Two Stroke Motocross

Two Stroke Motocross Forum => Technical => Topic started by: ashpeat on April 12, 2013, 03:30:36 PM

Title: Do you REALLY have to replace sprockets and chain at the same time?
Post by: ashpeat on April 12, 2013, 03:30:36 PM: Is it actually neccessary to replace the chain and sprockets at the same time or is this just renthals way of selling more stuff?

They claim if you only replace the chain, old sprockets will wear the new one out a lot faster, what do you guys do?, is their any truth in this?
Title: Do you REALLY have to replace sprockets and chain at the same time?
Post by: Lolerbabop on April 12, 2013, 03:44:42 PM: I suggest you replace the whole bike while you're putting on new sprockets and chain, just to be safe.
Title: Do you REALLY have to replace sprockets and chain at the same time?
Post by: factoryX on April 12, 2013, 05:06:13 PM: If I were running aluminum sprockets, maybe a 2-3 replacements then a chain but steel sprockets no way. Putting a worn chain on new sprockets will cause more wear on the on the sprockets.
Title: Do you REALLY have to replace sprockets and chain at the same time?
Post by: SachsGS on April 12, 2013, 08:21:44 PM: If you have an aluminum rear sprocket and an O-ring chain the sprocket will wear out before the chain and there is no way I'd use the worn chain on new sprockets.
Title: Do you REALLY have to replace sprockets and chain at the same time?
Post by: Coop on April 13, 2013, 12:22:39 AM: Quote from: SachsGS on April 13, 2013, 03:21:44 AM
If you have an aluminum rear sprocket and an O-ring chain the sprocket will wear out before the chain and there is no way I'd use the worn chain on new sprockets.

Agreed.
Title: Do you REALLY have to replace sprockets and chain at the same time?
Post by: Rm125guy on April 13, 2013, 03:34:28 AM: Somewhere I heard that the old chain on new sprockets will make the sprockets wear 20% faster... Just an unreliable statistic but true
Title: Do you REALLY have to replace sprockets and chain at the same time?
Post by: rlaj1004 on April 13, 2013, 02:32:37 PM: It will wear out the sproket quicker, not sure about steel. The chain stretches as you can tell since you have to adjust your chain tension periodically depending on how hard you ride. I have thrown a new sproket on without changing the front counter or the chain just to get back on the track but I had to change it out sooner that I should have. Have to work that out though, 2 -3 sprokets to 1 chain and counter is will still probably get you more time with less money.
Title: Do you REALLY have to replace sprockets and chain at the same time?
Post by: scotty dog on April 14, 2013, 02:56:39 PM: I always have changed the chain and sprockets in one go, if you are, get a good X-ring chain and you will get a good life out of the lot
Title: Do you REALLY have to replace sprockets and chain at the same time?
Post by: citabjockey on April 14, 2013, 10:03:05 PM: So when a chain wears out it appears to "stretch". This means the distance between pins is getting longer. We are talking mils here... Anyway, when this happens the chain "pitch" no longer matches that of the sprocket. So when the chain pulls (or gets pulled by) the sprocket it has a tendency to climb up the teeth -- further away from the center of the sprocket to the point where the worn chain matches the pitch of the teeth. When this happens the teeth are loaded further along their length -- i.e. in the weaker area. This tries to bend the teeth over. You have all seen dished teeth, right?

If you swap a sprocket but leave and old chain it will dish those new teeth pretty quick -- depending on the sprocket material and how worn the chain is.

the other way around? The chain wants to dive deeper into the sprocket. It can't so the load is on a few teeth instead of all the way around the sprocket where the chain is engaged. Same result, sprocket gets hosed quickly.

Not clear to me if the chain cares that much. If the teeth are so mismatched to the chain is "snatching" going on to or off of the sprocket as it rotates I suppose that would put extra wear on the chain but I can't picture that its more than the engine running full blast and the rider dropping the clutch.

I have bought bikes with missing teeth and it all operated ok until I could get the units replaced...

So I replace a sprocket if its teeth are showing obvious wear. I always buy steel teeth (even if the rest of the sprocket is alloy, it just lasts so much longer). I swap the chain when my adjusters run out of adjustment. With the high quality of chains these days this seems to be a good long time. I don't necessarily swap them as a set.
Title: Do you REALLY have to replace sprockets and chain at the same time?
Post by: TotalNZ on April 15, 2013, 03:10:32 AM: Yes definitely replace the whole lot at once. i'd never run new sprockets with an old chain or vise versa.
Title: Do you REALLY have to replace sprockets and chain at the same time?
Post by: opfermanmotors on April 15, 2013, 04:22:37 AM: Don't forget to replace the hand grips too since you usually hold on tighter as the chain stretches.
Title: Do you REALLY have to replace sprockets and chain at the same time?
Post by: SachsGS on April 15, 2013, 11:47:28 PM: The big scary thing is if the bike throws that worn chain - broken mag cover,hyd. clutch etc..
Title: Do you REALLY have to replace sprockets and chain at the same time?
Post by: ashpeat on April 17, 2013, 12:39:04 AM: Thanks all, i think i will deffinatly be getting a full renthal set!
Title: Do you REALLY have to replace sprockets and chain at the same time?
Post by: VintageBlueSmoke on April 17, 2013, 10:19:58 AM: Really, it comes down to the condition of the chain. I often do not change the chain or front sprocket (Steel) when the rear is worn. I can usually go 2 for 1 and get SIMILAR life from the second rear sprocket.

That said, if you can get a steel rear...do so. They only weigh grams more than an aluminum one and will double the life span. In fact, I usualy wear out a chain before the sprockets when I have steel. Any new chain gets new sprockets.

Of course you look like a N00b with a steel rear sprocket, but then you can take satisfaction in your intellegence and look at the kool kids for what they are; silly, BNG sporting, bling touting posers.

(If you don't know what BNG is...you might be a N00b.)
Title: Do you REALLY have to replace sprockets and chain at the same time?
Post by: TMKIWI on April 17, 2013, 10:36:52 AM: Don't forget the flat bill.
Title: Do you REALLY have to replace sprockets and chain at the same time?
Post by: Lolerbabop on April 17, 2013, 10:55:16 AM: Don't forget replacing the swingarm, wheel, frame and oh EVERYTHING ELSE!
Title: Do you REALLY have to replace sprockets and chain at the same time?
Post by: ashpeat on April 17, 2013, 09:12:05 PM: Ofcourse!
Quote from: Lolerbabop on April 12, 2013, 10:44:42 PM
I suggest you replace the whole bike while you're putting on new sprockets and chain, just to be safe.