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Tillerman6

To Nikasil or Not to Nikasil - That is the question.

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Guys,

   Need your opinion.  I still have time to specify what happens to my "new" cylinder from my TY 250A.  It won't get to Millenium Technologies for another few days.  And originally I was going to have it Nikasil plated, But now I am wondering if that is still a good idea?  It will get a new Wossener piston too unless there is some reason not to??  

The TY 250 barrel has a cast iron liner.  But the cylinder is still the old air cooled type.

There will be more heat expansion on this setup than would be the case with a water cooled cylinder, and it's a 2 stroke of course, but what are the advantages of a Nikasil lining for this application?

I will probably be riding trails most of the time rather than trials for whatever that is worth. So is the Nikasil worth it for an air cooled TY 250A??

 

 

Edited by Tillerman6
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From www.powersealusa.com.

Vintage-Steel-Cast Repair

There are many cast iron and aluminum cylinders with steel/cast liners in use today. PowerSeal USA offers a choice of upgrade and repair solutions for these.

A NikaSeal layer can be applied to existing steel/cast bores. This technology has saved many cylinders that are worn beyond available overbore piston sizes. Additionally, the NikaSeal layer provides a harder, better lubricating, and longer lasting wear surface than the existing steel/cast iron bore.

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3 hours ago, Tillerman6 said:

Guys,

   Need your opinion.  I still have time to specify what happens to my "new" cylinder from my TY 250A.  It won't get to Millenium Technologies for another few days.  And originally I was going to have it Nikasil plated, But now I am wondering if that is still a good idea?  It will get a new Wossener piston too unless there is some reason not to??  

The TY 250 barrel has a cast iron liner.  But the cylinder is still the old air cooled type.

There will be more heat expansion on this setup than would be the case with a water cooled cylinder, and it's a 2 stroke of course, but what are the advantages of a Nikasil lining for this application?

I will probably be riding trails most of the time rather than trials for whatever that is worth. So is the Nikasil worth it for an air cooled TY 250A??

 Why? Some of the original bores have lasted decades.  The Nikasil will not.

 

 

 

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If the nikasil is applied to an all-aluminium cylinder, then heat transfer is better and it is lighter than with a cast iron sleeve design.

In your case however, you would be applying the nikasil to the cast iron sleeve, so you would not get those benefits that nikisil can provide.

If your cylinder was worn beyond the size of the biggest oversize piston you can get, then nikasil would be a good option compared with resleeving.

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2 hours ago, feetupfun said:

If the nikasil is applied to an all-aluminium cylinder, then heat transfer is better and it is lighter than with a cast iron sleeve design.

In your case however, you would be applying the nikasil to the cast iron sleeve, so you would not get those benefits that nikisil can provide.

If your cylinder was worn beyond the size of the biggest oversize piston you can get, then nikasil would be a good option compared with resleeving.

Feetupfun,

  I do not have a bore gauge, but my telescoping gauges and micrometers are fairly accurate.  From what I could measure the new cylinder was still at nearly a stock size.  There was a "lip" at the top of the cylinder that you could feel, and this and the taper of the whole sleeve inside may cause them to take it out one or two sizes to get it straight again. 

But since I am a complete beginner at the whole idea of Nikasil and what it can do and what it is best used for, I thought it would be a good idea to find out as much as I could about the process and get everyone's opinion. 

So now I see that it can be applied to either the cast iron liner or for other bikes with just aluminum cylinders it can be used to improve the hardness and durability.  Sounds like a must have for those situations where there is no cast iron liner for sure.

 

Thanks again for everyone's input! 

 

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Back in the day when we were racing Sidecars with Yamaha 700 & 750 4 cylinder 2 stroke motors we used to Nicasil when doing a re-bore after seizure.

The problem was, you had to bed the motor in for 200 miles or so by which time the pistons needed replacing. if not, the motor would seize again.

The BEST motor we had, was a 750 that was made up from 2 Nicasil motors that had each seized up one barrel. The motor was very fast.

Just a note. The 700 was made up of 2 x 350 twin motors married on the common 750 4 cylinder crank.

Edited by johnsandywhite
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Your engine has probably went 30 years on the original bore. Bore it to fit the next piston size up, and go another 30 years

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I agree with faussy, and I would go the extra $ on a Yamaha piston kit, put good oil in it and sleep on it for a loooong time.

Guy

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Are the available rings compatible with Nikasil?  I thought rings were developed for specific bore materials.

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4 hours ago, mcman56 said:

Are the available rings compatible with Nikasil?  I thought rings were developed for specific bore materials.

What he said. 

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On 9/5/2018 at 2:54 AM, guy53 said:

I agree with faussy, and I would go the extra $ on a Yamaha piston kit, put good oil in it and sleep on it for a loooong time.

Guy

I will see if I can locate all the Yamaha piston sizes tomorrow.  The Wossener pistons were on my radar because they do list all the sizes as being available and up until today I did not have a source for the Yamaha pistons.  The other advantage for going this way is that you would stay very close to the original weight for the new piston, and balance is still an important consideration.

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On 9/5/2018 at 9:54 AM, b40rt said:

What he said. 

 

On 9/5/2018 at 5:18 AM, mcman56 said:

Are the available rings compatible with Nikasil?  I thought rings were developed for specific bore materials.

That is a very good point.  The company that does the Nikasil says that after the plating of the bore is done they hone the surfaces lightly.  And they did not mention anything about having to use special ring materials,  but the old tried and true cast iron liner and honing is probably more predictable because of the simpler process.

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You can write on the back of stamp, what I know about engines. However a guy in France I know Nikasiled his 250  434 as well as a few other mods, airbox and exhaust and its the sweetest sounding Yamaha I have every heard. While we are at it he Nikasiled the clutch basket as well, and yep its the sweetest smoothest TY clutch I have ever felt .  There is my two euro's for what is worth, hope it helps.

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