Ironhead 82 XLH struggling for power

[darkgizzard]

Well another thing I'm wrong about.

"When the throttle is suddenly opened, the air speed in the venturi slows, and consequently, the vacuum drops, reducing the delivery of fuel. For this reason an accelerator pump is provided. "

So opening the throttle fast reduces fuel delivery rather than the opposite.

Apparently I need to check the pump

[Ferrous Head]

I have two relatively cheap tools that I can use to sort out problems Well three is you count a systematic approach. (Probably the most important tool)

I always go back to basics. The engine needs 3 things to run correctly.
Compression
Air and fuel in the right ratio
A good spark at the correct time.

I always start with compression because it gives us an absolute measurement and tells us a lot of things about the engine with one simple test.

If it passes that test I now move onto number two.

There is now a cheap inexpensive tool to check that your carburation is not your problem. You can buy a "Fake" S&S Super E that will come jetted for your bike for a little over $50.

Simple substitution. If the bike exhibits the same symptoms as before - carburation is not your problem and you look elsewhere.

It is almost impossible to "tune out" the flat spot in the nid range on a bike running drag pipes. If the intake and exhaust dimensions are optimized for 6000 rpm it will not want to run at 3.

Try a good set of 2 into 1's and you'll never want to go back to singles.

Accelerator pumps are a crude way of overcoming the carbs deficiencies in coping with sudden changes in the air flow signal. Too fast on the throttle will make them go lean until the carb catches up.

[Iron Mike]

Sounds like a lean condition being masked by utilizing enrichener. Check for manifold leaks or partially plugged pilot circuit.
Regardless, ignition timing still needs to be set first before looking at carb.

[rokytnji]

I,ll just mention my caveman technique since I work solo.

It saves me time resting my hands around the plug wires and such to see if I get bit anywhere.

Plug wires can be touchy.

Good Luck. I love my 80's XL's.

Edit: PS. I put washers in my drag pipes. Beats taking em to the dump. Black VHT paint. Bobs your uncle.

[H.E.L.M]

Darkgizzard,

Have just read through this whole thing and have a thought to share.

Dellorto's are fine carby's that work extremely well, you just got to get to know them.
From the beginning when you first rode the bike home you commented that it ran fine and you thought it was great, so really it should still be able to be that way.

You have changed handle bars, throttle assembly, air filter and fiddled with manifold and identified a bad spark plug.

Replace that one spark plug that was wet wherever you put it.
Make sure the throttle cable has some slack (free play) but turn out the throttle slide adjusting screw first to ensure it is not holding the slide up, let that slide sit at rock bottom.

Set the mixture screw at 2 1/2 out (think thats about where you have it).
With the engine shut down and air filter off stick your finger in so you can feel the slide cutaway, then very gently turn the slide adjusting screw in till you feel the slide lift.
Play with this back and forth till you get that slide just lifted from rock bottom the tiniest bit.
Leave that setting right there.

Go to the throttle cable adjuster and set it so you have about 1/8" or a dash more free play before it starts to lift the slide, thats your free play.
From this point you should only need to adjust mixture screw no more than a full turn either way. Best to take your screw driver with you and go for a ride 20min+, stop along the way once she's hot and fine tune that mixture screw, take your time, do it 3-4 times.

If she ran fine before you should not need to bugger about with much else, if all is back to where it was.
Hope this is useful, otherwise ignore it.
cheers
Mick







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