[roatavator]

Thanks Charlie

[roatavator]

Probably 10am, usually is. Best to go in the morning. I don’t think they charge for spectators but most people make a donation, it’s run in aid of charity.

[roatavator]

Should be there in the playpen!

[roatavator]

I may have invented the knob for the extra shot of fuel. I think I’m confusing the Hirth with the Hatz. Old age I guess.

[roatavator]

I had a Howard 700 with Hirth which I sold recently. Compression was relatively low, but with the following procedure started fine.
1. Remove fuse holder and crank over engine a dozen or so times.
2. Put a small squirt of engine oil (SAE20) in cylinder.
3. Set full throttle and pull knob on side of engine which provides a shot of fuel.
4. Replace fuse holder and crank over smartly (compression should be at bottom of the swing, I turned the crank over slowly to handle at 12 o’clock position then swung down past 6 o’clock as fast as I could).

Using this method it would normally start first or second crank over. The squirt of oil increased compression enough to fire up even in cold weather. And I never had to use a fuse with it.

I believe spares are difficult to obtain.

[roatavator]

Ivan, I’ve sent you a pm connected to this thread.
Peter

[roatavator]

After lots of adjusting and modifications we’re finally there apart from reducing idle speed.

[roatavator]

Thanks Angus
But it’s not hunting, has a smooth tick over to my ears. The issue is inability to increase revs by use of the throttle.

[roatavator]

Could be Andy but I’ve tried increasing the governor spring tension (you can change the position it’s secured to the air cleaner housing) but then can’t get enough push from the cable. I figure if the spring pushing on the end of cable were stronger it would then be possible to adjust the governor spring to suit. I’m guessing with the too weak cable spring friction is coming into play.

[roatavator]

Finally here’s the view ins the barrel, the end of the throttle cable is visible. Behind the circular washer is a second spring. I reckon it’s this spring which provides the thrust on to the rod and this has weakened so there’s insufficient force to move the governor lever.

Attachments:

1. 

[roatavator]

And here’s the barrel with the rod poking out with the big spring behind

Attachments:

1. 

[roatavator]

This may explain better. Here I’ve removed the barrel which screws into the green collar I’ve indicated. At the other end of the collar you can see the end of the governor lever the rod acts on.

Attachments:

1. 

[roatavator]

Oh yes Andy. It revs fine if you move the governor lever. It’s just that the thrust from the rod onto the governor lever is insufficient.

[roatavator]

So here’s the set-up. The first photo shows the cable entering the barrel. The second photo shows where the barrel is in relation to the governor.
On reflection I think that the thrust on the rod at the other end of the barrel is provided not so much by thrust from the cable, but by the spring located between the cable end of the barrel and the plate in contact with the rod. If that’s the case it would imply that the problem is basically that the spring has weakened. Does this sound reasonable?

Attachments:

1. 
2. 

[roatavator]

Yes Geoff. I’ve been fiddling with it today and come to the same conclusion. Effectively the throttle cable has to push against the governor lever to achieve running speed, when you close the throttle for idle the spring on the governor closes the butterfly.
The throttle cable enters one end of a barrel which is secured to the machine. Inside the barrel is a spring pushing on a small cylindrical plate, the plate pushes on another spring which acts on a rod in contact with the governor lever. It’s clear someone has had a fiddle with it in the past. I’ve managed to get the bits inside the barrel to move freely but I can’t even with many adjustments of the spring tensions get enough thrust on the rod to open the butterfly. Or at least I can but then there’s insufficient tension in the governor spring to return the butterfly to idle when you close the throttle. I’m getting a bit stumped. I’ll try and post some photos once I’ve reduced them.

[Author]

Posts