Jump to content

Log in or register to remove this advert

The “Other” 261 Cylinder


Heavy Oil Saw
 Share

Recommended Posts

Log in or register to remove this advert

18 minutes ago, Heavy Oil Saw said:

2937866d06b111cc8f4ae5f28735b2f9.jpg
Is that any better? My opinion is she’s not got any life left in her. Need better lighting in the garage, in the kitchen it’s clear as day the Nikasil is ruined and a chip missing between the transfers.

Ok . Your call . I cant really tell about the coating . I can see what looks like some light scoring but .... if you can see worse ....

Link to comment
Share on other sites

That isn't good, looks like either a ring has failed, a foreign body has entered the carb or the big end has failed which is the most likely. When the big end cage cracks and breaks up, it flicks bits of white metal through the engine causing this sort of damage.

That damage has bruised those ports, the lower "Transfer" is in fact the strato clean air port, the two top ones are transfers.

Personally I would scrap this one, the previous one looked much sweeter.

  • Like 3
Link to comment
Share on other sites

That isn't good, looks like either a ring has failed, a foreign body has entered the carb or the big end has failed which is the most likely. When the big end cage cracks and breaks up, it flicks bits of white metal through the engine causing this sort of damage.
That damage has bruised those ports, the lower "Transfer" is in fact the strato clean air port, the two top ones are transfers.
Personally I would scrap this one, the previous one looked much sweeter.

Your right, looks like it was an internal problem, and metal was dragged around, it was hard enough to chip the cylinder anyway.
Cheers for pointing out the different transfers, I’m at a loss at which is which. Top allows in fuel/air mix and lower is the Strato fresh air (is that the air blower/supercharger in my terminology?). Used to two stroke diesels myself.
Link to comment
Share on other sites

Divots in the cylinder surface are one thing; bumps on the running surface are another kettle of fish entirely. Some of that damage is going to cause a few bumps for the piston and rings to run over.

I'd be surprised if you could hone it round without going through the bore coating.

 

Link to comment
Share on other sites

20 hours ago, peatff said:

Strato is to clear the cylinder before the new fuel charge is drawn in so you get cleaner combustion. 

 

 

Sort of; it makes a cleaner exhaust as less unburnt fuel gets past before the exhaust port closes, combustion takes place after that.

18 hours ago, Heavy Oil Saw said:


The supercharger/scavenger blower on a 2 stroke diesel clears the cylinder for a fresh charge, as well as feed air for the combustion stage, so to speak. If my days in classroom are to be remembered.

Yes and the diesel has the advantage that the fuel is only injected after the inlet and exhaust are closed. With a conventional two stroke the piston descending on the power/exhaust stroke scavenges the fuel-oil mix from the crankcase and pushes it up the transfer port into the cylinder. some goes directly through the exhaust port.

 

What the stratified porting aims to do is allow neat air directly, under the piston, through  the new ports in the cylinder and into the transfer ports without going into the crankcase. Then as the piston descends this neat air is the first into the cylinder followed by the fuel and air from the crankcase.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

  •  

  • Featured Adverts

About

Arbtalk.co.uk is a hub for the arboriculture industry in the UK.  
If you're just starting out and you need business, equipment, tech or training support you're in the right place.  If you've done it, made it, got a van load of oily t-shirts and have decided to give something back by sharing your knowledge or wisdom,  then you're welcome too.
If you would like to contribute to making this industry more effective and safe then welcome.
Just like a living tree, it'll always be a work in progress.
Please have a look around, sign up, share and contribute the best you have.

See you inside.

The Arbtalk Team

Follow us

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.