Chrome Pistons

Additionally why not the cylinders ?
My 68 Bridgstone 350 twin had chrome cylinders .
Someone in accounting says cost return ratio dosen't support it .
 
Chrome is way inferior to Nickle Silicon Carbide for cylinder plating. That said lots of 2 cycles had plated cylinders including in years gone by some 100CC kart engines. The early Honda and Kawi shifter engines were plated too. The issue is that if you stick it or something goes through the motor the cylinder is scrap unless you want to spend almost what the cylinder costs new to have it replated, and that is assuming it is just some delamination of the coating. A lot of RC and Saw engines still have plated cylinders today. The cheap ones it's chrome. The good ones, like say Stihl are Nikasil.
 
Thanks
I was thinking the nikasil would be a superior product .
There were only std pistons avalible . At 16 thats what it got .
Luckily only center burn't , scars and scrapes would damage one pretty bad .
 
sundog,

Typically, pistons are machined at a decently high feed rate in the piston lathe so there is enough of a machining pattern to hold oil.

Even on coated pistons, that surface finish from machining can typically be felt through the coating.

Something has to hold some oil... either the piston, or the bore (cross hatch in the honing), or sometimes both.

PM
 
In the model engine world chrome plating is much better than nikasil so I don't know where that info came from.

Chrome plating wouldn't smooth the surface unless it was machined afterwards. It could be done with channel porosity like aircraft engine cylinder bores.

I Just thought the coefficient of friction would be less in an iron bore. Maybe it's not cost effective or just against the rules? Seems to work good in my tater digger.
 
The Model RC engines are a joke. I personally have been to 3W and DA. I have 100's of dyno hours on their smaller stuff from 28cc to 100cc. Nothing comes close to a properly plateau honed Nikasil cylinder is much more durable as in last longer. As the hours build it also looses less power. Chrome is cheaper to apply in the way it is done on those small engines.
 
IDK if you look at HP per CC then model engines rule. OS Max, the largest manufacture of model engines went to nikasil to save money on their sport engines but still use chrome for the high performance truggy motors. Maybe it's different in the larger sizes for some reason.
 
IDK if you look at HP per CC then model engines rule. OS Max, the largest manufacture of model engines went to nikasil to save money on their sport engines but still use chrome for the high performance truggy motors. Maybe it's different in the larger sizes for some reason.
Their HP numbers are beyond optimistic. I have lots of dyno hours on all the smaller stuff. In general HP/ displacement falls off as displacement increases. A 100cc water cooled ICA engine is an honest 30 hp or even a little more. So that means an open CR500 motor should be 150 hp.... Or if you don't like that the top end Sweedtech CR125s are 48-49hp so a cR250 should be almost 100.
 
Their HP numbers are beyond optimistic. I have lots of dyno hours on all the smaller stuff. In general HP/ displacement falls off as displacement increases. A 100cc water cooled ICA engine is an honest 30 hp or even a little more. So that means an open CR500 motor should be 150 hp.... Or if you don't like that the top end Sweedtech CR125s are 48-49hp so a cR250 should be almost 100.
You are right. Water cooled ICAs were somewhere between low and mid 30s. Even on 4 cycles power doesn't grow proportionally with displacement. Otherwise Japs wouldn't have a chance with their small engines, right? In fact F1 fastest most powerful engines were the smallest, though they didn't last much and they were during the Turbo era. I am sure top bike manufacturers wouldn't mind charging some extra dollars to have a more reliable engine if chrome would help, especially for street bikes, so my guess is the perfect balance cost/reliability/performance.
 
You are right. Water cooled ICAs were somewhere between low and mid 30s. Even on 4 cycles power doesn't grow proportionally with displacement. Otherwise Japs wouldn't have a chance with their small engines, right? In fact F1 fastest most powerful engines were the smallest, though they didn't last much and they were during the Turbo era. I am sure top bike manufacturers wouldn't mind charging some extra dollars to have a more reliable engine if chrome would help, especially for street bikes, so my guess is the perfect balance cost/reliability/performance.
Chrome is softer. Even "Hard Chrome". The Si part is Silicon Carbide. You can sand chrome away with silicon carbide. Plateau honed Nikasil has all these beautiful valleys to hold the oil.
 
The only thing that is hard for me to believe is a CR making 50 hp when that is the hp declared for a KZ like a Modena or TM which are more powerful and proven faster, and I do have a Modena.
 
The only thing that is hard for me to believe is a CR making 50 hp when that is the hp declared for a KZ like a Modena or TM which are more powerful and proven faster, and I do have a Modena.
Those are the Swedetech house motors for their drivers. Customer motors are a lot less and obviously stock '99 and '01 are even less than that. I've talked to the insiders. The house open motors had ridiculously narrow power bands and were so opened up that routinely the port wall would fail leaking water into the engine. They were supposed super hard to drive. That said it it's really easy to make a dyno say what ever you want. I'd take a modern TM or any KZ motor as far as that goes. Notice how folks are offing the CR's? the ICP cup enduro last weekend the winning KZ was over a second a lap faster than the second place CR. In the open class Hegar's CR kicked butt.
 
Those are the Swedetech house motors for their drivers. Customer motors are a lot less and obviously stock '99 and '01 are even less than that. I've talked to the insiders. The house open motors had ridiculously narrow power bands and were so opened up that routinely the port wall would fail leaking water into the engine. They were supposed super hard to drive. That said it it's really easy to make a dyno say what ever you want. I'd take a modern TM or any KZ motor as far as that goes. Notice how folks are offing the CR's? the ICP cup enduro last weekend the winning KZ was over a second a lap faster than the second place CR. In the open class Hegar's CR kicked butt.

As I say I do own a Modena KZ and it is way faster than a built CR. Modena offers like 3 options, and I have one especially built from factory with custom made pipe and piston, etc. One to 2 seconds is usually the difference at most tracks between a Sweede tech or any other shop CR and a KZ. Now if we talk about open engines we need to compare apples to apples and find an open KZ since all the KZsaround were built subject to FIA/CIK regulations. Last TMs are also ridiculously fast.
 
As I say I do own a Modena KZ and it is way faster than a built CR. Modena offers like 3 options, and I have one especially built from factory with custom made pipe and piston, etc. One to 2 seconds is usually the difference at most tracks between a Sweede tech or any other shop CR and a KZ. Now if we talk about open engines we need to compare apples to apples and find an open KZ since all the KZsaround were built subject to FIA/CIK regulations. Last TMs are also ridiculously fast.
Agree, I was refering to open Swedtech CRs from past years. The new stuff is relatively tame. In general everyone has switched away from the CRs here except for the CR specific classes.
 
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