Adventure Bike Rider Forum

Subframe

Standard 640 subframe My 620 adventure subframe, slightly different but left side diagonal brace hits the tank What I knocked up, the extra added metal is valyrian steel which is fused together with dragons fire

it's a bit crude as work in progress, right side with 3 mounting points for tank

Left side with diagonal brace cut and a vertical bar fitted to compensate which back brace bar attaches to So I need somewhere to place the ecu, rectifier ect ect

Before it's been done like this Looked a bit crap so after fitting the rear light, mudguard and seat I found the ideal space so welded a tray on
Wires will be extended with release fittings should subframe need to come off. All wires securely tapped to frame lect side. Mudguard drilled to allow access for wires running under seat so only minimum exposer on frame edge near mudguard

The rally bike has a slightly different fuel tank compared to the 640 however the 620 adventure was made in 1997 so was fitted with the same tank as the rally bike. Its slightly larger than the 640 one and I think better quality. I have a standard 640 one also I compared this to


I then managed to get a fairing which is near same as the rally one. I will get this sprayed when I get to. That stage. I'm thinking of a ktm orange/white bike Got these larger foot pegs of ebay

So plans this week

Fit airbox securely as the holes on front horizontal bar don't line as I needed to drill them out so will weld another flat bar with holes pre drilled inline with airbox holes over the top as the already pre drilled holes are basically adjacent to one's I drilled.. see photo

New bar will tidy it up, I already fitted side gussets and drilled holes to secure the sides. I have a new mesh cover so will look like this when finished I am thinking of strapping a lightweight battery in the bottom of the airbox as still up in air over battery location hence getting it really secure.

I then plan to weld / bolt down the rectifier, ecu and solonode brackets on the rear tray and weld stud fittings adjacent for frame eath attachment

Then I will disc sand down the welds and stiffener bar edges as I beefed up the subframe with angle bar and gussets where required after researching on cracked 640 subframes..... Its heavy I would guess 20 to 30% more than Standard subframe but it has fuel tanks each side and luggage so that's ~40kg weight and then rider weight.

The standard subframe is flexible but as this has been strengthened its stiff so needed light tapping to fit it in. I think it's stronger if compared to the rally subframe.

The rally subframe is designed with left side diagonal bar missing I fitted the vertical bar on left side as well as rear braces, the side gussets and rear tray gusset really add strength. I also welded a horizontal bar on top Anyone recommend me a light weight compact reliable battery?

Will look to fit It in bottom of airbox with straps holding it down

Nice work and research, looking forward to following the build.
Motobatt seem to be a good spec with a selection of sizes and fixing positions.

Snaf MKII wrote: ↑Wed Jun 10, 2020 5:19 am Nice work and research, looking forward to following the build.
Motobatt seem to be a good spec with a selection of sizes and fixing positions.

Thanks will look later.

Any other items or ideas you guys recommend...…………..fire away

Thanks for sharing your build, I wish I could do all this stuff, but im happy to see pics of other people doing it!!!

also a 640A owner do you know of the engine weak points? Motabat used one once silly little terminals I understand the concept behind them but take a look before you commit,I can not comment about their reliability though, I would consider one of those fancy fusebox's if I were in your position. Will be watching thanks for going to the trouble, if you can make it look like the target pic, it will be nice. Will it be for the fun of the build or for a practical purpose for yourself if you know at this time .

bikenav wrote: ↑Wed Jun 10, 2020 1:02 pm also a 640A owner do you know of the engine weak points? Motabat used one once silly little terminals I understand the concept behind them but take a look before you commit,I can not comment about their reliability though, I would consider one of those fancy fusebox's if I were in your position. Will be watching thanks for going to the trouble, if you can make it look like the target pic, it will be nice. Will it be for the fun of the build or for a practical purpose for yourself if you know at this time .

Hi I already have one of those fancy fuse boxes, was thinking where to mount maybe under the seat as its a one bolt out job or maybe in view ?

Its for the fun of the build but also the main aim is for a reliable long distance travel bike suitable for continuous medium off-road (not hardcore stuff someone would take a 500exc)

I have always had a thing for a 640adv so might as well build the best one I can...………….or try to

Something ready to go for a RTW trip with no issues, hence why reliability is more desirable than weight as subframe is heavy duty now.

Not sure what to do once finished as I am more considering a sidecar outfit for myself and my son later on

Maybe for the next few years will be used for transport to buy a chai latte at weekends