Business question for the seasoned Engine Builders?

[Robbins Racing]

I rebuilt a two stroke and it cold seized on my dyno while breaking it in resulting in the need to replace the piston, piston pin and roller bearing. I ate the cost of all the replacement parts and labor to rebuild the top end again. Going on my 3rd year rebuilding engines for the racers at my local track and was wondering how you handle the situation were something gets damaged or broken when the engine is in your possession?

Thanks

 

[Chipg56]

Fix it, on your dime, just like you did.

 

[Colt sr]

Be transparent with your client as well about it. Some get to be impatient about how quickly they get their engine back.

 

[spincycle]

I rebuilt a two stroke and it cold seized on my dyno while breaking it in resulting in the need to replace the piston, piston pin and roller bearing. I ate the cost of all the replacement parts and labor to rebuild the top end again. Going on my 3rd year rebuilding engines for the racers at my local track and was wondering how you handle the situation were something gets damaged or broken when the engine is in your possession?

Thanks

Not a 2cycle engine expert by any means…what does “cold seized” mean? Thx! dr

 

[Robbins Racing]

Not a 2cycle engine expert by any means…what does “cold seized” mean? Thx! dr

Piston heated up faster than the cylinder which caused the seize. Some also call it a 4 corner seize.

 

[spincycle]

Piston heated up faster than the cylinder which caused the seize. Some also call it a 4 corner seize.

Is that caused by an overly lean condition? Or maybe not enough oil in the mixture?

 

[sundog]

Put enough clearance on the piston so it doesn't do that then don't run it, let the customer blow it up. Some customers get more clearance than others lol.

 

[spincycle]

I’ve heard of something that 2stroke builders do, though I don’t know the first thing about it…Nikisil (sp?)coating the cylinder wall? Is it something that could help?

 

[ABR #69]

I’ve heard of something that 2stroke builders do, though I don’t know the first thing about it…Nikisil (sp?)coating the cylinder wall? Is it something that could help?

Most karting two strokes are steel bore, so aren't usually Nikasil plated. So this leads to the aforementioned cold stick, since the steel bore heats up slower than the aluminum piston.

Coincidentally Nikasil plating does actually help with cold sticks, because it's coated directly on Aluminum usually. Which expands nearly the same as the Piston. But, setting the correct piston clearance and allowing the engine to warm up sufficiently before seeing heavy loads or high RPM will generally be enough to not have cold sticks in steel bores. Another problem is that people generally like to run Methanol and this further increases the complications. Steel bores can be Nikasil plated, but that doesn't eliminate the cold sticks issue since the underlying metal is still Steel and expands slower.

It's not really due to being lean or not enough oil usually. More oil will actually mean it leans the engine out if the oil is increased with the same jetting. So jetting correctly with the amount of oil you need for the application first will help insure it doesn't stick due to lack of oil.

 

[spincycle]

Most karting two strokes are steel bore, so aren't usually Nikasil plated. So this leads to the aforementioned cold stick, since the steel bore heats up slower than the aluminum piston.

Coincidentally Nikasil plating does actually help with cold sticks, because it's coated directly on Aluminum usually. Which expands nearly the same as the Piston. But, setting the correct piston clearance and allowing the engine to warm up sufficiently before seeing heavy loads or high RPM will generally be enough to not have cold sticks in steel bores. Another problem is that people generally like to run Methanol and this further increases the complications. Steel bores can be Nikasil plated, but that doesn't eliminate the cold sticks issue since the underlying metal is still Steel and expands slower.

It's not really due to being lean or not enough oil usually. More oil will actually mean it leans the engine out if the oil is increased with the same jetting. So jetting correctly with the amount of oil you need for the application first will help insure it doesn't stick due to lack of oil.

With no experience and not a lot of help with tuning a 2cycle, I tried running a kt100 and a 131 sudam for 2 seasons and had the issue of “sticking the piston” with both on a few occasions, I had never heard of this “cold stick” until now, almost certain from your description that it very likely was a cause of the problems I had…even still, running the 2 strokes was by far the funnest times I’ve had in my time in karting…

 

[CarlsonMotorsports]

I rebuilt a two stroke and it cold seized on my dyno while breaking it in resulting in the need to replace the piston, piston pin and roller bearing. I ate the cost of all the replacement parts and labor to rebuild the top end again. Going on my 3rd year rebuilding engines for the racers at my local track and was wondering how you handle the situation were something gets damaged or broken when the engine is in your possession?

