very gentle drift to one side....

Maybe a dumb question (apologies if it is) - but noticed the other day, when I let the bike drift along and I'd taken my hands off the bars on a deserted downhill one-way road in the countryside - that the bike has a slight tendency to drift to the right. You can control it will footpeg pressure - but it's definitely there. And it wasn't road camber (tried both sides to rule that out). Both forks appear the same distance 'up' in the yolk. Pre-load looks about the same. Is this kind of drift normal - or can it be tuned out? You don't notice it at all when riding, or even with only one hand gently on the bars.

 

Could it be that your front and rear tires are not in a perfectly straight line? I don't know if that's possible on a SSSA or not, but I know other bikes need to be aligned.

 

SSA do not require or have an adjustment like that, one of the benefits.

Is there any odd tire wear, or vibration at speed? If not, I wouldn't worry about it.

 

The BMW K-bikes are notorious for pulling to the right and it wears a flat patch on the left side of the front tire. They are SSSA but have an offset of the front and rear tires for some stupid reason, so much for so-called german engineering...

i haven't noticed it on the 3rd and 4th Gen but it is worth setting up the strings and checking alignment. if you feel it pulling right then the front wheel is likely offset to the right wrt the rear.

 

Could simply be due to camber-induced front tyre wear.:confused-new: Have you dropped the bike recently ??

 

Not dropped the bike, but only had it a year or so. There is no evidence of a hard fall on the bike. It might have had a gentle topple to right hand side, (as many VFRs have being so heavy!) Tyres are quite new.

 

How do I check the alignment with strings please?

 

Put the bike in gear on the CS. Get a piece of string about twice the length of the bike. Tie the middle of the string around the tyre and rim at about 4 o'clock looking from left. Now run both loose ends up along either side of the front tyre. Crouching in front of the bike pull both strings tight so they just touch across the back tyre edges so the strings are parallel to the back wheel. They should also be the same distance either side of the front tyre if all is aligned.

I assume you have properly aligned the front axle but if not do that first. Loosen the left axle clamp and bounce the forks a few times then re tighten.

If the bike still pulls to one side you can loosen the axle clamps and top clamps and top nut and tweak the bars while holding the wheel between your knees.


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I'd say there's definately nothing wrong with your bike. I have had the same problem on almost every bike I ride. I t mystified me for years as to why that would happen. Then I found that my spine was slightly out of alignment. I attribute the problem to that. It causes my weight to be uneven on the seat, more pressure on one side. If the bike tracks fine with both hands on the bars, don't worry about it.

 

what does your footing and body position look like? my fried was having the same issue and what happened was he kept his left foot under the shifter and his right on the balls of his foot on the peg. This caused him to put ever so slightly more pressure on his right peg. He changed his footing on his left and it corrected the situation. Also a thought is making sure you are perfectly centered on your seat and your balance is centered as well.

 

Did a quick aligment check. Difficult to be accurate, but it looks like the front wheel is within around 2 mm alignment with the rear. In other words, if anything, the front wheel is offset no more than 1 to 2 mm from the rear wheel (and offset to the left when viewed from behind the bike). I did lots of measurments and got values of between 0.5 mm to 2 mm for the offset. Does anyone know what the tolerances are for front to rear wheel alignment?

 

I don't know, pretty sure there's nothing in the manual on that. But if the front is slightly to the left that would explain a drift to the right. If your wheel/axle is in the right place (see my post above) then next would be to loosen the forks and twist the wheel right/bars left a little and see if that fixes it.


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Yes 2mm displacement to the left will cause it to pull to the right. The BMW have a spec of allowable 'toe-displacement' of 5 to 15 mm, and they pull to the right like MFs. i made some 10mm spacers to move the engine in the frame to correct it on a K75. i would think 2mm could be easily shimmed with some fat washers between the frame and motor mounts if necessary.

The front tire position is fixed by the steering stem, bearings, triple tree (yoke), etc. in the frame. The rear tire position is determined by the mounting of the engine in the frame.

Offset in alignment is not a common Honda design issue--Has it ever been dropped or in a wreck such that the frame is twisted or bent, or the forks might be slightly tweaked in the triple tree? Start at the front and inspect/check the forks, triple tree, frame, etc. and make sure all is okay before shimming the motor. A hard drop could twist the frame such that the steering axis is off.

 

Wow shimming sounds extreme for a "very gentle drift". I have had the front end apart a few times and confirmed that all parts are straight, so the drift I had was just the triples being slightly twisted. Loosening the front end and tweaking it as described will probably sort out your bike Viffviff.


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Loosened off the front (forks) and gave them a bit of a realignment. The bike runs much truer now. Only the very slightest hint of a drift - and that might be my imagination.. I guess 1mm of offset in alignment isn't that critical after all. Thanks again for all the advice.