Front fork knock

[AlexRu]

hi all. I have AT RD04 `90. It`s italian model. I bought it in Germany last winter. It`s a really good bike with 48000 km only. But I`m not pleased with front fork working. I feel a knock when the fork go down quickly. I`s usually feeling on a bad road when the front wheel is falling in dint. When the fork is quickly pressed the knock is not felt. The fork was completely inspected in service, oil was changed twice (5W and 15W). All parts inside like new! Today I had a test drive another AT RD04. I heard the same knocks! Is it normal?! I think the cause of knocking are springs. I whant to get a Touratech progressive springs.
Iam sorry for my english. I hope you will be able to understand it. I tried

[Zenarchy]

I've also got 1990 RD04 (by some strange coincidence it's also an italian import and with almost exactly the same KM as yours).

I haven't had it long, but I've noticed that I sometimes get a bit of a knock when I go over speed bumps at quicker speeds. I didn't notice this when I first got the bike, and haven't been riding it long, so it may have just been that I was riding more carefully to begin with and it has always been there. It doesn't seem to effect the steering but it's a concern for me too.

I've read here that a similar noise can happen when the steering head bearings need to be replaced or the steering tightened. If you've already had that checked out then I'm not sure though.

I'd also be interested to know if it's springs knocking. I bought a centrestand and fitted it yesterday (well -almost still need to get the springs on) so planning to check the steering for play as soon as I can.

Your English is perfect by the way!

[Lord Stig]

Yes, your description sounds a lot like place in the steering head bearings - look there first...

[AlexRu]

I have fitted a new steering roller bearings from Louis. And I have checked an adjustment. It`s ok. I also had a testdrive another AT RD07a `03. And I did not hear any knockings there. Is this a design defect of RD04 only...?

[Zenarchy]

I don't think it's a design defect of the RD04 or there'd be a lot more posts about it here. I seem to remember someone else mentioning experiencing the same thing on an RD04 then when they replaced the steering head bearings it fixed it, so I don't think all of them do it. I can't find the post unfortunately (was mentioned in passing when talking about something else I think).

I may be wrong, but there might be something you're missing or some other problem that hasn't been identified yet. What it is I'm not sure myself. Hopefully someone with more mechanical experience will be along soon who can offer more advice.

I haven't got around to checking mine yet, but when I do it'd be helpful to know what the problem is/was with yours for future reference.

It sounds like you've replaced and checked everything but the springs so perhaps you were right to begin with, though I haven't heard of the springs knocking. Is there a possibility that it could be knocking somewhere else up near the front of the bike and you're mistaking it for the forks?

Sorry I can't be much help. Hopefully someone else will spot this thread who's had the same problem soon and can offer some idea of what it might be.

[Zenarchy]

P.S. Just had a look in the honda service manual and under the troubleshooting section for 'Front suspension noisy' it says:

* Bent fork tubes
* Loose fork fastners
* Insufficient fluid in forks
* Lack of grease in speedometer gearbox

If you haven't already checked those things perhaps they might be worth a look. The troubleshooting section of that manual isn't very detailed so not sure if all of them would produce the effect you're talking about though.

One other thing that springs to mind is that the RD04 has little air nipples that might not be present on the newer models (I think - I'm not completely sure). Perhaps the air pressure is wrong, or the garage you've had looking at it didn't spot that needed doing? I'm not even sure if that would have the effect that you mention really, or if it's only an RD04 thing (though I seem to remember reading about it being only the earlier models at some point - I may be thinking of the oil drain bolts being only on the rd04 and getting confused).

Looking in the haines manual, it suggests checking the springs and damper springs for sagging and cracks when you have the front forks apart, so perhaps that could be an issue if the springs haven't been inspected yet? Again not sure if that would have the effect you mention, but might be worth checking into or finding out more about.

Good luck sorting it out anyway. Let us know how you get on. Might be helpful for other members with RD04s as it sounds like something a little unusual that you're experiencing as you seem to have checked the things most people do to sort out the problem already.

[AlexRu]

Ok. Let's wait. Unfortunately I cannot read a lot of technical posts about AT here. It is somewhat difficult for me.
I have tried to take away front plastic, tank, brake cylinders, control panel, front fender, speedometer. I have checked front wheel and a bearings. I have pumped 0.4 bar into the fork tubes. I also checked a tubes bend and a springs length. The bend of fork tubes is around 0.1mm. The springs length is normal. But I transported my AT inside a bus from Germany. It took me 5-6 days. All this time the fork was pressed by straps with ratchets. Maybe the springs was damaged but their length was not changed.

[africajim]

My old RD04 had the exact same problem, when you go over a bump the forks seem to fully extend and there's a sharp knock comes off them as they reach the end of their travel.
I'm not certain, but I do not believe it happened before I changed the fork oil, I remember it was a lot of oil, like 275ml each leg? Also tried putting air in but this seemed to make it worse?
My Tiger does the same, but it's done that since new so I know it wasn't my doing this time!
Sorry I can't help more mate.

[Whealie]

I could not rid mine of it without removing the forks again completely (just loosening them off did not work - they had to be taken out completely). I then managed to tighten the bottom yoke securing nut by about a quarter turn, which meant the top yoke also went further on. then I put the forks back.
I am pretty sure I had it all tight when I replaced the bearings a few months back and that it all just bedded in and worked itself slightly loose.

[AlexRu]

I could not rid mine of it without removing the forks again completely (just loosening them off did not work - they had to be taken out completely). I then managed to tighten the bottom yoke securing nut by about a quarter turn, which meant the top yoke also went further on. then I put the forks back.
I am pretty sure I had it all tight when I replaced the bearings a few months back and that it all just bedded in and worked itself slightly loose.

If I understood right, the cause of knocking was bearings. I thought about it. But I did not ride more than 5 km after the bearing was changed. I checked up it again first of all. I hear this noise from the top of fork. And I feel weak blow in the handlebar.