my '82 750 seca project with short valve springs look

hey all and thanks for peeking in my project

i have almost completed stage 1 and id like to share a couple pictures



so far i have

-rebuild calipers
-rebuild anti-dives
-new fork oil
-ss brake lines
-new headlight
-custom wiring
-clip ons
-gsxr master cylinder
-cbr clutch lever
-painted rims
-new wheel bearings
-spin on oil filter adapter
-just a little tail chop

 

Re: my '82 750 seca project

Nice, did you make the headlight mounts?

 

Re: my '82 750 seca project

no, it came with the headlights. i just bolted the thing on.

after reading the board a bit i decided to go for the mobil delvac mx motor oil

and yes i did drain the middle gear too, before reading all the warnings about touching it. i do think it was overtightened. the refill cap was so tight i had to use a pipe wrench to get it off

 

Re: my '82 750 seca project

great start keep us posted! cute lil tail light!

 

Re: my '82 750 seca project

Nice bike love what your doing with it!

 

Re: my '82 750 seca project

thanks guys


i took it for a spin. good riding position, it only needs a slimmer seat mounted a bit higher and more to the front. but that will be on stage 2 starting this winter

about the brakes. they were the reason i started doing work on the bike. my rotors were a bit crooked. i took them to a machining shop and they grinded them straight, or thats what they said. the judder has reduced but its still there. i have to look at them again after i break them in a little more. other machinist said i should just brake hard and they will straighten themselves. i kind of doubt that.

i think theres a little air left in the system too, i was missing some braking power.

this is what i love about old bikes, theres always something you need to tweak




one more question: i changed my fork oil and took the spring out. the coils are wound more tightly on the other end, does that mean they are aftermarket springs or were the oem springs like that too?

 

Re: my '82 750 seca project

how do you change fork oil in these bikes?

and where did you get the brake lines I keep looking but everyone is always selling 2 when i need 4 (two long ans 2 really short for the anti dive)

oh and ill contribute to your bike with this post I found
http://www.xjbikes.com/Forums/viewtopic ... +size.html
LED light that plugs your frame hole and makes the holes turn signals

 

Re: my '82 750 seca project

i just removed fork caps and anti-dives and let it drain overnight. added new oil accordingly.

i got braking brake lines. just measured how long i need and put them on. still running the oem short lines for the anti-dives. well not anymore but anyway.

nice contribution, i thought that as well but i chose not to run signals at all.

 

Re: my '82 750 seca project

I think the OEM fork springs are consistently wound; I'm guessing you have Progressive Suspension springs.

 

Re: my '82 750 seca project

yes, the OEM's are non-progressive. Yamaha was mighty proud of the anti-dive.
Don't do like I did and assume the suspension sucks w/o putting some air in it. Rode it that way for months *facepalm*

 

Re: my '82 750 seca project

sweeeet i have progressives 8)

ok where was the spacer suppose to be? iirc someone had spacers on top of the springs?

thanks M_B i need to try them with the air also. that may happen in the spring im afraid, the winter is close. keeps me from throwing away the anti-dives during winter i guess

 

Re: my '82 750 seca project

Mine came with (2) pieces of 27mm OD PVC pipe (about 1" OD) 47mm long (about 1 7/8"). Install on top of the spring. I think the directions also said not to use any additional air pressure initially (adding air sparingly to fine tune). I think the tuning/install instructions are still available at the PS site.

 

Re: my '82 750 seca project

the pressure adjustment IS very fine. recommended is somewhere in the neighborhood of 6-12 psi. MAX is like 35. I use a bicycle pump to fill up to about twenty then carefully air down with the gage to about 13psi. Fiddle with it. Make 2-5 psi adjustments and test ride. It's basically pre-load so you'll find you want more for luggage or a passenger. Also more for harder carving, later/harder braking in the twisties, etc. Me and my standard luggage load (tools mostly, rat riders don't leave home w/o 'em) add up into the low 200lb range and I carve pretty hard, thus me running in the "high" end of the range.

It's NOT like filling a tire. The volume in there is very small and "rigid" so the pressure almost instantly goes up to whatever is coming out of the hose. DON'T use a compressor or CO2 filler of any sort unless you know for certain it is regulated down to under 30psi. (if by chance you have some kind of CO2 rig reg'd down, don't use that either, liquid can get through the reg then boil off on the downstream side)
It helps if you can find an air gage with the smallest max you can get your hands on. If I could remember where I found this 0-45psi gage, I'd tell ya.

On my "to-do" list is plumb the two together so it only takes one fill and adjustment and so that if for whatever reason there is a leak they will at least always match.

With my 30 year old factory springs I was getting all kinds of front end dive when I got on the brakes (trained me to use the rear a lot though, almost never did before) 8psi later, that was gone. 20 was WAY too much. I know all about hard tailing but 20 psi felt like a hard nose ride...

 

Re: my '82 750 seca project

thanks guys, detailed info!

i have no spacers on top of my springs. soooo i will add spacers and fiddle with the air.

but first things first: amongst others my winter plans include a monoshock, new brakes (stock suck) and possibly(!) injection, to get rid of the carbs that need the airbox which is interfering with my rear suspension plans. i figure with the pod/likely rejetting hassle it would be the same if it was injection hassle

 

Re: my '82 750 seca project

update!

got meself a set of these!




i need to make caliper brackets



i lost the right side spacer, does anyone know the measurements so i can turn me a new one?

the speedometer side spacer is under work too. grinded the speedo mechanism out and i will tig the hole shut. i have no gauges

 

Re: my '82 750 seca project

rotors look good on it . I have seen a bunch of that type on ebay let us know how they work

 

Re: my '82 750 seca project

Hey I think I seen your bike on custom fighters! I need to join up over there, lots of cool stuff.

