minton mod question forks

aldo5468 said:
Well I'll be 70 early next year and I'm having a blast with the 650 I got 3 years ago Seems like we've earned the right to have a toy or two by this point in our lives. Enjoy!
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Just finished doing the Minton mod's to my front forks - I had replaced the OEM springs a couple of years ago with Progressives. Per 5twins comments, used a #45 bit for the two holes at the top. Had a new 6mm drill bit that I used on the lower four - it sort of splits the difference in diameter between #1 and 1/4" bits. Polished the metering rods and put in new All Balls elastomeric seals and enough 10w fork oil to come to 6" below the fork tops. Makes a noticeable difference in ride quality - soaks up the bumps much better than before when I was using the "spec" amount of 15w fork oil. :bike:
 
Yes, I've never felt it necessary to go any heavier than the factory recommended 10wt. oil. The 15wt. may be fine with emulators but for stock or Minton modded forks, I think 10wt. is the best.
 
5twins said:
Yes, I've never felt it necessary to go any heavier than the factory recommended 10wt. oil. The 15wt. may be fine with emulators but for stock or Minton modded forks, I think 10wt. is the best.
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I know someone who just had XS1100 forks done by Traxxion Dynamics. They installed custom wound springs with RaceTech emulators. I saw the spec sheet on the set-up. One fork got 15W and the other got 10W among other differences between forks. I've ridden the bike a couple of times and it's pretty amazing.

The RaceTech tuning guide calls for 15W, but Traxxion put 10W into the equation and I was/am impressed by the results.
 
jetmechmarty said:
I know someone who just had XS1100 forks done by Traxxion Dynamics. They installed custom wound springs with RaceTech emulators. I saw the spec sheet on the set-up. One fork got 15W and the other got 10W among other differences between forks. I've ridden the bike a couple of times and it's pretty amazing.

The RaceTech tuning guide calls for 15W, but Traxxion put 10W into the equation and I was/am impressed by the results.
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What is the rationale for setting up the two forks differently? Results rule, obviously, but I was just wondering -
 
aldo5468 said:
What is the rationale for setting up the two forks differently? Results rule, obviously, but I was just wondering -
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I have a Moto Guzzi in the garage. One fork is set up for compression, and the other for rebound. It's that way from the factory. On the top of one fork, there's a dial to adjust the compression, on the other, a dial to adjust the rebound. My guess is, the folks at Traxxion went to the same school. I'm here to tell you, that 1978 Yamaha with the Traxxion set-up drives better than a lot of new bikes!
 
I guess it's worth trying. My guess would be put the 15wt. in the side with the disc if you have a single disc set-up?
 
jetmechmarty said:
I have a Moto Guzzi in the garage. One fork is set up for compression, and the other for rebound. It's that way from the factory. On the top of one fork, there's a dial to adjust the compression, on the other, a dial to adjust the rebound. My guess is, the folks at Traxxion went to the same school. I'm here to tell you, that 1978 Yamaha with the Traxxion set-up drives better than a lot of new bikes!
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Thanx for your response - a very interesting approach!
 
Split function forks have been around for a while, and different weights of oil are tuned for each side. Not sure it traxxion is onto something with that or not, but that stock disc is a heavy slab, and may need the added control of a higher viscosity on that side for optimum performance. One for the notebook.
 
Anyone got tips for early forks? I got the 73 out on the back roads and it needs wipers and seals so I'll have em apart anyways. On Wisconsin back roads today I got my teeth rattled a time or five, on bumps, all stock components AFAIK. IT felt stable enough as far as I was willing to push a god knows how old rear tire with serious sidewall cracking. Plus my bud was plodding along behind me on my Shadow, he hadn't been on a bike in a while....
I will do the steering stem and swing arm bushes, probably find some better rear shocks, even with the adjusters all the way soft they were stiff sobs. Steering damper came to me snugged down good I left it that way.
 
The air space on top of the fluid is part of the tuning. Get it too smalland you risk a blown seal. More fluid limits fork dive.

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jetmechmarty said:
The air space on top of the fluid is part of the tuning. Get it too smalland you risk a blown seal. More fluid limits fork dive.

