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1985 XR250R Perf. parts/mods???

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New here! I have a 1985 XR250R (twin carb'd) that is bone stock. Out of curiosity I started looking a little for any performance upgrades or little tricks. As far as performance parts, I really didn't find much. I'm probably going to lean towards the little tricks and just tune it in to run its best but was still curious in case I would want to get more involved if there was some place in particular I should look. Any information would be greatly appreciated.

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IMO, I would leave it stock and just tune it a little. Make sure it is jetted correctly. and maybe get a higher flowing air filter for it. No pics?

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yeah, that's pretty much where I'm leaning. You know, I need to take some pics. Thought I had some but I guess I don't.

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its most likley not stock, the stock 84 and 85 xr200's and 250's had soft valve springs that floated the valves easily and destroyed the entire engine. My friend blew his up with just light rideing- we were in some tight woods and got the engine hot, my 1991 was running awesome his started to tick like a ford powerstroke, we checked the oil and it was fine so we headed back to the truck, when we got to a gravel road and opened them up side by side his engine locked up so bad even pulling in the clutch didnt unlock the rear wheel and he ended up wrecking, when we pulled the engine apart the valve faces were in the muffler and the entire pistion was in the gearbox- only the wrist pin and rings were left in the cylinder- Dirtbike mag ran a great 2 page article back in 1995 give or take a few years about this engine. If yours in somehow still stock get 1986 valve springs in that engine asap! Here is a freeze frame of the last video taken of that bike, he ended up scraping the entire bike (sad) a few years after.

Untitled.jpg

Edited by JRM

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I'm not going to say its a bad idea to replace 27 y/o valve springs but there is no difference between 84, 86, or 95 XR250 valve springs.

The one difference is an 84 makes power up to the point where the valves will float. The later bikes run out of power a lot sooner.

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Yeah, I don't know. The bike runs great. My cousin bought it new and I don't recall him ever saying he did anything to it but ride it. I'm probably going to stick a nice free flowing filter in it and check the jetting and just ride it. I've owned the bike for the last 5 years or so. It's not been rode hard and put up wet.

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The 84/85 bikes are known to overheat, but it mainly rears its head at slow speed trails or high loads in warmer temps. The only time I ever had trouble with mine was riding 60 miles of sandwashes in baja. Temps were well into the 90s.

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The 84/85 bikes are known to overheat, but it mainly rears its head at slow speed trails or high loads in warmer temps. The only time I ever had trouble with mine was riding 60 miles of sandwashes in baja. Temps were well into the 90s.

I have read about the 250/350 dual carb bikes having the potential to overheat. Could this be mainly a jetting issue or is something else going on?

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I have read about the 250/350 dual carb bikes having the potential to overheat. Could this be mainly a jetting issue or is something else going on?

Honda reduced the oil sump size and increased horsepower by revving higher. Jetting fat helps, but isn't a complete solution.

On the XR250 they stroked the engine to reduce revs, switched to single carb and added an oil cooler

On the XR350 they stroked the engine plus, switched to single carb and switched to a dry sump oiling system.

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Man I had one of those, mine was an '84 though. I beat the living hell out of mine and it just came back for more. I raced it a season and a half doing hare scrambles and my friend that I bought it off of raced it several races before he picked up a newer bike. My friend honed the cylinder and replaced the rings and it ran great. It was however very hard to start once warmed up and felt like it had no compression. I later found out from the guy I sold it to that the cam was a tooth off. I did have to replace the crankshaft trigger for the ignition. When the thing got hot it would shut down and not restart until it cooled off. Also the choice for a rear tire was lame because it was a 17".

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I will try and find the article and scan it in, they did come from the factory with defective sprigns- trust me! Dont rev it to hard until you get new springs

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