Thanks

Sounds like you did the right thing. It can be tough to swallow your pride and eat your mistakes, but it's still the right thing to do. Occasionally you'll find yourself doing "warranty" work that wasn't necessarily your fault too. It's just part of the job.
Hopefully the cylinder cleaned right up and didn't require an overbore piston. Engine building can be a very humbling experience, especially early on when you're learning.


-----
Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
www.youtube.com
35 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com

 

[Chipg56]

More oil will actually mean it leans the engine out if the oil is increased with the same jetting. So jetting correctly with the amount of oil you need for the application first will help insure it doesn't stick due to lack of oil.

Absolutely.

 

[fatboy1dh]

Sounds like you did the right thing. It can be tough to swallow your pride and eat your mistakes, but it's still the right thing to do. Occasionally you'll find yourself doing "warranty" work that wasn't necessarily your fault too. It's just part of the job.
Hopefully the cylinder cleaned right up and didn't require an overbore piston. Engine building can be a very humbling experience, especially early on when you're learning.

Brian is spot on. There will be a few lessons learned. Take them on the chin and keep moving forward. Open and transparent is the only long term viable option. When we first started, I had to call a couple of customers and tell them their clip was wrong in their carb slide 100% because I forgot to set it (we were dynoing at the time with the cap and slide staying on the dyno). . The honesty was greatly appreciated and might even buy you some credibility.

 

[Robbins Racing]

Sounds like you did the right thing. It can be tough to swallow your pride and eat your mistakes, but it's still the right thing to do. Occasionally you'll find yourself doing "warranty" work that wasn't necessarily your fault too. It's just part of the job.
Hopefully the cylinder cleaned right up and didn't require an overbore piston. Engine building can be a very humbling experience, especially early on when you're learning.


-----
Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
www.youtube.com
35 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com

Ya first issue I've had and it was a engine from a local team who is my biggest customer, I notified the owner immediately. And yes simple hone job and the cylinder cleaned up no problems. Thank you very much for you input!

 

[PKS]

I spent 25 years building 4 cycles and thankfully I didn`t see a lot of failures like that. As Brian said sometimes it happens and you just have to make it right weather it was a parts failure or mistake. customer satisfaction goes a long way.

 

[Robbins Racing]

Brian is spot on. There will be a few lessons learned. Take them on the chin and keep moving forward. Open and transparent is the only long term viable option. When we first started, I had to call a couple of customers and tell them their clip was wrong in their carb slide 100% because I forgot to set it (we were dynoing at the time with the cap and slide staying on the dyno). . The honesty was greatly appreciated and might even buy you some credibility.

Yes lesson learned. I'm getting better, faster and more confident with every engine I build.

 

[Robbins Racing]

I spent 25 years building 4 cycles and thankfully I didn`t see a lot of failures like that. As Brian said sometimes it happens and you just have to make it right weather it was a parts failure or mistake. customer satisfaction goes a long way.

This one was my mistake. It was the 5th engine I ran in that day, maybe a little impatient and didn't let it warm up long enough. Sinking feeling when a engine is spinning at 14K and just stops...

 

[Robbins Racing]

Put enough clearance on the piston so it doesn't do that then don't run it, let the customer blow it up. Some customers get more clearance than others lol.

This is the main reason I built a Dyno. Giving a customer a fresh engine and letting them fire it up for the first time felt like rolling dice. Break it in on the dyno and you can hand it to the customer with little worries.

 

[sundog]

Yes, of course I was just clowning. Racers are notorious for pushing things beyond their limits in desperation, ignoring all good advise. I keep the engine rich and cool at idle with no load for the first couple of minutes to let the parts smooth out just a little. Even if you have enough cyl to piston clearance you can still damage the seal between the piston ring and piston. If you've ever seen aluminum stuck to the bottom of a ring you know what I'm talking about. Also, don't try to get you clearance from break in, you have to hone it in. Break in is just for smoothing and mating the parts. Hope that helps.

 

[spincycle]

Yes, of course I was just clowning. Racers are notorious for pushing things beyond their limits in desperation, ignoring all good advise. I keep the engine rich and cool at idle with no load for the first couple of minutes to let the parts smooth out just a little. Even if you have enough cyl to piston clearance you can still damage the seal between the piston ring and piston. If you've ever seen aluminum stuck to the bottom of a ring you know what I'm talking about. Also, don't try to get you clearance from break in, you have to hone it in. Break in is just for smoothing and mating the parts. Hope that helps.

Curious, is the “cold sticking” thing more prevalent with alky motors more so than gas?