Gaining more power....but not to much.

[pieter.oneill]

OK so I've a question to ask the many who have modified there older gs models,
I've had many bikes over the years and can't help but fettle and improve even if the cost will.never be worth the return it's the cost of a hobby the way I look at it, I just got my harley sportster back from fast lane head works after head porting, cam change, valve seats and angles altered so it's running some power now and then I looked at the gs and got to thinking.
So current set up de-cat stainless exhaust with lazer can, k&n air filter, upgraded 1200 injectors, and a john gemi chip. Seen some used heads on the bay and thought I could purchase and send them for some head work if anyone knows anyone?? Also any air intake mods outnthere, seems a small area for air to enter on standard set up. Before anyone tells me to go buy a 1200/1250 ,although I'm trying to get a bit more power and improving what's there it's not why I'm planning on doing it, it's just for the enjoyment of tinkering. Cheers all she's an old 95 r1100gs with 114k.....so just run in .

 

[sproggy]

The R1100S engines makes considerably more power than the GS version, I think with different heads and cams. If memory serves it’s not a straight engine swap but you could potentially build a hybrid S/GS motor based upon the GS but using key S components. Others with more knowledge may have a more informed view.

 

[ThreeDawg]

Just fit the best suspension you can find, forget the rest. Or buy a twin cam 1200.

 

[JohnnyBoxer]

Just fit the best suspension you can find, forget the rest. Or buy a twin cam 1200.

Yep decent shocks will improve speed by 10% and make cornering more fun

 

[Paul Young]

As Sproggy said, the 1100S makes significantly more power and some of this is down to the inlet tubes being significantly bigger. The downside is a slight drop in torque at lower rpm but I got that back when Dynojet set up a PC3 on it.
I always had a project in mind to swap over the S cylinder heads, and have a set in a box somewhere. I now just need the cams, or could retain the GS cams and swap them over. The problem with this is the headers on the 1150 being different, but I have a set of 1100 headers and a link pipe that will fit with the Remus I have now. It’s all doable…

BTW, a fuel pressure regulator from the K1200/1300 fits, and raises the system to 3.5 bar which gives a snappier throttle response. Suspension, wheel/tyre, and braking improvements are also more worthwhile than some engine work IMO. I have Hyperpros, alloy wheels and bigger front discs.

Good luck with your plans - I’ll watch with interest.

 

[pieter.oneill]

Well my suspension, is all good brand new protech front shock set up for my weight and rear is a wilber adjustable rides great. As mentioned in the post I could go buy a 1200 but I like playing about with my old 1100, sproggy sounds interesting ill look into that set up. Bike has more then enough power I just like to fettle nothing to so with needing anymore got other bikes for that

 

[KMD]

Yep decent shocks will improve speed by 10% and make cornering more fun

This^

Our Lass sometimes asks me why I go to the lengths I do to achieve a result I want, but she views as completely unimportant. And my answer is always the same : because I want to. So I really get that you enjoy doing what you do, just for the sake of it. But genuinely, the best modifications I’ve done to any of my bikes is fitting Ohlins suspension. Admittedly an expensive mod, but they provide an immediate and very big improvement.

Edit. Just seen your post above

 

[pieter.oneill]

Cheers paul, yeah things like that with regards to the fuel pressure regulator are great for me to look into. KMD yeah sometimes we.blokes just need something to do also, it's about improving something that was made 30 years ago with modern advantages . Like the porting makes a huge difference on older heads where as newer bikes already have improved air flow designs so you.cant improve on newer bikes as much.
Also my heads are 114k into them so just getting valves reseated would improve the tightness although it pulls great I must have lost some ponies over the year

 

[GedJack]

Trust me Paul probably has everything you need in his garage 3x over if I know him

 

[pieter.oneill]

Trust me Paul probably has everything you need in his garage 3x over if I know him

Haha good to know, nothing like being prepared with every spare possible. They are cracking bikes to work on must say, so easy to get at everything.

 

[Wrigsby1]

My take it you've done a fair bit already and as I remember the engine unit itself was more difficult to add tune to in the usual ways... There used to be available air intake mods but I've sided with the way of using the power you have more effectively... I ride mine using more corner speed, torque and engine braking to make it flow but then I like the bendy bits way more than the straights ..

Ps... There was a US write up of a turboed RT oilheads...

