250r overheating

[xtracrispy]

Looks like you discovered the cause of your overheating issues. What’s your plan? Bore and hone and new piston or a big bore kit? LOL

That's what I'm trying to figure out now. I haven't fallen in love with the bike like I had hoped I would so its hard to commit to dumping a bunch of money in it, but maybe it just needs more mods 

 

[Sausage450r]

Here is your overheating issue.

coolant ports on gasket are blocked.

im bettin this thing blew a head gasket and the owner found all that you are finding and decided to unload this bike asap while prices are up and she still had compression

 

[Rorschach]

That's what I'm trying to figure out now. I haven't fallen in love with the bike like I had hoped I would so its hard to commit to dumping a bunch of money in it, but maybe it just needs more mods 

A new piston, gaskets and a bore job should only set you back a few hundred bucks. The guy that does my boring charges $75 to bore match your piston and chamfer the ports. For a little more he'll do some port work. A new top end on a Honda 250 is super easy and cheap to do.

 

[xtracrispy]

Here is your overheating issue.

coolant ports on gasket are blocked.

im bettin this thing blew a head gasket and the owner found all that you are finding and decided to unload this bike asap while prices are up and she still had compression

I’m afraid you’re probably right.
 

The small intake side coolant holes of the head gasket were definitely partly occluded by RTV. 

Took the cylinder off to check for rod bearing play. Seems like there’s a little in the big end. More evidence of porting, no marking or signature so who knows who did it. 
Here’s some more pictures, everyone likes pictures. 

 

[Sausage450r]

Ya that vertical scoring is no good. Wanna see some good cross hatching helps keep the rings lubed. Side to side play is normal within reason up down is no good

 

[Big_Daddy_Jp]

You can google how much play there should be on the rod from side to side. You will be surprised at how much is within tolerance. You shouldn’t feel any up and down. Have it honed and put a new top end in it. Probably about $350 for everything. Don’t use any silicone on the gaskets as stated earlier. Make sure your jetting is correct and most importantly your needle. When the carb is dialed in that 250r will fly!

 

[IDriveon3Wheels]

That's what the stock head gasket is supposed to look like.  The coolant passages are smaller/partly blocked at the rear of the cyulinder to divert more coolant towards the front, hotter section of the cylinder, although you should never use sealant on the head gasket.  I will say that I've never seen the top of a piston look like that.  Looks like tar, really odd.  I'd wager that the porting could be at least part of your issue.  Unless the person who did it really knows what they're doing, it's easy to end up with an engine that just doesn't run right.

BTW, Golden Spectro at 53:1 (12oz in 5 gal) is the only oil I have used for 50+ years, including racing in the desert back in the 70s/80s.  32:1 is too much oil, and will actually result in a lean jetting condition (fuelil is not the same as fuel:air).  Yes, you can somewhat compensate for it with richer jetting, but that's just putting a band-aid on it.

 

[wopachop]

32:1 is too much oil, and will actually result in a lean jetting condition (fuelil is not the same as fuel:air).  Yes, you can somewhat compensate for it with richer jetting, but that's just putting a band-aid on it.

Nah man. I get what youre saying but its too general. You can very easily have a 2 stroke running super rich and also running 32:1.