Tigcraft project

[alankelly]

Hi all

Need some advice please.

Ok just been offering up my front sprocket on the Tig’ project and it looks like I need to get an 18T sprocket with an offset of about 15mm.

This amount of offset looks about right as when the new sprocket sits on the original nut that is holding the original sprocket in place (like in pics below) the chain run looks good











Using a 520 narrow chain so my question is please do such things exist from anybody in the Uk or will it be the case of making a special?

(If not thinking of machining the old one round and then adding / welding some sort of offset extension ring to the old sprocket, so I can then fit the old sprocket using the original nut, then bolt the new sprocket to the old modified sprocket extension ring part using 4~6 m8 bolts??)

Lastly with this amount of offset do I need to think of adding an additional outrigger bearing that uses the outer side case to give extra support,or is 15mm acceptable without an extra outrigger bearing?

As always advice welcome

Best wishes always Al

[midlifecrisisrd]

Hi Al

15mm is unusually large

What rear wheel are you using again. What size tyre?

9mm is the usual max

Steve

[midlifecrisisrd]

This guy will do one up to 23mm according to his ad

www.ebay.co.uk/itm/324332283780


If you look at making one, be warned, they are very hard so machining is difficult and you need some serious amps to weld

Steve

[alankelly]

Hi steve

The tyre width don’t think is the real issue but the chain run down the side of the Honda swingarm



Best wishes Al

[alankelly]

Jan 30, 2023 22:29:03 GMT 1 midlifecrisisrd said:

This guy will do one up to 23mm according to his ad

www.ebay.co.uk/itm/324332283780


If you look at making one, be warned, they are very hard so machining is difficult and you need some serious amps to weld

Steve

Yes I saw that and think that may be my best option but alway good to ask first

Thanks Al👍

[midlifecrisisrd]

Ah, right, I see now

The other issue is getting the side case to clear

Other options depend on whether you can get some nachined off the rear carrier and machine the arm for the chain run

Steve

[alankelly]

Good shout on the side case possibly touching the sprocket 😔😔

Not had a chance to check this as frame is still waiting to be tweaked to fit the ac barrels and the alternator side case as current frame tube’s stop me fitting the side case fully😡

Think I will use the current two sprockets to “bodge” up a 15mm offset sprocket to check everything clears and see if I can move the chain run in a bit more to reduce the offset before I commit to that sprocket on eBay

Thanks again Al

[4l04ever]

Make sure the clutch push rod clears with an 18 tooth front sprocket. A non-heavy duty chain may help.

If you want to check the chain alignment more accurately, I have a Laser Chain Alignment Tool you can borrow.

An idea...

Make a top hat offset front sprocket adapter holder that a modified standard sprocket bolts to for cheaper replacements in the future. Maybe bore the centre out a standard sprocket and drill and tap a few holes for fixing.

[4l04ever]

Maybe use something like this for the separate sprocket. Use a flat 530 sprocket with pre-drilled holes in it so you only have to bore it out.

[4l04ever]

Or bore the above sprocket out to half way through the holes and have a CNC shaped top hat adapter that the sprocket would then fit straight on.

[dusty350]

Hi Al
I had quite a large offset on the 400e hybrid - cant remember what it was now but it will be in the thread. The concern with the large offset would be the extra strain on the bearing - an outrigger would be beneficial I think. Talon would do up to 21mm offset front sprockets - after that it was a special order at £100 a pop ! I juggled getting the offset down and ended up with a 9mm Talon offset front sprocket, and a new, wider spacer made for behind the sprocket. I think your chain can be "out" by a max of 2mm without undue wear to the sprocket teeth, but obviously that's not the ideal. You could consider counter boring the inner face of the rear sprocket - a 520 sprocket is 6mm wide, and I had 2mm machined off which effectively brings the rear in by 2mm, and if you can ally that to taking some off the hub you can gain some more. But, as already said, tyre and swingarm could be in contact with your chain if you bring it inwards too much. You could cut and shut a tunnel into the swingarm of course. I did that on the 400e frame as the chain was close. A different profile tyre might help too. It is a juggling act, but I would try and avoid a massive offset front sprocket on it's own.

Dusty

[alankelly]

Hi all

Thanks for all the advice it’s much appreciated

I think I will go down Robs route but make for now an “adjustable “ offset sprocket that I can pack with washers to adjust the amount of offset and then start to move everything in, and once I have taken it in as far as possible I can then maybe order a sprocket with the final offset

Have already taken 6mm of the rear sprocket carrier but there may be scope to take a bit more?

Lastly anybody know please what the clutch push rod diameter is so I can dummy up one (as not got one yet😉😉) to check chain clearance as it looks tight with a 18t sprocket but not silly

(Just so you know gone with a 18t front as trying to get the chain run right across the top of the swing arm as with a smaller sprocket the chain risks being pulled tight against the plastic chain guide so a bigger front and rear will lift the top chain run of the swing arm top face)

Who said this project would be easy 🤣🤣

Best wishes to you all Al

[dusty350]

My vernier shows 8.72mm on a new Lc pushrod Al

Dusty

[alankelly]

Hi Dusty

Thanks for that👍👍

Best wishes Al

[4l04ever]

Looks like we have found another imperial measurement item on an LC.... 11/32" diameter push rod (=8.73125mm)

[alankelly]

Ok new pushrod on order as easier that making dummy one and cheap enough too👍

Best wishes Al

[muttsnuts]

