1983 250R Seized Yesterday!!

[drhill]

Hi Everyone - I was out riding yesterday (in the mud!) with my new 83 250r and one of my buds had an accident on his dirtbike...so long story short, I had a newbie riding my 250r back to camp slowly and the motor seized on him! He was riding for maybe 20 minutes or so at slow speeds and motor did have a lot of mud caked on it...would this normally cause the motor to overheat?? I told him to get it up to speed occasionally but he was afraid...

In any case, I wan't rebuild it myself, according to the shop manual it looks really easy...it didn't say that I needed any special tools to install the rings on the piston, to install the rings and piston into the barrell or to install a new bushing into the small end of the rod??? Is this true or will I need some special tools or know how? I'm competent mechanically but most of my experience is with cars...

Thanks for any help or insight...you guys are the best!!!

[harryredtrike]

i doubt the mud was a factor,or the putting slow.two stroke's are in danger when your coming off high rpm's and you shut off the throttle

[KILLER]

it's not that hard . if you can turn wrenches and read a book you can do it . just have to send jug out to be bored for new piston . good luck .

[max]

i doubt the mud was a factor,or the putting slow.two stroke's are in danger when your coming off high rpm's and you shut off the throttle

The mud caked on a air cooled cylinder cruzing at slow speeds for extended amount of times could certainly cause problems. Its AIR COOLED.

The motor is super simple to work on. If you have mechanical ability, you shouldnt have any problems.

Start by just taking the cylinder off. I had this happen on my 84 and it was the intake side of the piston skirt had broken off and got down in the crank case and binded the crank from rotating. I got all the pieces cleaned out, checked crank for play. New piston/fresh bore then rocked it. If there is any doubt about the crank or bearings being bad. Split the bottom end.

You definately need a Clymer manual to help. If you need one let me know. I have one.

Good luck man

[harryredtrike]

i still doubt thats what did it.20 mins still moving i,e. air movement and so cal was only 60 something yesterday

[sbjones73]

i wouldn't think that the caking of the mud caused this. it could have gotten in hotter for sure, but enough to sieze it? i woudn't think so. got any pics of the jug, this will help.

as far as working on your engine yourself. like mentioned before. get yourself a manual and go for it. the only thing that i could recomend is get yourself a torque wrench. this will for sure help you becuase sometimes you think 25-30 ft lbs feels right then you put a torque wrench on it and it's off by like 10. that is my opinion.

[drhill]

Thanks for all the input guys! My bud was riding at about 15 mph for 20 minutes or so, finally decided to give it some gas and the bike started losing power fast until it stalled. Kicker was stuck...I freed it after a few minutes and there was no compression after that...

I just want to make sure there wasn't some other issue that could have caused this before I rebuild and run it again...I was running 40 to1 mix as per the previous owner...

A clymer would be great - does anyone have a copy online I could look at?

[Side Wayz]

I would just run 32:1.....40:1 is to lean, check your plus if its whitish to lean, if it's black and oiliy to rich, I wastold you want like a chocolate brown, see whats others say first.

[beets442]

+1.... 32:1 and keep outside of cyl clean..... Not to bad to do a top end, make sure tolerances and torque specs are correct....Account for all broken pieces, if any...if you have someone else redo cyl, give them the new piston to match to cyl.. Beets

[Macs]

With it seizing and then freeing up after a few minutes, sounds like it over heated to me.

These top ends are simple. You cant get much easier than a fooler.

[drhill]

Ok - the switch to 32-1 will be made. That makes sense...the bike ran great at 40-1, will have to adjust the carb at all with the switch?

I'll also post pics of the plug and parts once I get it apart. I just hope the bike wasn't running lean!

[RodKnockRacing]

most likely you wont have to monkey with the carb to much you will know real quick if you were running lean because you will see lots of scoring and burnt parts but most likely what happened was it got hot and the rings expanded in the cylinder causing it to seize then it cooled down and freed up it also could have busted the piston skirt and a piece jammed in the crank and moved just right causing the motor to turn you will find out

[drhill]

Pulled the head tonight but didn't get the jug off yet...I can see bad scoring on one side of the cylinder wall and metal shavings stuck to the top of the piston and underside of the head...I felt around the rest of the bore - hardly any oil...any ideas? Is this running lean or just overheated? I am concearned at the lack of oil and the heavy scoring...I'll try to get a better pic when I can get the jug off...

http://i697.photobucket.com/albums/vv340/drhill/IMG_4135.jpg
http://i697.photobucket.com/albums/vv340/drhill/IMG_4129.jpg
http://i697.photobucket.com/albums/vv340/drhill/IMG_4132.jpg

[RodKnockRacing]

looks like lean to me your definitely gonna need a new top end and most likely a fresh bore

[atctim]

By the looks of the plug in the head - it was very lean.

