marks in linar

Taffy · Aug 30, 2009

heres one for the geeks

i have a liner here that has done just 20 hours. it's relined but perfectly round, it's a supermoto 450 engine 2004 but used for 20 hours on the roads.

the rings have pressed so hard into the liner at BDC in two places; at 9 o clock that it refracts the light in the workshop. it's also not so good at 3 o clock over the cut away.

then, there are three places where the rings don't appear to be contacting the liner hardly. there are no vertical marks/scores. these are at front left and back (inlet end) left and right.

they are in line, but not necassarily because of; the piston corners. you know...semi slipper piston...well it's like the 4 corners. now there is no alloy in the wall, no scoring. ring gap is .25mm or .010" in old money. the areas where the rings aren't touching are inline with these corners.

weird or what! (what)

anyone any experience of this kind of thing?

regards

Taffy

berger · Aug 30, 2009

I have not seen this before. My question is, is there a problem? Oil consumption, compression?
I tend to think that most replated liners are not as perfect as we would like them to be. Between previous wear and removal of the old plating I dont feel they are as good as the new OEM.
On the other hand, if there are no syptoms, I'm not sure how much sleep I loose on it.

Taffy · Aug 30, 2009

c'mon ken!

3 from 4 perfectly symetrical gaps? left and right sides rubbing VERY hard? that isn't plating but it might be the OEM piston. but it's why it does it i can't get?

regards

Taffy

berger · Aug 30, 2009

Taffy said:
c'mon ken!

3 from 4 perfectly symmetrical gaps? left and right sides rubbing VERY hard? that isn't plating but it might be the OEM piston. but it's why it does it i can't get?

regards

Taffy

Just my point taff. I would trust the OEM piston before the plate job. If there was a batch of bad pistons I would think more people would have seen this.
I know I would bite the bullet for an OEM liner as opposed to a replate at 1/2 cost.

There could be other issues involved such as break in(was it done properly). As far as street riding is concerned i have never been a proponent of bergs being used on the street. I don't believe that was the engine developers intent. Long periods of steady mid to high rpm use. This may have wore the bore square in the first place.

Now with that being said, if there are no symptoms, I really don't know much I would worry.
Shoe on the other foot. If I am building the motor for someone else, it's probably something that should be addressed.

Just a different perspective taff. Nothing more.

fryguy · Aug 30, 2009

berger said:
Taffy said:

c'mon ken!

3 from 4 perfectly symmetrical gaps? left and right sides rubbing VERY hard? that isn't plating but it might be the OEM piston. but it's why it does it i can't get?

regards

Taffy

Click to expand...

Just my point taff. I would trust the OEM piston before the plate job. If there was a batch of bad pistons I would think more people would have seen this.
I know I would bite the bullet for an OEM liner as opposed to a replate at 1/2 cost.

There could be other issues involved such as break in(was it done properly). As far as street riding is concerned i have never been a proponent of bergs being used on the street. I don't believe that was the engine developers intent. Long periods of steady mid to high rpm use. This may have wore the bore square in the first place.

Now with that being said, if there are no symptoms, I really don't know much I would worry.
Shoe on the other foot. If I am building the motor for someone else, it's probably something that should be addressed.

Just a different perspective taff. Nothing more.

Taff, he's got some valid points, why are you taking it apart? Also, why were the parts replaced in the first place?

I dont' get 3 and 9...10, 2, 4 and 5 are cold seizing, and ....

can you check the piston in the bore, lookign from the rod end and use a long feeler gauge to determine if the piston or sleeve is the problem. Has the bigend too much side clearance and thrusting the piston around?

and Taffy...you should have known

bushmechanic · Aug 30, 2009

in both sets of cases I have, there is localised deformation of the aluminium at the joins around each bolt holding the 2 halves together near the "barrel"

so if you measure the ID of the hole for the linar at TDC and BDC its smaller front to back than left to right but only for 10-15mm either side of the join. I reckon with expansion the ally gets squashed by the bolts and creeps out encroaching on the bore for the linar.

dunno if thats related to the weird marks, might be something to do with it. my linar is less out of round when installed after I fixed the deformations.

Taffy · Aug 30, 2009

as i say the linar is perfectly round and fits freely enough in the cases w/o the o rings to turn just about easily. they look like transfer ports on a 2-stroke? weird! i also can't stop bubbles coming out of the radiator either. i've plenty of things to work on and see what cures all this.

however, if i don't take the engine down again a few of fry's questions will go unanswered!

all those numbers are clockface numbers fry. so you hold the linar how you would if sat on the bike. no not under you for a pee either!

regards

Taffy

fryguy · Aug 31, 2009

Taffy said:
as i say the linar is perfectly round and fits freely enough in the cases w/o the o rings to turn just about easily. they look like transfer ports on a 2-stroke? weird! i also can't stop bubbles coming out of the radiator either. i've plenty of things to work on and see what cures all this.

however, if i don't take the engine down again a few of fry's questions will go unanswered!

all those numbers are clockface numbers fry. so you hold the linar how you would if sat on the bike. no not under you for a pee either!

regards

Taffy

I do like to see your dander all messed up...

I get the clock thing, BLOKE

I had assumed you had the engine apart, when I suggest looking into the bottom of the sleeve to see the piston clearance. I am liking the idea about the clamping effect on teh liner distorting that, which I've heard about before. Did you post a year, and model...don't you know its important to provide some of these details.... :lol: :lol:

bushmechanic · Aug 31, 2009

have noticed a freely turning linar doesn't mean it is perfectly round when its installed.

can easily squeeze one 0.05mm out of round with 2 fingers

with the OEM piston to linar clearence being 0,05mm a freely turning linar still doesn't mean its all OK.

in any case I don't think a sightly oval linar would make those kind of marks, but then I haven't seen them so...

would be great to see a pic

ned37 · Aug 31, 2009

IT'S SPELLED" LINER" ](*,)

Taffy · Aug 31, 2009

ned37 said:
IT'S SPELLED" LINER" ](*,)

i know that but i like it this way!

regards

Taffy

ned37 · Sep 1, 2009

linar = taffspeak
well that's ok, but you are corrupting some of the other fellows. :wink:

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