What are the main factors of stopping me from bolting the throttle body and assorted electrics from say a 2010 crf onto a cr 125? obvioulsy fuel maps will have to be drematically changed and all sensors moved over. The throttle body may need to be made a bit smaller. Can you run pre mix through the fuel pump and injector? Will it lubricate properly?
Obviously im only scratching the top of a fairly indepth topic and if it were just a case of bolting on a throttle body then im sure manufactures would have done it some time ago
Fuel injected 2 stroke Not DI ?
Started by
Tom579
, Apr 13 2012 07:45 PM
27 replies to this topic
Posted 14 April 2012 - 02:40 PM
Yeah you can providing you can also mount the fuel pump, sensors and have a suitable power supply. The main issue with two strokes is tuning the fuel maps to run well given the broad range of cyl/pipe temps that they run at... It's hard to get them to run well everywhere... But certainly not not impossible. You can run premix through the pump/injector and it will lube everything fine.
Posted 02 December 2012 - 11:08 AM
Fuel injecting a two stroke isn't black magic....take a look at snowmobiles....
Posted 02 December 2012 - 11:46 AM
You can do it.
Somewhere I read about a nut that put mechanical fuel injection on a yz250. As in hillborne. I thought that was some bad azz sheet.
He said it worked better than the carb.
Now run some methanol through there ..... With a Verry high comp piston and head.
Will make 450s look limp wristed. Lol.
Somewhere I read about a nut that put mechanical fuel injection on a yz250. As in hillborne. I thought that was some bad azz sheet.
He said it worked better than the carb.
Now run some methanol through there ..... With a Verry high comp piston and head.
Will make 450s look limp wristed. Lol.
Posted 02 December 2012 - 07:07 PM
I'm surprised it isn't offered already. It works great and actually I think it needs to be offered to the public before DI. There is so much fanfare about DI but in terms of power it really shows no advantages and has several drawbacks in terms of size, requirements and usefull operating RPM at this stage of development.
There are no problems with pumping premix through a FI system.
Fi can be set up to run WAY better that carbs, across all temps pipe or otherwise. Heck you could even add another 0-5v sensor to compensate for chamber temp.
If people actually bought two-strokes, they already would be advanced FI systems on them. I just bought a new two-stroke, but you probably didn't. Consumers are driving FI technology.
There are no problems with pumping premix through a FI system.
Fi can be set up to run WAY better that carbs, across all temps pipe or otherwise. Heck you could even add another 0-5v sensor to compensate for chamber temp.
If people actually bought two-strokes, they already would be advanced FI systems on them. I just bought a new two-stroke, but you probably didn't. Consumers are driving FI technology.
Posted 03 December 2012 - 06:49 PM
Snowmobiles and 2T outbords use DI, and there a re a lot of aftermarket EFI units for 2T snowmobiles, just check out some snowmobile forums or shops for the latest and very expensive mods.
Posted 04 December 2012 - 08:34 PM
r_jackson, on 02 December 2012 - 07:12 PM, said:
It's been done and it looks awesome!
Neat.
How about the ossa?
http://twostrokemoto...ture-of-enduro/
Posted 23 December 2012 - 08:05 PM
One major problem with using speed density (SD) on a 2T is that they don't generate much of a manifold pressure (MAP) signal. What that means is that the MAP at idle or part throttle is not much lower than it is at WOT and that makes tuning difficult. Aftermarket standalone systems usually have features to help with this like alpha-n (a-n) fueling (based on throttle position only) or a blend of SD and a-n where MAP is ignored when the signal is worst and the system switches back to SD where the signal is cleaner. Some systems can also sample MAP at a specific point in the crank rotation not just to work around an erratic signal, but also to keep track of each engine cycle.
I don't know how much of the CRF's code can be tweaked in order to run a 2T and do it well. In my own research on the topic of adapting OEM systems to applications they weren't designed for, I concluded that it was necessary to have a lot of internal control over what the ECU does and how. I also concluded that "universal" aftermarket standalones make the whole thing a lot easier.
I thought that was a member here on TT, actually.
1.) I think the primary industry motivation for using DI was probably to clean up emissions, not necessarily to increase output at the same time. Manufacturers peddle it to the public by touting thebenefits new features no matter how overstated or inconsequential they may be.
2.) I agree.
I don't know how much of the CRF's code can be tweaked in order to run a 2T and do it well. In my own research on the topic of adapting OEM systems to applications they weren't designed for, I concluded that it was necessary to have a lot of internal control over what the ECU does and how. I also concluded that "universal" aftermarket standalones make the whole thing a lot easier.
englertracing, on 02 December 2012 - 11:46 AM, said:
You can do it.
Somewhere I read about a nut that put mechanical fuel injection on a yz250. As in hillborne. I thought that was some bad azz sheet.
He said it worked better than the carb.
Somewhere I read about a nut that put mechanical fuel injection on a yz250. As in hillborne. I thought that was some bad azz sheet.
He said it worked better than the carb.
I thought that was a member here on TT, actually.
36MotoMarc, on 02 December 2012 - 07:07 PM, said:
1.) There is so much fanfare about DI but in terms of power it really shows no advantages and has several drawbacks in terms of size, requirements and usefull operating RPM at this stage of development.
