piston pins keep failing

[ben4221]

yeah ill try running a bit richer and any recommendations for the type of oil i was using penrite air cooled 2 stroke oil it ran fine and had very little unburned oil spray out the exhaust but it does go thru pins like crazy, i have tried tcw3 boat oil and it sprays oil every where out the top of the exhaust but seems to not rattle as much at high rpm. and ive only ran it on premium 98 since having the first pin go, i used to run it on e10 ethanol every time before it was heavily ported, the bore and case have been welded where the transfer ports are and they've been opened right up . the carby is on the largest jet that i have aswell so i might have to order some bigger ones in cause it feels a bit lean at high rpm. and another thing is the gold head gets way hotter than the smaller cast heads i think its cause the cooling fins are too thick but i dont think that would cause pins to fail

 

[LewieBike]

Running from the cops? You want to live expensively apparently. I don't think that the stock pins and upper needle bearings, at least if my bike's 48cc engine is an example are really well engineered.

My upper needle cage assembly has about 4 or more mm end float.

This, I assume, is typical for these engines.

Maybe when you replace your crank next time get a Husky 10mm needle upper rod bearing, start using a little richer oil and stop running from the cops. They're eventually going to get you and if your description is on file as a 'eluder' you're gonna get smacked really hard ticket wise.

 

[ben4221]

mate i dont know what country your from but in australia nsw in particular these bike are highly illegal i once stopped for them 5 years ago and ended up having to appear in court and lost my car licence for 6 months haha. ive ditched then on a yz450 and cbr1000 and would prefer the motorized bike any day of the week to out run them just go through a park, havent been fined on it in 5 years or paid rego for that matter so id say say its living quite cheaply

 

[LewieBike]

mate i dont know what country your from but in australia nsw in particular these bike are highly illegal i once stopped for them 5 years ago and ended up having to appear in court and lost my car licence for 6 months haha. ive ditched then on a yz450 and cbr1000 and would prefer the motorized bike any day of the week to out run them just go through a park, havent been fined on it in 5 years or paid rego for that matter so id say say its living quite cheaply

Yep, I know about Australia's motored bike rules.

As a seppo, I'm in one of the few states in the USA that hasn't completely made IC engined motorized bikes illegal, but we're getting there. If you're confident of your eluding skills, more power to you. Been there, got the teenage performance awards over early in my life.

I'm in my 60's now, I don't elude anyone.

The other thing to consider, not knowing your local average daytime temperatures, especially if you have large changes in humidity in addition to daily temp changes, which could richen and (or) lean your engine's mixture significantly. Try running on the slight side of rich with a 25:1 fuel: oil mix?

 

[ben4221]

yeah actually i never had to rebuild it over the winter its only been happening since the start of summer so that might be it, i used to run it on a tiny jet in the winter but had to keep putting bigger ones in after it was ported ill try running it a with the needle on the richest setting and see how that goes and is synthetic or mineral oil better for not flogging out pins

 

[LewieBike]

yeah actually i never had to rebuild it over the winter its only been happening since the start of summer so that might be it, i used to run it on a tiny jet in the winter but had to keep putting bigger ones in after it was ported ill try running it a with the needle on the richest setting and see how that goes and is synthetic or mineral oil better for not flogging out pins

I'm using synthetic on all of my 2 cycle bikes and saws now. And decent synth oil like Lucas, Yamalube, Shell helix or Golden Spectro or... There's a lot of folks who like Motul, it's really pricey as a Swiss made lube though. You want premix, for aircooled engines formula oil, injection and marine oils tends to have a thinning agent.

Could start a nice argument thread talking about oils I'd rather listen to them ( Midnight Oil) instead.

 

[ben4221]

I'm using synthetic on all of my 2 cycle bikes and saws now. And decent synth oil like Lucas, Yamalube, Shell helix or Golden Spectro or... There's a lot of folks who like Motul, it's really pricey as a Swiss made lube though. You want premix, for aircooled engines formula oil, injection and marine oils tends to have a thinning agent.

Could start a nice argument thread talking about oils I'd rather listen to them ( Midnight Oil) instead.

haha yeah ill go get some quality synthetic oil and fix the end play in the rod and hopefully with a new pin and bearing it will be good. the current pin and bearing was put in on tuesday so its nearly lasted a week with no noise at all but ive been going extra slow on it. ill mix up some 15:1 oil and set the carby needle on richest and see how long it will last at 70 to 80kmh, ive raised the exhaust port .2 of a mm from what it was before so should easily get it up to 80

 

[ben4221]

it has way more power from midrange to top end with the exhaust mod but its definitely not healthy over the 70km mark, i forgot all about making a spacers for the wrist pin so ill rip it appart when it cools down and fix that i also got some synthetic blend castor oil so that might help lubricate the little end a bit more

 

[ben4221]

finally got the spacers into the wrist pin it was extremely difficult , i ended up cutting 2 coils of spring off the carby slide spring im just hoping that it doesnt come off the wrist pin at full throttle. it hold the liitle end bearing in the centre of the rod with slight spring tension so if this holds up it should be perfect, i broke the 4 base gaskets in the process so the piston hits the head with 2 head gaskets but ive fitted a new head to it that i ported out so the piston dome can come past the block 2mm the top ring is just bellow the block so it should be fine. i havent bothered to run a head gasket either as the piston seems to not hit the new head, ill bolt the motor back up and see how it goes it should have heaps of compression with no base or head gasket

 

[Lukesky36]

when you do put a new pin in squirt a happy amount of oil in the needle bearing your better off having 2 base gaskets and 0 head gasket if your looking for high rpm changing the port timing for hp 1 base gasket and 1 head gasket seems to work well for low end all day thats if your running a stock jug compression is important but you should only do compression changes on the main head and the port timing's with the gaskets