Author Topic: A "Rockers" GT535  (Read 3498 times)

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Reply #30 on: April 19, 2024, 04:33:12 pm
It's nice to see the old ACE intake design from the Big Gulp thread making it into your bike!
Bill G
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Reply #31 on: April 20, 2024, 11:09:24 pm
Are the 3 centre to centre measurements identical for the 535 and 650? Or will you need to use your machining skills?

The hole centers all match up fine but there is differences.
The 650 top yoke takes like a tube nut with in-hex socket (allen key)
Where as the GT535 takes a big chrome nut.
The 650 tope yoke surface is curved so the GT535 nut won't seat nicely. So a flat surface (seat) needs to be machined.

I've started one here.
Half way through the conversion but had to move house.

To use it on the standard GT535 steering assembly it needs a bush/spacer to take up the shaft diameter diffences and seat on the bearing take up castle nuts and a seat machined on top for the chrome nut to seat on. Pictured here.

Here's the raw 650 Top yoke un-modified

The milling attachment for my lathe. Had to machine up a fixture to get it all to work. The tooling used is a fly cutter with a hand ground HSS tool. This can easily be done a on vertical mill. I just don't have one (..yet)

Job done.

This is far as I got then had to move house. I was going to use the nylon bushes and bar riser to mount my clubman bars but that has changed.

It's still getting done just waiting on some new older style chrome clip ons to arrive and also incorporating the old style steering damper the 50s and 60s model had.

I'll be machining up a new steering stem and cutting a new thread. Lengthening the whole assembly so the bottom yoke is still mounted in the factory position. The top yoke will be flush with the tops of the forks. Allowing more adjustment for the clip ons. I'll sort all the speedo clocks mounts to suit. Easy stuff.
Will unlock more of that iconic 60s image it was designed from.

Added bonus the 650 yokes are lighter, more slender in design and all aluminum.
Unlike the battle axe cast steel lower yoke of the GT535 and chunky cast ally upper yoke.

Once it's all done I'll do a post of course.
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Reply #32 on: April 20, 2024, 11:15:22 pm
It's nice to see the old ACE intake design from the Big Gulp thread making it into your bike!
Bill G

Yes. Absolutely, a wealth of technical information.
But made my own changes and upgrades by using a K&N filter vs the paper one supplied.
Also 1 M6 bolt to mount the air filter fixture. Not zip ties.
Also the cost difference was was the quarter of the price here in Australia.
Just a few hours of creativity and fun in the shed :)
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Reply #33 on: April 21, 2024, 12:25:32 am
A little post on tyres and gearing with the method behind the madness.
In other groups it seems to confuse people and they over think it.
Mainly the UCE 500 Classic riders that want to gear their bikes so tall to something that resembles a stationary engine slogging around in top gear. With a strange facination of not revving the engine higher than 4000rpm.

I won't bang on about it. Paul Henshaw seems to state his case continually.

Very Basic terms. Tall gearing and low rpm with more load in higher gears. More Load, More Heat, Less oil pressure = less of the good stuff moving around to lubricate it. The bottom ends cop the slogging. I've seen evidence of this first had on the big end and main roller bearings.

Slightly lower by 1 tooth on the front gearing. Less load, more rpm (only 250rpm more), more oil pressure and more of it moving about.

Here's a main bearing inner race from my 500. The previous owner is know top gear low rpm slogger.
The buffed areas are from impact/vibration from the roller bearings. That caused from exactly that, low rpm, higher gear slogging about.
I work in a railway wheelshop/machine shop.
Dealing with bearings and identifying defects is a day to day job.


This is for mainly those who are seeking info. Most of us regulars know all this anyway.

The control is 100km/hr (62mph) in top (5th) gear.
Because thats 95% of our highway speed.
With multiple lane highways are 110km/h (68 mph)

With stock tyre sizes with a tuned GT535 engine a few reported drop to a 17 tooth front drive sprocket is a good happy medium. Takes the load off the engine and doesn't affect fuel economy. I've tested that. A tuned GT535 actually benefits from it. Tested that also on here.

This is from A handy tool for working things out.

Above is the stock rear tyre size with gearing most go for to give you a idea.
19  - 36 (1 tooth larger)
18  - 36 (stock gearing)
17 -  36 (1 tooth smaller)

Above is a chart of the rear tyre I'm using. Bridgestone Accolade AC02 4.00x18. (They are larger in diameter) Which also acts like taller gearing as you can see in the rpm vs 100km/hr differences.

So installing a 17 tooth front sprocket with the Bridgestone Accolade rear tyre, it's the nearly identical comparison of rpm to speed as the stock gearing 18 tooth front sprocket with a stock sized rear tyre.

Now that's out of the way.

