Hello everyone my father has an S40 and we are thinking about making some mods to his bike to give it a better top end.

So far we have purchased a K&N air filter, we want to change the exhaust and jet the carb. I saw a post from Lancer awhile ago that laid out all the jetting sizes and tuning parameters but I cant find that post any more and we are not sure which HD Muffler we should ask for from the dealer.
Can anyone confirm if this bike actually has a rev limiter?

This bike spends most of its time on twisties in the mountains of British Columbia. The overall performance of the bike is good on these roads, it just needs a bit more top end.
Thanks in advance

If it has a rev limiter I haven't hit it yet, wiesco piston, ported head , mild cam , crazy carb mods , header , lighter flywheel , I really don't think it has one ! You could gear it up alittle , I think Dave sells the bigger counter shaft pulley !

[Advance warning - the numbers quoted below are WAGs but they do reflect reality]

So a stock S40 makes about 25-26HP

Add an exhaust, air cleaner, jet it correctly and you'll open it up to 26-28HP. Investment maybe a few hundred dollars.

Get the gearing correct for the type of riding you do, no extra power per se, but the power available will be in an rpm range where you can make the most of it. Once again, the investment is maybe a few hundred dollars.

The next step gets complicated. To really open up this engine will require cams, new piston, reworked cylinder and porting and polishing of the head. You'll be making around 35HP at an investment of $2,000 to $3,000 (depending on what you can do and what has to be done).

After such a large investment your top speed will increase by 8, maybe 10 mph.

For a bike that just isn't much fun to ride above 70-80mph anyway, is it really worth the investment?

Dave wrote on 03/27/17 at 12:12:59:

We were just looking at the RYCA adapter and talking about there reverse cone vs the dyna... thanks for the info on the gearing changes we will look in to that! Dad likes the sound of the Dyna exhaust I figure thats the one we will check out  

I understand. And I also understand that you are looking for more top end. My point is even if you could increase the top end to 155mph for only $100, it doesn't change the character of the bike at 80mph.

Anyway, if Dad is gonna be flogging the back roads of BC on an S40 at elevated speeds, get him the Big Brake Kit for fathers day. The stock brake is unsafe at anything beyond parking lot speeds.

I would counter Gary in NJ comments a little (actually temper them is a better way of putting it.)

My suggestion would be to go the technical documents/reference section and in the stickies find the table of contents  http://suzukisavage.com/cgi-bin/YaBB.pl?num=1181745927

that has everything you need.

Now my suggestion would be to get a Mikuni VM carb, open up the exhaust donut as previously described, and put on the Dyna muffler and rejet.  You have now opened up the breathing and done it cheaply.  From there it is only a couple hundred bucks to drop in a cam.  Highly recommended.  At that point see if you have enough.   AT this point you are still under $1,000.   I think the hi-comp piston is overkill unless you really want to keep pouring the money in for diminishing returns.    

From there you can change the acceleration / cruising characteristics through gearing changes.  As noted Dave is a fan of the belt and talks about pulley changes.  I am a fan of sprockets and chains so I would recommend converting and have the ability to set up what ever you want.  The conversion is easy and the options then are endless.   It is easy to go higher than stock for more relaxed cruising or drop one tooth on the front sprocket and have more acceleration.

In my opinion riding in the hills doesn't call for to much more horsepower than stock,I would suggest be for dumping tons of money into the bike it may be better to 1( tune the idle screw 2(do the spacer mod.3)test the main jet 4(go to the Dyna muffler,5)buy the K&N slide in air filter. Next I would think about handling ,after market shocks and fork brace , possible brake up grade ,(maybe just organic pads) all could be done for about $300-400 bucks and be a vast improvement on the way the bike runs now .More hp on twisty mountain roads isn't likely to be used, or  useful if the bike can't stay on the road.

I guess I need to know what the OP means by "more top end".  In stock form the engine sounds happy up to 60 mph @ 4,000 rpm....beyond that it just sounds like it is working too hard (my personal opinion). With stock gearing at 70 mph the engine is turning 4,676 rpm....and at 75 mph the engine is at 5,000 rpm.  When my bike had the stock gearing....I just didn't like riding at sustained speeds much over 65 mph.

If they are looking for the ability to get on the highway and keep up with traffic when they need to - then gearing changes may be all that is needed.  However....if those highways include long steep uphill grades, the bike may not be able to sustain 70-75 mph with a stock engine and higher gearing.  However the spacing between 4th-5th is pretty small, and when you use taller gearing 4th is nearly equivalent to what 5th was before the gearing change was made.

If you add HP to the engine and decide to use that extra power...then I agree that chassis and brake upgrades are desirable.  I weigh 170 pounds and I could bottom out the rear shocks and their limited travel if I hit a big bump, and the front brake is a bit wimpy compared to what sport bikes or sport touring bikes have....it might be similar to what other cruisers have.