I've got an 86 250R, bone stock except for reeds and FMF fatty. Got a cracked piston and I want a little extra power without spending $1k. Ideas?

well, that is an open ended question...you could..mill the deck, port and polish, switch to a wiseco, get a K&N air filter, that would bump compression and improve flow....oh yeah, install a roost boost to the electronics...of course, for ever mod is the cost of reliability...I would leave it alone and enjoy it...of course, fix it first
The real question is, what do you want out of it? More torque, more RPM's, stronger and quicker tapout? What????

dude a K&N dosent raise compression

It has been a few years ago so lets see if I can remember how I did it.

I bought a 89 jug ( equal to a mild port job compaired to stock 86 jug).

Still used stock bore 86 piston. ( 89 motors / pistons have a different stroke rod).

Used a 86 atc head gasket to bump up compression a little.

K&N with outer wear with airbox lid removed.

Also Boysen reeds.

Spacer (Brand I don't remember) between reed cage and motor.

I can not remember how much it was but way less than a grand.

Also I still have a stock pipe so you are one step ahead there with the FMF Fatty.

And it always helps to mix in a little race gas

Anther tip for older TRX 86 motors are CR 500 clutch basket springs.
I put a Hanson racing clutch basket on later after stock one wore out.
Also keep a eye out for oil in the outter left case cover under stator. If you see oil there the seal behind the magneto is breaking down.

I went to the Trinity flat top piston, milled head, port and polish. Have a 38mm, carb that has a milled slide and run stock reeds (put boysen on, hated them) and I absolutely love it. On the 5th season on that top end! Cost me $550 the first time because I had to put a stock sleeve into the piston, if not, it's around $300.

I have a mild port, shaved the head, pro-X piston, K&N no lid, Paul Turner Hi-rev pipe, Fat boy Silencer, and Boyesen reeds. These mods woke up the motor a lot. I love it and can still run pump gas

[QUOTE]Also still have stock pipe so you are one step ahead there.
T2duner...you mentioned stock pipe and being ahead? Better to run 250R's with stock pipes?

My '85 has some portwork, a CR250 head gasket (thinner, higher compression), CR250 carb (from what I was told...not 100% sure), an FMF Gold Series pipe and I'm not sure what reeds. I have had it rebuilt once... new sleeve, Wiseco piston and better portwork and it only cost me $288 for labor and parts. The thing is a friggin rocket now. With the new work, I was told it was bumped up to 300-310 cc.

I asked the guy that rebuilt it to let me know everything about the bike so I could be sure what's going on with it but, for some reason he needs to see it again to be sure. We still need to re-jet it... it sputters at the very top end... so I'm gonna be there when he works on it this time.

Bronco-O-Boy11 - I was responding to Glamislvr3 's post that he already has a FMF Fatty pipe. I have not changed mine from stock yet so he is one step ahead of me there. After market pipes give you more power and you can pick one to improve where you need peek power. I messed up on that post so I see why you were wondering what I was saying. Sorry.

It's cool T2...i just thought there was some unknown secret down there that we didn't know up here about stock pipes. Only 1 of my machines has the stock equiptment and i'd prob. be better off if i dumped that too. Let me see....3 bikes....48 lbs per exhaust equals.....144 less lbs i have to lift off the back of the truck

Here's an inexpensive way to get a really good running basically "stock" motor.

Have the cylinder bored and get a new piston to fit, but then have the cylinder "match" ported. This is just to make sure all the ports are good and clean.

Then, install 2 base gaskets, and use a CR head gasket. By using 2 base gaskets you raise your port timing just a touch and allow a bit more fuel in. Use the CR headgasket to get your compression back up.

Install some decent reeds. You can use some Boyesens on your stock cage and they only cost about $35.

Clean your carb really good. Squeeze the gap on your plug down to less than .022, believe me, it helps.

Before you do all the top end work, make sure you get the dry side crank seal replaced! ! ! This is something a lot of people don't do and then smoke a motor 'cause all the pressures created by the new top end blow out this seal and you start sucking air and lean out the motor and fry your new piston or seize the crank. The seal only costs less than $20!

Good luck!

Washroad has got it right for a cheep way of getting good power.

If you want something done by a reputable mechanic the go to CT racing and have them install a Nat'l match kit for about 500 bucks, you will want a new 38mm carb also.

I have had one on my quad for over 10 yrs and love it...

You could sell and buy my TRX500R, 86 TRX with 87 CR500R motor, built to the hill, cromoly/billet this and that, over $10,500 invested, asking $6,000. Way too fast for me, and have new LT rail on way, only 3 hours since build, from ground up that is. Email julia-greg@cox.net for pics/spec sheet.

THE BOMB

I've never had a problem with sand getting past my K&N filters and have been using them for over 20 years. You need to make sure they are sealed good when installing them, oiled properly and use an outerwear. Then change/clean it frequently. I change my filter every-other day when at G, I keep a clean/oiled spare in a ziploc bag. I then clean and oil the dirty one.