With my GT535 tuned in using various AFR targets using the auto tuner.
18-36 (stock gearing) top speed run with my head on the tank. The engine could not pull top gear.
It would reach 5500rpm and just hang there around 155km/hr.
The stock rev limiter is 5750rpm (or there abouts)
Keep in mind this gearing is like running a 19 tooth with a stock tyre size.

Installed a 17 tooth front sprocket. Which returns it to close to the stock final drive ratio.
Rung it out to make sure everything is fine and working as it should.
It exceeded 160km/hr (100mph)
Touched the (stock) rev limiter at 164km/hr (102mph)

But it was a very slow crawl from from 150km/hr to 160km/hr. Which at a later date I'll lower the gearing again along with a 36mm throttle body with a re-tune and rev limiter raised. See how that goes!?
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Reply #34 on: April 21, 2024, 12:53:34 am
Went halves and purchased a pair of Powerage 650 brushed stainless silencers to convert them to fit Friends and my GT535s.

They are a nicely made for the price about $150AUD each it cost us. Fibreglass wool packed. Bolt in baffled also a decibel killer cone welded inside. Looks to be around 304-308 stainless.

Slip joins are a smaller ID and don't fit. No big deal. Pressed up some new ones, TIG welded them on.
Also cut off the heat sheild. Flush mounted it and fulled welded. Then sanded back smooth.
Shifted some brackets around and cut out the integrated Decibel killer cone from inside the baffle.
Bolted on, it looks like it belongs there.

My GT535 now sports a full stainless system. Hand built header and 650 Stainless silencer modified to fit the GT535 .

It's got a good bass thump.
This exhaust total length is 85mm shorter than the last setup (Did this on purpose for a reason).

As they came in the box.

The nasty decibel killer that needs removing.

Gone. This was a pain to cut out. Had to use a dremal tool with small cut off disc to cut it out.

New slip joins for the 1-3/4" header. I machine up my own dies etc on the lathe.

TIG welded in its new home. This is for my GT535, it runs a 304 stainless hand made header pipe.

I wasn't sure what pipe my friend was running so I made a adapter sleeve to suit the stock header just incase.

Fitted.  8)

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Reply #35 on: April 21, 2024, 01:10:40 am
Mid 2023 I had my engine completely out and I re-set the balance factor along with a few other little jobs. Added a extra breather in to the push rod tunnel up to the rocker box and replaced the lifters.

I've been reading and researching this for well over a year now! Going back as far as technical motorcycle books from the 1960s and articles from 30 years ago. It's a bit of a dark art. Finally got enough confidence to have a go myself.

Crank out on my "V" bearing jig. Double checked the run-out on the jig and between centers on my lathe. What I've found with 2 RE cranks I've worked on (so far) that the machined centers cannot be trusted on the shafts.
On the jig, The crank had 0 run out on the bearing landings and 0.01 to 0.02mm at the shaft ends. Not worth trying to improve on.
So far I've re-set the Balance Factor my 535 Iron Barrel/AVL Head hybrid 8.5kg crankshaft and assembled the bottom end and now my GT535.

Modified my jig so knife edges can be used for checking the hanging weight on the small end.

My GT535 UCE crank is a 8.3kg crank. Pretty well the same as a Classic 350 crank which is pictured on the knife edges, visible is the different balancing holes. Where as the Classic UCE 500 is a 10.5kg crank.

In stock form with the stock cast 87mm piston the Balance factor for the GT535 is 57%. With the Hitchcocks 87mm +10 forged piston was 58% due to the forged piston is 10 grams heavier than the stock cast piston.

I raised the Balance factor to 63% which seemed to common consensus answers I got suitable for the GT535 the crankshaft assembly needed to be altered by 30 grams. Which was done by strategic drilling on the light side.

Now on to the verdict. I've been riding it for 3 weeks now so I can ride it in all different conditions with the re-balanced crank assembly.
Vibration, What it didn't do was eliminate it, but it was a very big improvement. Worth the cost of a gasket kit and a weekend of tinkering.

As easy visual control for me was the levers, easy enough see and how bloody annoying it was. Around 3000rpm to 3400rpm (80-90km/h) the levers used to flap and buzz like crazy, previously I'd always had to rest 2 fingers on them to prevent this. Now around those rpms speeds it's super smooth, Probably the smoothest.

100km/hr is a little better than before. But where it shines the most is it will happily rev smoothly all the way to redline. Before it would make the speedo a blur and felt like it was going to shake itself to bits from 4500rpm to redline.
I've seen it's a common issue with GT535s and rode 2 other stock ones for comparison which were the same. They break speedo/tacho clocks by rattling their insides and also snapping the speedo mounts, one of which had a broken speedo bracket, the other on its 2nd set of clocks.

I'm quite happy with the outcome. And have a UCE Classic 500 shortly to change it's balance factor also. I've learned a lot why the crankshaft weights have changed over the years!
My area in Australia the common complaint about the UCE Classic 500 is vibration and how slow they are. But I think they are ridden slow due to the vibration. So I'll see if I can improve on my friends bike as a test.

