GX35 Honda 35cc 4stroke

General talk about successes. See older information on MSRUNS forum.
jsmcortina
Site Admin
Posts: 39585
Joined: Mon May 03, 2004 1:34 am
Location: Birmingham, UK
Contact:

Re: GX35 Honda 35cc 4stroke

Post by 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
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
New users, please read the "Forum Help Page".
PierreL
Experienced MS/Extra'er
Posts: 250
Joined: Sun May 08, 2011 9:49 pm

Re: GX35 Honda 35cc 4stroke

Post by PierreL »

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 !
compare a & b.jpg
[
ol boy
Super MS/Extra'er
Posts: 1532
Joined: Mon Sep 10, 2007 3:06 am
Location: Tucson, Az

Re: GX35 Honda 35cc 4stroke

Post by ol boy »

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.
PierreL
Experienced MS/Extra'er
Posts: 250
Joined: Sun May 08, 2011 9:49 pm

Re: GX35 Honda 35cc 4stroke

Post by PierreL »

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 use a small 50cc Yamaha injector.
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.
bubba2533
Experienced MS/Extra'er
Posts: 342
Joined: Wed Jan 28, 2009 6:12 pm

Re: GX35 Honda 35cc 4stroke

Post by bubba2533 »

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
97 Subaru Impreza 2.2L - MS3 w/ MS3/x
ol boy
Super MS/Extra'er
Posts: 1532
Joined: Mon Sep 10, 2007 3:06 am
Location: Tucson, Az

Re: GX35 Honda 35cc 4stroke

Post by ol boy »

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?
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.
PierreL
Experienced MS/Extra'er
Posts: 250
Joined: Sun May 08, 2011 9:49 pm

Re: GX35 Honda 35cc 4stroke

Post by PierreL »

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?
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.
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.
PierreL
Experienced MS/Extra'er
Posts: 250
Joined: Sun May 08, 2011 9:49 pm

Re: GX35 Honda 35cc 4stroke

Post by PierreL »

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
Hi 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
exemple.jpg
racingmini_mtl
Super MS/Extra'er
Posts: 9128
Joined: Sun May 02, 2004 6:51 am
Location: Quebec, Canada
Contact:

Re: GX35 Honda 35cc 4stroke

Post by racingmini_mtl »

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
jbperf.com Main site . . . . . . . . . . . . . . . . . . . . . . jbperf.com Forum
Image
PierreL
Experienced MS/Extra'er
Posts: 250
Joined: Sun May 08, 2011 9:49 pm

Re: GX35 Honda 35cc 4stroke

Post by PierreL »

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
Yes Jean, you are right and i would like to apologize to Ryan if i did "poluate" his post.
I did open a new thread "Unstable AFR" in Tuning Folder.
Pierre
ol boy
Super MS/Extra'er
Posts: 1532
Joined: Mon Sep 10, 2007 3:06 am
Location: Tucson, Az

Re: GX35 Honda 35cc 4stroke

Post by ol boy »

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.
Post Reply