How to prep used cylinder for new piston.
- Thread starter MrGiggles
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nobody around here re coats the piston after porting?
From LM Electosil. http://www.electrosil.com.au/news1.htm
Most porting cuts the coating around these edges where the bore feeds into the ports. This breaks the critical Nikasil coating around the port edges, and will always lead to flaking of the Nikasil. It won't take long before the cylinder has to be recoated. The lesson is that porting should only be done if the cylinder is going to be recoated immediately.
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From LM Electosil. http://www.electrosil.com.au/news1.htm
Most porting cuts the coating around these edges where the bore feeds into the ports. This breaks the critical Nikasil coating around the port edges, and will always lead to flaking of the Nikasil. It won't take long before the cylinder has to be recoated. The lesson is that porting should only be done if the cylinder is going to be recoated immediately.
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Justsaws
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Do not sweat the small stuff. If you read a lot of the threads about what people have done to their saws you will see that getting advice from a Ferrari dealer's mechanic about rebuilding your chevy 350 is not all that relevant.
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gink595
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For anyone that has ever made a "Works" bomb you know Works toilet bowl cleaner eats aluiminum and is avaliable from any Wal-Mart or grocery store. It has Hydracloric acid in it.
I am having some trouble getting it running good guys. We have been through the carb and it is clean, but still no go. It will sit and idle all day long, but the minute you give it any throttle it falls on its face. I'm stumped here. Carb is good, plug is good, it has a new base and carb gasket as well.
Could a cracked fuel line cause this?
Could a cracked fuel line cause this?
Steve K
ArboristSite Operative
Changed the filter, it doesn't have an impulse hose. Passages are clear for it though. Right now I'm really hoping it is the fuel line. My dad also swapped the carb and coil from the 50 Special and it still had the same problem. I'm really hoping the line is the problem.
Gab250
ArboristSite Operative
Why do you guys use any chemicals what so ever on the cylinders? On cars all you do is give the cylinder a light hone, and I wouldnt imagine it'd be too different to any other engine. As for the problem, check the obvious things first. Will it rev properley with the bar and chain off? Is it getting a nice, fat, blue spark? You possibly have a weak coil/magneto. Running good quality fuel through it?
Gab
Gab
tdi-rick
Addicted to ArboristSite
You didn't bother reading the posted replies or click on the links, did you ?
Have a re-read of all the thread.
Hey GAB you are out of line with this type thinking. Four strokes are totally different than two strokes. DON'T hone two strokes!
272super
ArboristSite Operative
Did you do an air leak test? You should do a pressure or vacuum test to make sure the crankcase is airtight. Without doing so, it could be running lean or have all sorts of running issues. You need to rule that out first.
pepsifreak28
ArboristSite Operative
leak test
if it was wasnt running before it could be carb diaphram but its quite possible if it ran to lean when it was super hot could have melted the seals...a leak/pressure test on the crankcase would let you know on bikes I just made 2 plates one for the exhaust one for the intake on the intake side drill hole put in a tire/shradder valve pump some air into with a pressure gauge im not sure what max pressure would be but maybe between 10-20 psi make sure piston is at tdc or not blocking the intake port.
if it was wasnt running before it could be carb diaphram but its quite possible if it ran to lean when it was super hot could have melted the seals...a leak/pressure test on the crankcase would let you know on bikes I just made 2 plates one for the exhaust one for the intake on the intake side drill hole put in a tire/shradder valve pump some air into with a pressure gauge im not sure what max pressure would be but maybe between 10-20 psi make sure piston is at tdc or not blocking the intake port.
Gab250
ArboristSite Operative
Why the heck not? the piston goes up and down inside a bore, the rings need to seal to the bore, that's all there is to it? an engines an engine....
Gab
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tdi-rick
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rupedoggy's just doing some s stirring I reckon, more towards me.
Saying an engines an engine is a little like saying a B&S is the same as an F1 Renault.
I posted reasons why not to use a ball hone on a two stroke Nikasil cylinder, although plenty of people use them.
