Small engines?

[Kram]

I've been looking at small baby wood chippers. They generally use the gx200-gx460 clone engines but most are under powered. This sort of thing

Rotatech 7HP Petrol Wood Chipper 100mm Heavy Duty Garden Shredder Mulcher – Self-Feeding Chipper for Branches up to 4 Inches : Amazon.co.uk: Garden

Rotatech 7HP Petrol Wood Chipper 100mm Heavy Duty Garden Shredder Mulcher – Self-Feeding Chipper for Branches up to 4 Inches : Amazon.co.uk: Garden

www.amazon.co.uk

The bigger machines use V twin engines, but too heavy for my use. Weight is a bit of a problem as I will need to move it by myself, so I'm going for the 460cc I think, possinly the one I linked with an engine swap. There is a larger 15hp version, but that also has a larger, double weight drum unit, with expensive 250mm blades. I'm wanting the smaller, lighter 150mm blade version.

I know the engines are also used for gocarts and it seems they can replace nearly all the parts to get a higher revving, decently powerful engine.
Does anywhere sell that as a kit or as a complete engine?

I'm looking to near double the rpm from 3k to 6k, if possible. That might sound like a lot, but small motorcycle engines will run at that quite happily all day long, provided they are cooled adequately.

I'm aware the conrod and flywheels are weak and can let go, generally prevented by weak cam springs and valve float. Cam shaft no good at higher speeds..

 

[MattF]

I'm looking to near double the rpm from 3k to 6k, if possible.

Why?

The flywheel/cutter weight is far more important than the revs.

 

[MattF]

I have this chipper.

Crytec | CRC400-R Wood Chipper | 4 inch/100mm | Petrol | 7hp 212cc

Prepare to be amazed by the CRC400-R Petrol Wood Chipper, a revolutionary machine that combines cutting-edge design with advanced safety features, ensuring both performance and peace of mind during your wood chipping endeavour's. Unmatched Power and Efficiency: Equipped with a robust 7HP 4...

crytec-power.co.uk

Movable by one person, but the tow arm being straight makes it awkward to move easily. A cranked arm would make it far easier to move, single-handed. Altering that is on my list of projects.

Power wise, that's done a fair amount of chipping, & it's handled it all well.

 

[Erie Fred]

I would concerned (very much) about over revving the cutter more than the engine.

 

[Kram]

Why?

The flywheel/cutter weight is far more important than the revs.

They are lazy engines with very low output for the displacement. More power for the same weight.

@Erie Fred I would be swapping the pulley, 2:1 and same speed on the cutter.

 

[Kram]

I have this chipper.

Crytec | CRC400-R Wood Chipper | 4 inch/100mm | Petrol | 7hp 212cc

Prepare to be amazed by the CRC400-R Petrol Wood Chipper, a revolutionary machine that combines cutting-edge design with advanced safety features, ensuring both performance and peace of mind during your wood chipping endeavour's. Unmatched Power and Efficiency: Equipped with a robust 7HP 4...

crytec-power.co.uk

Movable by one person, but the tow arm being straight makes it awkward to move easily. A cranked arm would make it far easier to move, single-handed. Altering that is on my list of projects.

Power wise, that's done a fair amount of chipping, & it's handled it all well.

With engine, hopper, chute and wheels/frame off, I need to be able to lift the components in and out of car boot on my own.

I was also looking at the Crytec, useful to know. Does appear better in that the chute has a hinge where the other one just the hopper is hinged.

 

[MattF]

That's too big, then.

 

[Kram]

That's too big, then.

Its a 100kg machine (Rotatech), Engine 25kg and other bits about the same, leaving 50kg drum assembly. I should be able to lift that.

 

[MattF]

Not if you value your back. 50kg is liftable. Is it safely liftable single-handed; No.

 

[Turbo]

The genuine Honda gx series are safe up to 4000 rpm. They run out of puff after that without modification.

Briggs are max 3300 and pushing it at that, 3000 safer.

