Finding chain line

Hey guys I’m in a the middle of a ZRX1100 swing arm swap. I would like to know the easiest and most accurate ways you guys find chain line? Anything will help. ( don’t mind my filthy work space)

The traditional way is to use a string that just touches the face of the rear sprocket, both behind and in front of the axle. When the sprockets are perfectly aligned, the string will also just touch the face of the front sprocket. I have also seen guys use a laser instead of a string. I have heard of guys using a metal straight edge, but they can be problematic in tight places.

I came across this tool years ago, and it has made my chain alignment a "peace" of cake ever since. Profi-Cat Laser Alignment Tool:

www.motomummy.com/shop-tools/profi-laser-chain-alignment-tool/

Great idea but pricier than it needs to be for what it is. I bet it is a godsend when you are lining one up.

ajsfirehawk wrote: Great idea but pricier than it needs to be for what it is. I bet it is a godsend when you are lining one up.

I have one - expensive, but totally worth it.

Just an idea. use a steel rod. roll it on a glass table or piece of glass at the hardware store to check that it's straight & true.

HomeDepot --- steel rod 1/8" x 4' --- $3

I had great fun sorting mine out. I fitted a Bandit600 wheel into GSXR600 swingarm with,I think, a 160 tyre, into my CSR1000 frame.
The whole process is in my build thread (somewhere!)
I started with centering the back wheel. I measured the clearance between the tyre edge and the inside of the frame downtube. Then subtracting the width of the chain,I was able to calculate the ideal position of the rear sprocket,leaving equal clearance either side of the chain ( I think I had about 4mm either side) . I needed to have about 9mm shaved off the sprocket carrier. That was it for the back end. Luckily the front sprocket turned out to be a standard sized offset.
A couple of things that came up. A lot of people seemed to think that the back wheel didnt need to be centered and could be run offset. This made no sense to me at all (and the fact that Harley do it on some of their bikes convinced me that it must be a bad idea!!)
I dont know the science behind it,others have their opinions about it but I wanted my front and back wheels running in line.
If youre using twin shocks rather than mono,keep an eye on the bottom of the left shock,you might have problems there with the chain.
And you may need some protection on the top of the swingarm over the pivot bolt, as the chain is prone to dragging on this.There are
different solutions for it.
That my tuppence worth. Good luck with it

thanks guys. im currently running an 3/8 offset on the front. i went and got some c clamps what looked to be the straightest piece of steel at the hardware store. with the straight edge, the front sprocket still needed to be offset by what looked like 3/16th of an inch. i had the material removed from the rear. sprockets still seem to be off a bit.

i think i need to try something more precise. The string method looks to be for aligning your front an rear wheel . does anyone have a good video or write up on a solid process for this . i like the idea of a string but im not sure how to rig it.

I used a cheap (10 Euro ) Cross Laser spirit level on an camera tripod to set the rear wheel (180 tire)into
the middle of the frame from my project bike.






Works perfect too, to set the chain, front(10 mm offset)/rear sprocket into a straight line.

Been building bikes for over 30 years now. I just eye ball it never had any issues with an of the dozens of customs I've built.

Yes baldy110, but my eye ball visual judgement need some technical support.!!!
I am 50+ years old and have to verify my visual judgement is OK for my age :laugh: :laugh: :laugh:

I too am north of 50. Just been dojng it that way for so long it works for me.