Flyer95

My Feedback: (1)

Hello,

Need some advice on camshaft timing for the OS 200S fourstroke, the non-pumped version.
I am running 10% nitro fuel and it seems like my engine is low on power by about 1000rpm compared to some readings on the RCU.

It starts fine but at full throttle it sounds rich and rough and missfiring or preigniting and if I am leaning it it sounds just more like preigniting at WOT.
Firstly I was thinking if the muffler is too restrictive and wont let all the hot exhaust out in time as this muffler gets very hot very fast and is extremely quiet compared to other fourstroke mufflers I have seen.

Or could it be that the camshaft timing is wrong by one tooth? Does anyone have a picture as about how the mark alignment on the camshaft should be?

I have dissassembly the engine and everything looks great on the inside and coated oil.

Any advice or thoughts about this engine would be great!

w8ye

My Feedback: (16)

Sounds more like you have a fuel problem

DSTIEBS

You could start by taking the baffle out of the muffler and see if that makes a difference. If it doe not then it could be starving for fuel.

Flyer95

My Feedback: (1)

I use large fuel tubing and can richen the needles on the engine easily so thats not the problem. Also use the same fuel in all my other two and fourstrokes with good results. The performance on this engine is low and at full throttle it sounds like preigniting and being rough and rich. Need to find out what to do to get better performance. Now it is almost 800-1000rpm weaker than my Saito180.

DSTIEBS, I did remove the end cone from the muffler but the performance is the same but a whole lot louder. It still preignits at WOT, cant understand it?


Anyone knows the about any problems with this engine? or how the dot mark on the camshaft should be positioned?

DSTIEBS

http://www.rcgroups.com/forums/showthread.php?t=685688. What are the RPMs are you getting before it breaks-up? Maybe the RCgroups.com can help you. Good-luck.

Flyer95

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I could get about 8800 peaked with an APC17x6 and I think less than 8000rpm with the APC17x8.
It sounds very bad at WOT "preignits" unless I richen it down by 1000rpm but then it becomes very low on power and can not fly my airplane any good. Will look at the RCgroups, thanks!

w8ye

My Feedback: (16)

Cam timing with the cross mark on the prop hub aligned with the casting seam on top of the engine in front of the cam box

Flyer95

My Feedback: (1)

Thanks w8ye,

I will put the engine together tonight and testrun it again by the end of the week. Will let you know the results!

Flyer95

My Feedback: (1)

Here comes an update! The camshaft timing was correct as it came from the factory but it was somehow fun now to see how this beautiful engine looks like on the inside

I assembled the OS 200FS and been out running it again today and now it runs great with gobs of torque and runs very clean and quiet turning a APC18x6w @7800rpm. The engine is still new and running rich so I assume I will se a higher rpm within a few tanks of fuel.

The problem must have always been my aluminium-spinner as the props seemed to slipp on the spinner and the spinner on the prophub. What dazzles me the most is how could I fly it for almost two tanks with the prop sliping on the crankshaft??[sm=confused.gif] Well it sounded bad as I said

Now I am however a happy OS200FS owner

thompsonlodge

When you removed the camshaft cover, you let the gremlin escape!!.... JS