250sl rear sprocket

[Hodaka250SL]

I was wondering if there are different size sprockets for a 1978 250sl. Or if there is another kind sprocket that will fit

[olddogs]

I found a note i scribbled in the back of a 250 SL owners manual that a Yamaha TT500 rear sprocket from the late 70s may work on the 250. I must have jotted it down for some reason 40 years ago. Cant guarentee it will fit but it may be worth a look.

[Hodaka250SL]

Ok. Was just wondering cus I want a smaller sprocket

[---]

Measure the bolt circle and shop online. Hodaka may have just picked a sprocket that was already available in the 70's rather than custom engineer one, so the bolt pattern may well match more than one Japanese bike.

[olddogs]

I think I also made a note on a front sprocket interchange. I will check. For some reason I assumed you were looking for a rear sprocket.

[thrownchain]

Any info for interchange ability is good to have, front or rear.

[Hodaka250SL]

That would be cool to know for when I have to replace them

[olddogs]

Found another notation that the front sprocket from a early 70s SL350 Honda would interchange. No proof, just and old note.

One good trick for this kind of data is to find old motorcycle accessory catalogs at swap meets. Look up any hodaka parts listed and write down the part number. Go through the rest of this particular section and look for matching part numbers under other brands. Levers, cables, piston rings, air cleaners and sprockets generally fit more than one model.

[thrownchain]

Working out of a Sprocket Specialties catalog. Rear sprocket part number 260, fits Hodaka with 520 chain: multiple Yamaha cross references,including the TT and XT 500, '89-02 350 Warrior and Banshee amoung several others. I don't have a cross for front sprocket......

[---]

Looking for a rear, or a front that is smaller? If you want to gear down, for example for better trail manners, I would look for a larger rear, not a smaller front. Preference is for more tooth engagement.

[thrownchain]

Header says rear, probably wants it for street use.

[---]

That's what I thought going in, but just wanted clarification. I can't imagine making a 250SL harder to accelerate by making the gears taller. It isn't the optimum highway cruiser by all accounts.

I would look at it this way: as geared, can I routinely redline the engine in top gear on the road? If so, am I within a reasonable speed, like 60 or 65? If yes, taller gears might work, or might help go the speed limit at slightly lower rpm. If not, making the gears taller would just make matters worse, but probably wouldn't make it go faster. I don't personally know if an SL will redline in top gear.

[Hodaka250SL]

That is my goal is to drop the rpm down just a bit. For better street use. I live in the city. And I would have to drive 50 miles anywhere to go trail riding. I'm mainly using it to go to and from work

[---]

If you can get a feel for what rpm range your bike likes best, compare that to the speeds at which you routinely travel at constant speeds. When cruising, if you feel it is revving more than is best for performance, dropping the rear sprocket size by one or two teeth may help. But if doing so drops rpm into a range below peak efficiency, all that will be accomplished is less fuel economy. It may seem counterintuitive, but slowing the engine does not always result in better economy. Running at the highest road speed with the smallest throttle setting generally will improve economy. You want to cruise without lugging the engine.

If you find what you are looking for, give it a try. If you have not already done so, I would start a log book and track your fuel consumption on the route you drive every day. When you change gearing, compare fuel consumption on the same route as between the two gear combinations. If consumption goes down, you win. If it goes up, put the gearing back where it was. If it makes no difference, it's your choice.

[thrownchain]

I would think he's like me and doesn't want to be bumping the redline to get a decent road speed all the time.

[taber hodaka]

Well I would try a front sprocket first, allot cheaper just to get a feel for gearing? Isn't one tooth larger on the front sprocket equal to about four teeth smaller on the rear? How many miles and how many years are we talking about here? I think it would be more for the comfort zone of the rider. -------Clarence

[Hodaka250SL]

That's definitely my main goal is to do what thrownchain said

[thrownchain]

How are you going to decide how much smaller a sprocket you're gonna try? You gonna buy a couple and try them?

[---]

What Clarence suggested is prudent. Front sprockets are a lot cheaper than rear sprockets as long as you are not trying to make a major shift in gearing. Assuming you can find a source. My guess is that there is one, but you might have to call around.

Perhaps the easiest way to figure out what you need is with a calculator. The bike has a torque peak of 5,100 rpm and a power peak around 6,700. That's a fairly broad window. The final drive with stock 14 x 44 sprockets is 3.14:1, which is already fairly low (tall gears, low ratio).

Changing the rear sprocket from 44 to 42 leaving the front alone would change ratios from 3.14:1 to 3:1, a five percent change. Changing the front from 14 to 15 leaving the rear alone would change things from 3.14:1 to 2.93:1, a seven percent change. If a 43 rear was found, that would change from 3.14:1 to 3.07:1, a three percent change. These changes would alter/drop rpm for a given speed by somewhere between 200 and 470 rpm. If that isn't enough, you would need perhaps a 40 rear or a combination of front and rear sprockets that gives you your target drop in engine speed. I would keep in mind that the way an engine presents its power is controlled to an extent by the gearing, so even a drop of 500 to 1000 rpm might make the bike a bit doggy, even though on paper it should still have enough torque to get the job done. It will just take longer to get rolling, or you might have to shift more on hills.

Have fun finding your preferred combination. If you find reliable cross references for sprockets, post them so others may know.