The same would go for a nikasil Porsche cylinder too, and Porsche don't recommend they be honed either.
Two strokes are more prone to piston melt downs than four strokes, hence the use of HCl to remove it from the bore.
All that will happen if you run a hone down the bore without removing the aluminium is load up the stones and clog the hone with aluminium, and you wont get all the aluminium out of the lowest depths of the 'valleys' unless you use a plateau hone IMO.
Again, running a ball hone designed for an iron bore down a Nikasil bore just buggers the surface, knocking the peaks off the nikasil and supposedly ruining the oil retention. The material in a generic hone isn't designed for nikasil.
It appears that the nikasil re-platers use plateau hones, which are specific hones using a nylon type brush impregnated with an abrasive compound.
They actually don't remove material per se, just clean out the valleys of any folded over material and debris, cleaning up the surface and making it truer and reducing the Ra value.
no longer collecting
ArboristSite Operative
Personally,
Any cylinder on newer saws and old saws that is made of a cast uses a porous aluminum electrostatic transfer ...this chrome layer is very hard/thin and should not be touched or permanent damage will be made.
Never HONE A CHROME CYLINDER...IT WILL BE DESTROYED. This is why they invented the chrome plating to avoid re-boring or honing and the used of a cast sleeve and reduce engine weight.
1200 grit paper with engine solvent will remove any crap inside and only the rings replacement are necessary.
If the saw has not over heaten and gauge dial does not show any "out of round" condition, a simple ring replacement will be required...no further touch required.
make sure you install them correctly...some have a lip for expansion on the 2 rings configuration to push them tight against the wall/make a tight seal and get optimum compression.
To re-chrome a cylinder would cost you around $250.... you don't want to go that route.
Alain,
Any cylinder on newer saws and old saws that is made of a cast uses a porous aluminum electrostatic transfer ...this chrome layer is very hard/thin and should not be touched or permanent damage will be made.
Never HONE A CHROME CYLINDER...IT WILL BE DESTROYED. This is why they invented the chrome plating to avoid re-boring or honing and the used of a cast sleeve and reduce engine weight.
1200 grit paper with engine solvent will remove any crap inside and only the rings replacement are necessary.
If the saw has not over heaten and gauge dial does not show any "out of round" condition, a simple ring replacement will be required...no further touch required.
make sure you install them correctly...some have a lip for expansion on the 2 rings configuration to push them tight against the wall/make a tight seal and get optimum compression.
To re-chrome a cylinder would cost you around $250.... you don't want to go that route.
Alain,
no longer collecting
ArboristSite Operative
Does the same without a B&C. Spark is great, fuel is fresh Stihl 50:1.
It was running before. My dad tuned it lean and the piston got scored up. The saw has been sitting more than a few years with gas in it. We dumped out the old stuff first.
I have not pressure tested it yet. I might try that today. How long will a good saw hold air?
KMB
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pepsifreak28
ArboristSite Operative
leak test
well if its sealed up it should hold air for a very long time if it dont your crankcase is sucking "extra" air from somewhere and extra air mixed with the fuel makes it more lean you said it was sitting for a good while...depending on where it was sitting and the temp and conditions you might have a dry rotted seal or bad gasket when you leak test it most of the time your going to hear the air comeing out somewhere and if you dont use some soapy water if its leaking air im sure you will find it rather quickly if you pump air into it and it has a small leak put more pressue in it until you find it just think about all those times you fixed your bikes innertube
well if its sealed up it should hold air for a very long time if it dont your crankcase is sucking "extra" air from somewhere and extra air mixed with the fuel makes it more lean you said it was sitting for a good while...depending on where it was sitting and the temp and conditions you might have a dry rotted seal or bad gasket when you leak test it most of the time your going to hear the air comeing out somewhere and if you dont use some soapy water if its leaking air im sure you will find it rather quickly if you pump air into it and it has a small leak put more pressue in it until you find it just think about all those times you fixed your bikes innertube
