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J D 803/08/2020 13:34:19
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1571 forum posts
85 photos

Red diesel and white road diesel are the same except for the red/pink dye that indicates it is for non road use only and has less tax imposed on it.

Foxfan04/08/2020 13:51:43
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931 forum posts
7 photos

So, Jon, what is a good solvent/cleaner for castor in your experience?

Cheers,]

Martin

Jon - Laser Engines04/08/2020 13:58:10
5614 forum posts
271 photos
Posted by Foxfan on 04/08/2020 13:51:43:

So, Jon, what is a good solvent/cleaner for castor in your experience?

Cheers,]

Martin

There isnt one. Take it to bits, throw the old bearings away and replace. Flush it out as best you can with old fuel and a toothbrush if you want and then use synthetic oil after that. Alternatively, change the bearings, leave all the castor gunge inside and just keep running the engine. After a few gallons it will have flushed it all away. Just dont stop using the engine as the residual castor will gum up the works again.

There are some products that can clean up the outside of the engine, but you dont want to be squirting them inside.

Doctor Chinnery05/08/2020 11:15:26
53 forum posts
Posted by Jon - Laser Engines on 03/08/2020 12:48:50:

Its a pretty simple job. backplate and head off, cam cover plate off, liner out, mark position then piston/conrod out (can be a fiddle), cam shaft out (photo position first), crank out with a few hammer taps, and then its time to toast it up with a heat gun or similar to get the bearings on the move. One they are out its the same job but backwards!

Sounds easy if you've done it a few/dozen/hundred times but to an engineering virgin: intimidating is the term that comes to mind, 'specially if despite much marking and photographing I get the piston & liner or worse (probably) the cam shaft wrongly aligned when putting it all back together.

Shame there don't appear to be Hayes or For Dummies publications on the subject.

Nigel R05/08/2020 11:29:30
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4066 forum posts
693 photos

"Now, where do I find a step-by-step guide to to the job, ideally specific to this individual motor rather than the generic videos on YouTube"

The OS motors share a common design with only minor variations, as far as I know. It took me about 45 minutes last time I changed bearing on a OS four stroke - I think I used a video showing a 48 Surpass as a guide for a 70 Surpass.

The basic construction is common, there may be small differences but the method of aligning the cam and getting the piston/conrod out is common (I think).

Anyway. Dave MacIntyre's channel has lots on OS four strokes...

40 Surpass being part disassembled (head removed):

**LINK**

40 Surpass, with the liner and cam out

**LINK**

pt2 of the above, annoyingly does not show piston removal

**LINK**

One showing piston pin removal

**LINK**

40 Surpass reassembly including popping in new bearings:

**LINK**

 

An older video, bit jerky, on a 52FS, a full disassembly:

https://www.youtube.com/watch?v=S_HrTCCO-GY

and reassembly part 1

https://www.youtube.com/watch?v=2WO9LRBIc_g&t=41s

part 2

https://www.youtube.com/watch?v=8FoLT8VjKqE

Edited By Nigel R on 05/08/2020 11:32:51

Engine Doctor05/08/2020 11:44:18
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2579 forum posts
40 photos

The link on piston pin removal is ok providing the pin is not siezed /gummed into the piston. Lots of heat , plus gas etc needed in those cases. Good luck .

PS a soak of all the bits in cellulose thinners will remove any Castor oil . It doesn't dissolve it if its gummed but pickles it a bit like putting cellulose paint on top of enamel and it then brushes off easily.

Engine Doctor05/08/2020 11:46:31
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2579 forum posts
40 photos
Posted by Doctor Chinnery on 05/08/2020 11:15:26:

Shame there don't appear to be Hayes or For Dummies publications on the subject.

That would be a popular publication but with Haynes manuals current quality probably not that good ,JMO.

Jon - Laser Engines05/08/2020 12:34:09
5614 forum posts
271 photos
Posted by Doctor Chinnery on 05/08/2020 11:15:26:
Posted by Jon - Laser Engines on 03/08/2020 12:48:50:

Its a pretty simple job. backplate and head off, cam cover plate off, liner out, mark position then piston/conrod out (can be a fiddle), cam shaft out (photo position first), crank out with a few hammer taps, and then its time to toast it up with a heat gun or similar to get the bearings on the move. One they are out its the same job but backwards!

Sounds easy if you've done it a few/dozen/hundred times but to an engineering virgin: intimidating is the term that comes to mind, 'specially if despite much marking and photographing I get the piston & liner or worse (probably) the cam shaft wrongly aligned when putting it all back together.

Shame there don't appear to be Hayes or For Dummies publications on the subject.

I understand your trepidation but once you get into it they are simple creatures so if you get something wrong its rarely terminal and you can just take it to bits again and fix it. Your example of the cam (which can be a fiddle with its helical worm drive), if its wrong you will know immediately as it will not align with the photo you took in the first instance. To be totally sure, turn the engine over very gently the first time round so that if there is a problem and a valve donks the piston there is no load on it. Dont just go ham and crank it with a leccy starter!

And as much as i dont like to disagree with ED as we are normally on the same page im not a fan of using cellulose in engines.

 

Edited By Jon - Laser Engines on 05/08/2020 12:34:33

Alistair Taylor05/08/2020 12:55:30
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602 forum posts
18 photos

If it's any help - fairy powerspray is a great remover of gummed up castor - but tends to dull the silver paint on the outside of model engines. Switch cleaner, sold by Maplin (online only) is also great for loosening gummed up castor.

This a great www for exploded views of most engines;

sceptreflight

I've taken apart and refurbished a few OS two and four strokes. Key tips that may help avoid a boo-boo;

- The cam has a mark / indentation to assist with getting the timing right marked on the outer face, i.e. there is a right and wrong way to reinsert it!

- There is a head bolt concealed under the rocker assembly you can't reach until the assembly is removed

- Use wooden rods / dowels to remove bearings to avoid damaging the engine case

- An appropriately sized socket is really helpful for reinstalling bearings (they are a tight push fit)

- To get the timing right, you need to hold the piston at TDC - you can make a tool to do this by finding a bit of broom handle / disk of wood that's a snug fit in the back of the engine case, and snading / drilling a slot just big enough for the conrod - this then holds the conrod/piston at TDC while you fiddle with the cam

- The cam timing is set like this (but feel free to google and watch a few other demos)- see also this from justengines

- it is difficult to get the conrod off the crankshaft until you remove the liner - then you can wiggle the piston to a position where the conrod will come off - NB remember this for reassembly!

- Make sure you have the correct replacement bearings!

Hope these help a bit

AlistairT

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