34mm forks minton mods and or YSS emulators?


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Hi group, I'm new and have an RD250 I know this is the wrong forum but searching minton mod always points here. I'm writing because I have an RD with 34mm forks the springs are terrible and since I"m a bit light at 135-140lb the suspension overall is rough. I'm buying some Hagon shocks on the back and need to fix the front. I bought some progressive springs but really thinking about emulators. I found out YSS makes them but can't get verifiable information on the emulator size I heard 23.8mm is the correct size to fit 34mm O.D. forks (old KYB to be exact). Wondering if anyone has knowledge and by chance if anyone has done the Minton mod or bought Racetech or YSS emulators on the 34mm forks. Thanks Dave
The Minton Mods were devised for the later 35mm forks but I see no reason why they couldn't be applied to and help the earlier 34mm forks as well. The later forks were over dampened. Enlarging the oil holes relieves or lessens the damping effect. This allows the forks to react quicker initially. In particular, this smooths the ride over the little bumps or the first in a series of bumps. Since the later forks had this problem, I'd assume the earlier ones did as well. Who knows, they may have even been worse.

You'll need to examine your damper rods, noting the size and number of oil holes present. If they're similar in size and number to what's found on the 35mm damper rods then I would say yes, the Minton Mods should help. The 35mm damper rods had 4 holes around the bottom about 3/16" big, and one very small one near the top, about a #49 drill size. Here's a chart showing the stock and modded hole sizes. If you don't have access to the numbered drills, the closest inch size would probably work as well .....


You could do the Minton Mods as an interim step before trying the emulators. If they work, it will save you the cost of those parts. To install emulators, you have to drill out the damper rod oil holes really big, rendering them useless. This lets the emulator take over the damping control.

I would also recommend using no more than 10wt. fork oil. It's very possible part of your current problem is due to some P.O. sticking 20wt. or something thicker in there.
Wow thank you so much, I will need to disassemble the forks but as you know one issue at a time. I have 2 sets of forks so that allows me to double check since many issues I've encountered are very different from the various manuals and guides I've found online.
I will check back later in a couple of weeks I hope.
If you demand performance, emulators are the way to go. Progressive springs don't work with emulators, as you're mixing two technologies, making them impossible to tune.

+1 on the fork oil. Heavier stuff slows high speed damping.
Have you done the easy stuff first? Drain the forks, let them sit upside down to get it all out, remount and fill to proper level. Just might be old fluid. My 71's forks were more or less pogos. Drained and refilled, huge improvement
I've installed Race Tech emulators in three bikes now, and they'll transform your front end. As to getting overdamped, undersprung damper rod forks to perform, the Minton mods are Bandaids on a gaping wound--better than nothing, but not by a lot. Race Tech makes emulators and straight rate springs in a range of rates so that you can get what's right for weight of bike and rider. Google Traxxion Dynamics and give them a call; they're a Race Tech dealer, and as Marty will tell you, they're top notch on knowledge, work, and ethics. They'll know what you need; be sure to give them a description of your damper rod top. If you buy from them you buy their tech support too, and it doesn't get better. You won't get good tech advice from YSS USA--bought a shock from them for my Zook GS500E, the guy who takes the orders had some ideas on setting sag that were--well, I'll be kind and say that I don't do it that way.

BTW, your forks are rough not because the springs are too stiff for your weight but because the damping is poor. It's easy to confuse the two.