Gearing/Popping

[elric8467]

I'd like to get some opinions on this...I've gone down a tooth in the front and I'm going up....4...... in the rear. Will I need a new chain . I only ask because I put a new chain on not three weeks past. Also I did a rejet and put on a hotbodies slashcut, and of course it backfires like crazy when I let off the throtle. I did not do new pilot jets b/c I couldn't figure out what the stock pilots were. Can I just turn the pilot screws all the way out until I replace the pilots in a week or three? BTW, if anyone knows the pilot sizes for the EX500 carbs....I tried to join their forum as well but they're having some techniical difficulties.

[elric8467]

Heeeeeeeeelllllllllooooooooooooooooooooooo out there...... can anybody hear me?

[Kerry]

Heeeeeeeeelllllllllooooooooooooooooooooooo out there...... can anybody hear me?

Sorry - my first quick scan only detected "bling" and "jetting" talk ... stuff that doesn't normally interest me.    But I missed this part:

Will I need a new chain.

Let's see ... thinking loosely in geometric terms, dropping a tooth on either sprocket will reduce the diameter of the sprocket by roughly 1/3 of the distance between the centers of two adjacent chain link pins.  (That translates directly into how much the rear axle will have to move back to tension the chain.)  Adding a tooth will force the axle forward by the same amount.

You've dropped one tooth and added 4, so you've effectively added 3 teeth.  That means that the rear axle would have to move forward by roughly one whole chain pin-to-pin distance.  Not knowing how much slack you have with your current chain, you'll have to tell US -- do you have enough adustment left to move the axle that far forward (and still have clearance for the tire under the fender)? 

EDIT: I thought this over while walking the dogs just now, and I realized that I'm off by a factor of two on the axle movement figures.  My description of diameter changes is about right, but the axle only needs to move by the change in radius ... or half as much as I said.  Sorry about that. 

[ohgood]

I was concerned with how many posts you have, and wanting to go up 4 teeth on the rear. Up 1 on the front may help keep the wheelies at bay.

Let us know how the setup works for you.

[lancemclaughlin]

I was concerned with how many posts you have

please explain how a member's number of posts is in any way related to his/her abilities or experience as a rider. maybe he has better things to do than to make posts all the time, or maybe he just reads mostly (as i do).

that said, going up four is a pretty squidly thing to do, so i can see where you got the assumption. but don't be a board nazi and pretend like post count is relevant in any way besides determining who has more free time, and who is using that time to do something besides actually riding. 

[elric8467]

I appreciate the info guys. I put on the 43 tooth sprocket last night without having to use a different chain. Clearances are good. As far as wheelies go I've got six seasons of riding under my belt so it's not too much of a problem I've built a GS-EX and the gearing was to tall with the 39 tooth sprocket. It's just a little in-town bike. It tops out around 110 with this new gear but boy it's quick to it. You right about going up a tooth in the front. Question: I thought one tooth in the front was equivalent to roughly 2.5 teeth in the rear. I.E. -1 up front  is equal to +3 teeth in the rear correct? It sounds like your suggesting they counter act each other? Have I been opperating under a false assumption? I'm not so hot with the math and all:laugh:

[elric8467]

It's okay :laugh:They're just watching out for us that's all. But you're right it's not a good habit to adopt. I am glad that some one cares enough to ask after us, though the number of post should never be assumed to be indicative of a member's experience. The wheel being so much father up and the gearing being pretty radical it could be a handfull for a relativley in-experienced rider. There's definatley a higher rate of turn in as well- something that almost took me off gaurd.

[Kerry]

Question: I thought one tooth in the front was equivalent to roughly 2.5 teeth in the rear. I.E. -1 up front  is equal to +3 teeth in the rear correct? It sounds like your suggesting they counter act each other? Have I been opperating under a false assumption?

Nope, no false assumption.  My discussion was all about the distance between the countershaft and the rear axle ... you're talking about the gearing ratio between the countershaft and the rear axle.

Dropping teeth in the front ... or adding teeth in the rear ... will both lower the gearing ratio.  That is, the countershaft will now need to turn more times to get the rear axle to turn the same amount of times as before.

On the other hand, dropping teeth in the front will effectively lengthen the chain, while adding teeth in the rear will effectively shorten the chain.

Weird how all that works, eh? 

[elric8467]

I'd say so, I hate elmentary physics  I do recall though, that too small a front sprocket will cause the chain to bind- correct?

[Kerry]

Correct.  From what I understand, putting a 14-tooth sprocket in the front is somewhat "iffy".  Any fewer teeth is "right out".

[dgyver]

My track bikes typically run a 14T up front. Never broke a chain, but usually get replaced often. There is additional wear on the rub guide on the swingarm though.