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How to Straighten? Nikki Primary Throttle Shaft Bend

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How to Straighten? Nikki Primary Throttle Shaft Bend

Old 12-07-18, 02:58 PM
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How to Straighten? Nikki Primary Throttle Shaft Bend

Hi Folks,

I got a spare 83 Nikki carb to play around with, to understand all that mess of linkage, try out a few things in a measured fashion... start with mechanical secondaries, maybe get to a hogged out version at some point. Unfortunately during shipping the shaft for the primary throttle and some of the levers got bent.

Anyone have this problem and fix it? I am thinking that firm, progressive and controlled clamping force.


Do I need to anneal it or does that introduce other problems (like weaking/warping) and if I do anneal would I then need to case harden it after the straightening?

And it's also very possible that I am overthinking this. I'm very good at that Thanks! Here are some photos

And a detail of the shaft, cleaned up:

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Old 12-07-18, 04:11 PM
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If you try bending it back from that angle, it will most likely break in the near future from normal use. That much stress took out a lot of its durability and will now be prone to failure at lower fatigue levels. Doesn't hurt to try.

If it does break you could clean up the edges, beveling the corners, building up a tig bead around and around to get the entire piece annealed and remelted. (over thinking, yes) Then a little turn in a lathe to add that snap ring back.

That is a relatively easy part to turn, mill, drill and tap. Would be a fun day or so. Maybe some semi hard 01 tool steel?
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Old 12-07-18, 07:55 PM
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Did the seller put any packing material in the box at all? I sell a lot on ebay, and if I sent you that I'd refund your money.
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Old 12-08-18, 12:08 PM
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You should slide it back into the baseplate so it has some support. Then use a deepwell socket or some sturdy metal tubing slipped over it and bend it back as straight as you can get it. I would not worry about losing strength too much as all it's doing is lifting the OMP rod which doesn't require much strength. Be slow and deliberate here. Pay attention to the main part of the shaft and check it for any binding. You might be able to do minor corrections on it if necessary during the process.

Don't bother using heat or doing anything exotic. Just bend it back.

Last edited by Jeff20B; 12-08-18 at 12:13 PM.
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Old 12-08-18, 03:56 PM
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I doubt its hardened, you shouldn't have to anneal it. Heating it up with some map gas would make it more pliable with less chance of it breaking. Know anybody who works in a machine shop? It can be straightened pretty close in a small press using a pair of V-blocks to support and rotate it with.
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Old 12-08-18, 08:39 PM
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Thanks Guys

This is all excellent advice. Years ago I worked in a fabrication shop (industrial design/prototyping) and had access to all the good stuff, milling machines, lathes, welding, air tools, paint etc. I miss that!

Anyway I'll give it a go with all of the above in mind and I'll post a shot of the results, perhaps it will be in one piece...

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Old 12-10-18, 10:50 AM
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i bent a wrench this weekend to get the carb off, and i heated it up on the stove and then bent it, it worked really well
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