Unique/dek bandit 400 blog

[Unique]

I asked my machinist to mill 3mm off the hub surface, the surface to be milled is where the sprocket bolts too, and is milled up to, but not including the lip which is needed to centralise the sprocket to the hub’ and therefore must be kept at all cost. The 3mm milling will bring the sprocket closer to the tyre.

I also ask him to improve-on the gap between my new sprocket and hub lip as the new sprocket wasn’t as tight fitting compared to the original sprocket.
When I went to collect the hub he had done a great job on the sprocket to hub fitment’ I couldn’t wish for a tighter fit.   Although later at home when I measured to see whether he taking 3mm off I could only account for 2.5 mm and not the 3mm, though I decided to stay with the 2.5mm.
 
When it came to sizing up what offset I needed for the new front sprocket,  I first looked at TJS http://forums.banditalley.net/index.php?topic=12977.0   photos as a guideline, but otherwise decided to carry out my own measurement. I first started with a straight edge but this soon proved not to be as a easy method as I first thought, so I bought a laser-align tool but still wasn’t getting anywhere so I put the old b4 swingarm back in and took measurement with the chain adjusted and unadjusted, the unadjusted measurement matched the RF swingarm measurement I was getting. So this is where I came up with the dummy sprocket idea.
  
Whether I used a straight edge or laser-align tool’ which in the end I used both, I found without adjusting the chain up I couldn’t pull the rear wheel inline with the front wheel and therefore in turn the alignment between rear and front sprocket no matter what I tried.

The dummy sprocket I made up, I had to make in two to three bits then glue them together, worked find for adjusting the chain-up but when I tried to rotary chain and sprockets more 60 chain links or so the dummy sprocket would come apart and need reglueing’ so whether they a problem here or just my glueing? We have to see.

After measure, measure and measuring again and now seam to be getting the same resorts each time and the straight edge would slide between the front and rear edge of the tyre and line-up with the back edge of the chain

and the laser was hitting the same spot on the rear of the chain/sprocket as well as the front of the chain/sprocket.... I made the decided its time to bite the bullet and send the sprocket to Scott/sprocket department @ TALON ENGINEERING LTD.

Beforehand’  I sent Scott, a few? More photos of what I had done. Hoping he spots anything I missed! .

I hear you say’ why not do some basic sums...I’m no mathematicians, very basic skills! Maths wasn’t one of my favourites at school, in fact neither was school.    

[TJS]

The 3mm I originally took off the rear sprocket hub was based on my front sprocket that was being made. I now use a stock gsxr hub with no machining to match the stepped out and machined custom front sprocket. The front sprocket is actually two 520 RM 250 sprockets welded together then machined.

[El Gringo]

Thanks Dek and TJS, useful info

Unfortunately I didn't get chance to make a start yesterday other than a few measurements for spacers etc.

I think i will have to run with short dog bones, will have to see how much it affected the ratio of the linkage.

Rather than clutter you thread i will start a fresh one when i have some pictures for a how to (or more likely how not to).

One thing i have found looking at the K series rear hub is that there is not much to machine off on the front before you hit the face of it - depending on how much needs to come off it may have to come of the back of the cush drive lugs and have the sprocket spacer shortened/outer spacer extended.

The other problem i can see is moving the chain right handed towards the hub is going to be hampered by the brace on the swingarm. I have an old RM250 sprocket from a previous project that i could use the middle of to make a stepped version but i need to do some measurements first.

Cheers

Chris

[Unique]

The 3mm I originally took off the rear sprocket hub was based on my front sprocket that was being made. I now use a stock gsxr hub with no machining to match the stepped out and machined custom front sprocket. The front sprocket is actually two 520 RM 250 sprockets welded together then machined.

Sorry... TJS  I assume the sprockets was cut first then welded, now thinking about it, that’s more logically. Talking about logically!.. I didn’t have 3mm 2.5mm taking off, without first checking things out for myself.. My logic? Rightly or wrongly was to do the work in stages.

stage one’ have the new 45 teeth sprocket and chain supplied.

stage two’ fit sprocket/hub/chain and then workout whether 3mm (2.5mm) would be find, then had the hub machined.

stage three’ refit items and workout the measurements for the front sprocket, this is where I decided 2.5 mm would be fine.

