Am I the Pontius Pilate of this CX500?
- Thread starter Odontologist
- Start date
I'm running dual TM34's on my BMW F650 (Rotax engine) and they are a treat. Perfect carbs for that engine. No clack, afaik.
the one on my xr650l is a kehin fcr42mx it clanks lol mind you its a bit worn and its a big bore high compression lumpy cam thumper
the mikuni tm36s on my 750 nighthawk and my gl650 are quiet as are the tm38s on my xs1100
just that fcr
i have a cx500 with a pair of fcr37 and they do it to a lesser degree so maybe they are just a bit noiser
the mikuni tm36s on my 750 nighthawk and my gl650 are quiet as are the tm38s on my xs1100
just that fcr
i have a cx500 with a pair of fcr37 and they do it to a lesser degree so maybe they are just a bit noiser
Odontologist
Umina Beach, Australia....Where does that part go?
The bike has been running very well with the Keihin carbs. Going for a big ride tomorrow.
It did however end up much lower than where it started.
As a result, the side-stand kept the bike way too upright, and the centre-stand was almost impossible to use....so much force required that I could do it twice, but not a third time. Hernia stuff.
I didn't measure before, but after, I took the following measurements for reference...
Ground to upper rear shock mount 710mm, and ground to middle of lower end of steering head stock 750mm
This didn't help me much, so I took a look at the centre stand clearance between the ground and bottom of rear tyre on the 650e, and it was about 20-25mm.
The clearance on my Cafe CX on the centre stand was 70mm.
So I decided to shorten the stands by about 40mm, and this is how I did it.
I marked and cut 40mm from the stems between the feet and the spring attachment point.
I did read through other posts that the feet was also a good place to cut, but although that would be OK for the side stand, the centre stand feet, once detached, could be a bit tricky to replace in the correct position, that's why I chose the stems.
It would be possible to re-weld the pieces back at this point, as the tube if pretty thick and could easily take a straight weld with either TIG, MIG or MMA, but I wanted to reinforce the cut sections so I used the bits that I cut off.
In the case of the centre stand, the tube OD is 26mm, and the ID 21mm.
I wanted to modify the cut segments to fit inside the tube to internally join the 2 ends and end up in the weld, but a 26mm OD piece does not fit into a 21mm ID tube.
Here is where some maths came in handy. Bare with me.
I want to end up with a piece to fit inside a 21mm ID tube, so I'll aim for 20mm. How much of the circumference do I need to cut to compress my tube bits to 20mm OD ?
To get a diameter (d) of 20mm, I need a circumference c = pi x d = pi x 20 = 63mm
The current tube however has a diameter (D) of 26mm, so it's circumference is C = pi x D = pi x 26 = 82mm
So to get a piece of tube of OD 20mm, I need to cut off 82 - 63 off the circumference = 19mm
Thanks for your patience with the maths, but if I'm going to post this method, I may as well spill it all. And I could have eyeballed it....or could I really?
The 2 ends placed together lining up some orientation lines I marked before cutting.
Welded, trimmed and painted with some self etch primer and Duplicolor Brake Caliper Black.
The centre-stand is now very easy to use, and the rear tyre clears the ground by about 10-15mm, a bit less than what I was aiming for, but practical nevertheless.
The side-stand received the same treatment, but the tube diameters are smaller.
BEFORE
AFTER
It did however end up much lower than where it started.
As a result, the side-stand kept the bike way too upright, and the centre-stand was almost impossible to use....so much force required that I could do it twice, but not a third time. Hernia stuff.
I didn't measure before, but after, I took the following measurements for reference...
Ground to upper rear shock mount 710mm, and ground to middle of lower end of steering head stock 750mm
This didn't help me much, so I took a look at the centre stand clearance between the ground and bottom of rear tyre on the 650e, and it was about 20-25mm.
The clearance on my Cafe CX on the centre stand was 70mm.
So I decided to shorten the stands by about 40mm, and this is how I did it.
I marked and cut 40mm from the stems between the feet and the spring attachment point.
I did read through other posts that the feet was also a good place to cut, but although that would be OK for the side stand, the centre stand feet, once detached, could be a bit tricky to replace in the correct position, that's why I chose the stems.
It would be possible to re-weld the pieces back at this point, as the tube if pretty thick and could easily take a straight weld with either TIG, MIG or MMA, but I wanted to reinforce the cut sections so I used the bits that I cut off.
In the case of the centre stand, the tube OD is 26mm, and the ID 21mm.
I wanted to modify the cut segments to fit inside the tube to internally join the 2 ends and end up in the weld, but a 26mm OD piece does not fit into a 21mm ID tube.
Here is where some maths came in handy. Bare with me.
I want to end up with a piece to fit inside a 21mm ID tube, so I'll aim for 20mm. How much of the circumference do I need to cut to compress my tube bits to 20mm OD ?
To get a diameter (d) of 20mm, I need a circumference c = pi x d = pi x 20 = 63mm
The current tube however has a diameter (D) of 26mm, so it's circumference is C = pi x D = pi x 26 = 82mm
So to get a piece of tube of OD 20mm, I need to cut off 82 - 63 off the circumference = 19mm
Thanks for your patience with the maths, but if I'm going to post this method, I may as well spill it all. And I could have eyeballed it....or could I really?
The 2 ends placed together lining up some orientation lines I marked before cutting.
Welded, trimmed and painted with some self etch primer and Duplicolor Brake Caliper Black.
The centre-stand is now very easy to use, and the rear tyre clears the ground by about 10-15mm, a bit less than what I was aiming for, but practical nevertheless.
The side-stand received the same treatment, but the tube diameters are smaller.
BEFORE
AFTER
pidjones
Over 1,000 Posts
10-15mm should be plenty on a flat surface. When I was teaching cyclotron engineers, it always puzzled me how people could get to that stage in life and not be able to USE math skills they had once learned. Nice looking results. I might have gone with a bit less lean on the side stand but you know how it "feels" and it may be just the picture. For me, the center stand is only used in garage and at shows so I removed the center stand and mounting lugs on my GL1000 cafe style in favor of spools and a padock stand. BTW, how did you "rounderize" the insert? Pounding, squishing with vice, etc?
crazypj
Split personality, I fake being smart
That's all basic math, same as stuff I do when boring cylinders, building wheels, and various other things. I thought everyone would know at least that much? If you start on differential equations or calculus I'm totally doomed, never understood it and probably never will. ;D As for Pi, I use 3.14159. More accurate than it needs to be but as last 3 digits are diagonal on calculator I find it easier than 3.142 
Odontologist
Umina Beach, Australia....Where does that part go?
Pidjones...I should have used maths to work out how much to take off sidestand. It is a little too over leaning but it works. But that's what hapens when you eyeball. I used a vise first which made tube slightly oval, then pounded with a hammer to close and return to shape.
I use several decimal places in calculation where they exist, lipe pi, but round off the result, after all, you can't mark and cut with a grinder to 1/2 mm, mybe even to a mm may be ambitious.
I use several decimal places in calculation where they exist, lipe pi, but round off the result, after all, you can't mark and cut with a grinder to 1/2 mm, mybe even to a mm may be ambitious.
