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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => Project Sidecar Motobricks => Topic started by: Sit on September 09, 2018, 10:52:50 AM
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Picked up a non running project hack a few weeks ago. It is a 90 K75RT with a Velorex chair attached. I got the bike running and have now moved on to the brakes. The rear brake on the bike is not working. Part of the problem is that the return spring for the pedal is not hooked up because the place it mounts to on the center stand is gone, there is no center stand on the bike as the sub frame attaches in its place. Anyone else run into this? Did you find or fabricate a point for the spring to mount to?I would like to get the rear brake hooked up to take a bit of pressure off of the front, which are warped, most likely due to doing a bit too much on their own. After this I will move on to the sidecar brake. I know, some don't use it, but its there, and I want it working. Looks to me like it has never been hooked up.
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Figured I should post a photo too, well just because...........
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If it's just the spring I'd fabricate some sort of hook or find a different length spring to hook somewhere. Hopefully the hydraulics are not shot from non-use. Nice find there, that earls fork may be worth a small fortune just by itself.
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Kind of what I am thinking, just find a spot. Was hoping someone already had. Also pretty sure the seals or what not in the rear master a shot, but that is what happens when things are not used and just sit. You should have seen the gas tank. It was really bad with about 2.5 gallons of gas that stopped being gas a few years ago. Several hours of cleaning and a new fuel pump, mount, lines etc, the thing fired on about the third crank. Smoked for a while, but then cleared up and seems to run fine now, stopping, not so much, but gets going.
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That rig is beautiful! Keep posting!
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Yes, very nice.
Keep us updated as to your progress.
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Thanks, I will. I bought it not knowing if it would even start or run. New battery was put in and all new fluids. This encouraged me a bit because the fluids all looked good. Gas tank though was bad. Fuel lines crumbled when touched. Lots of varnish and lots of chunky crap. Took fuel pump out and found it frozen and the rubber damper was goo. Put vinegar in the tank while I got a new pump, lines, filter, and mount. Put the new inards together and cleaned the tank. The vinegar worked great and after some work, mounted the new pump etc, mounted the tank and gassed her up. Cranked three or so times and started. Ran fairly smooth but there was not a mosquito within blocks. After several minutes the smoke stopped and the high idle could be turned off and the bike idled nicely. Took it for a spin and the gear box seems to work. Scared myself in the first turn because the chair came up real easy. I am use to a ural which apparently is a much heavier chair. lol. As stated, the brakes need work and I need a new sender for the tank. The rest from there will be cosmetic and preventative. Needs a glove box door. Need to fix the lock on the sidecar, need new tank roundels, etc. at some point will check the splines and dig deeper into how it was put together. Just happy for now that my $3000 got me a rig that starts.
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A throttle return spring from your local auto parts will let you make one of various lengths.
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You sound like you already know your way around a k bike.
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I talk a better line than I actually know. My main ride is a 12LT, so with a book and tools I don’t mind getting into the older simpler Ks. I have a 100 RS SE that I can use as an example of what it’s to look like so I get even more adventurous. My first K75 was a S picked up for $500. Put a clutch and main seal in, just followed the book, and kept it for a year or so. Just sold it prior to the hack for $2000. I just like tinkering with them.
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Problem solved. Had to rebuild the rear cylinder as it was frozen in place and the cylinder was full of gunk. Took apart and cleaned, put back on and bled. As for the spring, keep it simple. Bought a return spring from Ace, hooked it to the pull point and then just pulled to the edge of the subframe and hooked it there. No alterations or anything. Seems to work, pedal returns with the pressure of the system and the spring helps and the brake light is not always on. Success.
Now to work out the front brakes. They work but need to be bled too. One bleeder does not allow anything out and can’t get to the other one for some reason. Something is too close to it to allow the wrench to go on. Will have to take the calipers off to replace the bleeders and see what is going on.
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New glove box cover, lock etc. starting to look good. Just have to put the new roundels on the tank and get the front brakes dialed in and it will be road ready and I can start building confidence in that the bike will stay running when I want it to. During winter I will take care of deeper maintenance, looking at splines etc.
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After this I will move on to the sidecar brake. I know, some don't use it, but its there, and I want it working.
:2thumbup: The single pot Brembos could really use the help when a sidecar is added, from what I've read. Thanks for the photos.
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The previous owner did not have the rear brake working which might explain why it appears I have a warped front rotor(s). Even pulsing, the bike stops good even with a person in the sidecar. Once I get all bike brakes up to snuff, I will look at the sidecar brake, thinking I may try to find an electric trailer brake to put on it, a percentage one that can be dialed down to a low amount that will just help a bit. Don’t even know if they make one small enough but will look into it to see what is a available.
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Soooo
How did the sidecar brake install go? Any progress.
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Have not dealt with the sidecar brake. After rebuilding the rear master, the rear brake now works fine; bought a return spring for the pedal and just hooked it to the edge of the subframe, works fine.
A few test rides show the bike rides fine and stops, like a galloping horse. Need to get new tires ordered up, when funds come available, and at that time will dive into the front brakes to figure out if the calipers need work and if the rotors need replacing. I have not even been able to bleed the front due to a wonky bleed screw on one side and something is in the way on the other side to even get a wrench on it. Figure it will be all easier to see what is going on after they are off the bike and I can really look at them. If they get worked out, don't know if I will even worry about the sidecar brake. The thing is so light, my few test rides really did not even notice it was there, even with a passenger. I was used to a Ural and those rigs are much heavier, and noticeable.
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I was used to a Ural and those rigs are much heavier, and noticeable.
Not to mention the K actually produces some HP :hehehe