Gs850 power increase?

[Guest]

So i have been searching around for ways to increase my 82 gs850gl's power output.
so far havent had any luck, ive been considering either increasing compression by:
a) machining cylinder jugs to decrease the space between piston and head.
B) swapping cylinder sleeves with an 1100 and use 1100 pistons to run bigger bore
c) swapping 1100 crank and rods to run bigger stroke
d) b and c together

has anybody ever attemped anything like this? Swapping 1100 jugs or crankshaft to increase power
i have read of people doing full engine swaps, but 1100 engines are quite expensive qnd if i can make one out of just jugs and cranks the price goes way down

that being said the simplest and cheapest alternative might involve milling down the stock jugs to increase compression, although i might run into valve clearance issues and chain length issues as well
i have full access to machine shop so im not worried about machining pistons or jugs

Has anybody ever attempted this? On an 850?

[bwringer]

There's a guy in New Zealand who built a big bore high-compression 850 and was pleased with the results. He spent a fortune on custom pistons and machine work. It's been quite a while, so I don't know where to find the writeup.


Most folks searching for more 850 juice:

1) Twist the throttle harder. It's a damn shame how many people putt around like little old ladies on their 850s, never sampling the delights above 6,000 rpm. Keep it on the boil between 6,000 and 9,000 rpm and it's one of the more entertaining engines you'll find.

2) Drop in a 1000G or 1100G engine. There are plenty of parts bikes out there, since there are also plenty of morons who lose the titles.

3) Buy a 1000G or 1100G.

I don't know if the bore spacing is different, but I'm fairly certain there are fundamental issues preventing the use of 1000G or 1100G top ends on 850 bottom ends -- I don't recall that this has ever been done. The 850 was developed from the chain drive 750, but the 1000G and 1100G shafties were not developed from the 850G.

[GSX1000E]

Sell the 850, have custom pistons made with the smaller 16mm pins or just buy a GS1000G or 1100G and call it a day and save a bunch of time/money.

[Muguerza]

I have found a couple engines and or partsbikes but none of them worth while, most of them with really bad internal damage or others that are asking waay too much.
i have put too much time into this bike and i absolutely love it, it would be hard for me to see it go, i would love to be able to keep it as an 850 and building it instead of swapping it. It would give it a more unique touch than doing the swap, that being said, a swap would be the easyest and least time consuming, but nothing great was ever created without dedication.

And everyday i get on the bike i rev it to 9k, there is a certain rush to it, and it is pretty quick, i would just like a bit more torque.

my 850 is a shaft drive so if i were to do a swap it would have to be a shaft drive engine, or i would need an entire parts bike to do a chain conversion

Im just looking for the "non full engine swap alternative" to making more power on an 850

[GSX1000E]

I have found a couple engines and or partsbikes but none of them worth while, most of them with really bad internal damage or others that are asking waay too much.
i have put too much time into this bike and i absolutely love it, it would be hard for me to see it go, i would love to be able to keep it as an 850 and building it instead of swapping it. It would give it a more unique touch than doing the swap, that being said, a swap would be the easyest and least time consuming, but nothing great was ever created without dedication.

And everyday i get on the bike i rev it to 9k, there is a certain rush to it, and it is pretty quick, i would just like a bit more torque.

my 850 is a shaft drive so if i were to do a swap it would have to be a shaft drive engine, or i would need an entire parts bike to do a chain conversion

Im just looking for the "non full engine swap alternative" to making more power on an 850

Header, pods and 120 main jets. Report back when completed.

[posplayr]

Just throw a 1470 cc in like this guy. Just remember to hid the oil cooler under the seat same as this guy.

http://www.thegsresources.com/_forum/showthread.php?159159-Craigslist-quot-funnies-quot&p=2099712#post2099712

[49er]

There's a guy in New Zealand who built a big bore high-compression 850 and was pleased with the results. He spent a fortune on custom pistons and machine work. It's been quite a while, so I don't know where to find the writeup.


Most folks searching for more 850 juice:

1) Twist the throttle harder. It's a damn shame how many people putt around like little old ladies on their 850s, never sampling the delights above 6,000 rpm. Keep it on the boil between 6,000 and 9,000 rpm and it's one of the more entertaining engines you'll find.

2) Drop in a 1000G or 1100G engine. There are plenty of parts bikes out there, since there are also plenty of morons who lose the titles.

3) Buy a 1000G or 1100G.

I don't know if the bore spacing is different, but I'm fairly certain there are fundamental issues preventing the use of 1000G or 1100G top ends on 850 bottom ends -- I don't recall that this has ever been done. The 850 was developed from the chain drive 750, but the 1000G and 1100G shafties were not developed from the 850G.

Brian, never let the truth get in the way of a good story.

Yes, I did spend money on specialist machining to fit larger sleeves, but the cost of custom pistons works out the same as buying stock OEM. The CR of stock pistons being a lot lower though.

I haven't documented the 1023 cc rebuild here, because I keep forgetting to take enough pics along the way.

The engine is complete but hasn't run yet. I have fitted it to a GS850GT which I'm restoring. I was tempted to fit the engine to the GT before restoring it, but the suspension, brakes and tyres wouln't have been up to the performance. After fine tuning, it would have needed stripping down for restoration, so I decided to be patient and do it this way.

A cheaper overbore is using custom HC pistons in the standard sleeves out to 72 mm. I only went to 71 mm on my current GN.

I'm happy with my current 894 cc engine. It's slightly quicker than a stock 1100G, which surprised me and many others at the time. I expect even bigger gains with the 1023 cc engine.

