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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: americanteek on July 30, 2014, 06:38:57 PM
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I'm a newbie to flying bricks but have been riding a long time. This weekend I'm going to look at what appears to be a really nice k75s. I spoke with the seller and he said the bike does pull to the right when he takes his hands off the bars, like it is changing lanes on its own. I'm very mechanically inclined and not afraid to fix something, but I'm wondering what this could be, alignment of the rear wheel? Fork issues? Bearings? I looked around and couldn't find anywhere that anyone else had this problem. I realize as well that road crown can account for this somewhat, but it appears to be more than that.
I know he did the spline lube and had the injectors service recently (pictures of both). I've read a lot about these bikes and have a pretty good handle on them but I'm unaware of how to check for the alignment issues and how much that should affect price.
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Rear wheel alignment isn't really 'adjustable' as such... If you do want to check it though, lay a plank (or something else straight) against the rear wheel, then 'measure' the distance to the front wheel - then do the other side and compare...
(http://0.tqn.com/d/classicmotorcycles/1/S/l/5/-/-/Wheel-alignment-drawing-452x338.png)
To cause handling issues it'd have to be a long way out though.
Check the tyres carefully, including the pressures as that can cause strange things to happen.
See if there is somewhere that you can ride both ways in the same lane to see if it pulls the other way with a different road camber - again soft tyres will really follow any slope.
Headrace bearings could be shot too...
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Bent frame? I wouldn't buy a bike that doesn't track straight on a level surface.
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lotts of straight motobricks to be had... i would not even go look at one pulling left or right...
j o
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+1 what Johnny said. Find another dance partner. :-)
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You can do the alignment check with a stringline, same principle...and fits in your pocket. (although you need something to 'hold' it up) I bought a wrecked k1100, had a bent frame (neck area) and bent triple tree. I don't recall it pulling per se, it must've crabbed down the road. I did replace the frame and triple tree. Its quite a process, but not that bad (get a label machine for wires, tubes etc.) if you like to work on bikes...you will learn it inside and out.
If you can get it for a really cheap price, frames, parts are available. Just know that your looking at a salvage title type bike when done. Guys are café-racering these bikes all over the place, would be fun project...although a 75S is café racer mostly...good luck!
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Might not even be an issue. I don't ride with my hands off the bar so maybe my K tracks to the right too. Road crown, tires, saddlebag loads, steering head bearings, and wind could all effect it.
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Thanks for the tips and suggestions.
I think some of you might be jumping to the conclusion that the frame is somehow tweaked. Having never ridden one, I'm unsure, but do these K-bikes tend to pull right? This article http://www.bmwrt.com/faq/pttr.htm (http://www.bmwrt.com/faq/pttr.htm) mentions this being a problem for K as well as specific R bikes due to the spline/drive/camshaft/transmission all being on or weighted towards the right hand side of the bike, which would tend to make it lean (and pull) to the right. http://www.motobrick.com/Smileys/MB_Smiley/falldown.gif (http://www.motobrick.com/Smileys/MB_Smiley/falldown.gif)
I guess what I'm getting at is as someone who hasn't ridden one before, is there a "normal" amount of pull that is acceptable. On my bicycle and some motorcycles I've ridden before I could go hands free for miles and steer with my knees or leaning slightly. Is that the case with a k75?
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you said... pull to the right when he takes his hands off the bars, like it is changing lanes on its own...
my motobricks when riding with no hands on a flat surface with no crown go straight... absolutely straight... can influence tiny bit right or left or absolutely hard left right or left with knees or arms...
on a crowned road still straight with slight hunt to which way the road is crowned... can keep it straight with slight body position adjustment...
butts at no time do they feel like they are changing lanes on its own...
j o
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+1 on what Johnny said