Posted via Mobile
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Absolutely! variances can come with the final dimensions of the spring. Generally speaking 10mm higher or lower is the typical range available for fine tuning. More airspace equals more air that can compress before the fluid gets forced through the metering orifice. People who like a supple ride generally end up here, but you burn up stroke with that compression, and your big bump capacity suffers. I prefer a tighter suspension that is more responsive with less dive, but I don't get the magic carpet ride on road ripples and such, but the high speed, high load handling is choice, so I live with the irregularities. Not that they upset the chassis, just more of a feel for the early suspension action through the bars.
 
jd750ace said:
Split function forks have been around for a while, and different weights of oil are tuned for each side. Not sure it traxxion is onto something with that or not, but that stock disc is a heavy slab, and may need the added control of a higher viscosity on that side for optimum performance. One for the notebook.
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I hadn't considered that the forks might see different loads, such as for a single disc on one side - makes sense. Here I am, damn near 70, and still learning good new stuff almost daily. Fortunately, there's several ways to go to get a lighter disc on an XS650, either aftermarket or OEM Yamaha - I've got a thinner one from some other Yamaha model that bolts right up.
 
I don't think the air space above the oil has much if any effect in the oil flow through the dampers or emulators.
The air compresses, a large air space has more air to compress, this lets the forks dive more under braking. A small air space has less air to compress and limits the fork dive.
I guess if you made the air space too small it could blow the seals.
This is similar to the way an air shock works. With the pressure set low, like 2 or 3 psi it can compress the air easier, letting the forks compress farther. Increase the air pressure to say 14 psi the forks can't compress the air as much, so you get less fork dive.
Adding air caps to a stock fork is easy to do.
Oil flow through the dampers will happen even with no caps to seal the forks. The dampers are completely immersed in the oil. As the forks move the oil has to flow.
The only thing that can effect the oil flow is oil weight and orifice size.
gggGary, on your 73 once you have the forks apart you can determine if the damper has two or four holes and their diameter. If two smaller holes adding two more and increasing the diameter increases the oil flow through the dampers. This lets the forks respond quicker to road surface irregularities.
This is the main thing the Minton Mods address.
Adjusting the oil weight also changes the quickness of the forks response. Thinner oil flows faster so the forks respond quicker. Thicker slows response.
Increasing the oil level improves fork dive. Altering the oil weight and level is an easy and not to costly thing to experiment with. It doesn't take much oil to fill a fork.
Springs just push the forks out and control how much the forks compress under any given bump. Weak springs allow the fork to compress more on a bump than a stronger spring will on the same bump.
The strength of the spring also has an effect on how well the wheel returns to the road surface after the bump. weak spring won't return the wheel as well as a stronger spring.
Even the right spring won't work as well as it could without the right preload. Before I replaced the spring I would try adding a bit longer spacer. This will increase the preload. This may be enough to get the sag where it should be. 35 to 40 mm for a soft ride, 20 to 25 mm for a firmer ride.
Adding longer spacers work well, just be sure that increasing the spacer length doesn't cause spring bind.
A bit of a forum search will help you find the threads that discuss these things in more detail.
Leo
 
Just one more thing. On the different fork tuning side to side, some of the Harley touring bikes use a damper fork on one side with a cartridge fork on the other.
Seems strange to me but if it works how can I complain.
Leo
 
XSLeo said:
Just one more thing. On the different fork tuning side to side, some of the Harley touring bikes use a damper fork on one side with a cartridge fork on the other.
Seems strange to me but if it works how can I complain.
Leo
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Valkyries are like that. I'm not sure anyone but Showa is doing it that way.
 
I've just stripped down my forks to carry out the damper rod mod. Joe's original article says "There are two quarter-inch holes near the bottom end of the damper rods. Drill two more quarter-inch holes through the rods so that there are a total of four around the bottom of each rod." which suggests that the holes already are 1/4 inch. Mine are 5mm in diameter which, in terms of area, is a fair bit smaller than the area of a 1/4" hole. Soooooo .... do I:

- Open out all the 5mm holes to 1/4" and add two more, or

- Just add the two 1/4" holes, or

- Just add two 5mm holes?

TIA
 
It's an "error" in the Minton Mods instructions. Minton says you'll find 2 at about 1/4" and to drill 2 more for a total of 4. That's wrong - there are already 4 - but they're 3/16". Just enlarge them - don't drill any more.
 
There's also an error pertaining to the one small hole at the top of the rod. Minton tells you to enlarge it slightly using a #54 drill bit and continue drilling through to create a second hole on the other side. The existing hole is already bigger than a #54 drill bit. All I can figure is the numbers got transposed when the article went to print. He meant to say a #45 drill bit, the numbers got flip-flopped, and it went to print as a #54. A #45 drill size works nice.
 

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