[Muguerza]

Brian, never let the truth get in the way of a good story.

Yes, I did spend money on specialist machining to fit larger sleeves, but the cost of custom pistons works out the same as buying stock OEM. The CR of stock pistons being a lot lower though.

I haven't documented the 1023 cc rebuild here, because I keep forgetting to take enough pics along the way.

The engine is complete but hasn't run yet. I have fitted it to a GS850GT which I'm restoring. I was tempted to fit the engine to the GT before restoring it, but the suspension, brakes and tyres wouln't have been up to the performance. After fine tuning, it would have needed stripping down for restoration, so I decided to be patient and do it this way.

A cheaper overbore is using custom HC pistons in the standard sleeves out to 72 mm. I only went to 71 mm on my current GN.

I'm happy with my current 894 cc engine. It's slightly quicker than a stock 1100G, which surprised me and many others at the time. I expect even bigger gains with the 1023 cc engine.

So you machined the stock sleeves to 72? Is that the bore of a 1000? Or 1100 or is it completely custom?

[bwringer]

49er, my apologies for getting the details a bit wrong. And for somehow thinking that you weren't still around.

Where and how did you get custom pistons made for a reasonable sum? With Suzuki's recent increases in parts prices, stock bore OEM pistons are $52 each and OEM 0.5mm oversize pistons are $87 each. Rings add another $35 per piston, so if there's a good way to get high-compression (or even stock replacement) 850 pistons, that would be fantastic.

And what did you do for camshafts?

[49er]

So you machined the stock sleeves to 72? Is that the bore of a 1000? Or 1100 or is it completely custom?

I only bored to 71 mm, which leaves 2 mm wall thickness on the sleeves. You could go to 72 mm leaving 1.5 mm sleeve thickness. I used custom JE 10.5-1 pistons. You can't use 1000 pistons because the wrist pins are larger than the 850 ones. 18 mm instead of 16 mm. Well you can but you'd need to disassemble the 850 crank to bore the little ends on the con rods. I believe that would weaken them too much.

[GSX1000E]

Wiseco and J & E will both make pistons to fit with 16mm wrist pins. I am working on using a 72 or 73mm bore though.

[49er]

49er, my apologies for getting the details a bit wrong. And for somehow thinking that you weren't still around.

Where and how did you get custom pistons made for a reasonable sum? With Suzuki's recent increases in parts prices, stock bore OEM pistons are $52 each and OEM 0.5mm oversize pistons are $87 each. Rings add another $35 per piston, so if there's a good way to get high-compression (or even stock replacement) 850 pistons, that would be fantastic.

And what did you do for camshafts?

Not sure where you got your Suzuki prices from Brian.

On the Alpha website they list the 73 mm (1 mm OS) GS1100 pistons as $133.60 each. The wrist pins are additional at $11.74 each and ring sets are $39.38 each. I know you can get cheaper from other sources. Just a handy reference.

In 2010, JE charged me $138 each for a set of 76 mm 4032 high silicon ali pistons and pins, plus $22.30 per ring set. The biggest potential deal breaker was the freight of $110 to NZ.

I stuck with the stock cams (GS1000 grinds). They work really well with the extra capacity/ HC and high flow rates of the '79 small port head.

[ShadowFocus603]

Just throw a 1470 cc in like this guy. Just remember to hid the oil cooler under the seat same as this guy.

http://www.thegsresources.com/_forum...12#post2099712

OMG what the hell did I just read lol. The stupidity in that listing made my eyes bleed. Thanks for the link Pos.

[Steve]

On the Alpha website they list the 73 mm (1 mm OS) GS1100 pistons as $133.60 each. The wrist pins are additional at $11.74 each and ring sets are $39.38 each. I know you can get cheaper from other sources. Just a handy reference.

Just wondering why the fascination for Alpha, mainly from our members overseas.

Over here (USA), they are the MOST expensive source of parts. Maybe they are the only ones that are willing to ship to you?

As an example, the pistons you mention are $102.09, the wrist pins are $7.63 and ring sets are apparently no longer available, but the 0.5mm OS rings are $28.11. These prices are at Parts Outlaw. That is a savings of about $40 per cylinder.

.

[nejeff]

There's a guy in New Zealand who built a big bore high-compression 850 and was pleased with the results. He spent a fortune on custom pistons and machine work. It's been quite a while, so I don't know where to find the writeup.


Most folks searching for more 850 juice:

1) Twist the throttle harder. It's a damn shame how many people putt around like little old ladies on their 850s, never sampling the delights above 6,000 rpm. Keep it on the boil between 6,000 and 9,000 rpm and it's one of the more entertaining engines you'll find.

2) Drop in a 1000G or 1100G engine. There are plenty of parts bikes out there, since there are also plenty of morons who lose the titles.

3) Buy a 1000G or 1100G.

Mr Wringer hits it perfectly, buy a larger cc bike or ride the snot out of the one you have. Suzuki made many models of the GS. For example, if the 450 wasn't enough gusto for you taste then you get a 550 and on and on. You could always kick it up a 100 cc or so and find happiness with Suzuki. If the 850 is not enough get yourself a 1000 or an 1100.

My 850 had prior work done to it based on PO's info which sometimes is not worth the paper it's printed on. I was told the bike I have has 100cc big bore kit in it and although I have no hard physical evidence to support it I have owned other GS850's and my son has a GS850 and my bike without question has a little more gusto. That said I would not have done it myself. I think it easier and more moneywise to swap bikes then try to wring a few more HP's out of what is essentially a touring style and not a sport bike anyway