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Discussion Starter · #1 ·
Good evening, thought I would start a thread on my "getting back into the fold" project bike.
I gave up bikes about 18yrs ago after riding since I was 16, mainly due to having a family and lack of time /money due to bigger commitments.
I used to be a serial bike modifier, always big sports bikes, things like big bore wiseco pistoned exups, factory parts and WP suspension ZXR750s etc.
However, the time and opportunity is now upon me to get stuck in again!
So, I bought this US import (we didn't get the 450 in the uk) cheap, not run for a number of years but all there.

The plan in my head is for something a bit different, i won't really be going for any particular niche, I just want to build something unique, and something to ride that's fun.
This will no doubt go against all the bike building rules, it doesn't yet run, needs shed loads of things no doubt to get it mobile, but it's now in bits.
I did a compression check first off, all fine with 150psi, cam timings good, old oil was good considering, it's got a relatively good wiring loom, and most of all the cases have never been apart, original cross head screws with absolutely no witness marks to show any sign of a screwdriver.
It's a simple motor, it'll run when it needs to.
This is what I start with.
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Discussion Starter · #2 ·
Despite not running for what looks like a VERY long time, the engine turns over fine on the starter with a new battery, with good compression.
Upon initial inspection I found a mouse nest in the airbox that had been used for multiple broods, the urine had filled the bottom of the airbox and float bowls at some point so everything in the floats was seized solid and a tad smelly!
So, the strip down and check over begins!

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Discussion Starter · #3 ·
So, next job is a full strip down, I removed all the trim and parts that will not be used again.
I still find it amazing how well built older bikes are, everything is made to last, pretty much forever, each front footpeg weighs a pound, so far it's been releived of around 45kg of weight that will not be added again.
I work as a carbon composites technician so I'll be using a little carbon fibre in details, such as the engine mounting plates, headlamp brackets etc.
Couple of
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Discussion Starter · #4 ·
So, first part of the modified story is the obligatory seat hoop. This was a little tricky as it needs to be square at the back and raised up to follow the lines of the seat pan I chose.
But it's welded in now.
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Discussion Starter · #5 ·
So, there's a few bits I can work on in my down time at work, the steel engine mounts are a bit poor so I've made some carbon ones
And the frame loop fits the seat unit perfectly
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Discussion Starter · #7 ·
Do any of you guys have any experience of velocity stacks with integral filters?
I'm aware pods of any kind aren't the best thing for these old bikes and setting the carbs up can be problematic, the pods are basically in the wrong place to be out in the open, taking in warm air from a low pressure area, when the bikes moving at any speed there's a vacuum area right where you need air.
I was thinking of long stacks, curving outward and putting filter material of some kind over or inside them?
 

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Your CV carbs need a chamber of relatively still air to draw from.
The volume of this chamber is also important.

Having the pods in a different location may help over the worst case (pods direct on carbs) but you will need an airbox to get the best from your carbs.

My suggestion would be to....
-Fit performance slide type carbs (pricey)
-maintain the original set up and put some side covers on the bike

With thought you could even create a custom airbox that matches the standard airbox's volume but better looking feeding the carbs
 

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Discussion Starter · #9 ·
Thanks for your time miniman, the standard airbox and side covers aren't an option really, but fabricating something else is certainly possible.
So I need to find a way to provide a metered amount of air to the carbs.
That should be doable I guess, not the easy route I know but I'm in no rush.
Cheers.
 

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Discussion Starter · #10 ·
Evening, I made a bit more progress on the bike.
I finally got all the welding done for the seat and subframe, including making a new tank mount for the back of the petrol tank.
Previously the tank had 2 fittings onto a bridge that was raised up from the top frame rails, this was making it difficult to get a good, neat solution for mounting the seat unit and seat pad. (You can see the bridge in the first pic)
So, I decided to lose those fixings and make a piece to weld into the back of the tank for a central mount, this is above a new cross piece with a raised collar and captive nut, about 10mm lower than before.
Then a couple of bars welded in to mount the seat and started the first part of the carbon undertray, this part will be the top of a carbon airbox, with velocity stacks the same length as the original rubber bellmouths going inside and a foam filter, top vented as the original airbox.
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Discussion Starter · #11 ·
Need some copper to put behind the old tank mount holes then I can fill them with weld and clean it all up with the grinder.
 

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Discussion Starter · #13 ·
They are the cheap Chinese RFY shocks, but they are rebuildable so they will be stripped and built properly before the bike goes on the road.
 

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I have seen the thread on rebuilding these.
Looks like a lot of work but worth it if you have the time and ability to do it.
 

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Discussion Starter · #15 ·
Yes, it's not easy from the look of it, it seems to be pot luck whether you get good ones or not,random amounts of oil and air / nitrogen.
I guess I could try them first, it's not like it's going to be a race bike.
There are valves on the reservoir so I can at least check the gas pressures.
 

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The shocks are “easy” enough to do and are Not bad in the end. I didn’t even try mine before I rebuilt them so I have no input there but nice when finished(y)
 

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Discussion Starter · #17 ·
Thanks for that Oldman, the bikes going nowhere for a fair while yet so I may as well give them a go.
They are a fairly good copy of öhlins in appearance, not sure how they would hold up to a salty winter though!
 

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Yes, it's not easy from the look of it, it seems to be pot luck whether you get good ones or not,random amounts of oil and air / nitrogen.
I guess I could try them first, it's not like it's going to be a race bike.
There are valves on the reservoir so I can at least check the gas pressures.
I wouldn’t say it’s “pot luck”. It is pretty much guaranteed that they will be short oil , and the N2 pressures are wildly erratic out of the box. The rebuild isn’t that hard. Just takes some ingenuity to set up tooling and taking a case of beer to a local machinist to dril, spot face and thread holes for a bleed screw.

Heres the thread. Unfortunately the video I referenced is no longer on YouTube.
 
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Discussion Starter · #19 ·
Can any of you guys tell me if there was any difference in carb spec from an 81 to an 83 bike?
I'm looking at a stage 3 dynojet carb kit, but the list is for an 83 bike, as far as I can tell they all had the BT34ss carbs but just want to confirm.
Cheers.
 
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