GS1000S Project Bike - Motorcyclist magazine

[trippivot]

weiscos' are nice pistons I have used both the 1085 and the 1105 kits - I could not tell difference between the two - but I could tell it had a lot more pep from stock. extra heat is not a big deal - you can put in colder plugs or do what I did when I lived in LA - put a fan under your carbs to blow on the cylinders - I don't always cut lanes - a sport bike radiator fan does take some power so use large gauge wire and a relay - if you choose to do that.


web cams 70-061 are super nice .395's (drop in) still can use the shim over buckets - but you should / will need to install a set of better valve springs. - this is the largest power increase with plenty of longevity. get a nice valve job when it is apart.

I really like the way CV carbs work on the street and in stop - go traffic Biggest thing is they are so much smoother/economical than regular mechanicals or - 33 or 29 smoothbores. I believe I got almost 12~14 more M.P.G. with a set of 32BS over the stock VM set. better overall - YES With Pods! - easy to tune - I don't understand all the fuss - if I can tune them anyone can.


I also really like Dyna ignitions - NGK spark plugs - remember to use the dyna wires and coils - it makes a difference. pistons cams carbs will make the engine run a little like a modern bike - double check your camchain adjuster - or get a manual one - double check your clutch basket just a word to the wise.

progressive fork springs - 15 weight / maybe 20 fork oil if you ride 2 up, a AGM battery - got the budget for ohlins out back?

Well just a couple things I would do.... glue your base/head/cam cover camchain galley gaskets - plus the oil supply o rings at the rear bottom of cylinders -and wipe clean - cam half moons too.... because they like to seep a little with the expansion and contraction of being an air cooled engine.

Cometic gaskets are really good - Yuasa batteries have the best longevity etc..... the very best of luck and success with your GS . trip pivot

 

[Chuck78]

Mitch, welcome aboard! Here on the GSR, you will find a wealth of knowledge which continues to amaze me how much in depth technical advice members of this forum offer.


For your original question, as for the engine, if the bores are at all worn out of spec, I'd just go for the Wiseco 1085 kit & rejet accordingly, then run the .380" lift megacycle cams. Stock carbs rejetted will do great but big top end hp improvements are to be had at 7500-10000rpm with VM29 or CR29 smoothebores on this setup. Modified clutch as mentioned previous in this thread.

If the bores are still in great shape, I'd check the ring end gaps & reinstall, then run megacycle .354" lift cams or .365" lift Web cams, degree at 106-109 depending on where you want your power, k&n filter (s), and rejetted stock carbs. The clutch mod and aftermarket springs is still a great idea here.

 

[Chuck78]

For starters, the biggest problem with a stock GS's original regulator rectifier. Search eBay for a Polaris RZR ATV unit with the OEM number 4012941. That will get you the latest series regulating technology which allows the stator to not have to run at full load 100% of the time, it simply disconnects the stator at rapid cycles to regulate the voltage whereas the old style shunt units found on most bikes would rapidly cycle the excess of voltage directly to ground, which runs the stator and the entire engine hotter from the oil spray that cools the stator. Also if yours has a headlight that switches on and off, one of the stator leads is run through the headlight switch before it reaches the regulator rectifier. With the upgrade, completely bypass this wire. As with most old bikes, clean all the wiring connections very well and inspect the harness, and use some DeOxit contact cleaner to thoroughly clean the ignition switch contacts as well as the run stop kill switch contacts.

If you have a sealed beam headlight, definitely upgrade that to at least a 1980's GS reflector assembly that takes a replaceable H4 bulb. Then you could drop in and ADV Monster led bulb or the Cyclops LED bulb, or the old reliable Sylvania SilverStar halogen h4 bulbs. Drastic improvement in visibility right there! If you want the ultimate in visibility and don't mind a modern look, the TruckLite Phase 7 LED reflector assemblies are very awesome. All three of these options are discussed on the board if you use Google to search for them on this site - search "Truck Lite site:www.thegsresources.com" this works better than using the forum search functions.

If you are going to keep the stock fork and wheels, absolutely look into getting salty monk Dan's brake caliper adapter brackets. run stainless lines while you are at it. This will be a substantial upgrade, and much lighter. Then you would absolutely want to modify the forks to use racetech cartridge emulators. Not quite the ride of a modern sport bike, but this is vastly improved and very pleasing. More performance and less harsh of a ride. Then just drop in some Racetech or Sonic springs and the proper amount of tubing for spacers to get the correct preload. A Tarozzi fork brace is a very nice improvement and an easy direct bolt-on.


Are those some old OEM cb900f Honda shocks you have on there? If they are, those are not rebuildable but I did see an article where a guy managed to pry them apart and rebuild them.

 

[rudeman]

Mitch,

I forget what year exactly, but Joe Minton did a hop-up article on the GS1000 motor in Motorcyclist. Early '80's I would guess. Lot's of good info in it.
I'm fuzzy on a lot of the details, but I do remember an overbore (I think to 1100cc) and 29mm Mikuni smoothbores.

"Great Bikes of the '70's" I still have a pristine copy stashed away.

The best article was in Cycle Guide; 1176cc RC Engineering GS1000 vs 1100cc Yoshimura Z1R. The GS ran away from the Z1 on that one.

 

[Nessism]

Lots of solid advice being offered up in this thread, only Mitch hasn't been on the forum since early September.

 

[Frank Z.]

What Ed said. Subscribed.