What do you guys think of my 250r? It's an 86. I bought it last year for $3000 off some guy at work. He said it ran great, but it was jetted for 1/2 avgas (100 octane low lead) and 1/2 91 pump gas. I tried that mixture but it sputtered at the top end. It's all stock except for a DG silencer. Everytime seems to be in pretty good shape. Frame doesn't seem to have any cracks as far as I know. I think the shocks are weak now and need replacing/rebuilding.

He had a 39mm mikuni carb with a twist throttle. I found a stock 34mm carb and thumb throttle and put that in. I also closed up the 4 holes he drilled in the airbox and replaced it with a new unifilter. Sanded and painted some rusty parts.

Only problem now is that I need to find the right carb boots. I got one from an 86 for the airbox side, but it's still too short. About 1/4 inch. The boot on the reed side looks original, but it must be something he put on. I'm going to try to find an original one to put on and hopefully the carb will fit then. If not I'll have to get a reed spacer or something. You can see the gaps where the carb mounts.

Just don't want the boots to slip off and suck in dirt. After that I'll take it out and see how it runs. What do you guys think I should jet this set up as? Not really good with jetting.

The original owner said that he's never done a top end on it. It's on the original bore. I talked to a shop about it and they recommend a complete teardown and rebuild of top/bottom for about $1200. They said if they just do the top, it could end up blowing the whole engine. What do you guys think?

I've had it for about a year, but never even got to ride it. I've just finally had the time to start working on it. I'm trying to decide on whether to sell it now and break even and buy a new bike, or spend the $1200 to get it all up to snuff and start riding. Was $3000 for this a decent deal? It seemed like it at the time, but with the new 450's out, not so much any more. Seems hard to sell 250r's lately.

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Get a shop manual and do a compression test. If the compresion is fine I wouldn't tear it down. If it is low you can rebuild it yourself and check the bottom end while you have the top end off. If your going to keep a 20 year old quad you need to be able to do the work yourself. The 250r is a very simple motor to work on and if you get just a few specialty tools you can do the complete motor yourself for only probably around $600 including the few specialty tools you will have to buy.

If you changed the carbs out you probably only need the stock jetting and forget about the av gas, just run straight pump gas. Also put in a new plug before you do any adjustments to the card. And you may have to get a brand new boot to make it fit if you got a used one. The rubber gets old and won't stretch far enough to get on the carb good. A new one will stretch more, but if you do have a new one he probably did something to make the other carb work, a reed spacer should fill in the gap.

In my opion if you could afford it I would sell it and get a new 4 stroke. Look at all the motorcross bike guys I dont think a single one is riding a 2 stroke anymore. But if you can't keep it and enjoy it it is an awsome quad, just learn to do the work yourself. I could do a COMPLETE teardown of my old r in about 30mins, and that included spliting the cases and pulling the crank and gears, only beacuse I did it so much.
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thats just what mine looked like 3 years ago. cl;ean and original. take top end off and check play on crank and go from there. my bottom end was just done last winter thanks to a leaking carb cap!! it was on its first bore then...and still is now .030 over and 20 years old!! i love it.the bottom end ran about $450 or so for rebuilt crank,new rod,bearings, seals etc. all the gears were fine !! clutch basket was replaced with a hinson though.that price of $1200 is bs. he is trying to _uck you .... do go for it !!! the top end is about a buck and a half or so . $600 is a roundabout number. get the head shaved and use a cr250 head gasket....big power hit for almost no money!! mine is ported now and has less torque than with that setup. but it really rocks when on the pipe...wow!!if your front shocks are beat look for a good deal on 450r take offs,they work very well. my opinion is all quads look similar... but the 250r is just a cut above the rest as far as build quality. the 450s are faster... but not necessarily better overall. as far as the carb..thats a stocker i believe.the air box is somewhat adjustable also. you can get almost 3/8 of forward play out of it.i tried a 38 mm mikuni flatslide on mine and lost too much torque and went back to the stocker.a 36 mm would be better for my type of riding. rip the top end down and go from there... you can always put it back together and sell to someone who will rip it all the way down.[img]i/expressions/face-icon-small-smile.gif[/img]

 

450r shocks drop right in with no mods?

