'79 GS425E cafe project

[TheKevin]

I just started converting my 425E to a cafe style, looking to go stripped down/bare style, minimalist if you will. I plan on starting with the front: handlebars (just installed), controls, dash, etc... My biggest concern at the moment is replacing the brake lever/ MC. Its my understanding that brakes are somewhat important, so I wanna make sure its done correctly. Does anyone have any technical info on the GS425E MC and/or recommendations? i.e. volume/piston diameter/etc.

 

[roeme]

Not sure why you leave a rusty screw when you had to take it out anyway to replace the handlebars. Also, those look uncomfortable as hell, slanted down and very wide. Strange combination.

Its my understanding that brakes are somewhat important...

...if there ever was an understatement, that's one.

Does anyone have any technical info on the GS425E MC

Go there: http://members.dslextreme.com/users/bikecliff/

 

[thebrandonbeezy]

Get a set of clip ons if you want the "committed" caf? flavor. But then youll need rear sets to keep it comfortable. If youer gonna cafe it actually do it. I was going to cafe mine but its turned into a resto mod more than a cafe

 

[thebrandonbeezy]

Also you need to understand the difference between a cafe racer a brat and a brat tracker and a tracker

 

[storm 64]

I generally don't give a hoot what people do with their motorcycles. But why the 425E? I've been looking for a nice original 425E for a while. There are so many 450L 's out there to cut up. Also Hondas make better Cafe' bikes anyway. They're easier to modify, cheaper and a higher resale value. I would seriously consider getting a Honda to a Cafe'. I'll give you a fare price for your 425E if you decide to sell it...

 

[TheKevin]

I've had it for a few years and just want to change it up a bit., maybe cafe style wasn't the correct term. http://i.imgur.com/stWNkVI.jpg I'm gonna do whatever I want to it, I like the cafe style and that's were the inspiration is coming from. Not trying to do anything permanent in case I decide to sell in the future. I am keeping all the original parts that I have reinstall if I decide to sell.

 

[thebrandonbeezy]

425 will make a good cafe just needs effort and set in stone vision of what he wants. And hondas have hipster tax so where you can pick up a running gs400 here where i live for about 4-1000 depending on condition a cb400 not running but all there will typically go for 800 +

 

[thebrandonbeezy]

When i started my build i only knew i wanted to make it a single seater so the rested ended up being all miss matched and looked goofy. Im in the process if fixing that, dont make that mistake

 

[TheKevin]

I have a general idea of what I want to do, it will just take time.

 

[storm 64]

I have a general idea of what I want to do, it will just take time.

Time, money and SKILL. It's very rare to see a finished cafe project. I can't wait to see how this one turns out. Good luck

 

[roeme]

Not trying to do anything permanent in case I decide to sell in the future. I am keeping all the original parts that I have reinstall if I decide to sell.

Good to hear - you definitively preserve value here.

In any case, since you aim for a caf? look, consider narrower handlebars. Also, the indicators need to be way way smaller and closer to the bike, if you don't want to remove them completely.

If you need/decide to rebuild the brakes, you need: new seals (there are complete kits available), brake fluid of course and new brake lines (unless you got new ones on recently?),
best to spend the $$$ for braided brake lines. Re. Brake Levers I have no recommendation (yet). Rebuilding the brakes is easy, if I'm not mistaken on Cliff's page there's a guide.

 

[TheKevin]

I currently have a braided brake line installed, my biggest concern right now would be where/how to find a master cylinder that is appropriate for the 425e. Prob not going to rebuild too much as the bike runs great as is, I'm just ready for a little change ride wise and aesthetically.

 

[Chuck78]

Rebuilding the original master cylinders is one of the few things I swore I would not do ever again on a GS! What a pain.

If I measured correctly, my gs425e stock rotor mounted on the bike still is a 275mm.
Dan aka Salty_Monk on this forum sells a bracket and spacer kit to fit some modern brakes onto the front of a stock 275mm dual disc GS. I think that this kit would swap over to the GS400/425 forks as well. See the thread titled something like "twinpot brake mod for 78 skunk" that is in the performance/mods section near the top usually.
I am thinking just one 296mm Honda rotor and one side worth of Dan's bracket/spacer kit will swap onto yours and give you a late model 2 piston sliding caliper from a Ninja 250 or EX500 or Concours or something (myself and others have posted a definitive list work in progress of calipers and rotors several times in there), basically the late model GS500 1st gen caliper '89-02-is but the left side. Then run a new-ish used GS500 master cylinder up to the last year 2010. Then you'll be running any number of Honda CBR/VFR/Firehawk 296mm rotors. This us a great setup.