2.) Fi can be set up to run WAY better that carbs, across all temps pipe or otherwise. Heck you could even add another 0-5v sensor to compensate for chamber temp.
2.) Fi can be set up to run WAY better that carbs, across all temps pipe or otherwise. Heck you could even add another 0-5v sensor to compensate for chamber temp.
1.) I think the primary industry motivation for using DI was probably to clean up emissions, not necessarily to increase output at the same time. Manufacturers peddle it to the public by touting the
2.) I agree.
Posted 24 December 2012 - 01:51 PM
on the way,
...ktm and yam rumours
they developing it
...but another shop know of
FI'd a kart 125, and got
57 hp, sensors not aligned,
and jetting way off.
...will keep posting as development,
and results come in, but this company
has found bullet proof parts, and tech
from around the world, ... and are
projecting 60 to 70 hp from a 125
...call bs now, if ya dont believe it,
...but all the results will be posted,
positive, and more importantly,
negative.
...got nothin to prove, but the end
result ...and somebody that can
hang on to it !!!
...ktm and yam rumours
they developing it
...but another shop know of
FI'd a kart 125, and got
57 hp, sensors not aligned,
and jetting way off.
...will keep posting as development,
and results come in, but this company
has found bullet proof parts, and tech
from around the world, ... and are
projecting 60 to 70 hp from a 125
...call bs now, if ya dont believe it,
...but all the results will be posted,
positive, and more importantly,
negative.
...got nothin to prove, but the end
result ...and somebody that can
hang on to it !!!
Posted 24 December 2012 - 02:10 PM
You could convert a 2t to fuel injected if you wanted to, I ride with two people who have converted their bikes. The fuel injected bikes run alot more efficient. You can also change the performance dramatically. One guy I know has his injector firing twice per power stroke.
Posted 24 December 2012 - 02:40 PM
yamaha7442, on 24 December 2012 - 01:51 PM, said:
on the way,
...ktm and yam rumours
they developing it
...but another shop know of
FI'd a kart 125, and got
57 hp, sensors not aligned,
and jetting way off.
...will keep posting as development,
and results come in, but this company
has found bullet proof parts, and tech
from around the world, ... and are
projecting 60 to 70 hp from a 125
...call bs now, if ya dont believe it,
...but all the results will be posted,
positive, and more importantly,
negative.
...got nothin to prove, but the end
result ...and somebody that can
hang on to it !!!
...ktm and yam rumours
they developing it
...but another shop know of
FI'd a kart 125, and got
57 hp, sensors not aligned,
and jetting way off.
...will keep posting as development,
and results come in, but this company
has found bullet proof parts, and tech
from around the world, ... and are
projecting 60 to 70 hp from a 125
...call bs now, if ya dont believe it,
...but all the results will be posted,
positive, and more importantly,
negative.
...got nothin to prove, but the end
result ...and somebody that can
hang on to it !!!
I don't doubt the high numbers, its the reliability that I always doubt.....
Posted 25 December 2012 - 12:40 AM
There's a company in Italy that builds
very high quality con rods, ...have'nt seen
one fail yet, running 50 to 56 hp @
16,000 rpm on methanol, on a 150cc
High rpm injectors are probably the
hardest part of injecting a 2 stroke
Heard a rumour years ago, that Aprilia
developed a fuel injection system
for their 125, 250cc GP bikes,
probably using Magneti Marelli
system's, ...but the power was too
violent for the riders to handle /
would light up the tire too easy
coming out of corners.
Those 125's are supposed to have
about 58hp, ...and the 250's
( twin 125 cylinders ) were said to
have about 108 rwhp, with carbs.
very high quality con rods, ...have'nt seen
one fail yet, running 50 to 56 hp @
16,000 rpm on methanol, on a 150cc
High rpm injectors are probably the
hardest part of injecting a 2 stroke
Heard a rumour years ago, that Aprilia
developed a fuel injection system
for their 125, 250cc GP bikes,
probably using Magneti Marelli
system's, ...but the power was too
violent for the riders to handle /
would light up the tire too easy
coming out of corners.
Those 125's are supposed to have
about 58hp, ...and the 250's
( twin 125 cylinders ) were said to
have about 108 rwhp, with carbs.
Edited by yamaha7442, 25 December 2012 - 12:41 AM.
Posted 26 December 2012 - 12:17 PM
yamaha7442, on 25 December 2012 - 12:40 AM, said:
High rpm injectors are probably the
hardest part of injecting a 2 stroke
hardest part of injecting a 2 stroke
Perhaps with DI, but not so much with more conventional injector placement. The issue is getting enough fuel injected in the time between cycles and at an acceptable duty cycle. Injectors that do that at peak power often have poor low-load manners because the commanded pulsewidth drops into the injector's lower nonlinear range. There are simple ways around this using common automotive injectors, such as staged injection and overlapping injection events between multiple injectors.
Posted 26 December 2012 - 05:44 PM
<a href=
Just trying to organize how to post photos?
This is an EFI twostroke. Crank case injectors, runs on ethanol / petrol, E90.
Uses a Link computer and a Ignitec Ignition. Goes quite well.
Just trying to organize how to post photos?
This is an EFI twostroke. Crank case injectors, runs on ethanol / petrol, E90.
Uses a Link computer and a Ignitec Ignition. Goes quite well.
