Experience of big bore kits on 80 G/S

[Shurv]

I'm getting my reinforced and gusseted frame back soon from the powder coaters, and will start to build my Dakar replica. I want to up the cc to at least 1000cc. Has anyone got any experience of this and can point me in the direction of the best kit to use. Motobins have 1000cc barrels, but the Siebenrok stuff looks tasty but expensive, and the 1070 kit looks amazing. I also want to put a revised cam in and play with the carbs and airbox. Any one got any bits for sale would also be useful.

Cheers,

Marcus.

 

[Kenny]

On two of my previous 80g/s I

(a) bought the Moto Bins kit, which were 1000cc RS barrels and pistons. The kit gives everything you need from gudgeon pin circlips, rings gaskets etc etc.
This kit caused a slight pinking but I didn't have the unleaded conversion done on that particular bike. This kit gave the g/s the biggest boost for your money and in my humble opinion...

(b) is a better option than the Siebenrock kit !! The Siebenrock kit is smoother as it has a lighter piston but the power increase is smoother but less of !!! I think the Siebenrock takes the humble 80g/s up to about 60 bhp but as I've said, a lot smoother and quicker revving than a standard 1000cc lump.

If I was to do it again and I ( personally for the use I do wouldn't mess with camshafts etc etc ) then I'd simply fit the Moto Bins kit.

I didn't have to alter any timing or carburation with the Moto Bins kit, which also claimed 72 bhp..and it did feel a lot stronger than the Siebenrock kit. However, if you are to put an RS camshaft in there then I'd be fitting the Siebenrock kit and have the carbs/ignition proffessionally tweaked and you'd have one hell of a GS then !!

Hope this helps.

 

[Shurv]

Thanks Kenny. That was very useful. I want to build a very special "special" as it will be my only bike. I'm looking for 70 bhp at the rear wheel. I'm planning new heads with the bigger 44mm intake valves, some gas flowing, 40mm carbs, a one off exhaust ( 2 into 1, no collector), I've already got upside down forks going in, a very bling gold talon front hub, excel rims front and rear, 320 mm disc, a 50mm extension to the final drive and a Wilbers shock.38 ltr tank and single seat. Will have a nice ally box on the back too.Can't wait to get it al together.........

Marcus

 

[Wreford Miles]

Thanks Kenny. That was very useful. I want to build a very special "special" as it will be my only bike. I'm looking for 70 bhp at the rear wheel.

Marcus

Mine with siebenrock and a high torque cam knocks out 43.6 bhp at the back wheel - Tourque is a nice flat curve off 46 ft lbs from the moment you wack the throtle open.

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[Sean Kelly]

Hi

Andrew Sexton swapped my 80GS paralever bottom end with one from a 100RT using the original 80 top end (twin-plugs) and carbs. Kept the 80 bevel drive but fitted a taller top gear. Picks the front wheel up on the throttle in first and 54 (dynojet) hp at the rear wheel. Lumpier at tickover than the old 80 but smooth enough once underway and good economy to boot.

Sean

 

[chasbmw]

this is a dyno report on my 1070 seibenrock kit, built by Jim Cray with dells, twinplugged, flowed etc etc. seems to go well and uses less fuel than the original engine.

Charles