Suzuki DR650 Regearing

Regearing a chain-driven motorcycle involves changing the Final Drive Ratio that, in turn, changes the engine's performance characteristics. Increasing the final drive ratio (i.e. gearing down) improves acceleration and low end torque. Decreasing the final drive ratio (i.e. gearing up) smooths top end performance generally increasing speed for highway applications. 

Chain driven motorcycles have three drive ratios. They are the Primary Drive Ratio, the Gear Box Ratios (one for each of gears 1 thru 5) and the Final Drive Ratios. The Final Drive Ratio is the relationship between the countershaft (front) sprocket and the drive (rear wheel) sprocket.

Below is a summary of all ratios as provided in the DR650 Service Manual.

• Primary Drive Ratio: 61:28, 2.178
• Gear Box Ratio (1st Gear): 29:12, 2.416
• Gear Box Ratio (2nd Gear): 26:16, 1.625
• Gear Box Ratio (3rd Gear): 26:21, 1.238
• Gear Box Ratio (4th Gear): 21:21, 1.00
• Gear Box Ratio (5th Gear): 19:23, 0.826
• Final Drive Ratio: 42:15, 2.80

The Final Drive Ratio of the post-1995 Suzuki DR650 is 2.80 which is calculated simply as the number of teeth of the drive sprocket (42) divided by the number of teeth of the countershaft sprocket (15).

As mentioned in other posts, I previously had a 2016 model DR650 and recently purchased a 2012 model year. As it related to the 2016 gearing, I retained and was perfectly satisfied with the stock gearing (42:15) over the term that I owned it. That ratio supported my dual sport rally hobby that generally requires 50% on-road and 50% off-road riding. 

As it relates to the 2012, the prior owner had changed the countershaft sprocket to a 14T, increasing the final drive ratio from 2.8 to 3.0. Increasing the ratio (i.e. gearing down) naturally has the affect of increasing the low-end torque/acceleration (good for off road; more rpms and grunt in the low gears) at a cost of top speed reduction and a loss in the smoothness of engine operation at the top end of the powerband (bad for on road; requires more rpms to achieve the lower top speed). 

Top Speed with 42T Drive Sprocket (Source - Gearing Commander):

• 13T Countershaft = 84.8 mph
• 14T Countershaft = 91.4 mph
• 15T Countershaft = 97.9 mph
• 16T Countershaft = 104.4 mph

Back in April 2016, I put my DR650 (stock gearing) to the top-speed test and after multiple attempts the motorcycle topped out at 93 mph, measured using a GPS device. (Suzuki DR650 Top Speed)

I ran the 42:14 ratio on my 2012 model year DR650 for about the first 750 miles, which included the two-day, 500 mile 2021 Trans Florida Dual Sport and Adventure Rally. Overall, as you may expect, the better grunt in the low end of the powerband was better on the trails. However, those improvements did not outweigh the cost on the top end. As mentioned, increasing the ratio deceases speed and engine smoothness in the upper powerband. The speed wasn't the issue. The issue was the loss of smooth engine performance as the motorcycle began to hit highway speeds (around 65 mph). This is how final drive ratios are weighed and it's an individual, case-by-case situation. I went back to the 42:15.

Good news/bad news:

The good news is that changing out countershaft sprockets is all of cheap, easy, and quick. One could change in and out of sprockets that are suitable for different rides quite easily. The sprockets run around $15 for a good aftermarket branded sprocket, like JT, and it's all of 3 bolts to remove/replace. That doesn't include the fact that the rear axle and chain pullers also require adjustment. 

The JTF.1448.15 Countershaft Sprocket was $15.25 on Amazon. 

The bad news is that there's a school of thought out there in motorcycle circles that it is preferable to address "increases" in Final Drive Ratios (i.e. generally installing smaller countershaft sprockets) by changing only the rear drive sprocket. The thought runs that smaller countershaft sprockets are bad in that they require a tighter turn at the drive shaft that affects both the chain life and tension on the drive shaft.

