Author Topic: Offset front sprocket  (Read 638 times)

Offline Frankie 2 sheds

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Offset front sprocket
« on: November 14, 2018, 09:59:02 AM »
Hi Guy's. Still in the process of re-building a special. The K6 engine has now been completely re-built and have turned my attension to the frame. I'm using a 2004 GSXR 600 doner for the front and rear. Having now got the GSXR rear swing arm and wheel on I now need to line up the main drive. A 10mm offset front sprocket will get me there or there abouts. There is very little room to fit a new standard sprocket let alone a 10mm offset one. Before I layout £80+ for the offset has anyone else fitted an offset on a fully assembled engine block??? or are my worse fears coming to fruition in that I would have to strip the engine again......Frank

Offline Trigger

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Re: Offset front sprocket
« Reply #1 on: November 14, 2018, 11:25:39 AM »
A off set of 10mm will only leave you about 7.5mm with a STD chain and 5mm with a Xring which is getting very tight for that area. The problem with any off set sprocket, is the more you off set the more the final drive bearings are under load and don't last very long.
I have seen this done on drag bikes but, they are rebuilding and up dating the engine constantly  ;)

Offline Frankie 2 sheds

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Re: Offset front sprocket
« Reply #2 on: November 14, 2018, 12:18:24 PM »
I totally get that trigger and I understand the conseqences. But it's the actual fitting of the offset sprocket that concerns me. Will it fit without having to split the gearbox, that's my concern.....Frank

Offline Trigger

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Re: Offset front sprocket
« Reply #3 on: November 14, 2018, 12:31:59 PM »
Not sure as i can't see a STD final drive shaft taking a off set sprocket of that size  ;)

Here is a picture of a STD set up on a K6, i will let you do the maths  :o


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Offline K2-K6

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Re: Offset front sprocket
« Reply #4 on: November 14, 2018, 01:41:57 PM »
Have you considered a 520 sized chain?

It's 3.2mm narrower than 530 before you start to consider alignment,  it'll also reduce the loading on the output bearing that could give some respite to having the load path moved away from the bearings.

Offline Frankie 2 sheds

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Re: Offset front sprocket
« Reply #5 on: November 14, 2018, 02:19:48 PM »
Yes I have considered a 520 chain but I think I can only get the offset sprocket for 530. Thanks for the pic trigger. It looks do-able just but that is with the sprocket already in place. My engine is complete. So it goes back to the original question. Can you fit an offset sprocket on the shaft as is?? I have the same set up as your picture using an old bottom half and you can only just fit a standed sprocket on as my attached pic shows. I don't think for one minute that an 9.5mm offset sprocket can physically fit on the shaft without having to split the engine block, unless I'm missing something. Your thoughts please....Frank

Offline Frankie 2 sheds

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Re: Offset front sprocket
« Reply #6 on: November 14, 2018, 02:31:42 PM »
I've just noticed that the bottom end I have in the frame is slightly different to my completed engine in that like your pic trigger the casing oppersite the drive shaft is rounded off with the bolt further back which might help. Now I'm totally confused

Offline K2-K6

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Re: Offset front sprocket
« Reply #7 on: November 14, 2018, 02:46:54 PM »
It is kinda a catch 22,  can see reluctance to shell out if it's not going to fit.  Has the supplier any leeway to let you try?

On the 520 sizing, they only differ in thickness to the 530 as far as I know.

Sooooo, if you machined the back face of the teeth area only (nearest gearbox)  off a std sprocket to fit the 520,  then that moves chain centreline out.

Then machine a recess into the front face to allow the retaining plate to sit "in " the sprocket,  this would move the whole sprocket outwards also. 

The combined total may give you what you need,  bearing in mind that the rear sprocket in a 520 would bring the outer face inwards and so come closer to front alignment too.

Could the three shifts give you what you need?

Offline Frankie 2 sheds

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Re: Offset front sprocket
« Reply #8 on: November 14, 2018, 03:05:58 PM »
Now that is what I call a brilliant idea. Just thinking outlound I don't think it will give me the full 10mm but what it will do is allow me to go the 520 route which brings the gsxr rear wheel into play as it is already at 520 and I would of had to go to a JT1800 530. Thanks K2 I'm off to play ;D ;D ;D

Offline Frankie 2 sheds

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Re: Offset front sprocket
« Reply #9 on: November 15, 2018, 11:36:44 AM »
Problem solved I think. I have been using a bottom end engine pre 1977 as seen in earlier pic. Thankfully the engine that will eventually go in is 1978 pics attached. As you can see there is room to accomadate a 10mm offset socket. Talking to the supplier they have supplied 15mm before. They make any sprocket to order. So I will be ordering a 10mm x 520 offset. Thanks guys.....Frank

Offline Trigger

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Re: Offset front sprocket
« Reply #10 on: November 15, 2018, 01:54:57 PM »
Just make sure it is a 18 tooth sprocket, any less and you will get back lash off the chain  ;)

Offline Frankie 2 sheds

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Re: Offset front sprocket
« Reply #11 on: November 15, 2018, 02:10:29 PM »
will do, thanks trigger

 

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