Scraper ring being difficult

[John Roberts]

I broke the original one while trying to put the cylinder back on the piston. This time I've taken the piston off, it's on the bench and now it ought to be a doddle to push the piston and rings in.

Well, it isn't. The scraper ring has a backing spring behind it in the ring groove and despite having its two ends butting up to each other it does seem to have the effect of making it very difficult to compress the oil ring enough to get it into the bore.

I don't have a piston ring compressor or a Jubilee clip, but should they really be necessary FFS, I've never needed one before. Or is this type of ring awkward to insert- I'm puzzled because I got the other cylinder in without much bother while still on the engine.

Any suggestions, please?

 

[DrFarkoff]

It's easier to Build the piston into the bore while off and just leaving clearance for the gudgeon pin to go thru

Have a think as well which hand you are happier with to work in a closed space with the circlip pliers?

If you are happier right handed leave pin to rear of right piston and left of left piston OR vice versa

Also make sure all your o rings and bits are where they should be Before offering piston to Conrod

 

[John Roberts]

Thanks Jay.

What I have tried is to wrap one turn of dental floss in the groove around the ring, I tied a nut to each end of the floss for grip, and pulled it tight to compress the ring.

It doesn't work as I have to pull uncomfortably hard to compress the ring enough. Pity, if it did go in then it should be possible to pull the floss out through the cut-out at the base of the cylinder skirt.

 

[Steptoe]

the ring groove

Land, it's called the "piston land".

 

[Kenny]

Tis definately the right size ?

 

[John Roberts]

Land, it's called the "piston land".

Is this correct?

 

[Timolgra]

Is this correct?

Sort of, there a top land, second land etc.

Like Kenny says, is it the right one, or do they need to be gapped?

Try using a cable tie.

I'm in north Wales and have a ring compressor if it's of any use to you.

 

[John Roberts]

Hi Tim, my sketch was in response to Steptoe's post, to be honest I'm not sure what he was getting at, I only put an arrow to what I think is one of the lands, if I had drawn an arrow to the other one above it it would have crossed the other two arrows showing the compression rings. Face-to-face explanations are so much easier!

And I'm still saying that the backing spring is in the ring groove (in the piston) rather than in the land It is of course in the groove at the back of the oil ring as well. Perhaps I'm not explaining this very well, I can be obscure at times.

It's kind of you to offer the ring compressor, I was passing Traws to Bala on Tuesday but not for a while again. 'Course, if the bike was mobile...! Thinks: there was a single cylinder BM once, wasn't there?

No, it is the correct ring, the gap is on the large side, 15 thou. The cable tie idea sounds good, the "buckle" would fit in nicely into the cut-out in the cylinder base.

PS Should it be this difficult to get a measly ring in FFS? As I said the other side went in no probs without taking the piston off.

 

[bustupbiker]

I have one you can use i'm at LLoc Holywell just off the A55
Lyn.

 

[(RIP) Kaister]

from the top
crown-land-groove-land-groove -land-groove-skirt

http://www.cardictionary.com/definition/piston-land.html


sorry steppers

 

[John Roberts]

I have one you can use i'm at LLoc Holywell just off the A55
Lyn.

Hi, Lyn,

Don't suppose you happen to have an urgent job at this end of the woods tomorrow? Shall I fill the kettle ready and dig out some Bra Brith just in case?

 

[Timolgra]

I like Bara Brith too and only in Buckley, I'll feel a piston ring piss up looming

 

[fayeslane]

from the top
crown-land-groove-land-groove -land-groove-skirt

Sounds like a new dance step

 

[bustupbiker]

Hi, Lyn,

Don't suppose you happen to have an urgent job at this end of the woods tomorrow? Shall I fill the kettle ready and dig out some Bra Brith just in case?

I like Bra-Brith i does PM'ed you John.
Lyn.

 

[cookie]

i've never needed a ring compressor for any bike i've worked on until i started pissing about with airhead bmws.

i just can't get them on with my fingers when the piston is still on the con rod. dunno why

i've done the assemble into the cylinder, then fit the wrist pin thing, but now i find it easier to use a proper ring compressor.


ps. make sure you use one you can remove after the cylinder has gone on though

 

[cookie]

Is this correct?

yes.

nice drawing BTW

 

[John Roberts]

i've never needed a ring compressor for any bike i've worked on until i started pissing about with airhead bmws. ... but now i find it easier to use a proper ring compressor.

Well, that makes me feel a bit better, so it isn't just me then.

I like Bra-Brith i does PM'ed you John.
Lyn.

Hi Lyn, PM on the way back to you once I've emptied my PM File.

I like Bara Brith too and only in Buckley, I'll feel a piston ring piss up looming

Sorry, Tim, but I'm the other way, out on the Llyn peninsula. The Bara Brith is still available, though, I've scanned it for your and Lyn's approval.

There ya go, one freshly scanned Bara Brith. Smells lovely, does that. Two teas? Sugar? milk?

EDIT I don't want to appear small-minded here, so shall I cut some for Kaister and fayeslane as well? Air travel is so much more convenient these days. You'd be back home in Oz in a jiffy. And Kenny, you're just down the road on the Wirral, you can pick Steppers, Cookie and Jaythro up on the way, no bother.

Thinks There seems to be a gap in the market here for a piston-ring/bara brith piss-up smiley. ​

 

[John Roberts]

An update on progress (lack of.)

I popped the scraper ring in the cylinder (by itself, that is- NOT on the piston) and then tried to get the backing spring into the groove in the back of the ring, just to confirm that it was possible in case they had given me wrong spring. It was a hell of a job, in fact I gave up, but it did show how much pressure it takes to compress the spring.

I have since found the old ring and backing spring, and, yes, they seem to be identical.

Perhaps the spring is this strong because it's harder to clear the oil in a horizontal cylinder and to stop it smoking on start-up??

So, lesson learnt: I shall have to stop pissing about and get a proper ring compressor. For which, of course, I thank you Lyn and Tim for your offers, but I shall be calling in a favour nearer to home. Very kind of you both.

 

[fayeslane]

EDIT I don't want to appear small-minded here, so shall I cut some for Kaister and fayeslane as well? [/I] smiley. ​

Sorry John, can't make it still trying to bleed the ABS on my K1. Bloody nice of you to offer though Also the overuse of the term 'ring compressor' is making me squirm in my seat.

 

[John Roberts]

Sorry John, can't make it

That's OK, I'll have your slice then.

Also the overuse of the term 'ring compressor' is making me squirm in my seat.

What do you call it then? Or don't you need one- I did the job in five minutes with the one I eventually borrowed, as I said I just couldn't manage it at all with only ten fingers.