I have a problem with my 84 R overheating alot when I run the heck out of it. It will all of the sudden - loose power and stall out. Then it is really hard to kick over from the expansion. This is normally after a race where I am really pushing that motor hard at super high RPMs for 10 - 15 minutes at a crack.

After sitting for 30 minutes or so it always fires right back up. Hopefully you will be that lucky - but looking at the head in your pics I kind of doubt it. You need to look at your carb settings - jet sizes and needle setting. You gotta fattin her up a bit.

[drhill]

Lean...hmmm...the guy I bought it from had it sitting for quite a while, cleaned the carb and got it running...seemed like it was running really well. MAYBE...just maybe, he didn't get one of the smaller circuits cleaned all the way and the low speed riding just burned it up...I was ripping on it pretty good up until them (for a few hours) and no problems...

Does that sound like a possibility?

Carb kit sounds like a good idea...I'll get the jug off and pull the carb apart to see what jets are in it and overall condition...

[atctim]

be sure to tell us what position the clip on the needle was on. They always run best right before the blow!

[harryredtrike]

stock runs 20-1,most people are around 32-1.

[max]

I ran 40:1 on my 84 for 2 years. Never any problems!!

[Enginerd]

Here's a link to an online manual for the air cooled 250R's. It might prove to be very helpful to you. Good luck!

http://airfoolers.com/?page_id=134

[Shawn72]

DRHILL, I think all this led to your problems. If I were you, I would definately switch to a 32:1 mixture, and then set my carb to stock settings which is a 130 main and the needle in the 3rd position down. You also need to stop at first opportunity and clean cakes of mudd off the cylinder. Letting is sit on there will make it heat up much faster and run hotter. Also check around your reedcage and carb for air leaks.

[yammer hammer]

man that guy was a pansy, trailprotrailprotrailprotrailpro he was scared to open er up, and it seized. Man if someone drove my wheeler to slow and it seized I would be like wtf man pin er!!!

[Useless]

Your problem sounds similar to the time I melted mine. My main jet was fine since I usually cracked wide open often. One day I decided to make a half throttle cruise and the jetting wasn't at all right for that. I'm betting you were lean.

http://i931.photobucket.com/albums/ad152/Uselessone/81%20R%20Build/IMG00250.jpg

[Ol Deuce]

Thats Really lean man...........Ol Deuce

[Ol Deuce]

Here's a link to an online manual for the air cooled 250R's. It might prove to be very helpful to you. Good luck!

http://airfoolers.com/?page_id=134

You did good Enginerd..... That place has good Information.

[mtriplehorn]

drhill,
Check out
http://airfoolers.com/
Its the best place for any information on the air cooled 250R's you will find anywhere.
& themembers there are awesome as well!

[mtriplehorn]

drhill,
Check out
http://airfoolers.com/
Its the best place for any information on the air cooled 250R's you will find anywhere.
& themembers there are awesome as well!

tha would be AIR FOOLERS , but all one word

[drhill]

air foolers huh? I've heard of that site...I'll visit! Gotta get the jug off tomorow and order up the carb kit and, piston kit and gaskets...oh yeah...and a torque wrench!

[drhill]

Took the jug off tonight and pulled apart the carb a bit...just like some suggested - Small jet was clogged..also it was a 48, I think stock should be a 50? Anyway - getting a carb kit to make sure this thing is right. The top of the piston is actually burned off on the exhaust side! Also - I can't get the pin out of the piston...I got both clips out but the one on the side that got hot was a real pain...Is there a good way to get this thing out w/o damaging the rod or crank?



http://i697.photobucket.com/albums/vv340/drhill/IMG_4152.jpg http://i697.photobucket.com/albums/vv340/drhill/IMG_4150.jpg http://i697.photobucket.com/albums/vv340/drhill/IMG_4144.jpg

[drhill]

OK - got the pin out of the piston by using a socket and a c clamp...but I noticed small metal shavings and pieces on the crank and some in the oil as I spin the the crank around...is there any way to clean this stuff out without having to tear into the bottom end? I'm sure they are peices of piston and clylinder wall that came apart...

[harryredtrike]

flush out bottom end with kerosine or gas,might have to do more than once

[drhill]

thanks HarryRed...is there a drain plug or do I have to pull the entire engine and flush it out on the bench...??

Thanks!!