Break-in procedure

[yz250-ridercro]

Is the procedure of break-in the same when i change the cylinder and the piston, or just the piston???
Should i use a 1:15 mix or 1:32??(in yamaha yz250 manual it says 1:15)
Can i adjust my ignition timing without that timing tool?? If i can how??

Thanks

 

[hot125mod]

32:1 is fine i have heard it is better to use a castor or non synthetic oil for break in. do you want me to write up the break in procedure I have a really good one.

 

[Patman]

Just use the search feature on DRN and you'll get loads of "procedures", then pick one that seems reasonable to ya'.

 

[yz250-ridercro]

32:1 is fine i have heard it is better to use a castor or non synthetic oil for break in. do you want me to write up the break in procedure I have a really good one.

Can you write me your procedure??

 

[hot125mod]

It's a matter of putting the new piston through several heat-cool cycles, and allowing the new bearings to match the surfaces.

1. Start the engine and warm it up gently, with small throttle blips to keep it from loading up. No high revs! After it is completely warm, shut it off and let it cool completely.

2. Repeat #1.

3. Warm the engine, then ride it gently, using no more than 1/4 throttle, for about 15 minutes. No high revs! Let the engine cool completely.

4. Repeat #3, this time using 1/2 throttle.

5. Repeat #3, going to 3/4 throttle. After 15 minutes, do a couple of full throttle runs through 2 or 3 gears to ensure that rings are properly seated. Let the engine cool completely.

6. Now you are ready to rip. Don't wring the snot out of the engine for the first 1/2 tank or so of gas, and you'll be fine. As CM says, it is recommended to pull the cylinder after break-in and sand any high-spots from the piston, but I don't do this, and have never had any problems.

I probably use excessive caution with my break-ins, but I use forged pistons, which are very seizure-prone during break-in if not done properly, so I err to the side of caution.

 

[Kwakasaki]

It's a matter of putting the new piston through several heat-cool cycles, and allowing the new bearings to match the surfaces.

1. Start the engine and warm it up gently, with small throttle blips to keep it from loading up. No high revs! After it is completely warm, shut it off and let it cool completely.

2. Repeat #1.

3. Warm the engine, then ride it gently, using no more than 1/4 throttle, for about 15 minutes. No high revs! Let the engine cool completely.

4. Repeat #3, this time using 1/2 throttle.

5. Repeat #3, going to 3/4 throttle. After 15 minutes, do a couple of full throttle runs through 2 or 3 gears to ensure that rings are properly seated. Let the engine cool completely.

6. Now you are ready to rip. Don't wring the snot out of the engine for the first 1/2 tank or so of gas, and you'll be fine. As CM says, it is recommended to pull the cylinder after break-in and sand any high-spots from the piston, but I don't do this, and have never had any problems.

I probably use excessive caution with my break-ins, but I use forged pistons, which are very seizure-prone during break-in if not done properly, so I err to the side of caution.

Well put!,,,,,, finally someone that understands heat cycles on break in proceedures. :laugh:

 

[hot125mod]

thank you

 

[kx125412]

I did the first heat cycle, then rode her easy with some strong bursts, then rode it like normal with no problems and it broke in perfectly fine.

 

[makyz125]

Are forged pistons more prone to a cold seize if you don't warm up the bike properly? Or are cast pistons more likely? Or is there a differnce? :blah:

 

[hot125mod]

yes a forged piston takes longer to start its thermal expansion because the material is more dense so take care if you have one. once the radiator is too hot to put your bare hand on you should be good to go.

 

[Bigdogdaddy69]

Im happy to see no one said to run tanks of gas through the bike then its broken in.