OS 50H Sounding a bit rough!

Hi all - I started my OS 50H with TT redline 3D Hi-flow after fitting new bearings but she sounds bit rough to my untrained ear. I cleaned it out at the same time, the piston and ring has been cleaned up and lubed so the ring can move freely.
As you can see, even after it is warmed up it will only restart if I give a little move throttle stick than normal.

I was wondering if you guys could have a look at the videos and see what you think. The first video shows what it sounds like from low to med range revs and back down and the second video shows how the revs pick up after the fuel line has been shut off.

Video 1

Video 2

Thanks Guys

[jwatts007]

Dont know what pipe you have a good one helps a lot...spinning it up unloaded lake that will not do it any good either you would be better sorting it at the field...

[Raving Jim]

Does sound rough when you throttle down , when you put the new bearings in did the crank spin nice an freely with glow plug out , also I take it you have the piston ring seated ok ?

[dbull46]

Dont know what pipe you have a good one helps a lot...spinning it up unloaded lake that will not do it any good either you would be better sorting it at the field...

Hi - I am using a TT Redline 3D Hi-Flow pipe and Opti 20%. Thanks for the tip about spinning up unloaded. I was doing a test on the msh Brain Bailout mode to see if the swash plate would sit level when activated and so far it looks good there.

Does sound rough when you throttle down , when you put the new bearings in did the crank spin nice an freely with glow plug out , also I take it you have the piston ring seated ok ?

Jim, Yes the crank did spin nice and free after the new bearings were fitted and the open ends of the ring is seated over the pin in the groove of the piston which is also smooth to turn over from the end of the crank shaft.

Thanks

[waveydavey]

You need to load the engine up Dave before you can tell whether you've got problems. Why did you have to free the ring up

[dbull46]

Dave, The engine stood for a few months and when I tried to start it for the first time it would only start with the throttle half open. This made me think it was a compression issue and when I stripped her completely down, the bearings were rusty as hell and the rear one was practically seized. The ring was jammed in the piston groove but did remove it aright and give it a good clean up inc the groove too.

Cheers
Dave

[waveydavey]

Ah got you, might just need to clear its throat so to speak. Did you clean the carb if it's been sitting for a while as the oil can make them a little gummy

[dbull46]

Erm! I Don think I did cleaned the carb this time. Some think to do before I start again.

Thanks Davey

[dieselcarb]

just a thought but did u put ring on the piston the same way up? cos although it doesnt matter with a new ring a used 1 MUST go back the same way it came off or it wont seal propperly

if you so much as think you might of put it in the wrong way i'd be richening it up and fitting a new 1 and give the liner a wee hone if you do.

if its the correct way then all should be fine providing the ring didnt soak up much heat when it was stuck in the groove when you run it

p.s hard to tell anything from vid if its got new bearings and a fresh new plug it should run great if carbs fine if it rattles probly needs a con rod if its just running like crap its probly carb or ring

[dbull46]

Arh! I have no idea which way the ring went in or if it got too hot when it was stuck in the groove. What you are saying about the ring going in the same way as it came out makes perfect sense so better buy a new one. Not sure what you Ment when you said give the liner a wee hone if I changed the ring?
I'll give the carb a good clean out and try again.

Great conversation guys
cheers :-)

[aww]

This is what honing is and why it's done ( I use a wheel cylinder honing tool , About £10-£15)
https://www.youtube.com/watch?v=xy_g1rG7mKQ

Anthony

[dbull46]

This is what honing is and why it's done ( I use a wheel cylinder honing tool , About £10-£15)
https://www.youtube.com/watch?v=xy_g1rG7mKQ

Anthony

Thanks you for that link aww, so let me see if I've got it right. The honing process cleans off any burs of imperfections inside the liner so when a new piston ring is fitted, the liner surface will be flat to produce a good seal to the ring.

Dave

[waveydavey]

Thanks you for that link aww, so let me see if I've got it right. The honing process cleans off any burs of imperfections inside the liner so when a new piston ring is fitted, the liner surface will be flat to produce a good seal to the ring.

Dave

It roughens up the surface so the ring can bed in well.

[dbull46]

"Roughens up the surface so the ring can bed in well"
Got it. Thanks Dave.

I think there is a way I can do this without having to fork out for a new tool. If I get a m10 cut the head off the end and make a slit straight down the middle about 15mm so a strip of wet and dry can be wound around the bolt until it fits snug inside the liner then put the other end of the bolt into a drill, gently working it back and forth and hay presto job done.

What do you think?

[kev2009]

dave

go in to alfords or b&q and get a 1inch scotch glaze buster, they fit dremel I think shaft 1/4 inch, about 2to3 pound, does same thing, you only need to glaze bust it,

kev