Reinhoud

This exhaust (Marshall) was very good! Bike ran like lightning and sounded very nice! I was young and hadn't heard of ceramic coating yet, also wasn't to educated how to fix small holes in thins steel... If only I knew then what I know now..

If you're serious with gainig power, the exhaust is pretty important. Look around and gather information before you buy anything. I made a bigger diameter muffler inside my Marving, that made a bit of difference, but still nothing to brag about

That's the Marving I have..

I'm reasonably impressed with the quality, the sound alright, I think the chrome and the whole of the exhaust is alright, just don't expect any power gains from it. No clue what the performance is in regard with a stock exhaust. I was told that the flat collector is the problem, may be someone here can tell me/us if that's indeed a/the problem with this sort of exhaust..

That's the one I have laying arond, they sound alright, but they're NOT high performance..

If that was the case this forum didn't exist

Yes! BUT!! it depends a little bit on the sort of engine how much you notice the difference. You won't get more power, you just change the rev range. When you have a 500cc 1 cylinder, 10/15cm difference is well noticable. When I took 60cm of the exhaust of my Range rover I moved the start of the powerband from 3500rpm to 2500rpm. I'm pretty sure when you take 20cm of a 4 cyl bike engine you lower the rev range with about 1000rpm. Experiment with it. Also, with stuff like this, give the engine time to break in with this, don't take it up and down the street once, take it for a longer ride. Exhausts are weird things. I had a Merc 5 liter V8 with a DIY exhaust, not very loud, but if you stood next to it or 50 meters away, it sounded the same. For my DR500 I made trumpet exhaust, gained quite a bit of power, pretty loud when you were standing next to it, when the bike was at the end of the block you would hardly hear it..

Regarding valves/seats. In the past I had the bores of the seats increased, this made a bit of difference, not a lot, but the bike didn't had to work as hard to get it going. I was told that bigger valves increase the flow around the valves when they're open. I'm not sure if this is true, hopefully somone else can give a proper answer to this.

Ca you post a photo of your Marving? I'm getting curious..

What sort of Marvin exhaust do you have? The Marvin I know isn't exactly high performance.. I would go for a stage 2 cam, may be higher CR and bigger displacement. Mikuni RS carburfuckingettors are a nice additive, my experience not more power, but an incredible throttle response.. Porting the head can give a nice result too. Not more power per se, but a nice flat torque curve is quite a win too. Keep your exhaust short, stop it before the rear axle, the shorter the exhaust, the lower the amount of revs your powerband starts, not more power, but you move it through the rev range.

You need the size your bike runs properly on, don't look at someone elses bike, you can use it as a base, but not for fine tuning, if you don't have an A/F gauge yourself, put it on a Dyno, this will take the guess work out. Too lean or too rich can somewhat give the same symptomes..

I know my limits, I'm sure someone who knows what he's doing can go faster on my bike, but I don't realy care, I know I'm also not the slowest.. My brother in law got an accident about 8 years ago, just a stupid accident, misjudged a corner, still on his learner, he landed very unlucky, the results were VERY serious, he's lucky he survived, he still can't walk like before, I always have that in the back of my head.. When I ride my mates GSXR I can go faster on that bike.. Where I live there are corners about every 300/400 meters and going up and down continually, most of the corners you can't see through, when I can't see through I just don't have the guts, like I have troubles lining up the bike properly to take the corner. Couple of weeks ago my mate and I were in the "local mountains" hair pins and stuff. Because I'm slower then my mate I was up front, going through the hair pins, at one point we got overtaken by other bike riders, when they were in front of me they were only a little bit faster then me, but the antics they did to go that little bit faster, they needed 2 lanes..

On the last photo it does look bigger... Mine doesn't come close to 300hp. What size do you have?

Photo's? Stock engine? There aren't many GS1000's with a GS1000 engine with turbo.. One hand, with the smaller turbo it isn't overly fast, but when I have to get close to my mate again, He has a 2006 GSXR and is a better rider and has more guts - VERY windy where I live, I'm behind him pretty quick..

Your turbo looks even smaller then mine..

This is how I did it when I put another turbo on it. Be aware, when you weld a pipe on the flange, the flange will bend because of the heat ot the welding. Therefor weld a pipe to the flange, put the pipe in a lathe and turn it flat again, then weld the pipe to the manifold

Oh, looks like I'm running mine with the wrong sort of battery..

I once bought a new alternator for my GS1000, this one was supposed to have a higher output then the stock one, but can't find it anywhere anymore, no idea about the brand. But this together with the Electrex regulator I haven't had any problems anymore.. Even with an electric fuel pump it works alright.

That's it!

This!

In my opinion, the back looks best when the tail piece and rear tyre stop at around the same point. and try to keep the gap between frame and rear wheel about equal wherever there is frame. I deleted the rear mud guard and welded plates in the frame instead. These plates turned out to be useful later on to weld / bolt other parts on. Here a photo of my butchered GS to show what I mean;

Electrex

Can you calculate the difference in top speed between both ratios? May be that wil give you a better understanding.. Calculate it back to the amount of revs what you're riding with at an average speed.. May be it can give you an idea in difference? When you ride your bike, do you feel the need to shift up a gear? If not, I wouldn't worry about all this.

I just read half of what you posted, and not many responses... My opinion/preference/experience regarding a better performing engine; more displacement, slightly higher CR, cams; stage 2, or just more lift. Now, don't pin me down on this please; I think that when you go more lift, you automaticaly change the timing. My experience is, don't go for too wild, with just a bit more lift/timing you get a better mid/high range, most likely you get a very well performing engine from "low" down. Hopefully someone can correct me, or explain it better. What you win at the top, you lose at the bottom, keep that in mind. But personally I pefer an engine what is torquie over a lot of HP

A sort of good way to tell if valves are bend, make something you screw into the sparkplug hole, where you can connect a hose on, the other end to a compressor. Slightly increase pressure, if a valve is leaking you will deffenitly will hear it. You'll feel it to on the crank when you try to lock it with a spanner. Don't ask my why I know this sort of dodgy stuff.