cheapnewb24 wrote on 01/23/16 at 17:31:06:


I just traveled 780 miles the last 2 days on a trip to Orlando with a 17T cs and the standard rear sprocket which is a 43T.  The gears are stretched out farther; but, their is not much more of a risk of "lugging it".  I averaged 78 mph on the interstate with about 4,800 rpms.  The 17T is the biggest one that can fit on the front and I had to dremmel the sprocket cover to make it fit.

Incidentally, it was 37 degrees on the Gulf of Mexico this morning in Panama City and I don't think it made it to 50 by the time I got to Orlando.  

But, it is still better than looking at snow.

Best regards,

There may be something to this lugging thing. I now have both Kaw pulleys, and a 150/90 15 rear tire. It turns less than 3400 rpm at 60mph in 5th. After 800 miles of LOW rpm riding to play with the new gearing, cruising speeds as low as 35 in 5th, I had to add 8oz of oil for the first time ever. I am going to make it a point to not go under 40 in 4th or 50 in 5th and see what happens. There may be a limit to how slow we can thump!

MM, I basicly have to ignore the stock speedo now & go by the gps all the time. I built a holder for a android phone w/a gps app over the bar clamps. 35 in 5th here in Fla on the flat actually feels pretty smooth. Won't make a habbit of it thou. I'll keep the revs up a little higher and try not to go under 3G in 4th or 5th. I have been getting 6o to 65 mpg over the road, and next time I have the ex pipe off I'm going to mount a fitting on the adapter for a O2 sensor. I have a mixture gauge from when I built an airplane that reads on ratios 13 to 1 = max power, 18 to 1 = best mileage.

That is just cruzing on the level. If I give it a lot of throttle it will chug and jerk. I didn't ride miles & miles that way, but in traffic it will do it.

MM, My gauge is a old analog one I think I got it from JC Whittney back in the mid 90's. New ones are digital like this.

http://www.ebay.com/itm/White-Auto-Car-2-52mm-Red-Digital-Color-20-LED-Air-Fu...  

When you learn to fly a small plane you learn to lean out the mixture for best cruse. I was taught 13 to 1 for power, 18 to 1 for cruse.  Airplane carbs are made to be pilot adjustable, to a point.
The gauges need 12v power, and hook up to a O2 gauge in your exhaust pipe.

''The Flat ground around here is full of hills !''
And I bet those hills are full of Moonshiners!

Badwolf, I would think that atmospheric pressure, octane, etc. would play a part in an aircraft engine so you could lean it out to 18:1. That afr probably wouldn't be good for a motorcycle. You may end up burning a hole in the piston.

I wonder how lean Suzuki builds these things at the factory?

Took a while to get to sleep last night over thinking about this exciting topic. There's a lot that can be said about this, but I'll start by saying this:

I think that the factory Savage top gear is too short. It does not increase top speed appreciably, and may even be counter-productive.

Take a look at this:

http://www.royalenfields.com/2009/02/new-royal-enfield-adds-performance.html





Now, that little 500 thumper can come mighty close in performance to our 650, but it's top gear is substantially higher. It's power/torque curves are a little different, but they are similar overall. At 6500, it is rated around 108 mph. Not sayin' it'll do that. Just showing that it's taller geared than ours. (97.3 mph at same rpm.) (Check Gearing Commander). From what I've seen in videos, the Enfield can reach 140-145 kph (86-90 mph).  This is pretty close to our top speed.



It has been suggested on this forum that because the stock bike can't reach redline, there is not much (or anything) to be gained from increasing gearing. This is close to the truth, but may not be exactly the case in my opinion.

Supposedly, stock, our bike reaches 80.8 mph at it's power peak of 5400 rpm. Funny thing is, from what I gather, our Savage can generally do quite a bit better than 81 mph. .  By the time it's crossed the 85 mark, she's doing about 5700. By the time 90 comes-- if you can squeeze that out of a stocker-- she is doing over 6k. For such a long stroke, that's too much.

If you guys have an accurate way of measuring both ground speed and engine speed, and, under varying conditions, you are able to regularly even approach 6k in top gear, much less redline, on a stock engine (no hot cam or anything),  you are geared shorter than necessary, perhaps even too short. While top speed might not increase much, it's not likely to decrease much either from increasing the gearing. I don't care if you push 10,000 rpms out of that poor thing, it's not going to help the top speed. The power curve, with stock settings, is done by about 5800. Doing 6k on a stock engine is generally counterproductive, especially with our weird gearing.

As long as you can reliably reach, maintain, and not exceed the plateau range of the horsepower curve, he theoretical top speed attainable for those instantaneous conditions will neither increase nor decrease appreciably due to any change in gearing.

Furthermore, as long as you are able to reliably reach and maintain the plateau (mid 5k range) under a reasonable range of load/road conditions (light headwind/grade/extra weight), there is not much reason top-end-wise, to be any lower in gearing.

Someone talked about the 140/90-15 tire decreasing top speed. I wonder if he was considering actual top speed or indicated top speed, as indicated speed  would decrease. Acutual speed shouldn't decrease substantially, assuming tire friction is the same.

I would take a guess that even the 17/43 chain conversion would not decrease actual top speed much in top gear-- maybe by only a few mph??? At 5k, it would be doing 87.5 mph. 5k is not far from the peak, but it is a little low. In 4th, however, the top speed ought to be reachable on level ground.

As far as wear is concerned, wouldn't engine stresses be worse due to engine speed compared to the stresses of engine load? I'd think so.

Of course, this conversation doesn't mean much if you never get the bike past 45 mph.

Here's power/torque curves for the Savage that various members have posted. Many of them have mild mods like muffler, air, and carb tuning.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1185590369





http://suzukisavage.com/cgi-bin/YaBB.pl?num=1243819864





Any comments?