Right now I know the airbox carb is original, but i'm not sure about the reed boot. I'll try to get my hands on an original one of those and see how it fits. I did play with the airbox too and tried to push it forward, but it wouldn't go far enough. If all fails, I will get brand new boots from servicehonda.

Yeah I'm not going with the avgas any more. That's the whole reason why I put the stock carb back in.

 

mine kicks at 190-195 with no ping on 94 pump. and yes the 450r shocks bolt right on front it will raise the front up 1-1.5 inches at rest. im 230 lbs. so for me they are super sweet. if your 160 lbs. they might be too stiff. my rezzys are facing the front so as to not hit my super shiny custom shrouds !!once i get the back shock revalved to compliment the front... ill be in business!!!

 

You say it ran but sputtered on top end? Why not try a 1 or 2 sizes smaller main jet. Why did you change the carb? Unless you do alot of riding in water, why cover the airbox holes? Seems to me you could have left it the way it was, rejeted 1 or 2 sizes smaller and had some fun. Why do you want a smaller carb on that 250r? Also 2-strokes have a way of telling you they need re ringed. They become hard to start when cold {25-55 kicks}, but when warmed up they start 1 or 2 kicks. Thats a sure sign of low compression. Nice bike btw.

 

Well this is why I changed out the carb. It was a large 39mm carb on an otherwise stock engine. I don't think the engine can really take advantage of that carb. And it was set up for that avgas mixture which I wanted to stop using. I closed up the airbox because where I ride there is a lot of fine dusty sand. Gets in everywhere. Making sense now?

It is really easy to start now with the smaller carb. Much easier than with the 39mm. This morning I kicked it over for fun..one kick with the choke on, then turned off the choke and it idled nicely. Actually starts cold better than my 250ex. I guess that's a good sign.

 

your right about the carb size. my engine is ported and i still run the stock carb. a larger carb will yield better top end with a sacrifice on the bottom. thats what mine did.its all about velocity in the intake tract.same carb with same jets will draw more fuel when ported= more velocity higher flow. a 36 would be better on mine ,but i like the crispness of the small carb.drags and dunes = bigger carb.trails and woods = smaller carb. i like the right now kind of power. sounds like your motor is fine if it starts in 1 kick....$1200 huh. what a joker!!have fun with your classic atv !!

 

The carb has nothing to do with the octane rating of the gas you use. If you don't have a high compression piston in there, there is no reason what so ever to run high octane race gas, or avaition gas. Let me put it this way. Say you had your 250r jetted perfectly. Then you decided you wanted to use a high compression piston for more power. You would have to use high octane gas with the high compression piston, but you would not change your jetting. The use of high octane gas has nothing to do with jetting..... Have you seen a dune bike? Most don't even have an air box. Just a filter clamped to the carb, and there is more fine dust and sand at the dunes then anywhere. The air box doesn't keep dirt out of the motor, the filter does. Unless you ride in water, open that box up. Dude, don't get me wrong, do what you want, it's your bike, but before I would take anyones advice on the atv connection forum {except for the bomb guys} I would find a 250r only site, where people aren't talking out there @ss [like this site], and where you can get educated, and experienced advice from hundreds of dedecated 250r owners. I found a great banshee site where people know their ****, and when I want FACTS from people I trust, I go to that site {which will remain nameless}. and do indepth searches on topics I want to know about. It helped me out alot with my bikes. I'm sure there is a great 250r site out there. I only post on this site for entertainment. Nice 250r dude, real clean. Long live them 2-strokes!!

 

When I say people talking out there @sses, I not talking about anyone who posted on your topic. Strong advice from all.