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[jawa-enfield]

Now i really don't know what i should look for anymore..
i think i have to swap plans and leave the manifold and carb.

[stinkwheel]

Right. If it was me. Here's what I'd do to fit that manifold.

I would buy a pack of long 5/16" bolts with a different thread system. Like these 5/16"UNC x 4" ones:
https://www.ebay.co.uk/itm/183927572059

I would also buy a 5/16" cycle thread die like this one:
https://www.ebay.co.uk/itm/265200721065

The bolt will have a fairly long un-threaded section below the bolt head. I would cut off the threaded section with a hacksaw, clean up the end with a file and use the die to cut a new thread on the remaining bolt.

[ChrisD]

Jawa-Enfield. Why not trim down the rubber manifold? That's what I did on my 1996 500.
ChrisD

[jawa-enfield]

Right. If it was me. Here's what I'd do to fit that manifold.

I would buy a pack of long 5/16" bolts with a different thread system. Like these 5/16"UNC x 4" ones:
https://www.ebay.co.uk/itm/183927572059

I would also buy a 5/16" cycle thread die like this one:
https://www.ebay.co.uk/itm/265200721065

The bolt will have a fairly long un-threaded section below the bolt head. I would cut off the threaded section with a hacksaw, clean up the end with a file and use the die to cut a new thread on the remaining bolt.

I do not understand the last bit, i know it is me

[jawa-enfield]

Jawa-Enfield. Why not trim down the rubber manifold? That's what I did on my 1996 500.
ChrisD

Because i think it will give ruptures, it is really a thight fit. See pics
I will leave the whole bike alone for a week or so. í'm -menatlly'stuck..

It must be possible to get allen bolts in this CEI, BSC, ITP 5/16 26 Thread???

Thanks everyone to try to teach me simple stuff only i have trouble with..

[stinkwheel]

I do not understand the last bit, i know it is me

The trouble is this thread system is very old and there were no socket head bolts when it was in common use.

Here's what I was trying to convey in "international language".

recut.png (206.45 KiB) Viewed 2531 times

[Davedup]

Right. If it was me. Here's what I'd do to fit that manifold.

I would buy a pack of long 5/16" bolts with a different thread system. Like these 5/16"UNC x 4" ones:
https://www.ebay.co.uk/itm/183927572059

I would also buy a 5/16" cycle thread die like this one:
https://www.ebay.co.uk/itm/265200721065

The bolt will have a fairly long un-threaded section below the bolt head. I would cut off the threaded section with a hacksaw, clean up the end with a file and use the die to cut a new thread on the remaining bolt.

That is genius! Hat off to you, would never have thought of that.

[jawa-enfield]

I bought 2 M8 allen bolts with a bare neck/part whithout thread, sawed off the part with thread, made a conical shape at the top and tried to make the desired 26 tpi thread with the cutting tool showed above.
It did not work, the result is bend and won't go into the head.

Need to think of something else..

[Adrian]

Let's keep this simple. Drill out the treads in the carb flange on the cylinder head with an 8mm drill. The get an 8mm Heli-coil kit and use that to fit a pair of M8 ISO coarse thread inserts. Then buy a pair of M8 socket-head cap screws (Allen screws to the rest of us) of the desired length.

Why is this proving so difficult?

A.

[jawa-enfield]

Maybe this is indeed the way to go... Never did a helicoil job before though.. Is it possible to ruin the job?