OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Honda Engines Honda GXV160 power increase ?

Hi all,
is there a way to increase the output of this engine (apart from raising the speed).
I would like just a little bit more power to tackle steep hills head on.
Just wondering as I really don't want to go to a bigger engine on my tracked mower.

Hi Gambler, I can't help you but I have one and it just revs and drops constantly on the governor, is this correct? Not sure if you can bypass the governor to increase the revs

Hi NormK,

I am trying to avoid having to go above manufactures spec with the engine speed.
Knowing my luck it wouldn't last long or worst , throw a rod!
There are several suggestions on the web regarding the increase of hp but I was hoping that someone would have a simple and prooven solution.
I really don't want to change the engine.

NEVERRRRRRRRRR bypass a governor or recommend it !!!!!!!!!!!!!!!!!!!!

Hello Gambler and contributors

That would be a gamble. I concur with vccomm.
ODK cannot recommend any bypass of the governor, but I do not
believe Norm was actually recommending that.

Too many times have I see broken conrods, but without oil starvation.
The reason - over-revving.

Best advice for more horsepower: a bigger motor; sharper blades

---------------------
Jack

My answer was a question more than an answer, with the governor on these should the engine revs constantly rise and fall with the motor just running?

Gambler, just how short on power is this motor, it should have plenty to play with, all that motor is doing is driving the car alternator and the blades, the ground drive is by electric motors

There are plenty of people racing these Chonda 6HP in go karts. There are step by step how to's on the net to take you through giving them more grunt including replacing cams, changing valves etc. One of the first things is, take it apart and throw away the governor and use a manual throttle. Of course you have to limit the RPM but according to the race boys if you do the work using performance parts you can easily rev the little suckers out to 6000 RPM or more.

Trev, with the little Greenfield Stallion I just put the 6hp Chonda motor on, I just got a text message from the bloke I sold it to saying he was rapt with it, personally I had my fingers crossed and took a gamble. Usually most things I gamble with turn around and bite me.

Hi Norm,
it's hard to guess how much more power I need.
This engine was a donor from my next door neighbour (Jims Mowing franchise).
It starts first time everytime and does not blow smoke. I am unsure of how many hours this engine has done but guess being commercially used it would be heaps.It might just be too tired to make enough power.
You are correct in saying it only drives the alternator and blades however , the alternator then makes power for the drive motors and our property is very steep.

Might have to look at a larger capacity engine to suit my application.

Hi Gambler, what speed are you running the alternator at? They produce very little power at low RPM so perhaps dropping the pulley size down on the engine or putting an intermediate pulley set to up the alternator revs will give you the extra voltage you need.

Apart from the power shortage how is the little beastie going, it is a work of art.The little 6hp Chonda motor I fitted on the Greenfield is driving,cutting and carrying the rider and seems to do that ok. I'm not sure how much power the alternator would pull from the motor. Are you starting with a fully charged battery? Does it seem to slow down as the battery power drops and the alternator has to start working harder?

Aussietrev,

I am running a pulley ratio of 2 to 1 with Alternator speed around 7200 rpm.


Norm,

Its going great!
there was room for improvement on the tracks and i am currently trialing a new track system using motocross tires which hopefully will be a lot more maintenance friendly then the
previous setup. I am also trialing a floating deck and new height adjuster ( an old gas strut from an office chair).

The batteries are always fully charged before each start by design.
The travel speed is constant but the engine tends to bog down on steep hill-climbs, that's when i back off the travel speed until the engine revs come back up.

Maybe it has a governor problem or as mentioned before is just too old and tired.

What a beautiful machine, the best of Aussie ingenuity, well done. So obviously the alternator is working very hard because the drive motors are really sucking the power and this is loading the Honda right up. How thick is the grass you are cutting?

Hi Norm,
2 weeks worth of growth in Qld does add up to a generous height of grass however, even just driving it up the the slope with the deck raised to its highest point will cause it to struggle.

I think in future I will start on the top of our property and work my way down side to side rather then up and down.

