WTD: 748RS/749RS airbox engine breather valve (59310192A)

rarer than a rare thing, you can cut turn around and use any of the std ones with a bit of patience

 

Is there such a thing as a 749RS?

 

he heee......

 

Indeed, here's one I made earlier;

 

On my soon to be fitted engine it has an STM one I think, I removed it for cleaning and took it to pieces at the same time only to find the reed had completely broken up, after a long search on the net I couldn't find any replacement reed anywhere, so I have improvised with a carbon reed from a mini moto engine, it fits perfect without any cutting and the hole centers were spot on as well.

 

I have a spare couple or so. £10 posted next week. I am in spain at the moment.

Mike

 

I tried 'uncrimping' but it would have damaged the plastic so I cut the top 'lip' (one at the pointy end) off but cut as little as possible because you need as much material as possible to re-crimp it afterwards.

Once apart the valve 'plate' is a separate piece, you just need to flip it and then cut the threaded part off the old base (which will now become the top) because there is a taper inside that prevents the valve fitting unless you cut the 'top' (was the base) off.

Cut it to the thickness of the valve 'plate' but if possible leave a small amount of the lip as a retaining lip because the crimp is only just enough to cover the valve plate and hold it all together.

You also want to plug the oil drain hole between the reeds (I used a 3mm bolt) as there is no no need to have a return hole in the airbox.

If you only cut off the very end of the ally sleeve, there will be just enough to push it over the whole assembly and then using a small hammer you can peen (re-crimp) it around the tapered part. I also used araldite to hold it all together before re-fitting the sleeve for 'belt and braces' strength.

I actually made a couple but the first was not so pretty because I cut the square crimped end off (as it was easier to get at) and cut a little too much in doing so - the 'square' crimped end sits neater on the new valve top as you don't need to hammer it down and it is narrower at the opening so it gives better 'coverage'. I also then had to grind some of the plastic on the taper to be able to peen the ally over it and it doesn't look as neat, although perfectly functional.

Once you've cut it open you'll see what I mean, I have got some pics of the process so if you want I can make a 'how-to' but once apart it'll be obvious and as long as you leave the ally sleeve as long as poss you'll be fine.

 

Inlet end peened over, not as neat as factory pressed but good enough for me;

 

I think it is just a 7 day rest period.