe I am jumping out the truck to prove it, you too are an idiot!

Dellorto floats have their weight printed on them.

Ships float, they weightless to ?

Edited December 26, 2014 by b40rt

[tomch]

Have both an ossa and a montesa. No problems with the montesa at all... i drowned the Ossa in the Ssdt and had it remapped when all was in bits.

No problems with either of the fi systems after i learned to always have a spare plug handy for the ossa. I have abused the ossa viciously leading to a broken dogbone..

The nice thing is clean running bikes with no dribbles at all, absolutely no "rainbow water" in mountain streams and no stinky petrol fumes when stuck halfway up a rift valley cliff.

For a beginner such as myself i think it is great not having to adjust anything whether riding at 15ft asl (fort william car park to 8600ft asl (Molo, rift valley)...

[jon v8]

Do not think an O2 sensor will work in a 2T due to oil contamination, nor would a mass airflow sensor.

All the same, good fueling may be done using basic inputs and proper mapping for the motor as in the Montesa. Throttle position, manifold pressure,temp,baro, rpm are all that is required with a given fuel pressure. Closed loop does nothing for performance. Maintaining stoich is not ideal!

They work, but on a Mont with no battery you gotta keep things spinning fast enough to keep the capacitor charged for electrical power or they flame out because of no battery!

Maybe closed loop is a bit OTT for a trials bike,but you are wrong about it doing nothing for performance.It need have nothing to do with maintaining Stoich either,wideband sensors could be a great help with valve problems mentioned earlier.Being able to accurately hold mixture at 12.5/1, air / fuel for max power without the risk of lean mixtures along with a knock sensor could make the motor last a lot longer.

[dadof2]

Regarding the floats, Copemech has confirmed my thoughts. This is the way I pictured it, suppose you ride the bike off a 1 m high boulder, initially it accelerated downwards at 1 g and floats and fuel are effectively weightless, then for last 160mm it decelerates at about 6g, Therefore floats and fuel effectively weigh about 6 times as much as normal. Normally the floats have a (a bit loose on the exact physics / terminology here) density about 1/3 that of fuel.

Take fuel as 7 gms / cm3 and float as 2 gms / cm3, multiply this by 6g and the fuel is now 42 gms / cm3 and the floats 12 gms / cm3. The ratio of float density to fuel density remains the same so it could be expected that the fuel level / float displacement remains constant during the drop off and land manoeuvre. Be interesting to see exactly what happens if anyone had a centrifuge, a clear float bowl, floats and a high speed camera.

On the subject of 4RT cut out at low RPM. Does anyone know at what revs this happens and for sure if this is due to lack of electrical power to ignition or EFI. I wondered if valve overlap could be a factor. When valve overlap is sufficient to give a wide spread of and decent top end power it often results in rough idle or cutting out at low RPM.