Here is a 310mm single disc version of what I am talking about from member tkent:

 

[Chuck78]

If your forks have any rust pitting on the chrome sliders, or you want a big performance upgrade, get a set of 89-2010 GS500 fork legs and caliper and master cylinder and axle (with spacers if possible). Then get an 82-82 GS1100E all aluminum triple clamp set. Then get AllBalls conversion bearings to fit the 425 frame and 1100 triples.
Then run a 98-99 CBR900RR 310mm right side rotor on the GS hub (as with many of the 296 Honda rotors, same 6 bolt pattern but we need the 6mm holes drilled out for 8mm bolts).
Now you have your 33mm forks upgraded to 37mm with an aluminum triple clamp and needle roller bearings, 275mm solid cast iron rotor upgraded to a lightweight 310mm s.s./aluminum floating rotor, & your old single piston short swept pad area caliper upgraded to a long swept area 2 piston sliding caliper!

To take it even further, I'd add RaceTech gold valve dampers to the GS500 forks with 10 or 15w oil, & test ride to check spring rate compatibility. If too soft, start chopping out coils and adding copper/PVC pipe spacers with about 1" of pre-load on the springs until you arrive at a great blend if comfort and performance.

Compare the offset on the gs425 triples to the offset on the gs1100e triples. If the 1100E has much more offset, don't go crazy adding talker shocks to the back, as a longer offset triple will reduce the steering trail to a sporty figure, & so will 1/2" or 1" taller shocks. Both may make the steering very quick but could lead to high speed head shake unless you do some math with head tube steering rake angle, triple clamp offset, & front tire radius- in order to arrive at no less than 3.75" of trail

Trail is the distance measured on the ground in front of the bike that an imaginary line through the center of the steering stem projected to the ground back to the point on the ground directly under the front axle.

I only caution you because I think the stock shock height will be spot on with the 1100E triple as the 1100E had a taller front tire than the tiny 18" on the twins. Should be more offset than stock gs twins which will reduce trail to a sporty steering figure.

With stock forks, the same thing can be accomplished with 5/8" or 7/8" longer rear shocks. Steepens the head rake angle which in turn reduces trail

I hope this information overload helps you out!

Here's a 93/94-is cbr900rr 296mm version of the brake upgrade, mounted to dual disc GS650 35mm forks that may possibly get transplanted to my GS425

 

[Chuck78]

Oh, more food for thought... 2 of the Wiseco GS750-844cc 10.25:1 pistons bored into a 400/425 block yields 449cc and 10.5:1 compression ratio. I think Big Jay on here from APE Racing/APE Performance Products sells them in pairs and has head gaskets made for this overbore as well. Vroom vroom hot rod GS449! K&N pods or airbox filter and a MAC GS400/450 exhaust with performance baffle and carefully tuned (rejetted) carbs will yield a very fast and agile mini-monster!

I'm trying to build up a 475cc/489cc/502cc version of the same thing basically. But oversized valves, ported head, Megacycle .380"intake/.354"exhaust lift camshafts, MAC header or some old 2 into 1 header I have with custom mid pipes and Kerker System K aluminum muffler cans. Maybe GS650 dual 296mm disc forks or maybe single 310mm disc RF900R 43mm cartridge forks... wire spoke wheels and longer GS1100E aluminum swingarm (custom narrowed to fit the twin frame) to help the bike accelerate better off the line instead of just pulling massive wheelies with all that extra power!

 

[Chuck78]

P.S. those drag bars (handlebars) in your first post's picture are far more comfortable and functional in the proper position rotated up and back about 90 degrees!!! You have them in a very un-ergonomic straight across and bent down position, you really will not enjoy that at all, they need to be fairly flat across the top to give you the sweepback that makes them comfortable to ride.

 

[Weasel]

Looking forward to seeing what you do with it.