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New to me 1995 XR250L


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Well, I think I've reached a point of a few decisions with my new toy, and now I need some advice.  I picked up a 250L for $1100, and it needs some TLC.  It's got a bit of a smoking habit on cold start and the head gasket leaks oil out the left side.  Other than those things, for what I've ridden it this year, it has been a fantastic little bike that has taught me a lot about motorcycle control...(and almost highsiding)  Coming from riding a VFR for the past 5 years, this thing is really refreshing.  I am planning a ride up the Trans Wisconsin Adventure Trail next year, and I want to turn this bike into a reliable, light, and reasonably torquey mount for the trip.

 

I've got some time to think my mods through before actually beginning, as I have to do a valve adjustment on the VFR (not fun).  I actually just de-snorkeled the airbox and tightened up the spring on the accelerator pump and it woke the bike right up, but I have more planned, just looking for some guidance.  I tried the link to Gordon's mods but it wasn't working.  

 

Glad to have found the forums, this  little machine looks like it could me into a really rewarding hobby (and/or potential money pit, but that's cool too).  

 

 

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When I tear into it this winter, I will have a look at the head bolts first and either do a time-sert if I can, or llook at a new cylinder.  Apparently this one had a 277cc big bore kit installed but I am not 100% sure.  I know someone has been in the engine since the cam cover has one bolt hole helicoiled. 

 

Regarding the carburetor, what is the depth to which I can make jetting changes on the L model carb? I've noticed it has always run lean, seemed to ping when it got hot even on 93 octane. 

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My troubles were with stock bore and stock compression.  Don't continue riding this model without an oil cooler.  Yours may have high compression piston, also wrong.  You need stock compression on air-cooled XRs.  You said you want reliable.  

 

My bike is perfectly jetted. After you go through the carb and service the fuel screw, let us know what jets you have.  With stock bore, you need 40,42 pilot jets and 130,135 mains, also washers to raise needle.  With big bore some need smaller jets because of increased velocity/vacuum through venturi.  

 

Fuel screw passage may be plugged.

 

My buddy has built some reliable later model XR300s with big-fin heads, 400 cooler, and frame reservoir.

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Good to know.  Yeah I mean if I want to go fast, I've got the VFR.  This bike would be more to explore trails and learn on.  I can get a bigger DS bike later.  My friend has a KTM 530 EXC-R that was a BLAST to ride, but I don't think I'm ready for that kind of power yet.  What do I need to look for if I am trying to spot a high comp piston?  Looking at stock pistons, it seems there is a sharp cutoff between piston dome and piston crown, like if you took a cross section it would be a trapezoid.  The high-comp pistons look more hemispherical. 

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Compare it to a stock piston.  The piston can be shaved down to stock compression.  

 

My 250 has a 4.2 gallon tank and on my last trip, I rode 230 miles before I was able to get gas siphoned out of a rusty Jeep can.  The 530 can't do that.

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  • 1 month later...

Sorry to bring up a somewhat dead post, but I've torn down the engine to the point where I'm going to have to decide what to do.  I plan to get the oil cooler, so I am looking to source an R side cover and the cooler/lines.  This engine recently had work done, but I am not sure I like what's been done.  It has a 73.5mm bore, but what appears to be a Wiseco 10.5:1 compression piston.  This would explain the gross looking oil as well as the pinging under extended hill climbs.  There are a couple of ways I could go with it from here in my mind.  

 

I can return to a stock 9.3:1 compression piston and get some reliability back like you had said, Baja, but is it still needed given what I have planned for the carb/exhaust?  I plan to use the stock pumper carb, as from what I've read it has more responsiveness down low than a Mikuni 34mm flatslide.  I can jet it up a size or two and shim the needle when I rebuild it since I plan to run an aftermarket pipe .  Now the header I have is stock, but it appears the only flow restriction is a weld inside the end of the header pipes where they mate to the head.  Can I just grind this out and gain flow, or is the entire pipe smaller?  I also have gutted the airbox and plan to run a UNI filter for good filtration.    

So I guess to summarize: 

 

1. Engine. Is a stock piston still better in your opinion or will I be fine running the Wiseco? it's clean, no scoring, nice bore too.  

2. Exhausts.  Is DG a good pipe or what about XR's Only or FMF?  Is the header I have able to be ground out for flow?  

3. Carb.  Is the 30mm pumper going to work for me?  I plan to build for tractability and midrange, not a zillion revs and top end (I have a sportbike for that 🙂 )

 

I am heading out now to check the head torque and scrape gaskets and list new gaskets/parts I need.  

Edited by V4Rider
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Install the 250 oil cooler and see if pinging goes away.  That may be enough in Wisconsin.  I ride sand in 100F heat.  

 

I'm running stock pumper carb and stock header with stock welds.  It's fine for tough single track and will go 75+ on highway.  Low gearing for single track is more important than header.  Also, XR500 UNI filter with required air box mods.

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Well I popped the carb apart tonight and lo and behold, 122 mains and 38 pilot.  No wonder it runs like poo on the top end, it's dry as a popcorn fart.  I also measured the piston diameter vs. the bore.  I'm going to take the jug and liner in and hot tank clean them at work tomorrow then go about finding a machine shop to verify the tolerance is right on the piston vs. the bore.  I wire brushed off as much carbon as I could on the head but I am not super worried about that.  I think I'll go ahead and throw in new valve seals while I am at it since the whole goal of pulling the head was to get rid of my oil consumption issues, why not narrow it down a bit.  I inspected the threads and they looked fine, but I will verify they take torque when I put the head back on.  

 

Regarding head and top end gaskets, I have heard quite a lot of Cometic brand gaskets, but what are some other ones I can be looking at if I want something a bit better than stock, or is stock the way to go with these things?   

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Before you remove the head, check the torque on the large head bolts to see which ones are stripped @ 29 ft. lbs.  

 

 

  I inspected the threads and they looked fine, but I will verify they take torque when I put the head back on.  

  

 

It's too late now.  Checking the torque at installation won't tell you anything.  

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