Rotivator
Turbo Mini Forums

Hi guys i thought some of you maybe interested in this and also maybe able to help.

An old chap up the road from me is a collector of vintage mowing equipment and has given up on this rotivator. I think its of early 1900's era and from australia. It has a few markings on it but google finds nothing.
The story goes that he rescued it from a barn about 10 years ago and it was in there for +40 years. Its been totally stripped, rebored and rebuilt. Its a right fecker to crank over though. Need to be built like a brick shit house to turn it, and im not im 8st pissed wet though. I actually thought that was the reason it wasnt starting (not cranking quick enough). So i removed the head, Made it easier but still difficult to turn. Then removed the block from the "transmission". Everything felt fairly easy to turn though so i bolted everything back together.
Im convinced the cam timing is right but im unsure of the ignition timing. Ive set it somewhere around 15 degrees BTDC. Ive got a feeling this should be 15 degrees ATDC. Ive got it to pop back twice and it nearly took my fecking arm off.
It has a decompression lever but when this is pulled there is no vaccum on the carb, so wont draw any fuel. It operates the exhaust valve and i think is only used to stop the engine.

My next stop is to play with the ignition timing a little more and eat plenty of spuds and meat to get more energy.


Matt.

Not a huge help as you may know this but a couple of things, firstly im sure someones shown you how to hold the handle when turning, put all your fingers and thumb on the front side of the handle-dont grip with your thumb at the rear as is the natural way because if it kicks back you can break a thumb.

Tbh I have only really ever played with crank start diesels which also have a decomp on the exhaust, but idea is you operate the decomp to be able to get it turning and get the flywheel some mometum then drop the lifter and hey presto it starts from that.

Although this is petrol I would suggest it has decomp for the same reason-ie starting, because I was told by someone in the know as you should never stop and engine by dropping the decomp it can cause damage, if its a diesel the rack on the pump has a stop position/petrol you cut ignition by shorting the spark plug.

A lot of the vintage petrol motors we used to mess with were reliant on the carb flooding for easy starting, does it have a tickler or owt on the carb?

On 5th Oct, 2014 Shauna said:
What that's crazy, you go commando hahaha! How heavy is your helmet ?

It has a plunger type thing. Press it a few times and it floods the carb. Its not often i play with a crank handle, suppose its just practice.

Ive heard it can help if someone else opperates the decomp while the other cranks.
As for stopping the machine, the only thing i can see is a fuel tap.
Theirs no choke on the carb, just a throttle spindle.
Im convinced that the ignition timings out though. Makes it harder having NO marks what soever on anything.

On my old moped I had as a youth you had to pull in the decompression lever, run down the garden, and then jump on whilst releasing the lever to get it to start.
From what oli was saying is sounds like you may need to decompress, crank it over and then release?

Hmm that moped story makes me sound older than benross....

Well that all sounds right, its a magneto on this which I havent ever really played with so yeah it certainly sounds like ignition timing but you would be best doing some research on the magneto imo.

To stop the engine all you need to do is short the top of the spark plug to the body of the machine, they are nearly always missing but usually there is a spring steel finger bolted to the head-the end of which hovers 1/4 inch of so above the plug and you just shove it down to stop, but you can use anything screwdriver, hammer owt with an insulated handle, I have a cement mixer with an old briggs engine on it, usually stop it with a dirty trowel and wet hands and fail to get it on the head first- resulting in 50000 volts going up my arm!

I had a mate in Sheffield who is big into this I will see if he has any tips, when we used to fook about with some of the larger motors he had like petrol tractors there was no need/real possiblity to spin the thing-you just turned in over to just before the compression stroke and then one great big heave to flick it over 1/4 of a turn and off they went-usually!

Diesels were the opposite you had to wind them up get them spinning like a mad man, drop the lifters and pull the handle off sharpish!

On 5th Oct, 2014 Shauna said:
What that's crazy, you go commando hahaha! How heavy is your helmet ?

get a feckin big turbo on it and some nitrous

give em hell

If there is no choke or other enrichment device you do need to flood the engine using the "tickler" on the float chamber (Old British motorcycle terminology)

You may need to do this more than once.

Have you tried choking it with something blocking the atmospheric side of the carb ? Once its running you may need to do this to keep it going until it warms a little.

Lastly, have you seen if your efforts so far have drawn fuel in anyway - is the plug wet with fuel ?

Thanks for the replys and help :)

I havnt been able to work on it tonight but ill deffinatly be back in the garage tomorrow. Ive only cranked diesels and this is when like oli says, spin the thing over and flick the lever.
Petrols by the sounds of it just need a quick flick on the compression stroke.
I got it to pop when i firstly put my hand over the carb without decomping it to test for a vac. It drew nicly and there was s puddle of fuel on my hand. I cranked it again and it popped and kicked back like a bugger. Which led me to the timing being out.
I dont think turbos were invented when this thing was made. Theirs no exhaust on it at the moment so if i do get it running its gonna be LOUD.

Ill keep you informed.

Matt.

I would say looking at it and from experience if you get it started and into some soil that will only be the start of your troubles, I wouldnt fancy trying to hold onto it, and I weigh nearly double what you do! Looking at it the magneto is fairly simple, should have a set of points, you may have done this but you havent mentioned how you timed it, wind it to the top of the compression stroke and see if they are closing around there somewhere ?

On 5th Oct, 2014 Shauna said:
What that's crazy, you go commando hahaha! How heavy is your helmet ?

I have timed it up by dropping a welding rod through the access hole in the head and finding TDC. Then moved the magneto to the point it sparks and locked it up. Probably not the right way to do it but i dont know how else to do it.

yes your catching me up Nick, .....lol

i love this sort of thing, if you want to see more of them in thier hundreds, also a giant! carboot full of parts....... go to llandudno north wales transpot festival the first saturday in may, mayday weekend its on sat, sun & monday its on a 72 acre field and its packed all over the bank holiday weekend,

also includes in the town the Victorial Extravaganza with over 1000.000 excentric people attend from all over europe & the uk........ of coarse i make one for this its my annual piss up ......lol

Edited by BENROSS on 8th Feb, 2013.