OS55 won't fire up

[pgkevet]

I've finally managed to get the old ring off...broke it out in sections with a knife point...it never slid in the ring groove throughout that process. Totally stuck. To my mmeory the ring pin was a bar across the groove.. here (as best i can see with a magnifying glass) I have a tiny round stud. So is this just residual part of that pin or adequate? Did I ping the pin out?
The rest of the engine has cleaned up fine but the question is whether a replacment ring and liner honing is going to do the job or if that groove pin is damaged will i just get blow-by....

[chris jones2.4]

the pin just looks like a tiny roll pin push in the side of the piston in the groove

[Johnny Bravo]

The pin is a roll pin and it is there to stop the ring rotating . If the pin is damaged or missing the ring will rotate and snap off in one of the ports in the liner.Game over......The ring is stepped on either end to overlap the pin whilst being held in position so it cannot rotate.Just be careful when you put the new ring on that the ends overlap the pin .

[rachel]

I've finally managed to get the old ring off...broke it out in sections with a knife point...it never slid in the ring groove throughout that process. Totally stuck. To my mmeory the ring pin was a bar across the groove.. here (as best i can see with a magnifying glass) I have a tiny round stud. So is this just residual part of that pin or adequate? Did I ping the pin out?
The rest of the engine has cleaned up fine but the question is whether a replacment ring and liner honing is going to do the job or if that groove pin is damaged will i just get blow-by....

oH err you don't want "blow by"

Use the old broken ring to carfully clean the ring grove with the end , just scrape it out.

as for the "Pin" its job is to stop the ring rotating and the end of the ring dropping in to a port which equals disaster !!!!

If the pin is missing or damaged its a new piston too please :-(

Any problems feel free to send me the bits and I will help if I can .

X Rachel

[pgkevet]

the pin just looks like a tiny roll pin push in the side of the piston in the groove

That's what Ive got :-).. I probably didn't look properly at previous ring changes and assumed it was a vertical bar across the groove.

I'll see what it's like when the new ring is fitted and make the final decision on using the piston then.

Use the old broken ring to carfully clean the ring grove with the end , just scrape it out.

Rachel... i would normally do that but we're talking 1/2 cm bits pinged somewhere in the barn!! I cleaned it using another item.

Any problems feel free to send me the bits and I will help if I can .

What, no home visit <g>? I generally prefer to fix my own damage so long as within my abilities. I do have a couple of 450's I'm too lazy to sort though.....and the car locks need retumbling, back window seal needs sorting and a loose fan belt, a bit of a blow job on the back end wouldn't hurt either (as in paint..).......

[pgkevet]

New ring arrived saturday..wasn't until yesterday i had time to finish cleaning up the crankcase and ring groove and fit new bearing and the ring etc. One of those times when everything fiddly that could need extra fiddling happened.. you know the sort of thing...usually get the liner in first or second twiddle, but no, this time it was about the 8th go before it all lined up and slipped onto the stud instead of being a fraction off and refusing to be rotated without removal...

Refitted this am and test startup with blades off on the workbench in the barn (rain!)...took a while to get my oils and stuff pumped through and it to actually fire but once running it's sweet and restarts easily. Just need a dry day...

That leaves two 450's I've neglected to sort little irritations on, and I still need to figure why my gasser cuts out when i flip it (and, yes, I've checked the obvious stuff...)

[trillian]

I've got a list of heli things that need doing and it just never seems to end. Some of it is me being overly ambitious, like deciding to resurect my old Trex450 V2 with some new Fusuno frames and fins, buying the Fusion and Hirobo SDX. I have two engines that need bearings and I'd rather bake them at the same time but I only have bearings for one so need to order some this week, etc. And all the while neglecting the Predator as it sits lonely and un-loved on the shelf :-)

I have the Avro going again now though. It seems like the problems were just the check valve (touch wood and fingers crossed).

[pgkevet]

............ And all the while neglecting the Predator as it sits lonely and un-loved on the shelf :-)

I have the Avro going again now though. It seems like the problems were just the check valve (touch wood and fingers crossed).

My Blitz almost went electric this week! I hadn't flown it for a while and took it out for a quick spin earlier than i usually fly. With the sun behind me I was pootling around and it was so stable i decided to shoot a low flyby with a double roll..and then remembered the power lines to the house!! I think i skipped over them by inches...

...I must use the other field that time of day...

I had nothing but trouble with my YS's and check valves. it's a much simpler system on the crank pressure from my cline carb modded 90 SZ on the blitz - just an in-tube flutter valve - foolproof but not sure if they are still available.