 Not to worry...

Ratios come down to simple math. 

A desired ratio of 3.0, the result of a 42/14 sprocket configuration, can be accomplished a number of ways. If 3.0 is desired and one feels it necessary to retain the 15 tooth (or higher) countershaft sprocket, then the desired ratio is achieved my multiplying that ratio x the countershaft sprocket teeth: 3.0 x 15 = 45 tooth drive sprocket. 

Similarly, a desired ratio of 3.2, the result of a 42/13 sprocket configuration, can be accomplished using the 15 tooth countershaft sprocket and a 48 tooth drive sprocket: 3.2 x 15 = 48 tooth drive sprocket.

You can do the math on other configurations. Or, JT Sprockets has a useful Gearing Ratio Cross Reference Chart available on their website that can be downloaded in .pdf and used as a reference.

Chain Length Considerations:

The stock chain on the post 1995 Suzuki DR650 is a DID525, 110 Links. Changes in sprockets may result in different chain lengths. For determining whether more (or less) links are required, consult the Gearing Commander Chain Links Calculator. 

Tusk D-Sports for the DR650

My recently purchased (used) 2012 Suzuki DR650 came with a set of Shinko 804/805 Big Block Tires (40% on road/60% off road). The 804 (front) was near new, the rear was a thousand miles away from replacement. 

I'm very familiar with the Shinkos. I had a set on a past KLR650 and the Shinkos were the tires that I purchased to replace the Original Equipment Tires on my former 2016 Suzuki DR650 that I purchased new. My problem with the Shinkos is, bottom line, I never liked them; not so much the 805 (rear) as the 804. Likely a great tire for more intermediate terrains, such as gravels and hardpans, the 804 isn't suitable for the soft sand, loam, mud that we have in Florida. Here are the Shinkos on my 2016 DR tearing up a muddy trail out on Devils Creek (Brooksville, Florida).

Notwithstanding my feelings for the Shinko, I gave them, as installed on my recently purchased DR, a shot on the 500 mile Trans Florida Rally in mid-November, first rally on the 2012 DR. Only to confirm what I used to think of them as stated above

So, between the Trans Florida Rally and upcoming Polar Bear Rally, I've slipped on a fresh set of tires more suitable for my needs. Those are the Tusk D-Sports (Front: 90/90-21 $54 @ RMATV, Rear: 130/90-17 $64 @ RMATV). Since RMATV released the D-Sport under it's Tusk Brand, I've had two sets of the D-Sports, these will be my third.

 

The width of the outermost knob is:

• Rear 135mm
• Front 90mm

The D-Sports are generally believed to fall into the 30% on road/70% off road category of dual sport tires, which seems right based on my experience with them. The tread pattern provides thick knobs that hookup and wide/deep grooves that channel the soft materials out the sides, thus maintaining traction on the sandy and muddy Florida trails and forest roads. 

Online reviews and comments can be found that suggest the D-Sport front isn't effective on soft surfaces, basically capable of washing. Well, all tires wash in sand and mud, but as a generality, those comments are simply not true. All you need to do is look at the tread pattern to see that those comments are wildly exaggerated. I believe the reason behind disparaging comments about this tire (and certain others) are that the comments are coming from riders that don't have experience riding in sand and mud as do I. That stuff is difficult for everyone.

The D-Sport tire compound seems very similar to the D-606 and has a consistent wear life to the Dunlops. The D-Sport carcass is relatively stiff compared to other aggressive DOT knobby tires such as the Kenda K760 TrakMasters, but I find it's stiffness to be similar to the D-606. 

Online reviews and comments that indicate stiffness to the point of difficulty in spooning or limited air-down levels are wildly exaggerated. I've spooned three sets with my basic hand spooning tools outlined for you below, no problemo.

As for on-road, the D-Sports, like the D-606 and K760s, are a long way from a smooth ride on the pavement. Rough and noisy. Similarly, like all other DOT knobby tread designs, caution should be exercised on wet pavement. Other than that, the the D-Sports hold-the-road pretty good. Here are the D-Sports (mounted on my classic 1985 KLR600) sticking to the off-camber hairpin turns of the Tail of the Dragon. 

