025 will not start

[drogueman]

I just finished up putting new rings and crank seals in it and got it all back together. It has 100 psi but it doesn't hold the pressure. I did do a few seconds of honing on the cylinder so I am guessing the rings need time to seat. It kicks and sputers but will not run. The only thing I can think of is maybe the carb ajustments or bad diaphram . I tried a little gas down the carb but it didn't help. Spark plug seems to get very wet after a dozen pulls. I know what you guys said , it needs 125 psi or better but I was hoping the rings would seat and it would get better. Sure appriciate any help !

 

[windthrown]

Naw, at 100 psi there is not enough compression, and if that is leaking down then the engine will not run. I have 110 psi in my scored 250. Its starts and runs for about 5 seconds and dies. Rings seating should be minor issue with compression... maybe 10 pounds at most. You are suffering the likes of 50-70 missing psi.

 

[TRI955]

Not enough compression, with break in you'll only gain maybe another psi. You still have problems, sorry.

Thanks windthrown, you beat me to it.....

How does one become a Proud Member Of The Official Rep Ho Club? How many members are there??

 

[drogueman]

Ok, well I have about $70 in rings and crank seals , is there anything I can do to bring it back to life ???

 

[windthrown]

Wow, that is a lot to put into a DOA 250. I have sold complete used 025 engines for about that. Seals and rings should seal that baby up. Are the rings in the right position? Did you hone the cylinder?

 

[Dan_IN_MN]

What was the condition of the piston and cylinder?

Ok, well I have about $70 in rings and crank seals , is there anything I can do to bring it back to life ???

What was the condition of the piston and cylinder? Have you done engine work before?

Dan

 

[drogueman]

Yes I did hone the cylinder but only for a few seconds, do you think it needs more honing? I had the rings all lined up perfectly when I put it together, maybe they got some dirt on them and got stuck in the grooves of the piston. I am going to tear it apart again and check everything.

 

[drogueman]

The pist was in good shape , it just had a lot of carbon built up on it and caused the rings to stick in the grooves. The cylinder was in very good shape too not a scratch. It didn't run when I got hold of it and as it does now only had 100 psi.

 

[scotclayshooter]

How about pop the plug out and put a few cc of 2 stroke oil onto the piston top and swill it around that should give it a little more compression,
Maybe just enough to start and the combustion will force the rings out and bed in.

When you put the cylinder on did you wash out the crankcase with mix?
I did this with my 262XP and didnt let it evaporate off properly and it flooded for a long time! I have a couple of blisters for my trouble lol

 

[drogueman]

What was the condition of the piston and cylinder? Have you done engine work before?

Dan

Sorry no, I am just trying to learn at my own expence and pace. I am still learning as you can tell but I do like to do this kind of work . Thanks for helping.

 

[drogueman]

How about pop the plug out and put a few cc of 2 stroke oil onto the piston top and swill it around that should give it a little more compression,
Maybe just enough to start and the combustion will force the rings out and bed in.

When you put the cylinder on did you wash out the crankcase with mix?
I did this with my 262XP and didnt let it evaporate off properly and it flooded for a long time! I have a couple of blisters for my trouble lol

I will try that idea before I tear it apart. I did clean everything up and it was very clean and dry. I have to keep trying , I have too much money invest now, lol. I see no reason why this thing should not have the proper compression unless the rings are stuck again.

 

[scotclayshooter]

I will try that idea before I tear it apart. I did clean everything up and it was very clean and dry. I have to keep trying , I have too much money invest now, lol. I see no reason why this thing should not have the proper compression unless the rings are stuck again.

The usual method is to break the old ring and use it to clean the ring groove.
And unless the cylinder is scored Lakeside says theres no need to hone the cylinder on a 2 stroke.

 

[drogueman]

The usual method is to break the old ring and use it to clean the ring groove.
And unless the cylinder is scored Lakeside says theres no need to hone the cylinder on a 2 stroke.

Thanks, I will take all this advise and put it to good use. I still have a few pieces of the old ring I can use to clean out the piston grooves, I feel sure this is the problem.

 

[Dan_IN_MN]

Did you use 2 stroke oil when you assembled it?

I will try that idea before I tear it apart. I did clean everything up and it was very clean and dry. I have to keep trying , I have too much money invest now, lol. I see no reason why this thing should not have the proper compression unless the rings are stuck again.

Did you use 2 stroke oil when you assembled it?

Dan

 

[andrethegiant70]

You know, I'm just spitballing here, but there are TWO different diameters of 025 piston, 42 and 42.5mm. Is it possible that you got the wrong rings for the piston? I honestly don't know if you could get them to install, but I think it may be possible to squeek the 42mm rings on a 42.5 mm piston. That would explain your troubles. The other thing I would do is mic your piston down around your piston skirt.... if the diameter is too small around the skirt, the piston might not seal very well.

Good luck.

 

[Dan_IN_MN]

Make sure you only take out carbon!

Thanks, I will take all this advise and put it to good use. I still have a few pieces of the old ring I can use to clean out the piston grooves, I feel sure this is the problem.

Make sure you only take out carbon! That shiny stiff (Aluminum) needs to stay with the piston!

 

[Fish]

I just finished up putting new rings and crank seals in it and got it all back together. It has 100 psi but it doesn't hold the pressure. I did do a few seconds of honing on the cylinder so I am guessing the rings need time to seat. It kicks and sputers but will not run. The only thing I can think of is maybe the carb ajustments or bad diaphram . I tried a little gas down the carb but it didn't help. Spark plug seems to get very wet after a dozen pulls. I know what you guys said , it needs 125 psi or better but I was hoping the rings would seat and it would get better. Sure appriciate any help !

I would look at that flywheel's key, myself..... well first.....

 

[drogueman]

You know, I'm just spitballing here, but there are TWO different diameters of 025 piston, 42 and 42.5mm. Is it possible that you got the wrong rings for the piston? I honestly don't know if you could get them to install, but I think it may be possible to squeek the 42mm rings on a 42.5 mm piston. That would explain your troubles. The other thing I would do is mic your piston down around your piston skirt.... if the diameter is too small around the skirt, the piston might not seal very well.

Good luck.

Anything is possible but i just checked my packing list and it did say (piston rings 025 42mm pre 2000) so I am hoping they are the correct ones. I will know more after I get it apart, thanks for your input.

 

[drogueman]

I would look at that flywheel's key, myself..... well first.....

Fish I did remove the flywheel nut and took a look, it was still lined up. If you remember I had originally busted the key out on the flywheel and took a chance and filed in a groove on the flywheel and got a key to fit . It seems to be holding so far but has not run yet which will be the ultimate test. I haven't forgot you have a spare if need be. I still think the rings are stuck because the compression is the same as when i tested with the bad rings that were stuck. Guess i didn't do a good job cleaning up the grooves in the piston.

 

[litefoot]

I just finished up putting new rings and crank seals in it and got it all back together. It has 100 psi but it doesn't hold the pressure. I did do a few seconds of honing on the cylinder so I am guessing the rings need time to seat. It kicks and sputers but will not run. The only thing I can think of is maybe the carb ajustments or bad diaphram . I tried a little gas down the carb but it didn't help. Spark plug seems to get very wet after a dozen pulls. I know what you guys said , it needs 125 psi or better but I was hoping the rings would seat and it would get better. Sure appriciate any help !

If your compression tester isn't holding pressure, then the problem may well be your tester, not the saws compression. Can or did you try it on another saw?