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Correct Front Sprocket Install


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Hudtm60
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Correct Front Sprocket Install

Wed Mar 19, 2025 5:25 am » Post: #1 » Download Post

Hello Everyone,

I was reading thru my thread to try and find a picture of my front sprocket before I tore the bike down and was reminded of some supportive and encouraging comments from Lesviffer750. I'm sorry that he's gone. and I'll never get to meet him or that he never got to see the end of this build....not that this stuttering project would have been at the forefront of his (or anyone's) mind...but the real point being that it seems like us NSR fans are a relatively small bunch, and one less is never good. God Speed Lesviffer750.

Quick question on the correct placement of the front sprocket: on the parts diagram (Part #22) it looks like the raised portion of the sprocket faces the engine, but as you can see my bike arrived with the raised portion facing out which I think is incorrect and as hopefully you can see in the fourth pic would have the chain off-line if you go by the wear on the rubber protector

New 15 tooth front (top) will go with the 42 rear, if I remember rightly it's bucking the trend of the tried and tested 15/40 this forum prefers, but I like a bit of acceleration and being a street bike don't need the top speed. we'll see. proof, pudding etc.


In this diagram raised portion faces the engine...


...but not in this case....this is how it was when I got it...and I was pointed out previously, tabs ain't right.


with raised portion out facing doesn't look like the chain line would be good.

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ericandchi
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Front sprocket

Wed Mar 19, 2025 1:26 pm » Post: #2 » Download Post

Hopefully this pic makes it clear. The rubber part faces "out".
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Hudtm60
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Wed Mar 19, 2025 2:05 pm » Post: #3 » Download Post

Thank you Eric. You might be lucky enough to have an OEM part, as my raised portion isn't rubber. Looks very clean in there for a running bike!
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Hudtm60
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Wed Mar 19, 2025 7:42 pm » Post: #4 » Download Post

I still think the parts diagram shows it facing the engine
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ericandchi
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Thu Mar 20, 2025 5:12 am » Post: #5 » Download Post

OK so you have an aftermarket sprocket which maybe fine. On the diagram, part 23 is what essentially keeps the sprocket from coming off the shaft. Key is that once you tighten the two bolts that position and hold part 23 to the sprocket, you need to have the front and rear sprockets inline. As long as you have them aligned you should be fine. The sprocket does float a little from left to right but should not be forced to one side or the other by the chain as that would cause excessive wear on both sprocket and chain.

If you install it one way, then the other, with the chain and rear sprocket, it should be obvious. If it's not working either way you should reconsider using it. I imagine you could shim it, but I don't advise that when the correct sprockets are available.

Eric
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Fri Mar 21, 2025 11:21 am » Post: #6 » Download Post

Here's a JT Sprockets front fitted on an F3.



Raised part with the enggravings to the outside.

The OEM sprockets have rubber on both sides, hence why the parts manual looks like it's raised on the inside.
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