The next little modification was making the breathing system a little better. Inspiration from what Bullet Whisperer does to his Bullet builds along from the "Bunn Breather" systems. I'll be doing the "Top Down" style. Since the oil pump sends near 4 litres a minute around the engine oil will want to be forced out of the upper breather. So a one way valve needs to be installed.

Arrows are non return valves and blue is a filter. It could be plumbed back into the airbox. But I decided it looked neater without hoses going everywhere.

Found a suitable spot in the RH side case casting above the Lifter keeper bracket. A circular blob in the casting, drilled a 3mm hole, tapped a thread incase if its a failure and I need to bung it up.
Even makes me wonder if it was there for a single stud for a tappet cover like the Iron Barrels.

I found that the engine could of had breathing issues, despite having a open type breather on the breather fitting on the RHS case. First was brand new kick starter seals leaking. Replaced them, then other leaks and issues with o-ring seals despite my efforts. 3 weeks of riding with the new breather system in and no leaks at all now.

Here's the plumbing so far to make sure it's all working as intended. A non return valve is drilled and tapped into the Exhaust Rocker box to the right for clearance. Spun up on the lathe a little fitting bracket to mount the breather pod filter.

Also using the RHS case breather chamber as intended. Which works like a little internal catch can trapping any oil mist and sending in back to the sump whilst letting cooled crank case gases out to atmosphere. No mess on the floor yet either. So far so good!  :)

While I was at it I replaced the lifters. A common trend I see with Indian RE bearings is the case hardening of their bearings and races aren't really up to par with European/Japanese made bearings. Hear you can see the roller of the lifter with a bit of de-lamination. I think there's a American lifter that can be purchased that is a common item in their V8s? But I ended up installing standard ones again. They lasted 30,000kms without failure, just delamination. 

Did I need to do all these things? Probably not. But this is a hobby, I do 99% everything myself and enjoy learning and taking notes from those who are in the know along the way. Then getting to test and ride my efforts. :)
Most of all, proud of my work.

Have a great weekend chaps.
« Last Edit: April 21, 2024, 01:45:08 am by StreetKleaver »
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Reply #36 on: April 21, 2024, 01:45:51 am
Now! Finally up to date where I'm up to in 2024.

Newest modification to the GT535.
Bored the throttle body assembly out from 34.6mm to 36.6mm.

Since the brass valve doesn't close on a 90dg angle. A mandrell/fixture had to be machined up to clamp the brass plate to machine the chamfer on the outer edge that seals against the throttle body bore. Rough pass with the end mill then cleaned up with the fly cutter.

Brass Butterfly is 1.2mm thick. Closing angle is 9dgs

Roughed out with the end mill on my lathe using the milling fixture.

Cleaned up with the fly cutter. I got the indexing of the bolt pattern wrong here. I just had to drill 2 new holes vertically of this orientation. Silly mistake, what you get for doing things tired!

With the butterfly fixture completed (and hole pattern corrected Haha)
In the lathe it went to get the chamfer machined on the butterfly valve.

Swapped the chucks out to the 4 jaw. Trued up the throttle body and bored it out from 34.6mm to 36.6mm.
(measured via bore gauge and micrometer). Not the Vernier's as pictured.

All finished and ready for a polish!

All performed on my Australian 1963 Hercus 9" Lathe. Total cost $10 in brass offcuts.

Not a huge increase in size but should gain a little more oompf past 4000rpm. Haven't been able to test ride since its non stop raining. But from the small rides I've done with the auto tuner it has not affected the bottom end at all. It seems to be a lot more happier after 4000rpm.

More testing and tuning to come. Along with raising the rev limiter from 5700rpm to 6500rpm and installing a 16 tooth front sprocket (equivalent as a 17 tooth front sprocket with my tyres)


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Geoff Vader

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Reply #37 on: April 21, 2024, 01:08:44 pm
Nice work Ben, it’s great to see others who do there own work, and in their own way.
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Reply #38 on: April 21, 2024, 03:07:17 pm
Nice. I'm looking forward to reading what it's going to be like on the road  :)


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Reply #39 on: April 28, 2024, 12:05:29 am
What turned out to be just a filter clean and new spark plug to re-tune for the bored 36mm Throttle Body...
Ended being a complete re-design of the re-design I did on the airbox previously 2 years ago. (Because the stock airbox with the filter inside is a poor design)

Based from the "Big Gulp" thread in this forum with my own little improvements in user friendliness and how its fastened along with fitting the biggest filter I can in under the cover.

After a bit of searching about. I found a Yamaha XVS650 (V star) is the biggest air filter I could squeeze in there, about 127mm in diameter, 50mm high and 85mm internal hole diameter I opened up.

