250-500cc kehein pkw as2 stripped bolt

[Bryan M]

Anyone ever strip one of the bolts that holds the cap of the carb on. Two allen bolts hold the cap on and one wont get much tighter than finger tight. What did you do to fix it? Right now its finger tight and blue loctite.

 

[Big Timmy]

I would epoxy or loctite a threaded stud portion of the same thread pitch into the worn out stripped hole on both of them probably and use a couple of nuts on it to avoid trying to rethread it or drill it deeper. That's the best use of a stud, it will save the threads themselves from wear and tear. Simple fix.

 

[juicypips]

stud is awesome idea but to make it double fixed tap it one size larger an loctight it then the studs in fresh threads that are strong.
post^^^ truly hit the nail on the head there.
Only retap if there is enough material.

 

[Kyle Tarry]

Helicoil is the right solution, IMO. As long as there is enough meat to go to the larger hole OD required. It will also give you steel threads to reduce future wear.

Most PWKs have a screw top; which models have allen screws for the cap?

 

[johnnyboy]

Just dug a old PWK out of a box ! there is plenty enough material to fit a heli coil and as above this would be the right solution for a proper fix.

 

[WVdag]

Y

Helicoil is the right solution, IMO. As long as there is enough meat to go to the larger hole OD required. It will also give you steel threads to reduce future wear.

Most PWKs have a screw top; which models have allen screws for the cap?

My PWK has a screw on cap as well. The/my Lectron has Allen screws though.

 

[johnnyboy]

 

[Big Timmy]

Well yes, a Helicoil would be good option if there is enough meat in the area. Didn't have one of these carburetors to look at or a picture so just made a cheap, simple, suggestion. If there is enough meat for a Helicoil I would still go ahead and just tap it one size larger myself and leave the expensive Helicoils at the parts store and again go with a stud to stop using the threads over and over again all together. Its a much better permanent fix. After looking at the 4 pictures above it doesn't look like there is a whole lot of extra meat to fool around with on any of them.

 

[Dirtdame]

View attachment 44241

I remember one like the second one from the left on my KX. I didn't know whether to rejet it or plug a string of Christmas lights into it.

 

[Bryan M]

holy cow, the stud option sounds like an idea, as does heli coil...not sure if i should attempt it myself or not. there is enough meat there...but i wouldnt say there is a whole lot of room for error either.

 

[Big Timmy]

Exactly, simple is good. Helicoils in my opinion are a joke and a total compromise of the component if done incorrectly. Plus they set up for dissimilar metal corrosion in aluminum castings even though they are Stainless Steel for the most part. Steel screws can seize into a Helicoil just as bad as aluminum itself. If you continue to use the threaded Helicoil instead of using a stud in the Helicoil. A Loctited stud would eliminate problem entirely forever. Cost-- about 20 cents.

 

[johnnyboy]

Depending on what thread is knackered if you go the stud route you will never get a nut on there let alone do it up ********************************************************************************!!!
If a jobs worth doing its worth doing well as my dear old dad used to say

 

[juicypips]

Well its clearly knackered an if he cant stud it use a helicoil/ nutsert an if you bugger it completely buy a lectron . If that goes pearshaped buy a new bike etc,

 

[ohmygewd]

If you can't get a helicoil or not confident, the bolt holes are a M4 but l'm unsure whether they are .35mm pitch or .5mm pitch...if it's a .35 pitch (ultrafine), then you can can get an M4 .5mm pitch tap and M4 .5 pitch bolts.
If they are thoroughly rooted, just retap the offending hole with an M5 and matching bolt and pitch size.

The PWK threads are really soft so occasionally retapping them cleans up and prevents stripping...that's if you are regularly pulling the bowl off.

 

[Kyle Tarry]

Helicoils in my opinion are a joke

I build multi-milion dollar machinery for large multinational aerospace companies, and at least one of them specifically requests that we heli-coil any threaded holes in aluminum where the fasteners are frequently removed (such as for adjustment, consumable parts changes, etc. I would disagree that they are "a joke."

 

[Big Timmy]

Then Disagree. Good for you! I'm proud of you Kyle. For standing up for what you think is right. Does that offer a quick fix to his carburetor cap having only 1 secure screw?

So on that note:

I've had to use Helicoils on hundreds of things Kyle. They are on a few areas of my "Indy Cylinder Heads" Maxx Aluminum Hemi Blocks as well but I don't like them, not on my race motors because if you stud everything to begin with, this problem doesn't rear itself and become an issue. Keenserts on the other hand when space permits, once installed are much more permanent. Plus they use common size taps and are staked into place requiring machining if you ever want to remove them. A Helicoil insert is held in place by spring tension alone and can be easily damaged. They can usually be removed with a small hand pick. Try screwing an average sized bolt into one about 2 1/2 to 3 turns and pull on it to one side.

We are talking about the tiny area of the top of a corner of a carburetor's slide area. With a hole that small the granular structure of the aluminum exponentially is coarser. Just a bit different than probably your "multi-million dollar machinery for large multinational aerospace companies".

So I guess that at least one of these "multinational aerospace companies" who has you build "multi-million dollar machinery" doesn't have the confidence in the product enough to trust holes threaded directly into the Aluminum. I'm sure your work has the facilities to install them straight up and down and you don't do them by drilling holes freehand with a hand drill either.

Are the companies that specifically request the Helicoils smarter than the other "multinational aerospace companies"? Or do they know when a problem a customer may have had in the past, may become a major problem to their bottom line which can result in litigation?

All causing Space men to be falling out of the sky with bolts and fasteners as well.

 

[Kyle Tarry]

I'm sorry that I don't agree with you, you don't need to turn it into a rant and/or personal attack.

Like I said, the reason they request helicoils in these locations is because the hardware is frequently removed and reinstalled, and they/we have found that over time the holes in relatively soft aluminum (especially things like cast MIC6). It has nothing to do with drilling holes freehand with a hand drill, or litigation. I was simply trying to point out that threaded inserts are used in more critical places than a carb cap and probably can be trusted.

It's hard to motivate yourself to go out of your way to help other people when the end result is a pissing match over nothing.

 

[juicypips]

If the space is there i would helicoil as they are stronger think about it an m6 thread into aluminium is weaker than an m8 due to surface area alone?
Not much space for a tiny heli in a carb so stud would be the best solution imo just retap a fresh thread an lock that baby in there, its clear the threads have worn out for one reason or other so a studs second to none.



Abuse please

 

[Big Timmy]

Hope Bryan's carb is fixed already.

Thanks for all the ideas, got a few new perspectives on new solutions myself thanks.

This forum seems to be always full of pissing matches of people who don't agree with one another, Kyle. Sadly that's the Joke. No harm done though. I'm over it.

What the hell is a pissing match anyway? No please don't answer that.

Just made my observation of comparing multi-million dollar machinery to a 4mm stripped carb cap screw with very little space around it. The next size longer screw may have fixed this carb problem.

I agree Helicoils have their place. I've used them too for about 40+ years, seen many of them fail also.

 

[Bryan M]

Well I the loctite held on the partially stripped hole. It will hold for know. Im still torn betwwen both the stud and the heli coil. Both will work, just not sure which way to go. Maybe this is my calling to get a lectron