Help! RD400 fork questions......

RD425gehr said:
It's all apart right now, including the engine, ...............................
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How do the damper rods look? do you have a picture of them and the fork leg with damper rods fully extended?
 
Sounds like someone fitted 35mm XS650 forks? The stock springs are identical to the progressives I've fitted in several sets (I don't think I was 'lucky' enough to only have multiple sets of forks someone else had already fitted progressive springs in?)
 
Nope, 34mm!

Got'm all back together this weekend. A few little custom tweaks and they feel great. Once the engine is back in I'll be able to set the the sag........the fact I'll be able to set sag is revolutionary, let alone getting rid of the hard top out completely!!!
 
Early 650 (XS1) was 34mm Could be the tubes and springs were swapped to get extra ground clearance and extra height adjustment for production racing? (seen it done a few times) Friend had an RD400 with TZ pipes and carbs plus various other bits he made and modified. Was way quicker than the Bonneville he had been proddy racing (130+mph)
 
Here are pics of my RD350 forks apart, you can see there isn't any sort of spring on the damper like you were showing.

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Here is another view (with a valve, not standard)

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Mine looks nothing like that! :o

The changes I've made have made this fork so much better, looking forward to the first ride to really feel the difference.
 
ApriliaBill said:
I see what you're saying. I guess none of my bikes used this type of fork. Are you sure the Rd has this type of set up? In the setup I found, it doesn't look to have one. http://www.cmsnl.com/yamaha-rd400-1979-usa_model8704/partslist/D-05.html#results Maybe there is another part missing. Almost every bike I've rebuilt forks on, the p.o. used motor oil instead of a decent fork oil, and usually the volume is off.
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I've been rebuilding forks about as log as you and 'top-out' was well known if oil level was low or seals bad
It's been the most common type of fork since at least 1950's
The spring (#10) is listed as top out spring i some manuals
 
PJ, early XS legs are longer but they were used back in the day to convert a TD3 from those heavy old drum brakes we all adore to OEM XS or RD disks which worked much better and were lighter.
 
Thanks to global warming/climate change myth the 70* February day we had made for a great first ride! Front suspension feels awesome, no abrupt top out now and a lot less vague than before.
 
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