So here is a thing, my PR7’s coolant bottle is rubbish. Now I can’t tell if the design of it is less than acceptable, or if it is me who damaged it or whatever… but it does leak coolant now, and that’s the main concern for me.

I like where the coolant bottle is positioned, I like how it looks, it is softish so it shouldn’t be very easy to break it, but… Pretty much every ridout I noticed that I’m losing a bit of coolant somewhere! If I fill it up more than half of the bottle, it will dump quite a good amount pretty much straight away, and when it’s at normal level and tipped over – it will leak through the cap and even under normal riding – it will just disappearing somewhere and the only explanation I have found – coolant bottle vent.

Since it vents right out through the cap, vapour has no chance of condensing and running back into the bottle, also the cap won’t seal that well, as the threads on the bottle’s neck are less than perfect too… Anyway – here is what I came up with.

To stop coolant leaking through the cap, I had a plan to fit a ~~17mm~~ 18mm (or even 19mm) rubber bung under it – inside of the bottle’s neck, but since Snail-Mail lost my parcel somewhere – used a rubber disc cut out from the old inner tube for now. The cap is still usable to fill up the bottle, but it wont leak anymore even if tipped over! (coolant bottle’s (neck’s) ID is 17mm – and 17mm rubber bung turned out to be too small, huh!)

And to cover for the blocked off vent – a bit of silicone hose (4mm ID) and Nylon elbow tube fitting, with barbed end for tube and threaded end for the coolant bottle.

Since there was no way I could just drill a hole in the bottle, push the tube fitting and secure it with a nut and washer from the inside of the bottle, and since plastic is not quite thick to cut the thread in the hole to secure the fitting, I opted out with a bit different approach – plastic welding.

Both coolant bottle and nylon fitting can be melted, and if both plastics can be melted, probably they can be welded together. And that’s what I did.

First step was to drill a hole in the coolant bottle – a bit smaller than the threaded part of the nylon tube fitting.
Second step was actually to join them – so I gently heated up the coolant bottle with a lighter till it turned almost transparent around the hole, and at the same time heated up the nylon fitting till almost all threads were molten and gone, and just pushed them together. It came out quite nice, but I wasn’t quite happy to leave it like that, so..

Third step was to build some plastic around the fitting to make it stronger, for that used soldering iron and my very last white cable tie. 1st, gently soldered around the nylon tube fitting, then added extra plastic all around by melting the cable tie, making sure that it forms a good seal all around – messy and smelly business that was!

Once I was done, I was happy about it, not so much about pretty much toasted soldering iron, but because weld came out pretty strong, not so pretty, but should hold!

To finish it off filed down the extra plastic from the areas where I didnt need it, rinsed coolant bottle with water, fitted it back in place, refilled with some coolant, routed new coolant bottle vent pipe up and over the relays, back down and to the right side of the bike – under the brake pedal. Easy!