Jett's 750 Kawa chopper #2...

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Prof
Founder, Choppers Australia
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Joined: Sat Oct 22, 2005 3:54 pm
Location: Willunga, South Australia
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Jett's 750 Kawa chopper #2...

Post by Prof » Wed Jun 10, 2015 11:30 pm

With the steering head done, I get a start on the seat rails and Jett cuts some discs to cover the holes at the rear of the original frame. They are chamfered so they can be welded and ground back without loss of strength. The tubes leant out slightly, so we wedged and chamfered them ready to weld. On Josh's XJ600 we welded threaded bungs into these as exhaust mounts which camouflaged them nicely, but Jet is having his pipes run to one side, so a different mounting system will be used...
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Jett bent the seat rails and cut them to basic length and shape and I finished them off. They have to be shaped to be a close fit at each end for welding, and this is tricky as they have to be kept level as well as lining up with the top of the backbone for neat gusseting and seat mounting.

While doing this shaping we have to regularly check for level and front and at the tyre. Bike is levelled using a spirit level across the rocker cover, and then spirit level is kept perpendicular to bike centre line. Easiest way to align it is to 'eyeball' it against the bottom cross tube...
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Seat rails welded in. You can also see that Jett has made a gusset that ties the rear of the backbone to the top of the seat post (you can just see a bit of the gusset and the weld. Gusset is made of 5mm plate. Wall thickness of seat post and backbone is around 4mm; little value in gussets being more that about 20% thicker than tube wall thickness...
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I like to use a substantial top cross member to help stiffen the rear of the frame. It is under a lot of stress particularly in cornering and especially being rigid. This is 50x25x3. Once again a close fit is important when welding to prevent pulling and stresses. One side has been curved to match the round tube...
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Inside measurement is made with a callipers turned inside out...
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Final job is to drill mounting holes for rear guard. Guard is carefully sat on the tyre once wheel has been aligned (Tyre is pulled all the way forwards to locate the cross member; leave 15mm clearance). Making doubly sure (measure twice or thrice and drill once!) guard is centred over wheel, centre point and then the two holes are marked. Once this is done it can be welded into place...
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However, while I am welding and making a front engine mount, Jett makes up a pair of gussets which I then weld in. They are tacked one point at a time an then lined up using the steel ruler before doing the next weld...
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Welded and linished back. A couple of pieces of 25x3 flat bar are yet to be cut and curved to be welded into the rear of the gussets...
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The front engine mount has to incorporate a removable bracket. A curved piece of 19mm heavy wall tube with look schmick...
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It is held in place while location of removable bracket is marked...
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Bracket will be secured with two M6 bolts. Threaded crush tubes have been made and holes are drilled in the tube using a step drill. A step drill keeps centre better and does a nice round hole...
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Here about to be welded. A piece of angle is used for part of the removable bracket. The crush tubes are bolted to it while we weld to keep everything aligned...
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Two ears being measured up...
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Making the curve around the hole is marked with a callipers, cut with angle grinder and linished...
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All done. Let's get her on some wheels. Jett wants a girder, but we measure up a 70's springer I have for sale and it is the right length, so...
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... we put it on so Jett can feel the stance of his new love...
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Might as well check for 550RidikulusRool... Red arrow shows centre of headstock. Spirit level give as a vertical line to measure forwards from. Blue arrow shows where 550mm comes to. If this was a telescopic fork axle would be at this point. A springer takes axle forwards a couple of inches. Jett wants us to build a girder which we can set up to bring the axle to this point. Disadvantage of springers with the small rakes we are allowed in Australia is that they reduce trail significantly, but we will get this back with the girder...
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Next step is the guard mount, side stand and sissy bar, so stay tuned...
Chopit'nrideit... Prof

Bearcx
Posts: 1898
Joined: Thu Oct 18, 2007 12:31 am
Location: Gawler, Sth Aust
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Re: Jett's 750 Kawa chopper #2...

Post by Bearcx » Thu Jun 11, 2015 11:57 am

Oh Yeah........love that stance.!! Jett must be a happy chap. 8)
The brave may not live long, but, the cautious do not live at all.

Prof
Founder, Choppers Australia
Posts: 5622
Joined: Sat Oct 22, 2005 3:54 pm
Location: Willunga, South Australia
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Re: Jett's 750 Kawa chopper #2...

Post by Prof » Mon Jun 22, 2015 9:51 pm

Sissy bar now built and rear guard mounted. A righteous electrics box has been made out of an old oval Villiers fuel tank. Petrol tank will be mounted up Wednesday and a unique taillight (he's a musician), number plate and a cool medallion is to be mounted next. Jett will be here Wednesday night and will begin to tackle mounting the rear bits.

Pics and report soon...
Chopit'nrideit... Prof

Youngblood
Posts: 341
Joined: Wed Oct 24, 2007 1:48 pm
Location: North-Eastern suburbs- Adelaide

Re: Jett's 750 Kawa chopper #2...

