ASP 120 & SC 120 Four strokes, are they identical?

[martin collins 1]

I removed an ASP 120 four stroke from an airframe to convert it to electric, now 6 months latter i have decided to fly it glow, i sold the original engine off so now want another ASP 120 as i know it fits into the custom made mounting and cowl of this model. I am being offered SC120 Four strokes and the owners seem to think they are identical in dimensions and castings, is this correct?

Edited June 25 by martin collins 1

[GaryW]

Basicaly ASP SC & Magnum 4 strokes are all the same engines made in the same factory

Edited June 25 by GaryW

[Martin Harris - Moderator]

Only the crankcase casting is different…and that difference is only the badging!

[David Davis]

I have cetainly swapped parts between an OS 52 Surpass and a Magnum 52FS.

[GrumpyGnome]

I've swapped parts between ASP and SC - not a crankcase though....

[Engine Doctor]

They are the same engines just different badges and cases are interchangeable from the same series. The outer dimensions are exactly the same and many internal  parts will fit into OS engines and vice versa as the Chinese copied them . The SC,ASP etc are however much lower quality than OS . One good swap is the OS 52 crank will fit into an ASP etc 52 and 60 FS and results in a much smoother running engine 

[Cuban8]

I don't think that describing ASP/SC/Magnums as "much lower quality than OS" is completely fair. True, OS engines are a better product in terms of fine detail and certain areas of their engineering - carburettors, for instance - but for a product that was usually half the price or less than the OS, the Chinese copies were perfectly serviceable and reliable and gave a real alternative to some folks ( e.g. me) rather than an otherwise expensive outlay. 

I have a lovely OS 120FS (non-pump) that I bought in boxed as new condition from BMFA ads a while back for £200 - a brand new full priced version I really couldn't justify at the time. The difference is there compared to my Chinese copies, naturally,  but as a sport flyer I don't notice a huge difference between the makes on a day to day running basis. The copies do vary a bit - some just seem nicer than others but still run fine - I think the best of the bunch is my ASP 52FS which must have been lucky to get all the really good bits on a lucky day in the factory!

[Manish Chandrayan]

To Cuban8's point, and especially when it came to 2 strokes, the piston and cylinders from ASP were much better than OS for the OS 46 FX. When these were available Just Engines used to retail the ASP piston liners as replacement for the OS 46 FX. I have personally used them as replacement parts on few of my OS  

Edited June 26 by Manish Chandrayan

[Christopher Wolfe]

22 hours ago, Cuban8 said:

I don't think that describing ASP/SC/Magnums as "much lower quality than OS" is completely fair. True, OS engines are a better product in terms of fine detail and certain areas of their engineering - carburettors, for instance - but for a product that was usually half the price or less than the OS, the Chinese copies were perfectly serviceable and reliable and gave a real alternative to some folks ( e.g. me) rather than an otherwise expensive outlay. 

 

This may be perfectly true but just remember it was OS that spent all the time and $$$ to develop these four stroke engines so any clone is just that,  a clone produced in certain countries where copyright is often ignored -pretty sad IMHO

 

* Chris *

[Engine Doctor]

On 26/06/2024 at 11:07, Cuban8 said:

I don't think that describing ASP/SC/Magnums as "much lower quality than OS" is completely fair. True, OS engines are a better product in terms of fine detail and certain areas of their engineering - carburettors, for instance - but for a product that was usually half the price or less than the OS, the Chinese copies were perfectly serviceable and reliable and gave a real alternative to some folks ( e.g. me) rather than an otherwise expensive outlay. 

 

Hi Cuban 8 .Yes servicable for a time but lower quality in terms of materials and finish.

ASP. Look at ASP  cranks. Pressed in crank pin that can sheer or come loose, often rough sharp machining , rocker arms that wobble all over the place and occasionally snap, cyl heads that leak past valve inserts. On two strokes pistons that gudgeon pin slop about in if engine is given any stick as piston material is not as good.

OS. One piece crank machined to  a very high standard. Rocker arms that have no side play, heads that dont leak. 

One area that ASP etc did get it right is with the plating on the cylinders - it stays on ! So every cloud etc.

As  sport flyer you wont generally notice the difference in use if you dont abuse your engines . But used for higher performance the Chinese copies quickly fall by the wayside.

As for OS engines they are  not created equal now days and the lower end range and especially the two strokes are definitely built to a price  as the çhrome/nickosil plating on the cylinder done in Tiawan shows.

As you Say for half the price ASP etc were ok engines that did a job and if not asked too much of would ladt well.

Edited June 27 by Engine Doctor

[Cuban8]

4 hours ago, Christopher Wolfe said:

This may be perfectly true but just remember it was OS that spent all the time and $$$ to develop these four stroke engines so any clone is just that,  a clone produced in certain countries where copyright is often ignored -pretty sad IMHO

 

* Chris *

Of course, the Japanese had just the same MO after WW2 in terms of copying many western products - eventually improving on the originals and winding up where we are today. 

China is doing exactly the same with cars, motorcycles and domestic products etc.Their space programme is also very impressive.

 

 

[martin collins 1]

So if they are copies of an OS 120 does that mean the OS is identical in external dimensions and position of carb, exhaust etc to the ASP 120 that was in the model?

[Engine Doctor]

Yes totally interchangeable

[Paul Marsh]

The company who made SC/ASP/Magnum and some West 4 stroke engines all were made by Sanye Precision Machinery Co, sadly no more.

[Engine Doctor]

1 hour ago, Paul Marsh said:

The company who made SC/ASP/Magnum and some West 4 stroke engines all were made by Sanye Precision Machinery Co, sadly no more.

Yes . They were I believe made as a side line , a bit like lasers and the company moved onto other things .

[Paul Marsh]

The SC's were always bit more expensive than the ASP's, don't know why,but they were. Someone mentioned that he heard a few ASP crank pins snapped off than  SC. Bought a broken ASP engine last weekend - with a broken crank pin, replaced it with a scrap SC crankshaft.

SC crankshaft on right, ASP (broken one) on the left.

 

[Richard Acland]

On 26/06/2024 at 11:07, Cuban8 said:

I don't think that describing ASP/SC/Magnums as "much lower quality than OS" is completely fair. True, OS engines are a better product in terms of fine detail and certain areas of their engineering - carburettors, for instance - but for a product that was usually half the price or less than the OS, the Chinese copies were perfectly serviceable and reliable and gave a real alternative to some folks ( e.g. me) rather than an otherwise expensive outlay. 

I have a lovely OS 120FS (non-pump) that I bought in boxed as new condition from BMFA ads a while back for £200 - a brand new full priced version I really couldn't justify at the time. The difference is there compared to my Chinese copies, naturally,  but as a sport flyer I don't notice a huge difference between the makes on a day to day running basis. The copies do vary a bit - some just seem nicer than others but still run fine - I think the best of the bunch is my ASP 52FS which must have been lucky to get all the really good bits on a lucky day in the factory!

I have 2 SC 52 four strokes. They are lovely engines, easy to tune and an incredibly low idle without cutting out.

[Martin Harris - Moderator]

2 hours ago, Paul Marsh said:

The SC's were always bit more expensive than the ASP's, don't know why,but they were. Someone mentioned that he heard a few ASP crank pins snapped off than  SC. Bought a broken ASP engine last weekend - with a broken crank pin, replaced it with a scrap SC crankshaft.

SC crankshaft on right, ASP (broken one) on the left.

 

Not exclusive to the clones.  I’ve seen broken crank pins on OS - and Saito too.
 

In the case of the fairly new Saito, the owner returned it and the importer denied any liability, claiming user misuse.