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Monster M900 Fork Compatibility

J

jones5563

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Jul 27, 2025
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United Kingdom
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M900
Hi all, this may have been covered already but I am looking to gain some info on fork cross-compatibility.

I have a M900 1997 and one of the fork stanchions is pitted so badly that it is eating seals. The stanchion diameter is 40mm, which seems to be quite an odd size!

I am struggling to find any replacement forks from a M900 of a similar year, however I have located a decent pair off a M750. Does anyone know if the M750 forks are directly compatible? Or (even better) does anyone have a decent pair of M900 forks they are looking to move on?

Cheers, Andy
 
They are different but will fit. 750 forks dont have any adjustment, they are a more basic fork. Also depending on the year because they changed the caliper mount in '00 but anything up to 99 should use the old style 40mm mount. The later post 99 ones are more readily available because they were used in more models but you would need different calipers, mudguard etc.

Yours can be hard rechromed and be better than new.
 
Darren69 said:
Yours can be hard rechromed and be better than new.
Click to expand...

Don't know if it's still the case but when I had some forks rebuilt with radial mounts by Ktech, I wanted them Ti-Nitride plating.

They quoted me for re-plating mine but also for supplying new tubes and there wasn't a lot of difference in the price and given that new tubes meant no need to remove the old mounts, I went with new.

I then sold the old tubes with the axial caliper mounts fitted and recouped pretty much the difference.

My point is, it might be cost effective to buy a new tube?
 
Hi all, thanks for the replies. I have managed to find a decent looking pair of forks for £100 (bargain I thought!). They are allegedly off a M900, so should fit okay. Next question is - does anyone have a link to a decent rebuild video/document for Marzocchi forks? (they need new seals and oil). Cheers, Andy
 
I can understand the desire to do the work yourself and would respect the skill to do so, however.
I can heartily recommend the services of MCT near Stowmarket, Suffolk.
Darren has serviced a few forks and shocks over the years for me and you just can't beat his experience and the advice which he freely gives. He also has most of the bits needed on the shelf or a day away and usually turns a set of forks round in a week.
Geography no problem, he is used to a postal service.
I guarantee you'll notice an improvement after he's done his magic.

I reckon a thorough going over with any bits replaced that are needed would be less than £150 for a pair of Monster forks. He'll ring you and give you an appraisal when he has them apart anyway.

MCT. Darren 07359339967

P.S. It's well worth sending your shock in at the same time if it is a re-buildable one. You will notice that it's wanting if you only do the forks.
16000 miles is the recommended maximum service interval for forks and shocks.
 
Last edited:
Mr Gazza said:
I can understand the desire to do the work yourself and would respect the skill to do so, however.
I can heartily recommend the services of MCT near Stowmarket, Suffolk.
Darren has serviced a few forks and shocks over the years for me and you just can't beat his experience and the advice which he freely gives. He also has most of the bits needed on the shelf or a day away and usually turns a set of forks round in a week.
Geography no problem, he is used to a postal service.
I guarantee you'll notice an improvement after he's done his magic.

I reckon a thorough going over with any bits replaced that are needed would be less than £150 for a pair of Monster forks. He'll ring you and give you an appraisal when he has them apart anyway.

MCT. Darren 07359339967

P.S. It's well worth sending your shock in at the same time if it is a re-buildable one. You will notice that it's wanting if you only do the forks.
16000 miles is the recommended maximum service interval for forks and shocks.
Click to expand...
Cool, thanks for the tip! I plan on giving it a bash myself (I have spent far too much money on this bike recently!) but if that goes tits up or I decide I don't know what i'm doing after I've taken it to bits, then I will give him a shout! Cheers, Andy
 
I do all my own servicing and repairs but, I take my forks and shocks to a specialist.

Last year I had my 916 forks serviced by Ktech, IIRC cost me about £200. I could do them my self but you really need special tools to dismantle and re-assemble and they likely cost about the same as the service plus, you need the oil & seals etc. and most of all the know-how.

Given that the last time they were done was well over 10 years ago, it's not worth the bother/expense for something so infrequent plus, at my age this may well be the last time time I need to do it... :oops:

Rear shocks are even more specialist because you need to be able to re-gas and the kit for that is likely very expensive if you can even buy it.
 
Plus 1 for MTC, they serviced and set up the ST4s forks and ohlins shock I have on my S2r, made a hell of a difference
 
Hi all, I thought I had cracked it but unfortunately I am back to square one.

So I managed to source a very reasonably priced set of identical forks with stanchions in immaculate condition. I swapped out the stanchions and fork internals from one of these into the fork upper from the bike, and fitted new oil seal and dust seal with the appropriate quantity of oil. When tested stationary it seemed to be absolutely perfect with not a single trace of oil showing on the chrome (and there was much rejoicing). However, I took it out for a short test ride today and this is how it looks after about 10-15 miles (Ignore the cracked fender, this will be repaired in due course!).

Looking for some suggestions and advice please. Did I fit the seals wrong somehow? Are the two sections not compatible? Should I have changed the bushes too? Is it because I used fairly cheap seals or the wrong oil? Thanks in advance! Andy

1332a1de-4e49-48ea-a3f7-4d4222b1a3df.webp
 
They're upside down forks, you haven't fitted the seals the wrong way up (or down) it's an easy mistake (any fool could make it) guess how I know.... ;-)
 
It's definitely possible! I tried to match how the old ones looked as much as possible. Installed them with the writing on the seal facing down (as installed), i.e. with the seal in place you can still read the writing (if the dust cover was removed). Other than that I couldn't think of a logical way to dictate which way up they went.
 
Have watched the video and I am absolutely none the wiser! Have attached photos of an identical seal (I bought a set of two but only one side is leaking), any suggestions welcome. One side has writing on it, the other does not. No obvious asymmetries with regard to the side profile of the seal edges.
 

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Maybe you damaged the lip when putting it over the top of the fork leg - did you protect the seal with some tape over the metal?
 
Is it actually leaking or is this just residue from the change? I'd wipe it clean and go for a ride to see if it re-appears.

For future reference I grease seals around the lips and put a plastic bag over the leg before I slide the seals over it, this protects the seals from damage.
 
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