Posts
2901
Joined
4/17/2009
Location
High Desert, CA
US
Edited Date/Time
10/20/2014 7:32pm
Ok so after ignoring my project for a week this Saturday was time to take a look at the heart of the matter. The engine. I also detail out everything that is not going to get replaced. Again the frame! I swear it looks like it rolled off the showroom floor. As much as I would like to strip it down and go Factory white am not. I know this will rub a lot of people the wrong way, but I decided to not to a replica but a combo of the factory look (96 1-800-collect). And also money ain't what it used to be so The red will stay.
Again, I have never done a 2 stroke top end. I do have decent mechanical abilities. But I am learning my way through this. So tell me what you think. Looks to my like this dude ran this bike very rich (wait till you see the power valve). And in doing so probably kept the engine well lubed. The cylinder walls appear to still have the hone marks from the last go around. There are barely any vertical marks or scoring. And the wall surface is as smooth as a mirror when i run my finger nail around it.
From there I checked the play in the rod bearing. I rotated the crank all the way around and checked for up and down play and there is absolutely zero. I triple checked because I was a little giddy as this means (if I am correct ?) that the bottom end is still good to go.
So I am thinking new piston and rings. Opinions? Take a look at the cylinder and tell me what you think?
Is this normal?
Again, I have never done a 2 stroke top end. I do have decent mechanical abilities. But I am learning my way through this. So tell me what you think. Looks to my like this dude ran this bike very rich (wait till you see the power valve). And in doing so probably kept the engine well lubed. The cylinder walls appear to still have the hone marks from the last go around. There are barely any vertical marks or scoring. And the wall surface is as smooth as a mirror when i run my finger nail around it.
From there I checked the play in the rod bearing. I rotated the crank all the way around and checked for up and down play and there is absolutely zero. I triple checked because I was a little giddy as this means (if I am correct ?) that the bottom end is still good to go.
So I am thinking new piston and rings. Opinions? Take a look at the cylinder and tell me what you think?
Is this normal?
yes rings like that are completely normal. funny video but its good youre asking questions.
you compress the rings together when you slide the cylinder back on and they expand inside the cylinder to make a tight fitment.
watch this video next for some extra learning:
https://www.youtube.com/watch?v=ViEjQ7B1uM8
Also, what year CR250? Does it still have the stock carb? What jetting is in the carb? What does the silencer packing look like?
These answers will help analyze what's going on.
In conclusion, grab a micrometer and check your parts to try and re-use them as it looks VERY good. I rebuilt a top end that had 4 hours on it and it looked a lot worse. You lucked out man!
The Shop
Stock Carb. 175 main. 2nd clip from the top. Not sure on the air screw or pilot.
Black Spooge all over the swingarm, out the end of the silencer. Silencer feels like it weighs 10 lbs.
I am sure the prev owner ran a rich mixture and roxe it like a grandma.
If I remember correctly, I think I usually ran a 170-172 in my CR250's back in that time frame unless it was cold out, then 175-178.
Post a reply to: My top end. Opinions?