1981 XS650 Project Something or other (going cafe-ish)

[xb33bsa]

Re: 1981 XS650 Project Something or other

wow that sim is very cool and tells more than my keybord can,butteye can try
it just wont work unless the rocker is totally re-located lower and forward somewhere above the swinger main pivot
you must have the actuation from the swinger to be AIMED in the direction of the MOST active motion, which is far from what you have now
what you are looking for is a rising rate that is as the wheel comes up it starts loosing advantage on the shock,in other words the further into wheel travel you get the more shock travel you get
even a slight change in rate is better than none but idealy the rate is on a curve that steepens near full travel
keep at it !!!! you can do it you got plenty practice so far

 

[arkcom]

Re: 1981 XS650 Project Something or other

Here's a quick and dirty mockup that would give a progessive rate.

Blue is the arc of your swingarm clevis.
Red is your new bell crank, the important part is the new bottom linkage location.
Yellow is the new tie rod.

edit- probably need to rotate the swingarm clevis to the top of the brace.

 

[billyp]

Re: 1981 XS650 Project Something or other

That's intriguing. So if I understand you and your diagram correctly, it would then become a pull rod instead of a pushrod?

 

[arkcom]

Re: 1981 XS650 Project Something or other

Yes, It would pull. The bell crank could be whatever shape you want.

 

[billyp]

Re: 1981 XS650 Project Something or other

Thanks for the constructive input and for offering a solution arkcom. Much appreciated!

 

[dualero]

Re: 1981 XS650 Project Something or other

You may have to modify your swingarm brace and bellcrank length (red in previous mockup) anyway, to a point where the motion ratio of the swingarm and bellcrank suit the shocks travel

Sent from my GT-I9300 using Tapatalk

 

[billyp]

Re: 1981 XS650 Project Something or other

My plan, once I get ready to start fab and mock up on the new parts, is to make a bellcrank model out of some mdf i have laying around, and make the lower arm with multiple holes so I can get the wheel travel to shock movement ratio dialed in. Then I'll use it as a pattern to finish fab the new bellcrank. Dualero and arkcom, if it's ok, I may pm you guys pics of the mock up for opinions.

 

[tort]

Re: 1981 XS650 Project Something or other

Who doesn't like a thorough build?! Keep it up 8)

 

[billyp]

Got some work done on the frame and rear sub frame, with an angle grinder, a cutoff wheel and a flap disc, I can rule the world!

Cut some gussets out of 3/16 plate.

A little welding, a little grinding and VIOLA!

Then I added a 1 inch hole for a little flavor

Welded in a sleeve for a little extra strength

Needs a little filler weld but,you get the idea

 

[billyp]

Re: 1981 XS650 Project Something or other

Then I added some support to this area..

Just need to do the other side, then all the finish welding and grinding and the rear frame will be done.

Before..

...And after, much cleaner

I've been trying to decide on a style or a direction for this build. I finally decided to lean towards a cafe-ish type bike. The actual tail section will have a lot of slight curves and "flavor" and will be made out of fiberglass. I made up a quick mock up of a tail section, just soI can get an idea visually of dimensions and a general overall shape.

 

[Cuba Libre]

I believe you've taken many liberties with that frame. It looks swell, I just hope it holds up to the task (strength and rigidity).
I can only imagine what you have in your mind for the tail section. It's not bad - it's quite nice actually, more of an 80's superbike sort of thing - but my heart is set on the older school, curvier tails...
(You're mighty handy with a torch and a welding machine, aren't you???)

Keep up the good work!

M.

 

[billyp]

Finally got the rear suspension sorted out, just waiting in the final bits to arrive in the mail so I can finish fabing up all the parts. I re did the rear sub frame and mounting for the shock, cleaned it up a bit. While I'm waiting for the material to show up for the fabing of the bellcrank and the rest of the rear suspension, I started on a tail section. The actual thread is over in the Tanks and Seats section, but I thought I would at least post the highlights here.

I went thru 3 different iterations of the tail before I settled on this one. A little more refining and smoothing and it'll be ready for fiberglass.

 

[billyp]

Ready to lay some glass

 

[billyp]

Finally got some glass on the tail. Couple of more layers and it'll be good to go

 

[treitz]

Nice work! You've got some fiber glass skills sir.

 

[billyp]

Nice work! You've got some fiber glass skills sir.

Thank you for the compliment. It's actually my first time doing fiberglass work and it's very much been a learning process

 

[billyp]

So I've spent the last couple of months re doing the rear section of the frame. I wasn't happy with the way it turned out and the mounts I used for the rear shock looked like a second thought just added on and didn't flow with the frame the way I wanted. I also decided to make a tail section and wanted the frame to a kick up at the end instead of being flat like it was.

The actuation of the rear shock needed to be re done as well to make it function proper and to make it safe. To do that, I re did the bellcrank, the swingarm brace and the push rod mount on the swingarm brace.

For the bellcrank I fab'd up the two sides out of 1/4 inch plate, the large hole in the center will hold a needle bearing for the pivot of the whole unit. There's still some fab to do with mounting points for the shock and the push rod but this is the new shape..

Sleeve, needle bearing and bolt sleeve

Tacked the sleeve for the bearing on the inside of one the plates to set the position, didn't get a pic of that..

Lined up the two sides with a couple of bolts and nuts for spacers and welded the sleeve to the bellcrank. It will be ground smooth

Old bellcrank for comparison

 

[billyp]

Worked on the swingarm brace and pushrod mount next. I welded a new hoop section on then added a brace for the front using some 1x2 stock.

Made a mount for the heim joint (rod end) that will be on the end of the pushrod for adjustability. Didn't get any pics of the mount but I used some 1 1/4 square tubing, notched it, and drilled two holes so I can move the pushrod up or down if needed to keep the relation to the bellcrank at the right angle. Also added some gussets on the side of the square mount tying it into the tubing of the brace, then cut a gusset out of the 1x2 to connect the front brace to the mount for the pushrod, tying them all together. A little overkill, but this will be a high stress area so I want it to be strong. Still need to do some shaping and grinding to make it all purty

I'll be fitting and welding a gusset tying the back side together too

 

[xb33bsa]

how are you resizing the sleeve for the drawn cup needle bearing after welding ?

 

[billyp]

If needed I'll have a friend machine it with his mill, I'm hoping it didn't shrink too much so I won't have to.