Good day mates.  I am doing a whole cafe racer project on my 85 k100 and I really am hating how the overflow tank looks.  I am wondering could i just remove this all together and have the bike function fine or I was thinking could I just use a larger brake fluid reservoir , about the size as the factory rear reservior, as the overflow tank.  It is probably a stupid question but I am new to this and since I just started this project be prepared for more stupid questions from me.  I would appreciate any help.  P.s I have read on the forum about the special functions of the overflow cap already.

My solution was a baby bottle, on a bit of a lark.

Cut a small hole in the nipple and force the hose all the way to the bottom, then fill it half way. It's clear so you can see the contents. It's small so easy to tuck it away. It's held in by a wide cable tie.

I am always getting asked about its function. Enlarge the photo and see it behind the right hand side near-vertical frame rail. A brake fluid reservoir would be barely adequate, and you need a receptacle for the hot coolant to occasionally burp into.

Two Wheels Better wrote:
My solution was a baby bottle, on a bit of a lark.

Cut a small hole in the nipple and force the hose all the way to the bottom, then fill it half way. It's clear so you can see the contents. It's small so easy to tuck it away. It's held in by a wide cable tie.

I am always getting asked about its function. Enlarge the photo and see it behind the right hand side near-vertical frame rail. A brake fluid reservoir would be barely adequate, and you need a receptacle for the hot coolant to occasionally burp into.

right on man.  I like the ingenuity.  I will think about doing that.  What type of brake rotors and calipers are on your badass bike?

Brembo four pot from any K100-16V, K1100RS, R1100 Oilhead and early R1150. The discs are 305mm from an F800GS. The wheel is from a K1200LT with a custom-made axle. The forks are K1100RS Marzocchi.

Type 'Big Block' into the forum's search engine for the story.

I did not, would not, paint them red...

Go on to Ebay and type in aluminium radiator catch bottle tank. The come in various colours and sizes.https://www.ebay.com.au/itm/0-8L-Overflow-Catch-Tank-Radiator-Coolant-Tank-Bottle-Header-kit-Aluminum-Silver/202066495436?hash=item2f0c1a07cc:g:orMAAOSwIylZy2Ub:rk:40
Regards Martin.

Ali express also has quite a few.https://www.aliexpress.com/item/Universal-1L-Alloy-Aluminium-Engine-Oil-Fuel-Gas-Catch-Can-Breather-Tank-Bottle-Coolant-Radiator-Overflow/32879858618.html?spm=2114.search0204.3.15.bbf0a0e357alO4&ws_ab_test=searchweb0_0,searchweb201602_3_10065_10068_10130_10890_10547_319_10546_5730317_10548_317_10696_453_10084_454_10083_10618_10307_5729217_537_536_10131_10132_10133_10059_10884_10887_100031_321_322_10103,searchweb201603_1,ppcSwitch_0_ppcChannel&algo_expid=cbd5c5af-5db2-4c28-9f30-71b55c11571b-2&algo_pvid=cbd5c5af-5db2-4c28-9f30-71b55c11571b
Regards Martin.

MartinW wrote:Go on to Ebay and type in aluminium radiator catch bottle tank. The come in various colours and sizes.https://www.ebay.com.au/itm/0-8L-Overflow-Catch-Tank-Radiator-Coolant-Tank-Bottle-Header-kit-Aluminum-Silver/202066495436?hash=item2f0c1a07cc:g:orMAAOSwIylZy2Ub:rk:40
Regards Martin.

oh hell yeah that will work just fine.  Thanks man

Great shot of the Big Block TWB, though you should try to get more of the graffiti in the back ground.  Kudos also to you for capitilising on the found resources that were provided by the grand kids!

Woodie wrote:Great shot of the Big Block TWB, though you should try to get more of the graffiti in the back ground.

You want graffiti? I got graffiti.

Pioneer Square lane, Seattle

Yeah baby, THAT's how you photograph a custom!  Now go and cut the rear frame loop off would'ya 

Done, by the wanker who owned the perfectly good K1100RS and who got halfway through the job and 'lost interest'. I gave him $300 for a 'fully complete it's all there' rolling chassis, minus the rear loop. The frame is in Big Block and the rest is going towards resurrecting a K1100RS.


BTW, the baby bottle is a tool in any self respecting mechanic's garage. I just reached for the closest thing to do the job and it stuck.

"the baby bottle is a tool in any self respecting mechanic's garage"  


Is the idea then that it is the best way to keep foreign matter out of your whiskey while you work away on the bikes?  Hadn't thought of that but it's brilliantly simple and quite effective I think.  Your knowledge, as always, is boundless!

Looking at those two coolant tank offerings from China...
.8 & 1.0 litre will be hard to hide if reducing your coolant tank is the order of the day. The baby bottle is 9oz or 270ml and it's a sore thumb.

According to this seller..."helping to relive (sic) pressure while increasing horsepwer (sic)." A coolant bottle that relieves your pressures and increases horsepower. I want it!

eBay coolant bottle

But this one is pretty schmick, and only 400ml!

eBay Puke tank

Or this tidy unit with a pressure cap - redundant.

eBay .35 liter

And last but not least, a .5l alu job.

eBay .5 litre

it will be more about getting rid of that ugly stock tank.  there are some very good choices to make it look more aestetically pleasing, since one needs to be on the bike.