Dommie Newbie needs tech advice please

[willywombat64]

Hi Guys

Billyboy here down in devon (uk). Picked up a 2001 dommie NX650X 6 weeks ago and whilst checking through the bike a number of questions are beginning to surface that
i'm hoping someone can advise me on. This'll probably be the start of many and if you see the same questions appearing elsewhere on similar sites then forgive me for casting my net a bit wider!

Anyhow.. I have acquired an original shop manual (although for the 88/89 models ) and also have the addendum printed in 1997 which I presumed would give me some info re data that may be different for my model RD08 . There's not a lot in the addendum to be honest but I did notice that it says the valve clearance on the exhaust is 0.1mm rather than the previous 0.12 .

Is this correct as I also have an XR650L manual which I believe uses the same engine and in there once again the clearance is given to be 0.12 .
If someone could clarify this I'd appreciate it .

To be honest I do wonder whether these manuals are generally spot on because i also noticed that in the 88/89 manual it states that the cylinder compression when new is 178 psi but in both the 97 addendum and the 650L data it says 92psi .....surely one of these must be a misprint and i'm presuming it's the 178?

thanks in advance for your views/advice/help
speak soon
Bill

[switch]

Bill mailed me the addendum. Looks valid. I'd love to get this info confirmed.

Any of you guys original buyers of RD08 Dommies? Or in contact with Honda Dealers? Could you ask them about the valve clearance issue? It's a pretty important aspect y'know!

Thanks!

[catteeclan]

I've come across this and have always adjusted to the larger. I'd rather have a little noise than a valve to tight.

[switch]

IMO, Honda specs > "I'd rather". That's why I'm trying to figure out what's the Honda Recommended clearance.

[Rubberchicken]

The existence of the errata sheet seems to indicate that it's now 0.10. Though I'll stick to 0.12, always used that and the bike's done 55k miles on it just fine. One of the mantras of a BMW Airhead: Loud valves are happy valves.

The cylinder compression has me stumped. The numbers you mention would be 6ish bar or 12ish bar, while off the top of my head it should be 8-9ish. I thought 12 bar was good going for a souped up supermoto...

[switch]

Don't confuse cylinder compression with geometric compression!

The dommie, with its 8.3 : 1 geometric compression ratio (BDC combustion chamber volume - TDC combustion chamber volume) has a cylinder compression of about 12bar at 600rpm (cranking speed). To get that value, you need to set the left exhaust valve to 1mm play (yes, one millimeter). With regular (0.1/0.12 whichever is correct) play you'd get 6 bar, on par with what the errata mentions.

EDIT: Errata is for late (97+, possibly all RD08.) NX650s only.

[kitped]

Bill mailed me the addendum. Looks valid. I'd love to get this info confirmed.

Any of you guys original buyers of RD08 Dommies? Or in contact with Honda Dealers? Could you ask them about the valve clearance issue? It's a pretty important aspect y'know!

Thanks!

I've looked all over the net and cannot find a copy of this addendum, any chance of a copy???

[switch]

I'd rather not post unconfirmed information, such as this addendum. It contains at least two typos. Not sure if the 0.10mm is indeed a typo, though it doesn't look like one. I'll post it everywhere I can if and when I can confirm the info.

[willywombat64]

Re the different compression values ..I was chatting with someone recently and they had an xr650L manual which gave 2 different values depending on the speed of the engine . I presume this relates to the auto decompression set up which needs 400rpm to disengage ? correct me if this seems nonsense but I wondered whether in the early manual the figure is for when the auto decrompressor is off (so higher value) and in the addendum for when it is on (ie at low revs). Blooming confusing ..especially for a novice mechanic like myself.

[switch]

Re the different compression values ..I was chatting with someone recently and they had an xr650L manual which gave 2 different values depending on the speed of the engine . I presume this relates to the auto decompression set up which needs 400rpm to disengage ? correct me if this seems nonsense but I wondered whether in the early manual the figure is for when the auto decrompressor is off (so higher value) and in the addendum for when it is on (ie at low revs). Blooming confusing ..especially for a novice mechanic like myself.

Yeah, that's somewhat it.

With decompressor engaging (regular valve play), at 600rpm (cranking speed) you get about half the normal compression.

With decompressor cancelled (1,00 (one) mm right ex valve), at the same cranking speed you get full (normal) compression.