 

[roofman]

The genuine Honda gx series are safe up to 4000 rpm. They run out of puff after that without modification.

Briggs are max 3300 and pushing it at that, 3000 safer.

Gx 390 is a perfect choice

 

[frank horton]

I have a genny with a 8HP Honda clone eng....
it's starts easily but it hurt's my shoulder to much.....SO bought an electric starter kit from Temu 70 euros....
45 for a decent small car battery......
So nice to use now....
Sounds like ur asking to much if u need to rev that high...

all the chippers Ive used, even home made ones, the engines are at the middle range of revs...and worked well....
I found it's more important to have a machine with extra rollers to push the sticks into the blades...self eeding...

 

[oldbikedavey]

Might be worth working out a bhp/1000 rpm/litre figure for the various available engines, and seeing where that leads.
A flat twin two-stroke might be worth looking at, if such things can be found......
I know that Villiers made one for use on portable rail saws, but that's ancient history.....

 

[Agroshield]

...leaving 50kg drum assembly. I should be able to lift that.

If you are going to change the engine, it might be possible to make the drum assembly skid mounted so you do not have to lift, but drag up a ramp.

What vehicle is it? I think there are swing cranes for lifting wheelchairs into cars. One of those could help.

Mounting the new engine on a hinged plate would make it more quick-disconnect. Some kind of quick release belt tensioner would also help. It would also give you a place to locate lifting handles.

Rotatech's website has a picture of the belt drive side of the machine. Space for a pulley twice as big might be tight (wheel looks close). Reducing the belt ratio reduces the wrap on the drive pulley so belt slip might appear. Clearly you would need a new guard, but again, quick release will help.

Looking at the machine from the side, the carburetor looks close to the discharge chute so that might influence the size and position of any replacement motor.

 

[Kram]

Not if you value your back. 50kg is liftable. Is it safely liftable single-handed; No.

Luckily I have two hands. The job involves a lot of lifting from big logs to dragging brush all day. A strong core protects the back..

I cant find reviews of it... French brand of chinese import. It has the 420cc engine, same 150mm wide blade/drum but appears to have a much lighter built frame

Pardon our interruption...

Briggs are max 3300 and pushing it at that, 3000 safer.

Generic unbranded imports are better quality than the Briggs!

 

[knighty]

not easier to add a tow bar than to lift it in and out?

for small chipper with power.... get small chipper and fit bigger engine instead of revving engine up? - don't think the next step up of engine is that much heavier?

 

[MattF]

The job involves a lot of lifting from big logs to dragging brush all day. A strong core protects the back..

You're not the only one in a physically challenging job, you know.

A "strong core" means nothing. You could throw your back lifting a penny off the floor. Lifting 50kg unaided is foolish, especially when it's a dead lift.

 

[winchman]

I have used this place for engines

Petrol Engines - Westbank Wholesale

We offer petrol engines from 100cc all the way up to 1000cc - a model to suit every application. Replace your Honda GX, Loncin, Briggs 2.5hp - 37 horsepower

westbankwholesale.com

But also used Ebay for really cheap ones, once got a GX200 clone for £60!

 

[Erie Fred]

They are lazy engines with very low output for the displacement. More power for the same weight.

@Erie Fred I would be swapping the pulley, 2:1 and same speed on the cutter.

It doesn't matter how you double the speed, it's the fact that your over speeding a cutter head.
Research the increase in forces for a doubling of RPM......

 

[Cato]

All the points already covered, a GX390 is more than capable of munching decent sized material in standard trim. Most machines fitted with them will chew through 3 or 4 inch branches at a governed 3,000 (max 3,500).

The other thing to keep in mind is that if you double the engine RPM to 6,000 when (not if) something jams the cutter it'll likely be a catastrophic failure rather than just the shear pin. The shock load will be way above design and likely cause damage upstream, and when the pin shears all that force being released will happen too quickly for the governor to react.