Hey all, I just picked up a '87 250r that i'm pretty much restoring. I've never really messed with quads, but i'm a tech and can put stuff together. LOL. I have it all apart now and i'm just cleaning it up and putting all new bearings in the suspenion. My main questions are with the motor. It runs now but is hard to start, and who knows when it was taken apart. So i'm going to rip it apart. I'm thinking unless anything looks messed up a piston, rings, hone the cylinder, gaskets, reeds, type deal. Any other advise on that from people who have done it before? What about boring, everyone talks about a bore, can you bore the stock cylinder? Or do you have to have it resleved or anything? Also, I was thinking about just honing the cylinder myself if it isn't bad and having someone press the piston on. However, I've heard that the cylinders on the 250 motors are hard to hone right..?? something about the location of the ports, and needing long stones that are hard to find. What other recomendations do you guys have as far as order of mods? I want to do a pretty cheap build up for now, and just get it going. I'm thinking just the rebuilt motor, a pipe, etc. When do you need a different carb, or jetting? With a pipe? Are there any other little tricks and simple cheap or "free" mods that get a little here and there like there usually is with most motors?

Then what about suspension and plastics? What would be the first suspension parts for improvement? Does anyone make a good aftermarket plasic, maybe different colors? Thanks in advance for any help. I'm sure i'll be back with more questions [img]i/expressions/face-icon-small-smile.gif[/img]

 

you can get it bored at any michine shop and yes it is hard to hone but i had little stones bigger would be a lot easier with a pipe and scilencer and open air box lid and v-force reeds i had to go up to a 290 main and down to a 25 polot jet. i live in pa elevation matters alot to . thats with the stock 34mm carb ill be gitting a 39mm in a couple days. cant wait to see how it will run then.

 

You can bore the stock cyl. to .080 over. Most machine shops charge about $40 for a bore and hone. Make sure to chamfer the port edges. A cheap way to make some more power is to mill the head to increase compression. This is about $30.

The hard start could have been bad jetting, low compression or weak spark. The carb may need rejetting after any changes (pipe, bore, head mod, opening airbox).

Maier is the only company that makes aftermarket plastics fot LT's, but they make a bunch of different colors. Suspension upgrades are expensive. You can get your rear shock rebuilt or 'regutted' for $200-300. The front shocks are not rebuildable and aftermarkets start at about $350 and go up from there. Extended A-arms and swingarms are also big $$$.

 

Sounds like you are on the way. I wouldn't bother with boring the cylinder out unless it needed it. Not really gonna give any more power a few thousands over. Plus it saves on the cylinder for the future so that if and when it does need a bore the material is there. A stone honing tool works just fine if thats all you need. The piston is not pressed on. Just take the circlips of the piston and the pin will slide out.[img]i/expressions/face-icon-small-smile.gif[/img] If you are a on a budget then the mods I would suggest are pipe and silencer combo, good air filter and some performance reeds. Then latter you can step up to a after market reed cage and carb. Feel the bike out first and get to know it then go from there. Makes it easier to troble shoot things later down the if something goes wrong. Yes jetting will be required when you add a new pipe.

 

Thanks for the help so far guys. Any recomendations on pipes? How about tuning and jetting? Is it pretty easy to do yourself?

Also, i finally started to take the motor apart. The head looks a little messed up. Right before the dome there are a bunch of little gashes. I also measured the bore, just at the top so far since i haven't pulled the cylinder off, and it was at 67.94mm. So i'm thinking sometime in the past hit blew a piston and was rebuilt and bored. I have an extra head though, so i'll use that one. I'm thinking about having it milled some. What is the stock compression? And what is a good compression to run with just mild mods that wont make it a pain?

Also, what is the deal with the rear end deal? LOL I thought these things would just have a straight axle, but it has a little box between the axles. What exactly is in there? Does it go bad or anything? And is there an easy way to get the rear hubs and axles off? Thanks again guys for the help. Sorry for all the questions.

 

Anyone?

 

Get a shop manual, it will answer almost all your questions.

Pipe- Paul Turner, FMF
Jetting - Can be challenging and expensive if you buy alot of jets trying to find the perfect one.
Compression- Need at least 150, can probably go up to 170 with pump gas.
Rearend - That little box holds your axle bearings, you slide it back and forth to get your chain tension right. The hardest part about removing the axle is the axle nut. They sometimes don't like to come off, you can't use heat, and may have to be cut. Remember that's a 17 year old bike and may have never been apart.