Onward...

Off with the Shinkos and on with the D-Sports. 

The front, having only recently been installed came off easy; the fresh D-Sport spoon on just as easy. The rear, on the other hand, was a miserable job getting off the bead. Such is the case when they've been sitting a long time and compound wears off on the metal. I would not have been able to break the bead on the trail. It's a good thing I did the change.

Cleaning a rim in this condition this requires a combination of wire wheel and solvent. 

I use the same tire tools in my garage as I use on the trails. Specifically, those are the Stockton 3-Piece Tire Iron Kit ($30 at Revzilla and Cycle Gear) and the very popular Motion Pro Bead Buddy ($17 at many stores). 

Removing the tire carcass requires all three of the tools in the Stockton Kit (see below). The longer bar has a bend on one side for breaking a bead; a normal bead, not like the one I needed my 6" clamp to break. Spooning the tire on the rim requires only the longer bar and the Bead Buddy as shown in the photo above. The Bead Buddy holds the bead in place at one point, then the long bar is used to spoon it on. The long bar in the Stockton Kit is the key to successful spooning. It has a bead breaker bend on one side and a special lip on the other that avoids needing to push the bar under the bead too much and possibly pinch the tube. I never pinch a tube sticking to these two tools. 

Spooning the D-Sport onto the nicely cleaned rim, with a fresh strip and tube, was a cake walk. As I previously mentioned, online reviews and comments that indicate that the sidewalls and carcass are so stiff as to interfere with spooning are wildly exaggerated. .

I'm looking forward to reacclimating myself with the Tusk D-Sports in early January 2022 at the Polar Bear Dual Sport and Adventure Rally. 

Final thoughts on Dual Sport Tire Pricing:

Continental Twinduro TKC80:

When I first got into dual sport in a very serious way, there was only one tire that I consistently used: Continental Twinduro TKC80. I consider the 40/60 class Twinduro to be the gold standard in dual sport tires from a pure performance perspective. Unfortunately, as time passed, Continental took advantage of the tire's popularity and following and all but priced the tire out of the market. While I just paid $118 for the set of D-Sports, a set of Conti's would have run me $250. That wouldn't necessarily be the end of the world; However, the one issue that the Conti's have is a poor wear life relative to other options. In a pure 50-50 road vs trail riding environment, the lifespan of the Conti is no more than 2,500 miles. I will get twice the miles under the same conditions with the D-Sports. 

Look at it like this, if the $132 price delta between the D-Sport and the Conti were projected to an average 10,000 mile year, tire costs would be $264 for the D-Sports (two sets) and $1,000 for the Continentals (four sets). I'll leave out tubes and strips that need to be replaced with every tire change.

Dunlop D-606:

Another tire worthy of mention is the 10/90 Class Dunlop D-606. An excellent dual sport tire, although a more gnarly tread pattern for serious off road work. The D-606s represent another example of popular tires who's price went off the scale in response to a broadening dual sport following. In fact, I was running the D-606 on my 2016 Suzuki DR650 when I sold it in 2016. Like the Conti's, I actually can't remember what I paid for them; however, today the set is $235. I will mention that the D606s actually had an excellent wear life for a 10/90, perhaps the best I've had in that category. 

One interesting observation that I had while reviewing some old photos of my 2016 Suzuki DR650 was how close the 10/90 Dunlop D-606 (right) and 30/70D-Sport (left) Tread Patterns are. From my first hand experience, I think its safe to say that the compound (stiffness) is equally similar.

Shinko 804/805 Big Blocks:

Since this post started with a discussion of the Shinkos, I will add that the Shinkos are another tire where popularity and following resulted in a massive price increase. A set of Shinkos for the DR, although not under consideration for the reasons mentioned, would have run $236. For the record, their wear lives exceed all other tires mentioned in this post.