I know you are now using stock oem rear sprocket hub from a '94/'95 gsxr 750
               http://forums.banditalley.net/index.php?topic=13508.msg107003;topicseen#new
I will wait till my front sprocket arrives and see what reading I get when refitted and will check the areas where you were having the problems, your gap between the tyre edge and chain looks smaller then mine this maybe just the angle of the photo.
My straight edge is about 9mm thick.

[TJS]

I'm very interested in your front sprocket! I know their is a place here in the states that custom orders stepped out front sprockets from the UK. But they only deal in bikes from the '70's and '80's. These sprockets look really good! Let us know how it goes and if he can do different mm of step out.....and can he "harden" the sprocket.
These are the guys:

http://www.fastfromthepast.com/servlet/StoreFront

[Unique]

I'm very interested in your front sprocket! I know their is a place here in the states that custom orders stepped out front sprockets from the UK. But they only deal in bikes from the '70's and '80's. These sprockets look really good! Let us know how it goes and if he can do different mm of step out.....and can he "harden" the sprocket.
These are the guys:

http://www.fastfromthepast.com/servlet/StoreFront

I' email Scott today regards to the above and this was is reply.....

Hello Derek
We can make special sprockets and ship to the USA, if the sprockets are standard we have a distributor for north America (Dubya
Your sprocket is nearly finished and should be going to heat treatment in the next couple of days.
Many thanks
Scott - Sprocket department.................

[Unique]

 I received the new sprocket from Scott/sprocket department @ TALON ENGINEERING LTD,  on Monday the 24 June,
everything seams to fit well.


*banned domain*.co.uk/2013/06/new-front-sprocket
some of you know it, my full blog link address wont show here...been here before! any trouble just...google   "unique/dek"
 

[El Gringo]

Looks great Dek!

What was the offset on the sprocket if you don't mind me asking.

Cheers


Chris

[Unique]

Looks great Dek!
What was the offset on the sprocket if you don't mind me asking.
Cheers
Chris

I measure it bit later and get back to you in about 1/12 hours.

By the way, yours is looking great too.
Thanks Chris

[Unique]

My Clarke calipers isn't the best of tools.

Rotation motion of chain/sprocket/wheel seams to run smoothly and in straight line with a good equal gap between chain and tyre as rear wheel turns a full 360

But then "TJS" thought the same back at the beginning of this build!
 

[El Gringo]

Cheers Dek, that's great, perfect to get me started.

I've made some slow progress, just waiting for a free evening to borrow a friends lathe to turn up my top hat spacers.

My biggest stumbing block at the moment is the lack of proper wheels, i can get the front and rear fitted but without the correct GSXR wheels i keep having to put the standard Bandit bits back in so i can roll it around. 

[TJS]

Really nice! I think there could be a market for those!

[Unique]

Hi Chris and TJS

Chris' Not to rub it in Its nice to open a door/switch light on, walk into a dry workshop, though I could do with more room like TJS or my mates workshop 24 feet sq. with a walk in loft as well.

I know all to well about slow progress.

TJS' I tried to point this out to Scott, Oh well if it does perhaps I see something in the post

At the moment part from spending time online trying to bring work my way "Business wise" I trying to find good set of front headlights as well as trying finding another way of mounting them, about order some else off ebay!!!.
and decided how I'm going to finish the swingarm, Wheels and other bits I will paint myself again but I could do with a new air compressor head pump....just thinking ebay might be where to look? money the trouble.......   

[TJS]

I saw you chromed or polished the front forks and triples. Why not do the same to the swingarm?
As for wheels?...you can get a good finish with spray cans and sand paper. Then when you have more $$$ coming in; you can do a professional paint or powdercoat.
My $$$ got tight for a while too. During that time I just road the bike around in full mock up form. This gave me time to test all the modifications.

[TJS]

This is how I did it before the garage.