new to me 1986 Honda 250sx couple questions

[MotorCity]

Hey all,

Just picked up a 1986 Honda 250 sx. Hasnt ran in a while and has flat tire in rear

1). the guy I bought from said to put in "green slime" and ride the machine, and it should fix the flat. Does anyone know about "green slime"? Or should I just spray on some soap water, fill with air, look for flat, and repair (rim leak, hole in tire?).

2). Anything else I should look out for on these machines?

3). Isnt the rear axle ratio different on the 250sx relative to the 250es big red?

4). Anyone know of any sites with aftermarket plastics?


I have a 1985 Honda big red, and i"m surprised at how much "smaller" the 250 sx is...I understand they are similar machines (same engine, shaft drive)... I"m "expecting" this to be more of a "sporty" machine, relative to my big red...

Any and all input anyone can provide, I would appreciate.

Thank you in advance.

Have a great weekend.

[shortline10]

1 definitely look for the leak first , green slime is ok and does a decent job of sealing leaks .
3 yes the ring gear is one tooth larger on the 250es but the 250sx also uses a 22 “ tires we’re the 250es uses a 25” tire so their about the same in the end .
4 maier sells the fenders

[350for350]

I don't like Slime myself. From personal experience, it seems to last great for about two years. Then the tire starts leaking again. I've also seen it rust rims from being inside the tire. I prefer Amerseal brand tire sealer. It lasts longer and doesn't rust the rim. Others may have different experiences than me.

[ps2fixer]

I've seen green slime rust rims too, I've used "Tire Sealant", jug sold at TSC. Isn't stuff to fix any problem, it's clearly best to repair the tire or replace than to patch it with a temp fix like liquid sealant. Also the liquid sealant can make the tire off balance, so if you do high speed riding much, it can vibrate and add extra wear to all the parts related to the vibration. AKA never put this stuff in a car tire except in emergency situations where getting home is the goal, not being cheap by not fixing/replacing the tire. Some people use it as a preventive maintenance item, like put it in their lawn mower tires, so if there's a small puncture it will seal and not cause them issues. Seems a lot of mowers have really thin tires, a thorn bush can make a stock MTD tire leak (know a guy that always has flat tire problems with his mower and it's small pin holes in the side walls typically).

As far as common issues for the ES/SX engine

• Shifter pin sometimes comes loose, basically shifter doesn't want to return to center after a shift, simple fix, just bolt the pin back in, locktite to keep it in.
• One way bearing on primary clutch, this effects the kick starter (slips when bad), engine braking, and a typical sign of it going bad is when you turn the engine off you hear a whirl noise on the right side of the engine.
• Axles tubes are prone to getting water in them, if you do mudding etc, take the axle tubes apart and replace the O-rings, or use RTV. It can wick into the splines that the ring gear rides on and rust them and cause problems, I've had two bad axles from this problem but I'm in Michigan, lots of swap/mud areas to ride and plenty of rain to keep them full.
• Oil filter can be installed backwards, just make sure when you replace it, it goes in the same direction as the old one, or better yet look at the photos in the service manual. If it's installed backwards it can starve the engine of oil, I think the cam generally gets starved first and is most noticeable there. Haven't ran into this problem myself though.
• Drive shaft tube seals are aging, so check if yours is cracked/ripped. This can allow water in the drive shaft axle tube and rust the pinion gear nut and if the pinion seal is bad can get water in the diff.

Besides that, it's just typical stuff, tires aged, CDI boxes aging, bulbs burnt out, wiring getting brittle/breaking, bearings wearing out from 30+ years of use (steering stem, front wheel bearing, rear axle bearings, rear diff bearings, and swing arm bearings). Never hurts to check your diff fluid too, it should look like gear lube, not milk (water) after a short ride to mix it up.

Just stuff off the top of my head, I'm sure there's something I missed. Overall it's a Honda, generally not a lot of problems except age related and normal wear of expected to wear out parts.

[MotorCity]

Thanks all for the input. PS2Fixer, good post. I plan on doing a lot of mudding, so I will be checking these seals. BTW, whereabouts you in Michigan?

[ps2fixer]

If you know Midland, that's my general area, north west of Saginaw.