I have an 88 R with a completely stock motor except for the old style FMF pipe and silencer. I was thinking about a Rad Valve and boysen reeds. The motor has never been rebuilt or bored over or anything. I bought it off some old dude who just stored it away under a blanket. I just want to make it a little quicker. I mainly trail ride but also play on tracks also. I am open to any suggestions. Thanks,

Nick

 

What kind of ridin do u do. I was going to suggest a resleeve 295 kit or bigger like a 330 or 350 kit. You can pick up a good used cylinder for $500-$600 including the pistion. This would be your best bet for more power.

 

have it bored and put a new piston in it-won't cost very much. 25-35 for boring and 100 bucks for piston kit

 

For starters, the top end has to be wore out if it is indeed the original top end. Have it bored to the next size. Use an 85 ATC250R head gasket. The gasket is a little thinner than the one on it now. It is good for about 15-20 psi of cylinder pressure. Pressure=speed. There is plenty of power to be extracted out of the 250R without going big bore. Port the cylinder, get a newer pipe, maybe a bigger carb, and jet the machine properly. You will be very surprised at the outcome for very little money. Big bore kits do produce heller power, but when they break they are usually more expensive to fix than your stock machine. If you can get a hold of a spare cylinder to do the port work to, you will be ahead of the game. That way, if you don't like the way it runs after the porting, you can change it back. Porting is an art, you don't just cut the hell out of the ports, there is some math involved. Make sure whoever does it knows their s@#$. By the way, I have a spare 87-89 cylinder if you are interested.

 

did you know a 87 and up cylinder can go 80 over but an 86 can go 140-i'm doing one now that is 100 over

 

What you need to do is, bore out the cylinder to its next size, take a good look at the head, to see if there is any damage. If you can, polish that yourself. Also polish the exaust port. Check the jetting on the carb. See if its the right size for altitude where you live. Get a Vforce rad valve, and spacer. Get a thin CR head gasket, and check that old pipe. If it still in good condition keep it. Oh if you can, take a look at the Flywheel and stator, they get rusty often and you might not get a good spark.
I did that to mine and it runs like a raped monkey. I beat alot modifieds banshees.
Later

 

I would first see how much comprosion that the engines has. If good, just change the metal headgasket. If not have it bored, and the gasket kit will come with the paper gasket. You can do many other things, but the headgasket change was the first thing that we changedback in the late 80's after we bought a new R.

 

SeaDooMan,

Hey I see your from Indiana. Do you reccomend anyone from Indy to do my motor work? I am not really interested in a big bore kit. Just port and polish and a new top end. Any idea how much that will cost me? Im basically a dumb *** when it comes to two strokes. Really I don't think my top end is too bad, I think the quads runs pretty strong for what it has done and still being origional. Reliability is still a big concern as is still being able to use pump gas. Keep the ideas comming guys. Thanks,

Nick

 

I am also from In. I build 250R's and race the GNC national curcuit. If you are interested in getting some work done on your "R" email me at
gnc@atvconnection.com and I can set you up.