Honda thread pitch sizes

[Kenneth S (222)]

Hi Guys,
My recent purchase, an 89 Honda CR250RK had one of the front fender mount holes stripped out. I have had the hole filled and now want to re drill and tap it. It is a 6mm bolt. Firstly, Does anyone know what the standard thread pitch is? I have a 6 x 1mm tap which seems to match the bolt, but it doesn't easily screw into one of the other holes.
Thanks,
Kenneth

[Paul552]

M6 x1 for sure mate

Pre drill 5.0

[Kenneth S (222)]

M6 x1 for sure mate

Pre drill 5.0

Cheers

[oldfart]

For some reason the tap sizes are tight in alloy cases .... if you run a STD  tap they are too  loose and will strip out easy.

[tony27]

My experience is that machine tapping generally gives a tighter thread, possibly due to only 1 tap used & the tap is held steadier by the machine

[Lozza]

Like a spoke threads in aluminium should be cold forged NEVER cut, that makes the thread weak. Good news is forging taps are cheap on ebay. They are a worthwhile addition to the toolbox as they can be used to repair a thread.

http://www.ebay.com.au/itm/HSS-Thredflo-Fluteless-HAND-TAP-M6-X-1-0-SUTTON-/191265412132?pt=LH_DefaultDomain_15&hash=item2c884e9424

[Momus]

For some reason the tap sizes are tight in alloy cases .... if you run a STD  tap they are too  loose and will strip out easy

The crankcase half and side cover threads on bikes are usually a standard M6 thread.
The threads that highly stressed fasteners, like studs, screw into are generally made with a carefully toleranced undersized tap to give a tighter fit.

There is a series of special taps to take account of this.

I use the 'Threadflow' fluteless taps that Lozza mentioned a lot at work. The tapping hole is drilled larger than for a cutting tap. The tap is wound in the normal way and displaces the aluminium (or steel or stainless steel) cold forming the thread. This gives a high strength slightly work hardened job with a good finish. There are no chips produced so this method is very safe for blind holes. These taps are quite a bit stronger than the usual type because the minor diameter is greater. The taps are more expensive but well worth the extra for fine work.

[FourstrokeForever]

Like a spoke threads in aluminium should be cold forged NEVER cut, that makes the thread weak. Good news is forging taps are cheap on ebay. They are a worthwhile addition to the toolbox as they can be used to repair a thread.

http://www.ebay.com.au/itm/HSS-Thredflo-Fluteless-HAND-TAP-M6-X-1-0-SUTTON-/191265412132?pt=LH_DefaultDomain_15&hash=item2c884e9424

Excellent advice. 

[mick25]

When I first had a go at redoing threads I got a scrap peice of 10mm thick alloy plate and done a few practice runs first best to get it right the first time on the job you are doing 

[Paul552]

If you are going to use a flute less tap that pre drill will be different for a roll thread

[FourstrokeForever]

If you are going to use a flute less tap that pre drill will be different for a roll thread

You really can't beat a rolled thread......but when in a pinch it seems the fluteless tap will do the job

[Lozza]

Normaly a cut thread drill size is 5mm for a M6 thread a formed thread the drill size is 5.5mm. Think it is normally almost the root diameter for cut thread and half that for a formed thread

[jerry]

Use a bit of kero as a lubricant too. J

[FourstrokeForever]

Use a bit of kero as a lubricant too. J

I use sewing machine oil to start and WD or similar to clean the schwarf away.

[jerry]

Bit like sex. Anything will do at a pinch! J