Hi folks, i'm new to 400GB. I have been restoring a 1987 VFR400R-H and have come across a modification which is sometimes carried out to the quieting gears on the cams and crankshaft, i have been told that it reduces rotational mass and allows faster accelleration and decelleration of the rotating parts of the engine due to the lowered mass requiring less energy to change the rotational speed.

While this makes sense and seems to be an obvious good thing i have read online about harmful vibrations and detrimental harmonics in the geartrain damaging the components over time, which is worrying. Having read up on backlash in geartrains ( http://en.wikipedia.org/wiki/Backlash_(engineering" onclick="window.open(this.href);return false;) ) it seems the benefits to the engine are opposed to greater gear noise as the tollerences between the rotating gears are not taken up by the spring loaded quieting gears, i am unsure of the number of geardriven assemblies which use quieting gears in vehicles, is this a very common thing or just something honda was trying out on this particular model of bike before they changed their mind and removed it?

Is it like valve noise which quietens as the vehicle warms up and the tollerences in the engine close up due to thermal expansion ? Ideally a before and after video or sound clip would be fantastic, my extensive googling has unfortunately not been very helpful.

I have searched on this forum but did not find anything which went into sufficient technical detail to allow me to make a decision as to whether or not to carry out the mod. I am well used to working on bike engines so the actual process would be fairly straightforward, i just need to make a decision.

Thank you in advance for any help and advice i may recieve.

It sounds very noisy and rattly - Is this going to be a road bike? If so, leave them in is my advice and opinion. No need for the nth of extra HP you are liberating.

Welcome to the site too - if you have a look in the older threads (such as my race bike build thread) there are pics and vids of the bike - as I removed the cam gears on that. I like the noise..on the race bike, but the road bike whirrrrrrrr whirrrrrrr sound is too good to lose.

Thanks very much, i will try to find your thread and have a listen, i havent had mine running yet to listen myself, i have the engine out and was trying to decide while its not in the frame as modifying it would be easier.

Its a road bike, i am the kind of guy who fits a pod filter to a two stroke because it sounds better, not for (possible) extra power. Extra power is never usually easy or cheap.

sure..it doesn't exactly sound nicer with them removed. It is not nice at all in fact....but you know the motor is making evil noises because it wants to...

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Cheers, i had a wander through the thread earlier, pretty impressive.

The sound clip is only a few seconds long and to be honest i cant hear any difference.

I was hoping that removing the quieting gear makes the engine whine louder, is that not what happens ? If it just makes it clank like its broken i wont bother. lol

It will not not wine without the gears fitted,it will just sound like a bag of bolts,
When an engine as had a lot of tuning work done then it sounds like a different animal.

Yes...it does not whine louder at all. It makes a rattly bag of bolts noise!

I gota be honest i really dont think it sounds all that bad with the gears removed. sounds better if you ask me although i did own a rattly old ducati before the NC with gears removed so any bike is gunna sound quite compared. If you can wait a few days i'll get a vid of both my NC's running so you can compare the two.

oh and welcome to the board painless You the same creature thats lurks about on the 125 sportsbike forum?

CMSMJ1 wrote: I like the noise..on the race bike, but the road bike whirrrrrrrr whirrrrrrr sound is too good to lose.

+1

I don't think I could live with it on a roadbike.

The standard engine noise is just so nice.

Drunkn Munky wrote: If you can wait a few days i'll get a vid of both my NC's running so you can compare the two.

I'll be looking out for that one too!! I'm also interested in this subject!!

Smev