How hot to heat engine

[Noobi06]

Hello, how hot can I heat the 2006 engine cases in the oven to install my bearings?
On my first case I did 80 Celcius and bearings in freezer but it did not go smooth. I used the hammer quite a bit, but there is no play luckily.
On the second case, I plan on using a spray to freeze so it gets even cooler. How hot can I heat the case though?

 

[swazi_matt]

i would think you can go much higher than that safely. a quick google shows 130deg C to be safe and other mentions of up to 150

 

[Zman]

That is strange. At that temperature the bearings normally drop in easily.

 

[Noobi06]

Ok this or next week, I will try around 120-130 degrees Celcius. I am also going to put bearings in over night in the freezer. Hopefully it goes smoother.

 

[SS109]

I normally do mine at 200F for half hour and I let the bearings sit in the freezer (in a zip lock bag) overnight. Seems to always work for me. I also freeze my crank the same way and everything just drops in place.

 

[Anders]

I used 120 C last time. Didn't freeze the bearings. The old bearings just dropped out, the new ones dropped in. No hammering needed.

Sent fra min YAL-L21 via Tapatalk

 

[Noobi06]

Will try, thanks

 

[Anders]

Well, I have to admit that my memory isn't always correct.
I found a video I posted on my instagram channel when I replaced the bearings. I actualluy used a small hammer and a drift, but no serious force was needed.

https://www.instagram.com/p/CLFfP6JBHN6/?next=/

 

[Noobi06]

Im gonna heat the cases to around 140C. I am also going to freeze the bearings and also use freeze spray. Maybe it falls in, maybe not. If it doesnt, hammer and a socket or something like that and a small love tap and it should fall in.

 

[Noobi06]

Dont want to start another thread, so I might aswell just ask it here.
The 125cc is unrestricted, but many is restricted for road legal use. Many just derestrict it after inspection. What is the difference in lifetime do yall recon? The piston unrestricted should be able to go 100h+ if not driven its ass off i believe. What about when its restricted?

 

[Anders]

I run my 200cc approx 100 hours per piston. That is with an old, slow guy in the dirt.

For an unrestricted 125cc on the road I would run less than 100 hours, but only experience can tell. Type of riding, type of oil, mixing ratio etc are all factors in the equation. My advice would be tonopen it up at, say 70 hours and inspect.

For a restricted 125? Hard to tell. How resticted is it? 15 HP?

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[Noobi06]

Around 12hp restricted

 

[Anders]

Around 12hp restricted

In that case I would expect a significantly longer piston life.

 

[(F5)]

The thing about restriction of a race cylinder, is unlike a low hp cylinder where the ports are small, a race cylinder you have the same piston running over the same large ports at the same revs (unless a different cdi) just with less force pushing it down as the inlet or exhaust has been flow reduced.

 

[Noobi06]

1. So theres basically no point in restricting it?
2. When Im driving on road, should I be in high or low rpms? Some say low rpms means longer lifetime for the piston etc. Also lower fuel consumption. Some others say 2 strokes should be at high revs. Which one should i be at? Or in middle?

 

[(F5)]

It's a 125, you won't have too much choice you have to cane it. Depends on your riding but you don't want it geared too low that you are needing to change into 7th when there isn't one as that would mean super high revs.

TBH I wouldn't want to go any faster than I'd trust skinny tyres and tiny brakes. Dirtbikes on the road are a wide compromise.

 

[Noobi06]

Im having supermoto rims and tyres with better breaks.
Im thinking of having it geared so im riding around 6k rpm

 

[Noobi06]

Today, when installing crank bearing, obviously, it didnt go smooth. After some punching on the outer rim, it went in all the way. Now, when I first spun it, it was sometimes getting stuck or binding. The more I spun, the less it happend. I also installed the crank just to see if the same thing would happen. After that, it doesnt get stuck anymore. Should I replace it or is it good to go?

 

[swazi_matt]

it is always going to worry you. easier to replace now than when it is back together or breaks, and bearing are pretty cheap

 

[Noobi06]

The crank bearing is 70 fuc*** dollars. I really dont want to buy 1 more as I already broke one.