Questions about Replacing Chain/Sprockets

[Bones85]

I have several questions about replacing the chain and sprockets and would appreciate if someone could answer them. I've done plenty of research but I'd like to hear everyone's opinion here.

This is the chain I'm considering along with a 15T front sprocket and 45T rear sprocket or 42T rear sprocket

1) How difficult of a job is this for someone who's never replaced a chain or sprockets before and which tools would you recommend?
2) I definitely want the 15T for the front but I'm not sure whether to stay with the stock 45T or switch to the 42T in the rear. Most of my riding is on the highway and I live in Florida so it's mostly flat here and I don't have to worrry about going up any big hills, etc.
3) Will the lower RPMs as a result of the new sprockets increase gas mileage and or increase the lifespan of the engine?
4) Does RK make good chains or should I consider EK or DID instead?
5) Can I expect to get 25,000-30,000 miles out of the chain and sprockets if they are maintained properly?

Thanks.

[csmith12]

How hard? - Pretty easy with normal hand tools. You will need a large socket for the front sprocket nut. 27mm if I remember right but don't hate me if I am wrong, I work on a few different bikes. You will do yourself a favor by having a torque wrench to tighten the sprocket nuts/axle nut to proper tightness.

Both 15 and 42? - Try just the 15 first and see how you like it. The rear is more expensive so you may just save the cost of that if your happy with just a front swap. My preference is also the 42 rear though... YMMV as each rider's happiness is a different measure.

Increased mileage or engine wear? - Straight up no right or wrong answer here. It all depends on how you ride it. When I went 15/42, I saw no changes.

Chain brand? - I only have used DID chains, maybe someone with experience with RK can comment

Chain/Sprocket longevity - It is not uncommon to get 20+k miles out of a well taken care of chain and sprocket combo. As well as keeping it well lubed and cleaned, don't forget to keep slack adjusted within spec.

[csmith12]

Let me add;

If your new chain comes with a clip style master link, make sure you install it the proper direction, walk away, then double check it. Us track guys also safety wire the clip or put a blob of silicone on it.

[rojoracing53]

So that chain looks like a good chain and it comes with a rivet style master link so you will some special tools. To install the chain your going to need a chain breaker and pressing tool for motorcycle chains, normal cost is $40-250 depending on the quality of the tool. The job is not hat hard but the chain is a rather important component so your going to want to make sure you do your research and do it right. I'm sure @Motofool or someone can link you to a good DIY thread for this.

As for gearing I personally run a 15-42 and I ride everything from flat hwys to mountain passes and I love my gearing. I'm even considering a 15-40 for my next sprocket setup. When I went back to stock for a couple days before my last trackday I couldn't stand the extra high RPMs everywhere and was happy to go back to the 15-42.

Taller gearing won't really make a noticeable difference on a hill other then you selecting a low gear to get the same RMPs as before. If you need 9,500 RMPs at 70mph to get up a hill then I doesn't matter if you need to use 6th or 4th to do it. The difference with taller gearing is the amount the RPMs drop when upshifting, so technically you drop farther below your peak HP point but its a minor thing in my opinion.

[bkh2]

I run 14/38 and I think the torque is fine for what I use it for (highway commute with some leisure riding).

Here are the gear ratios. The higher the number, the more rotations it takes for the front sprocket to rotate the rear sprocket once; the higher the number, the higher RPM per given speed:
R / F
38/14 = 2.714 (what I run)
42/15 = 2.8 (Jason's gearing)
45/15 = 3
45/14 = 3.214 (stock)

If you ever feel like you're lacking in power, just gear down. I am still able to red line first gear pretty quick with the gearing I have now, so that's not an issue for me.

Also, it's a 27mm for the front sprocket nut.

For gas mileage, my initial numbers show better gas mileage, but I will have to do more runs to get an accurate trend.

[rojoracing53]

If you take great care of your chain you may get 25k miles out of it but I think that would be if you took perfect care of it, 15-20k is probably a more common #.

[Motofool]

Originally Posted by rojoracing53

..........@Motofool or someone can link you to a good DIY thread for this.

http://www.ninjette.org/forums/showthread.php?t=40468

http://faq.ninja250.org/wiki/Final_Drive

[Bones85]

Originally Posted by Motofool

http://www.ninjette.org/forums/showthread.php?t=40468

Link in that thread is dead.

[Motofool]

Originally Posted by Bones85

Link in that thread is dead.

Sorry; that is our DIY.

[Bones85]

If I go with 15/42, I can still use the 106 link chain, correct?

[Qomomoko]

I got my 93 ninja 250 used with the following set up
14/45 Rims 16

and with the 2008 mods I am making it will be
14/41 Rims 17

will see how that feels....
I do Homestead speedway which is technical turns (point and shoot)
and I also do Palm Beach International Raceway, which has a pretty long back straight and sweeping turns (the back straight Is about 20-30 seconds on a ninja 250)

I have my vapor trail tech to yellow warn to shift at 12250 and red 2nd warning at 1300 rpm (its a 98 engine).

Exhaust is stock but will get ceramic coating I hope to keep it form melting my boots.. and the carb for now is stock but I will adjust the needles after I see how it runs.

41 rear might be a tad low but I'll see how it first before buying a 42 or such....

I have a feeling I'll take my wrench and end up putting 14/45 with my 17 inch rim mod...

[csmith12]

Originally Posted by Bones85

If I go with 15/42, I can still use the 106 link chain, correct?

yes sir