1985 Seca Project (Yes, the years correct!)

Just got me a 1985 750 Seca (Yes, the year's correct, I checked in three places, they were only made in Switzerland that year and my frame number is 98 out of 101 that were built that year.. Popular model!! )

It's not in a bad state, just needs a new set of tyres and a new battery to get it through the Swiss MOT (I believe)

Below you see my three bikes..

A 2004 XJR 1300 which has stage 1 Dynos, Airbox mod, K&N Filter, Hagon Nitro rear shocks, Ohlins progressive springs in lowered front forks (I'm looking to change the front end for a set of R1 USD's) and a few bits of bling.

The XL125 was my first project. (These pictures are in the wrong order) I found her in a junk yard looking sorry for herself. The tank was in a state, the Honda stickers covering all sorts of evil, I dismantled the whole thing, rebuilt the engine, with a new piston, a new jet in the carb (That was a difficult find) and a few other new bits and pieces I found on other junk bikes. I'm nearly finished now, just need to put the side panel on and sort out a short ciruit and she'll be ready for selling on..

And then we have my newest aquisition.. A 1985 XJ750.. Not sure what I'm gonna do with her.. I want to look through this site and see what mods people usually go for.. I'm thinking a black rat bike of sorts.. She's gonna be my main commuting bike, I've put too many miles on my XJR which ain't really nice for long motorway rides because of the wind blast, so I don't want to put too many things on that will attract the attention of the law.. But I'll keep this thread updated as I go along.. Any mods people can recommend would be really appreciated.

See you on the road.. If you feel like seeing the mountains! (How do I put in-line images by the way?)

 

Nice collection of bikes. What you have is a Seca 900 chassis that the factory stuffed a leftover 750 engine into. I bet it has Hitachi carbs instead of Mikuni. Tune your engine like it's a 750- - service the rest of the bike like it's a 900.

 

Thanks... That explains a lot.. End of line bike.. Sell it to a small market for whatever you can get for it.. LoL.. I wish its chassis number was 101.. It would have been nice to have the very last one produced. I'll take a look at the engine serial number, it may tell a different story to the frame.

I'll take a look at the carbs when I get home... If they're Hitachi is it worth swapping them out for Mikuni if I can find some? What bikes/models will fit this engine?

With that info I'm thinking to maybe swap out the 750 for a crash damaged 900 when this engine finally dies, if they swap out that easily.. LoL.. Maybe someone already has!!

 

Yup.. Hitachi carbs.. Now tell me that's a good thing! Please!

 

not a good thing or a bad thing, just tells you its certainly a 750 motor

 

Well, that's a good thing... It means I know where I'm at with this bike.. I guess if I'm looking for after market parts, I'm looking at 1984 model parts for the engine? What about the frame? What can be interchanged between models (Forks, wheels etc.) for my exploits into fleabay etc.

Is there anywhere that notes what changed on each model over the years?

I've no idea what I'll need/want yet.. Gotta finish my 125 first, either that or save up for a divorce!

 

The downside is you sorta need 2 repair manuals.
'81 - '83 Seca/Maxim 750 for your motor specs and carb info,
'83 - '92 XJ900 for chassis electrical, rear brake, forks.

You would need the motor, carbs, ignition box, coils and airbox to carb boots to convert your bike. You have impossible to find, unique airbox to carb boots, so don't ruin them !!

 

Um... Yikes!!! 8O

I wonder where they got those from.. I can't believe they made them especially for 101 bikes.. It would have been to expensive to make a mould for 101 bikes if their intention was to get rid of some left over 750 engines.

So either they're standard XJ boots from one of the models or the other, or they pulled them from another Yamaha transverse four of the same era.. Perhaps an XS11.. I wonder how I'd find out..

Anyone got some dimensions of standard boots? When I put the stage 1 dynos in my XJR carbs, I changed the boots for the carb for some larger diameter ones, it involved moving the airbox.. I wonder if I could do something similar if I needed to.

 

101 bikes in your country, 100 more in others- - it adds up.

There's a cheesy fix that involves household plumbing couplings (size 1 1/2 inch) That's your repair if you need it.

FYI - they also shoe-horned the leftover 750 engines into Turbo chassis and non-turbo "Seca" 650's. More custom boots needed.
This gave Yamaha a wide variety of 750's if you count the XS and the Virago.

 

Sounds a bit of a bees nest mish-mash. Oh well, means the bikes ripe for mods. What are the common after Market mods for an xj? Is it possible to stage 1 the carbs? What kinda power gains does that achieve? What about the shocks? Rear ones look pretty standard, I'll probably swap them out at some point, front ones are anti dive I understand, what kinda oil do they eat best? What about the front springs in the shocks? Turbo in a non turbo bike? Simple or big job?

Sorry for all the questions, but I'm trying to decide where to go with this, take it back to the original spec or "improve" it.

 

I thought it was probably time to post a few piccies of my commuter.. This wasn't supposed to have been a project, I was intending to get a bike that I didn't mind knocking around the city a little.. But I couldn't leave well enough alone..

First, this is what I started with:






First thing to do was change those dangerous tyres, then I set about fixing the tank, which had a leak in it.. The previous owner had tried to fix the leak with a weld, and made a mess of it.. Then plugged the resulting hole with some black glue type substance.. A quick look inside the tank revealed that it was pretty rusty too..



A days work with POR-15 tank sealer, and the inside is rust free, and the leak is gone..



Onto that horrible body work.. Ahh... I do love paint stripper..



Took me a while to decide on what I was going to do for decoration.. I knew the basic colours were going to be black, but then I eventually decided on two white stripes, one thin, one thick. Stripped the bike back to naked, dents filled, undercoat, both colourcoats.. One clearcoat, and the bloody dog knocked the damn tank off the table.. So back to the paint stripper, I stripped the tank back to nothingness again, filled all the new dents, and redid it all..

In the meanwhile, while I was waiting for the paints and fillers etc. to dry, I put a couple of coats of 800 degree black paint on the engine and sanded back the ends of the cooling fins. Polished up a couple of replacement crank shaft covers (the ones one the bike are knackered from a couple of crashes), polished the sissy bar, changed the worn out bar grips and put on some micro indicators.



I'm pretty pleased with the result..




Bodywork things left to do:

Fit the polished crankshaft covers.
Paint or polish (haven't decided yet) the swing arm bolt covers.
Paint the bottom tubes black on the front forks, and change the seals and the oil for something heavier.
Paint the same stripe design on the front fender.
Polish up the cross brace on the fender.
Tidy up the rest of the paint work
Change the seat cover.
Put on some CNC mirrors I have.

When I'm done with this, I'll set to it on the engine, probably go for some Dyno stage ones and a K&N filter.. and then a general clean of the carbs and do the tappets and balance the thing, but that's for later.. Now I'm done with the painting, I want to ride it a little.