I've been making some offset front sprockets, 16T, 17T and 18T, the 16's haven't gone so well as little meat left after cutting out the centre to make sure you can fit a nut inside and still get a 32mm socket on it to tighten up

Anyway, they are mega hard and tough to cut, I tried allsorts of lathe tools/tips etc, nothing would do it, I ended up having to outsource the cutting of them, I now have a selection of sprocket outers and inners, the only snag at the moment is they aren't exactly cut round on the ID, so I need to make a jig up to hold them so I can machine them round on the ID, then I can make a tube to fit, and make it any offset I want (subject to outrigger bearing etc if required)

If I get chance I'll post some pictures up, I might be able to help Al, but until I make one and test it, I am not sure how well they will work

oh yeah, they are a 520 sprocket

[alankelly]

Jan 31, 2023 20:43:57 GMT 1 muttsnuts said:

I've been making some offset front sprockets, 16T, 17T and 18T, the 16's haven't gone so well as little meat left after cutting out the centre to make sure you can fit a nut inside and still get a 32mm socket on it to tighten up

Anyway, they are mega hard and tough to cut, I tried allsorts of lathe tools/tips etc, nothing would do it, I ended up having to outsource the cutting of them, I now have a selection of sprocket outers and inners, the only snag at the moment is they aren't exactly cut round on the ID, so I need to make a jig up to hold them so I can machine them round on the ID, then I can make a tube to fit, and make it any offset I want (subject to outrigger bearing etc if required)

If I get chance I'll post some pictures up, I might be able to help Al, but until I make one and test it, I am not sure how well they will work

oh yeah, they are a 520 sprocket

Hi Dave

Yes they very hard and really only carbide tends to work but still very hard going

At worst I will treat the two sprockets I have a sacrificial ones and bung them in the brazing hearth to warm them up to take out the heat treatment to allow me drill and tap them to make an “adjustable” one and then later in the project sort a replacement with the final offset required

Best wishes Al

[muttsnuts]

no worries Al, I've had 10 of each sprocket done, so I should have a few spare once I've sorted out the machining and welding of them

[midlifecrisisrd]

I had a 4mm offset 16t one made and as Mutts says there isn't a lot of room left.

Ended up not even trying it so may be scrap

Started with 2 x 16t sprockets, had the centre cut out of one.

The other I had the outer cut off then machined like a shallow top hat to give it the offset and to centre it

The engineer complained about breaking a couple of tools doing it

Then took it to get TIG welded. He said he first welded it with a nice thin weld. Turned his back to do something else, heard a cracking noise and the weld had split as it cooled

He then got the big boys toys out and it was all good but took some major ampage

Steve

[alankelly]

Good to see Dave has used 18t sprockets as I had a vision of needing to “waist” the pushrod in the area by the sprocket as it looks very close

But going smaller (17t) would really make it harder work keeping the top chain run off the top face of the swingarm when the chain is under tension

Best wishes Al

[Tobyjugs]

Hi Al I've got a 24mm offset front sprocket under a 4LO sidecase. If you click on any photo I've posted you should be able to access lots of pictures and more detailed pictures of my sprocket set up.

[alankelly]

Hi all

Ok it’s not a pretty piece of engineering but now I have an “adjustable” front sprocket to allow me to experiment to see how far I can move the chain run over (including maybe taking some more material of the rear sprocket carrier if needed)





And once I get the final chain run right I can do a drawing of the final front sprocket to get one made👍

Best wishes Al

[sidney81]

I like it al 😎👌👌👓

[alankelly]

Hi all

Ok had a play in the shed tonight with my new “adjusta” sprocket 🤣🤣

Current sprocket to sprocket centreline off set is now about 12mm and by eye it does not look too far away





Got it closer to the swing arm and tyre




Think for now that the minimum I can go without machining a section out of the swing arm and reducing tyre width etc

But don’t think 12mm offset is too bad and hopefully with this off set the side cover should fit even if I need to shave of a small amount on the inside to clear the side of the chain but won’t know till frame is sorted to allow me to do final fit of the side case👍

Catch up soon

Best wishes Al

[midlifecrisisrd]

That's good news

I run 9mm on my hybrid with ypvs engine. With a ypvs spacer on the output shaft it will be about 12mm over an LC sprocket position

Steve

[JonW]

That looks pretty Good Al. Nice work.

IMHO you could leave it like that if you fitted a thinner chain like a DID ERVT2 520. I use these on builds etc. KTM uses these so we know they can take a pounding. Its an X Ring so high end and qood quality.

[alankelly]

As still awaiting my frame guy to do some alterations to accommodate the AC barrels and heads decided to make a start on the engine rebuild

Got a very nice set of cases from Reedpete (Thanks Peter) but like all old cases the shift selection shaft bore on the sprocket side was worn, so as they are bare cases at the moment took the opportunity to bore out and insert a split bush on both sides






Also never liked the shift drum running directly in the aluminium case bore on one end, so like my other engine rebuild took the plunge and bored out the case to take a needle roller bearing so shift drum rotated on bearings at both ends





Maybe a bit over engineered but as cases were set up on the mill to bore the shift shaft bores, an easy enough job to do 👍

Now that job is done can start the rebuild process

Catch up again soon and ride safe Al

[dusty350]

Great work Al
Well worth doing at this stage

Dusty

[donkeychomp]

Nice going Al. Over engineered is better than under any day!

Alex