Well at least all the hard development work is done and worst comes to worst you can bolt a 13hp motor on it. You can get those for $400 + post from Pinacle Engineering in Ballarat

Another option might be to fit one of the 6 hp Chonda motors for the cutting and use the Honda just to run the alternator. Would take a bit of work to setup but the 6 hp Chondas are very light so would not add a lot of weight to it. The 6 hp motors are $160 +postage Another alternative would be to fit a horizontal shaft motor to run the alternator, probably easier to mount that a horizontal shaft.
http://www.ebay.com.au/itm/6-5hp-MOTOR-4-STROKE-STATIONARY-ENGINE-HORIZONTAL-SHAFT-WATER-PUMP-GENERATOR-5-5-/250906055739?hash=item3a6b2a943b:m:mqs-haCcuOsKJcG-hB1NGkg

Another thought is a bigger battery so it has power in reserve for climbing the hill and hopefully it would be able to build up some charge when going down the hill because it is not working so hard.
I think you could probably slow the alternator down, I'm not sure but I think they would reach max volts output at probably 3000 rpm

Ok the more I think about it I think it needs a bigger battery and possibly a second alternator. These would need a second motor to run them and leave the existing motor just for cutting

Looks good with the motocross knobblies on it. Here's the question, what power are the motors? The equivalence is 5HP 4 stroke = 1HP DC Electric. So, depending on what size the drive motors are, you probably do need more power than even a new 5.5 can deliver.

In case you don't have horsepower specs for the motors, 1HP is around 746 watts. At 13.8 volts, typical alternator output volts, that would be about 54 amps current drain.

Good info there Trev, they look to be a pretty big motor. Looks like it might need to go to a 13hp motor and probably run 2 alternators. The 13 will handle that no problems

I think I will go for a larger capacity battery when the budget allows it and give that a go.

Hi Trev,
the current output of the dc motor controller is limited to 25 amps per motor.
that would make it 690 Watts or .925 Hp at maximum load.
You might be onto something here , I will put an ammeter into the battery and alternator circuit on the weekend (weather permitting ) to capture actual currents and volts under load.

Hi Gambler,
Two things I would try, Firstly, go to 12N24 ride on batteries, they will have much more reserve current capability to get up steep slopes and may be enough to compensate for the power drain under load. If it still struggles, replace the wheelchair motors with windscreen wiper motors. Very early motorised wheelchairs used them before purpose built motors became available. They have a worm drive reduction gear built in so could probably be used as direct drive to the tracks. The worm drives also have a natural brake ability when powered off and could provide a bit of added safety on those slopes.

Gambler, I'm also wondering how much drag is being put on the wheels with the motorcross tyres stretched like that. Did you cut the beads off the tyres? Are you able to turn the tracks with the drive motor disconnected. Could try the battery out of your car, just to see if we are on the right track. Amazing machine and so close to victory

Hi Trev,

I used the wheelchair motors over wiper motors for their durability and shaft size.
these motors are a lot more robust and were designed for heavy going.
after another short run today I noticed that the travel speed is not really slowing whilst climbing.
As mentioned earlier I will attempt to take some current measurements on the weekend and hopefully get to the bottom of this.

Hi Norm,
the side walls have been cut off the motocross tires to gdt them to flex over the drive wheels. There is quite a bit of tension on the system however, it moves freely and I can easily turn it by hand.

I think i will install a fully charged automotive battery on the weekend , disconnect the drive belt to the alternator and head for the slope to find out whats going on. This should separate the good from the bad

Well who would have guessed that 'less' can be more

Performed a load check on the system and found that all power was being supplied by the alternator and almost no current from the batteries.
No wonder the old Honda couldn't keep up on the slopes.

I have removed the alternator (temporarily) and fitted a car battery which i will give a good run tomorrow to see how it goes.

If the battery is strong enough to drive up the slope i might install a remotely operated relay to turn off the alternator circuit before i hit the slopes head on. That way there won't be any load from the alternator on the engine(apart from the free wheeling of course).
Once i have reached the top of the hill i can re-energize the alternator and then keep going.

I've been quietly watching your thread and tip my hat to you. Looks like a bucket of fun. Have you considered using a clutched pulley to drive the alternator like what is used to drive a cars air con? I reckon it'd be a simple way to remotely activate the alternator.

Hi slashnburn,

I had considered a clutch setup for the blades similar to a ride on in the early stages of this build but didn't go through with it due to the costs.
As I would need a relay to operate the clutch it might as well operate the alternator circuit electrically.
I just have to be careful not to switch the relay under load.

Hi Gambler, you may find with the bigger capacity battery the alternator probably won't have to work as hard,it should only have to top the battery up, you will be soon able to see if this is the case. You are nearly there, should be able to go into production soon, I see a market for these.