GX35 Honda 35cc 4stroke
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Re: GX35 Honda 35cc 4stroke
With a duty cycle that low, injector timing/phasing would be expected to make some difference. At very high duties probably less so. However, if you are seeing no difference, don't worry about it.
James
James
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Re: GX35 Honda 35cc 4stroke
quote="jsmcortina"]With a duty cycle that low, injector timing/phasing would be expected to make some difference. At very high duties probably less so. However, if you are seeing no difference, don't worry about it.
James[/quote]
But i do worry
The goal we have is to maximise the efficiency of our small 50cc single cylinder engine.
So what i did is to make vary the injection timing and look at the AFR changes on our inertial bench.
Unfortunately, WITHOUT changing ANYTHING, the AFR curves change so much from one test to another that we get crazy.
If you look at the image below, it is the comparison of 2 consécutives runs on the inertial bench.
No changes were made to the setup from run a to b.
And for instance, at the cursor, AFR (a) is 15.7 and AFR (b) is 16.6
It's fooling us, as we do not know why the AFR is changing that much (... and lag factor is already 40 ...)
If you have an advise for us , it would be very welcome ! [
James[/quote]
But i do worry
The goal we have is to maximise the efficiency of our small 50cc single cylinder engine.
So what i did is to make vary the injection timing and look at the AFR changes on our inertial bench.
Unfortunately, WITHOUT changing ANYTHING, the AFR curves change so much from one test to another that we get crazy.
If you look at the image below, it is the comparison of 2 consécutives runs on the inertial bench.
No changes were made to the setup from run a to b.
And for instance, at the cursor, AFR (a) is 15.7 and AFR (b) is 16.6
It's fooling us, as we do not know why the AFR is changing that much (... and lag factor is already 40 ...)
If you have an advise for us , it would be very welcome ! [
Re: GX35 Honda 35cc 4stroke
Honda has a nice little injector from there 50cc scooter. Small body package with nice spary pattern. What fuel pump setup are you running? Is it all battery powered or are you spinning a small generator too? I've measured total system draw down around 5w at idle and up to 8w at wot. This includes pump, injector, and ignition system.
306 SBFord, Torquer II EFI intake, 60 lbs injectors, 8 LS2 coils, VS Racing 7668 turbo, 4R70W, MS3x fw1.4 w/built in trans controller.
Re: GX35 Honda 35cc 4stroke
We do use a small 50cc Yamaha injector.ol boy wrote:Honda has a nice little injector from there 50cc scooter. Small body package with nice spary pattern. What fuel pump setup are you running? Is it all battery powered or are you spinning a small generator too? I've measured total system draw down around 5w at idle and up to 8w at wot. This includes pump, injector, and ignition system.
We do not use a fuel pump: the pressure (4 bars) comes from an air pressurized tank, pressurized with a pneumatic regulator.
So i suppose that pressure is quite constant, and the system does not consume a lot of energy.
Re: GX35 Honda 35cc 4stroke
I ran a 150cc briggs and stratton engine with MS and a very similar setup.
I used a Yamaha C3 fuel injector and throttle body with an LC1.
I had problems with stable AFR also, which I ultimately attributed to low flow of exhaust gases and being a single cylinder the pulsations through the exhaust probably didn't help. The only time I got reasonable data was at WOT in the mid to upper RPM range.
I know this may not help much, just thought I would share my experiences.
-Branden
I used a Yamaha C3 fuel injector and throttle body with an LC1.
I had problems with stable AFR also, which I ultimately attributed to low flow of exhaust gases and being a single cylinder the pulsations through the exhaust probably didn't help. The only time I got reasonable data was at WOT in the mid to upper RPM range.
I know this may not help much, just thought I would share my experiences.
-Branden
97 Subaru Impreza 2.2L - MS3 w/ MS3/x
Re: GX35 Honda 35cc 4stroke
I was woumdering how well a wbo2 would work on a single. Here at the shop we sniff the exhaust gases and try to use a stock type muffler to reduce the effects of the pulsing at low speed/load. Sometimes the only thing to do is keep fattening it up until it starts pucking black smoke then lean it out until it acts like its deing then pick the middle of that range.
How are you controlling timing? What ignition box are you using?
How are you controlling timing? What ignition box are you using?
306 SBFord, Torquer II EFI intake, 60 lbs injectors, 8 LS2 coils, VS Racing 7668 turbo, 4R70W, MS3x fw1.4 w/built in trans controller.
Re: GX35 Honda 35cc 4stroke
Sorry, but i'm not sure to understand your question : do you mean what ignition coil we are using ? we are using the original coil from the engine.ol boy wrote:I was woumdering how well a wbo2 would work on a single. Here at the shop we sniff the exhaust gases and try to use a stock type muffler to reduce the effects of the pulsing at low speed/load. Sometimes the only thing to do is keep fattening it up until it starts pucking black smoke then lean it out until it acts like its deing then pick the middle of that range.
How are you controlling timing? What ignition box are you using?
Thank you,
Pierre
PS: So, do you experiment same AFR "jumps" when you bench test a single cylinder engine ?
Last edited by PierreL on Tue Aug 12, 2014 4:23 pm, edited 1 time in total.
Re: GX35 Honda 35cc 4stroke
Hi Branden,bubba2533 wrote:I ran a 150cc briggs and stratton engine with MS and a very similar setup.
I used a Yamaha C3 fuel injector and throttle body with an LC1.
I had problems with stable AFR also, which I ultimately attributed to low flow of exhaust gases and being a single cylinder the pulsations through the exhaust probably didn't help. The only time I got reasonable data was at WOT in the mid to upper RPM range.
I know this may not help much, just thought I would share my experiences.
-Branden
Thank you for your input.
Here below is a complete picture of an acceleration test on our inertial bench.
The first part (left of the cursor) is iddle (+- 1700 t/min).
At the right of the cursor is acceleratio at WOT. (we have a poor accel enrichment, this is why the AFR grows that much).
I take the liberty to show that image because our AFR seems more stable at idle (left) than at WOT (right)
Please do not hesitate to comment...
Pierre
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Re: GX35 Honda 35cc 4stroke
Trying to solve your problem by posting in someone else's success story thread is not a very good idea. Start your own thread and post your msq.
Jean
Jean
Re: GX35 Honda 35cc 4stroke
Yes Jean, you are right and i would like to apologize to Ryan if i did "poluate" his post.racingmini_mtl wrote:Trying to solve your problem by posting in someone else's success story thread is not a very good idea. Start your own thread and post your msq.
Jean
I did open a new thread "Unstable AFR" in Tuning Folder.
Pierre
Re: GX35 Honda 35cc 4stroke
Its all good. Any info on running a single if useful to the group no matter where its posted.
306 SBFord, Torquer II EFI intake, 60 lbs injectors, 8 LS2 coils, VS Racing 7668 turbo, 4R70W, MS3x fw1.4 w/built in trans controller.