 

Re: my '82 750 seca project

yes im hanging over there also, awesome board! join up mate!

 

Re: my '82 750 seca project

...and what bike they are from so we can get some too!

 

Re: my '82 750 seca project

they are galfer waves for ducati 851/888. many ducatis share the same rotor dimensions, the offset being different. also some yamaha fzr, aprilia mille etc. closest match would be ducati 748/996/998 R models with 15mm offset.

i had adapters made


i got them off ebay uk brand new, dirt cheap

 

Re: my '82 750 seca project

Sweet, I am waiting to get some more progress done on my bike and have enough pictures to start a thread. Are you still monoshocking this baby? I am in the process of lenghtening the swing arm and monoshocking mine, just need to find a good day to go get it finished up.

You running the stock forks then? What are the calipers?

 

Re: my '82 750 seca project

yes thats the plan. since removing the airbox is mandatory and fuel injection will cost 1000€ i am going to do what you did with the stock stacks i need a jet kit.. .

calipers are brembo 4-pots off a ducati multistrada, matt black to suit my needs.

forks are stock, for now, i am trying to keep a budget here.. but since this project will last years i think a nice usd fork setup would come to picture someday.. or year i have clipons for the stock forks too so i will hang on to them..

cant wait to have a peek your thread!

 

Re: my '82 750 seca project

i see you have the tops still on the anti-dive units, are you still using them?
i put caps on mine with a cavity to let the piston fit into, fully extended, but if a guy were to put a screw through the cap to press the piston down it would be kind of like adjustable damping. maybe ?

 

Re: my '82 750 seca project

thats a nice idea polock.. and i think it would even sort of work. but isnt the anti-dive suppose to work only under braking? if the actuator would be screwed down it would make the forks stiffer all the time?

i have the tops on yes. i rebuit them and was using them but didnt have the time to start fiddling with them = never tried to adjust them or anything. so i dont know how it really should feel when working properly.
i want to try to make them work good again. i dont think my actuator part is moving freely enough, thus propably making the same effect as a screw would..

but if i ever decide to go with the stock front without the anti-dive, im copying you!

 

Re: my '82 750 seca project

UPDATE: the progress is slow but constant. theres a few things i would like to have your opinion about.. please read on. sorry about the cell pics..

i have been looking for a tig welder to do the swinger and frame. while at it i took off the head.



i want to sodablast it. i have 30kg of coarse blasting soda. i borrowed my compressor to my bro and im waiting to get it back. would you guys take the valve guides out before blasting?

i have been cleaning my valves. i have manual brass brushes but i have also carefully used a brass coated steel wire wheel on a drill.


now please have a look at my intake valves? it seems PO has had them machined. they look 25 years younger


ports to match:


imo the only thing left to do is to clean the sh!t out of everything and lap the valves in.


next, about valve springs.

my inner springs are out of spec, each about 0,5 mm short. would you guys recommend to replace them?


this one needs some cleaning too.. im not taking the jugs off, i just plan to get it clean. no polishing the piston crowns, just take away excess carbon and gasket leftovers... what would be the recommended approach? any tips not getting crap between the piston and cylinder and in the crankcase?

 

Re: my '82 750 seca project. UPDATED 04JUL11

sodablasting.

it took hours just to do the combustion chambers with my little 24 litre compressor. i need a bigger one..

before


after






anyone have ideas about the valve springs do they absolutely need replacing?

 

You don't need to replace Valve Springs.

You DO need to replace Valve SEALS.

If you Soda Blasted the Valve Seats you have to Lap the Valves.

Be TRUE to yourself.
After you Lap the Valves ... there should be a WELL DEFINED New Band around the Face of the Valve.
Uniformly shaped, ... about the Width of a Nickel.

If there are Spots where the BAND is Narrow or Incomplete, ...
Have the Valves done.
Recut and Refaced.

You won't regret it.

 

Where did you get those lights

 

thanks rick,

just wanted to ask cause my shop manual says they should be replaced if measured short.. each seat looks good and uniformly shaped already but i plan to lap them yes and replace the seals.

maverick the headlight is off a 50cc bike called solifer supermoto

 

Venlis I dont know if its the picture angle or what but that single valve looks to be bad.

 

The valve in the picture above is dished on the valve face (part of the valve that contacts the seat) that valve needs to be ground flat again. I would suspect the valve seat is in need of machining also. Bring to a good machine shop and have them do a valve job. If the guides and your valves seal properly the bike should be easy to tune and run well.

Good Luck with your project
MN

 

thanks for the observations. .

the picture is very accurate and all of my intake valves look like that. they have been refaced by someone, but not how the manual tells us to. all of my intake seats are machined too. by the looks of it whoever did it knew what he was doing, so i plan just to lap them a bit and put everything together.



the head gasket residues are next to impossibe to get off the block! i soaked it with gasket remover with virtually no effect!

 

If those valves were refaced intentionally like that the person who did it needs to be shot.
Speaking as a mechanic, those valves are past recovery. lapping them in will give you a running engine, but please don't ever sell the bike as having a top end overhaul.

It is not possible to face a valve properly (on a valve refacing machine) anything but flat. To get what you have (intentionally) you would need to lap the valve with grinding paste using a power drill and forget to stop before wearing a groove in the valve.

Why ask for an opinion about valves and then, when given advice from a few people on here who actually seem to know their stuff, you then say 'nah I think they are fine' When all the advice is contrary.

A quick google picture search to help explain;



In case you are unsure, those valves are past their use by date, unserviceable, buggered, stuffed and no good.

 

ok thanks for clarifying for the third time darkfibre. im not unsure anymore.

its just that to my eye they look machined, not worn. but im not a mechanic.

thanks again.