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xr250r crrb fitment

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i have a late model xr250r carb all cleaned and ready to install of the 230.

when i went to mount i found the the fuel inlet pipe points directly at the frame.

 

so i looked closer at the original carb. the inlet pipe if a fromed shape and the choke lever is dog-legged to clear.

do i have to exchange the fuel inlet pipes? what have others done to get past this little hickup?

 

 

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Ok there are several ways to make it fit and work properly.

1) loosen every single engine mount bolt and frame bolts /nuts until the engine can actually be moved slightly forward and backward in the frame.

It may take a gentile nudge with a 2' pry bar of some sort, but you can/should be able to see the engine move in the frame.

With your pry bar, persuade the engine to move as far forward as possible and do not ease up pressure on the pry bar while a friend snugs up all engine mounting bolts/nuts.

Then follow up with a torque wrench and again, finish torquing all mounting bolts to factory specs.

(You have a shop manual correct)

You can, at times, get as much 1/4" more clearance for the fuel line that way.

2) with your exhaust removed from the bike, refit the carb back on the engine and air filter hose. Tighten all hose clamps. Mark the frame with a felt tip marker above and below the fuel hose nipple for reference.

Remove carb and get an idea of where you need to gently grind the area away on the frame where the hose runs on/next to it.

(I use a die grinder with a cutter that's slightly larger than the diameter of the hose) DO NOT GRIND A HOLE IN THE FRAME, it's not necessary any way.

Touch up with silver spray paint to stop rust.

This process can get you up to another 1/8" clearance.

I have done a bunch of these and have never needed more than these two methods. BUT

3) you can get another .020 by removing the intake manifold gasket and just use the O'ring only.

4) other folks on TT have removed the hose nipple from the carb and fabricated/epoxied a longer and curved hose nipple in place.

That way they gain the thickness of the fuel hose for clearance because the hose nipple is longer and they don't have to slide the fuel hose all the way to the carb.

The 230's are easy because the cylinder is 8mm taller than a 150f.

On the 150f, since the cylinder is 8mm lower, there is a frame reinforcement/gusset that has to be ground on a lot more to provide clearance for the fuel hose.

Hope this helps :-)

Any other tricks out there on TT,

Please post, so we all can learn.

PS:

If you don't match/blend the 230 intake manifold to the XR 250 carb and to the intake port on the cylinder head, then your waisting your time with this swap and all this work will be for nothing.

So measure the ID of you intake port

And make sure you 230 intake manifold is the same size as the port first and then blend/taper the manifold to the same ID as the carb.

The whole manifold ID must be at least the same ID as the intake port opening with no steps, waves or edges.

You are going to need a larger carb hose clamp from an XR 250 also!

The 230 intake manifold clamp will be to small!

One more super secret trick...

After you are very satisfied and patting yourself on the back with your grinding and blending the manifold to the head and carb...

Place the manifold and the clamp on the carb and tighten the hose clamp like it will be when it's mounted on the bike for the last time.

Now take the carb with the clamped manifold out into the sunlight and notice how the rubber manifold has squished into the air flow and is causing a slight restriction that needs to be removed some more to be perfect. ( because you tightened the clamp)

So now disassemble again and grind some more until you achieve a perfect blend/match AFTER ITS CLAMPED.

Now get your bike back together, get your riding gear on and ride it.

Please let us all know how you hard work has paid off!

Edited by adnohguy

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