 

[jetjock]

As Sproggy said, the 1100S makes significantly more power and some of this is down to the inlet tubes being significantly bigger. The downside is a slight drop in torque at lower rpm but I got that back when Dynojet set up a PC3 on it.
I always had a project in mind to swap over the S cylinder heads, and have a set in a box somewhere. I now just need the cams, or could retain the GS cams and swap them over. The problem with this is the headers on the 1150 being different, but I have a set of 1100 headers and a link pipe that will fit with the Remus I have now. It’s all doable…

BTW, a fuel pressure regulator from the K1200/1300 fits, and raises the system to 3.5 bar which gives a snappier throttle response. Suspension, wheel/tyre, and braking improvements are also more worthwhile than some engine work IMO. I have Hyperpros, alloy wheels and bigger front discs.

Good luck with your plans - I’ll watch with interest.

Which front discs have you fitted ? Much modification required ?

 

[pieter.oneill]

Turbo talk!! Haha that's way out of then realms of what I was thinking, to much power for the type of bike, sounds fun for someone to build though like said we are all into different things. I think because I've had port work done on alot of bikes over the years I liked the idea of having heads ported to flow more air new pistons with a possible higher compression ratio then obvious if it flows more air improve amount of air she and get in, anyone know of anybody or company that does head work for the gs? My guy at fast lane just does harley heads, works incredible though.
Yeah I agree on effective other parts that improve the ride, I'd like to find some floating discs for the front as mine are quite ridged and always been a big improvement in terms of brake fade on heavy bikes. Great character out of the engine, I had a 2021 yamaha tracer 900 this time last year, fantastic bike but it just did everything so well that I felt like I may as well be in the car it had way to much power for the stock suspension too.

 

[Wrigsby1]

I tried a Crosstourer years ago and when on a quick run in the Twisties definitely needed all the brakes as so little engine braking .. Olihead GSs are my model for just about the right amount of everything...

 

[pieter.oneill]

Yeah ita great to just roll off and feel that compression slowing you down as you tip in, twins are great as the torque is always there when I'm in 4th on a sweeping A road it's.like riding an automatic I never need to change

 

[knucklemoto]

My 1150gs has 1200 injectors, a John G chip, decat y-piece and non standard (but baffled so not loud) can and a K+N air filter. She runs great, pulls well, ticks over like a clock and is a real world improvement over stock. As per the other posts suspension is a biggy for these donkeys, mine came with Ohlins front and rear.
The one thing I'd like to do is have the head flowed and new valves seated properly, that's about the extent of engine work for me, but I totally get your itch...
Just an observation with mine... she always runs better for the first couple of thousand miles after an oil and filter change... so I do it more than the book states. Just a me thing...

 

[pieter.oneill]

That's pretty much where I'm at and would like to go with it with regards to getting that touch more power and we'll seated valves make for good power. I changed the oil when I got her but going to Try fully synthetic on my next change. Midrange on these bikes is fantastic one of the best overtaking bikes I've ridden. My suspension isn't ohlins level but it fully adjustable and damps well. I'm thinking I've valves, and head work when I'm doing some major works but just planning it for back of mind ready. All these older engineers that gasflow/port heads are disappearing now the guy who does my harleys is in his late 60s there are no young lads wanting to know how to port 40 year old bikes so it will be lost art soon.

 

[Paul Young]

Which front discs have you fitted ? Much modification required ?

I’ve used a front wheel from an R1100R so it uses the slightly larger fully floating discs in place of the OEM semi floaters on the GS.

I just remembered that I also geared it up using an R1100R final drive. I used to get frustrated at hitting the rev limiter in 5th and it couldn’t pull 6th (E) when riding against the throttle stop. Now it has extra room in 5th to run flat out and 6th is just used when cruising/touring.

 

[pieter.oneill]

I’ve used a front wheel from an R1100R so it uses the slightly larger fully floating discs in place of the OEM semi floaters on the GS.

I just remembered that I also geared it up using an R1100R final drive. I used to get frustrated at hitting the rev limiter in 5th and it couldn’t pull 6th (E) when riding against the throttle stop. Now it has extra room in 5th to run flat out and 6th is just used when cruising/touring.View attachment 402043

Just checked that wheel out online that's a good little hack fully floating disc, I like the look of my spoked wheels though, there not a pain to clean as they are already well patinered so I just don't bother

 

[Paul Young]

I’ve just remembered something else…
A shorter paralever arm shortens the wheelbase and pulls the rear wheel underneath to raise the back end a bit. Together with the alloy wheels, this sharpens the steering quite a bit.