900 SD in original condition. How can I make it go faster?

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Will Rogers
Cucciolo - the Lil Pup
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Location: Lewes, Sussex, U.K.

900 SD in original condition. How can I make it go faster?

Post by Will Rogers »

I bought a 1978 900 SD Darmah from Motori di Marino in West Sussex last May and am interested in suggestions for increasing the power. It has done only 8,000 miles and is in completely original condition. I use it for town and country trips and would like to do the occasional track day.

I only recently found the BevelHeaven website and it is excellent.

Will Rogers, Lewes, UK.
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Craig in France
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A Faster SD

Post by Craig in France »

Hi Will

Well, for starters ...

40mm carbs and Conti silencers were the standard 'straight-from-the-factory' mod. There were also higher lift cams available, and some people fitted K&Ns - but to what effect I don't know ...

After that, I suspect you're into 'proper' tuning ... But I'd have to ask why? These bikes with their overlong wheel-base don't go round corners that great, and any modern 600 (and a lot more besides!) is going to blow you into the grass, anyway ;)

Craig in UK (SSD owner)
Will Rogers
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Post by Will Rogers »

Hi Craig

Thanks for the reply. I see that a lot of the SD Darmahs have been modified with 40 mm carbs. Can you give me some idea of what work is involved? Also, can the conti silencers be fitted on their own without any other changes - ie to carburation?

I probably wouldn't be making any other changes. I am planning to use the bike for many years to come and want to get the best, practical performance out of it.

I did a Moto Morini Club track day at Cadwell many years ago and that was a fun day out. I'm looking out for something similar this spring/summer. The roads around me in Sussex are just too crowded. It would be nice to have a blast around a proper race track occasionally. Any suggestions?

Will Rogers, Lewes, UK.
stanley

Post by stanley »

After the carbs & pipes a set of 88mm pistons will get you the greatest gain per dollar.

Dave
Will Rogers
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Post by Will Rogers »

Hi there,

I have just fitted a complete Keihan (Conti replica) exhaust system and the change in performance has been fantastic - probably a 15% to 20% increase in power at all rpm. The bike felt a bit flat - and even undergeared - with the original silencers. The only problem is that the decibel level is also 15% to 20% higher - though even some non-motorbiking friends say that it sounds great!

Best thing was that it was paid for by the car driver who tried to do a sudden U-turn and knocked me off last summer. His insurance finally coughed-up in January.

I'm still on the look out for any "classic friendly" track days in the UK if anyone has any recommendations...

Will Rogers, Lewes, UK.
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BevHevSteve
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go faster

Post by BevHevSteve »

Greets....... Several things you can do for your Darmah, no matter what others say....... I also must state that you can actually get around corners as fast as you want to once you set the bike up right...

1 Carbie Sync - can't emphasize enough how important it is to have your carbs in good tune. CLick the link here for a complete step by step http://www.bevelheaven.com/~BB/phpBB2/v ... c.php?t=10

2 change your gearing to 16/39

3 lube swingarm and steering head bearings

4 install dual rate springs in the forks and some new shocks in the back

5 raise the forks 5mm in the triple clamps
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Colin Linz
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Post by Colin Linz »

I took my old Ducati out for a track day two weeks ago. My son wanted to do one on his old RZ350 and I thought it would be good to see how the old girl went with it’s new 40mm Dellorto’s (by the way Steve I’m very happy with them, the bike is much nicer to ride and start).

I have done a few track days before, but only on modern bikes. It would be fair to say I wasn’t expecting much from the Ducati, given the wheel base, steering geometry, age of suspension, and the baised belted sports touring tyres that were fitted (Bridgstone BT45’s). This coupled with the design of Queensland Raceway, which is a brakes and horsepower track left me thinking that the Ducati would be out of it’s depth. As it turned out I was passing people around the outside in corners (not allowed up the inside). Sure, they would fly past down the straights, even my young blokes RZ350 was giving me a hard time on the straights, but come to the next corner and I would be looking to get past them again. The biggest problem I was facing was running off the tread on the front tyre, I will need to try some different sizes to get a better profile I think. Anyway we both enjoyed the outing a lot, although the 1.5 hr ride home after a day on the track was hard work.
Cheers
Colin Linz
Manray
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Post by Manray »

I own the same bike and have done all the mods already listed. The 40mm carbs will bolt right up (check the bolt spacing on the manifold to see if it will match-my carbs came with manifolds that had to be slightly modified) but the heads should also be modified to utilize the full potential on the carbs. The intake track on the heads are bored to match the 32mm carbs and should be opened up to for the 40's. A little flow work wouldn't hurt either and the extra cost would be only a modest investment (seeing that you'd have the heads in the shop anyway). Another thing you should also look at is whether or not the Carbs open completely at full throttle. I also added the "Imola" cams but found the power gain slight during normal riding and only noticable when flogging the bike. Yes a modern 600 may run circles around you at the track (depending on the rider) but they sure won't make a magic sound like those Conti's do or draw a crowd when your parked.
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