Post by Youngblood » Tue Jun 23, 2015 9:31 pm

Looking good so far......
8) 8) 8)
Youngblood

Prof
Founder, Choppers Australia
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Joined: Sat Oct 22, 2005 3:54 pm
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Re: Jett's 750 Kawa chopper #2...

Post by Prof » Fri Jun 26, 2015 4:28 pm

I forgot to include Victor's role in the exercise. He helped Jett with various bits and pieces as well as machining up the slugs for the down tubes... in between doing some jobs on his own cool chopper...
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First job was a less obtrusive mirror position. Reckons it gives as good a rear view as when it was on his handle bars...
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He is always playing around with it trying various things. We joke that he has a set of bars and pipes for each day of the week; with special ones for public holidays!!!

He initially ran jockey shift/suicide clutch, then converted to hand clutch/foot change. This weekend it was time to revert to jockey shift, but with set up that could be easily swapped back. This neat little stainless bracket is mounted with one bolt. The mount point on the clutch/gear lever is retained so it is just a case of undoing the bracket, pulling out the clutch cable and reinstalling the hand clutch cable and shifter rod...
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Nifty gear leaver on the ratchet top trans. Also is removed by undoing one bolt. Can you guess the handle's origin?
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Yep. That works just fine...
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Hey dude! Let's hit the road... bigtime...!
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Off home leaving us slaving (I mean having ball) in the workshop...
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Chopit'nrideit... Prof

Bearcx
Posts: 1898
Joined: Thu Oct 18, 2007 12:31 am
Location: Gawler, Sth Aust
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Re: Jett's 750 Kawa chopper #2...

Post by Bearcx » Fri Jun 26, 2015 6:48 pm

Look like a big ole screwdriver to me...nice one.

Being a muso, I thought Jett would use a drumstick.......bah ha ha. :lol:
The brave may not live long, but, the cautious do not live at all.

Prof
Founder, Choppers Australia
Posts: 5622
Joined: Sat Oct 22, 2005 3:54 pm
Location: Willunga, South Australia
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Re: Jett's 750 Kawa chopper #2...

Post by Prof » Fri Jun 26, 2015 10:40 pm

Not a screwdriver.
Chopit'nrideit... Prof

Prof
Founder, Choppers Australia
Posts: 5622
Joined: Sat Oct 22, 2005 3:54 pm
Location: Willunga, South Australia
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Re: Jett's 750 Kawa chopper #2...

Post by Prof » Sat Jun 27, 2015 10:44 pm

Next job... sidestand...

There are six criteria to be addressed to create the perfect chopper sidestand;
1. Because the chopper is much lower than its stock predecessor, it must usually be remounted higher so it doesn't scrape,
2. It needs to fold back enough to not scrape with hard cornering,
3. It must be easy to access when on the bike,
4. It needs to allow the bike to lean far enough to not easily be pushed over when the forks are on full right lock,
5. It needs to resist folding up and dumping the bike when the bike is nudged forwards,
6. It needs to fold back without pushing the chopper to the right if it is accidentally left down...

Here's a finished pic, to show 1. that the sidestand had to be moved up so it doesn't scrape, and rear wards so it doesn't' foul the gear lever with the mid controls Jett plans to run. Original stand was used. and 2. Quite a bit of the original mounting bracket was cut off because it originally sat down under the frame cradle. The ugly and now wrongly angled foot was removed and the end shaped on the linishing wheel and bent a little with heat. Without the foot, it will tend to sink into sand and soft dirt, but looks trim and minimal. A small 20mm wide flat may be welded to the bottom to reduce this tendency...
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Your chopper needs to lean on this sort of angle (no less) to make it safe when left on full right lock. You want to at least put some sort of dent or scratch in that bugger's car when he reverses into your parked pride and joy... and you want it to stay upright long enough for the dill to realise he has hit something...
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So the chopper doesn't accidentally roll forwards off the stand, you need to set it up at this kind of angle, forwards of centre. We considered a hidden spring and ball bearing for keeping the stand in place, but decided to leave the stock spring as it can be done later and Jett as a deadline of September to get this machine on the frog and toad...
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Setting up the bracket takes a number of test openings and closing to make sure we get the chopper at the right angle and also that the stand folds back parallel to the lower frame rail. Exhaust will not affect access to the stand as it will run to right hand side in front of the rear wheel.

When welding the mount, remember that a lot of weight is resting on that tab and what on jap bikes is usually thin frame tube. Spread your weld contact over a large area. This often means adding small gussets and/or lengthening the mounting tab. I have seen guy's fabbed sidestands rip out of frame tube, so better safe than sorry...
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Final pic of the finished job and how Jett's chopper sits... Spot on, the bees knees, perfecto etc. etc....
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Rear guard mounting next... will start a new post as this is getting long...
Chopit'nrideit... Prof

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