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max power

XR250 - so it blew the head gasket.....

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max power    18,642

 So she sprung a leak on the front left corner of the head gasket. I knew would happen eventually but was hoping to make it to winter. So I tore it down and discovered some interesting things along the way. 

 The PO told me it had been bored out to 280 but there are many aftermarket piston manufactures and 280 is a generalization. Couldn't know what gasket size I needed til I found out what brand kit was in it so the head came off.

found out that the aftermarket Mikuni 34mm flat slide carb is narrower than stock  so requires an adapter to fit on to the OEM airbox. No worries (must've said one of the PO's)  just hook it to the airbox and attach it to the intake manifold by butting it up to the end of the manifold (which is supposed to go over the end of the carb) and wrapping it with a chunk of rubber tire innertube And a zip tie! Cheap and lazy solution but I guess it kind of worked, even though the starting procedure for this particular bike was incredibly complicated, possibly due to the hillbilly velocity stack.  

Noticed it when I bought the bike, just figured if it ran for now, I'd deal with it this winter.  No big deal. My carb fitment investigations led me to a small biz in California called XRs only.com

Long story short, the mikuni is taking a vacation to cali for some cosmetic surgery. When it comes back, it will have a bigger, poutier air sucker. Giggity.  


Called my man @ponyjr for some parts (and subsequently lots of advice) and he quickly and expertly assembled a kit of all the parts I would need to do the job and talked me into taking it all the way down to replace the base gasket and inspect the crank. But more importantly, hone the cylinder as it's got a little uneven wear. 

That kid is incredibly knowledgeable about motorcycles and how they work and his customer service skills are top notch! You would think he's been immersed in it all his life or something.

Parts are in. Hitting the pony early tomorrow. 


To to be continued......





















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max power    18,642

 Tore the little bastard down and sent the carburetor off to California to get reworked and an adapter put on it.  

 Slapped the new rings on the piston, replace the gaskets and bolted the engine back together yesterday. Then I realized I didn't check the direction of the rings ( turns out there's a top and bottom) so will be tearing it back down hopefully tonight.  So far the biggest pain in the ass was cleaning the gasket mating surfaces.  Oh, and finding out after you put it back together that there's a top and bottom on the rings. It's a learning process.




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max power    18,642
17 hours ago, marlboro man said:

Shit bubby don't be cynical carbs to California it'll run like a tree hugging bitch

Sent to XRsonly.  The aftermarket carb needed an extension adapter to work correctly and it has to be welded on.  They rebuilt it while they had it. Good as new. I hope. 

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