(5"diameter 2" high and 3.34" internal hole for those whole use the barely corn counting system.)

There was an offset flange original. Easy enough to cut off and sand with a flapper drum sanding wheel on a die-grinder. There's a nice out lip to seal on.

The previous K&N filter was from a DRZ/KLX 125cc four stroke dirt bike which is 100mm in diameter and no longer made by K&N. Now at least the filter is matched to the engine capacity. It worked well, But I always looked at it that I can do better.
How I've mounted the velocity stacks remains unchanged. It works well and is secured.

A new aluminum base plate was cut out for the filter to seal against and a gasket. The outer lip of the airbox sanded off smooth. I use rubber grease on the airbox gasket and filter seal. A method I've been using with dirt bikes for 25 years. Works well.

Top hat is hand fabricated stainless steel. All TIG welded up. Some aluminum crush tubes spun up on the lathe to apply just enough pressure on the filter to seal without crushing it. All hardware is M6 304 stainless bolts.

Stickers for visual horsepower of course. (and visual orientation)

The outer cover needed trimming to fit this behemoth in. The camera angle looks drastic but it can only be seen if "you know its there" type deal.
But everything fits, everything clears and nothing rubs. Very tight though!

From every other angle it's business as usual. Nothing out of the ordinary to see.

Inside the airbox I've made up a few different lengths of stainless velocity stacks to try with the larger throttle body when I get the time. Very easy to change out.

I'm extremely happy how this turned out!  :D
I think if I ever get around to it I'll machine a top hat out of aluminum if I get round to it. The stainless is thin gauge and looks nice anyway.

Everything was made out of offcuts. Fun morning of arts and crafts!

I should give the bike a wash though. It always seems to be raining in South East Queensland lately!
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Reply #40 on: June 02, 2024, 02:33:44 am
Finally got around to doing a final tune with its Huge air filter and 36.6mm Throttle body I bored out a few months ago.
Here's my efforts. No fluff, speculation or bollocks.

RevXtend was set to 6500rpm (new rev limiter) since with the stock limiter it was still pulling.
Tuned with the DynoJet auto tuner. AFR set from 12.8 to 13 in chosen areas. Some ignition advance in some. But not far off the ignition map Hitchcocks has set.

Method is I lay a piece of marking tape on the twist throttle switch housing and mark with a pen the targeted throttle percentages I have set in the target AFR columns.
Starting off with 40,60,80,100%. Find a section of road and simulate DYNO pulls in 3rd,4th and 5th gears at a chosen throttle percentage I want it to tune.
Once they are sorted and no more auto-tune trims are made to those, I work on the smaller openings.

Then just some general riding around like I would so it fine tunes the areas I'm mostly riding in.

Before anyone says Why didn't you use a dyno tuner?!

The nearest one is a 4 hour drive away and $600. Expensive day at $800 just to wank over HP readings knowing that'll it put out mid to late 30HP at the wheel.

Not much bragging rights when there's other things in play like the payload that's blobbed on top of some of these bikes they got to lug around.
Luckily I'm 80kgs without taking a sh*t and haven't got the "being in my 40's extra cake belly" yet.

I've gotten much more value out of the auto-tuner which has cost more than half the above cost.

So far its done what was predicted and report by everyone has done the upgrade.
Positive is that it's a lot more happier higher in the rev range. Spinning up to 6000rpm is no issue at all.
With the crankshaft balance factor set at 63%, its smooth from 2500rpm to redline.
Didn't affect any bottom end in any noticeable manner. It is gear lower 1 tooth in the drive sprocket.

Still hits a smidge over 100mph, just gets there quicker. Previously it was a slow crawl from 90mph to 100mph.

Here's the fueling map with the stock 34mm Throttle Body, but with all the other fruit this bike has copped over the years.

Remember this is adjusting/tuning the map against the stock map of the ecu. Its not creating a brand new map.
Some people get confused why there is some wild changes in cells on the spreadsheet. This was all done gradually over a course of a few weeks (between rainy days)

Here's the final results. It's thrown a lot more fuel in the higher end throttle opening percentages and rev range. It pulls well all the way to 5900rpm and tapers off sharply at 6000rpm.
That would come down to exhaust and velocity stack length. Feels good where I have it right now.

Cells that a wildly high in fueling numbers are most likely to be "no mans land" against the stock ecu fueling map where there isn't any fueling values at all since the engine in it's stock state didn't even run there.

How it is now it's great. This motor is most happy from 3000rpm to 5900rpm. So much fun zipping around town and through twisty stuff. About a 2hr ride from where I live it becomes hilly and twisty, where it really shines.

Touring/Highway speeds on our roads are 100 and 110mk/hr (62mph and 68mph).
Hums along at 100km/hr at 3800rpm and 110km/hr at 4000rpm with plenty in the tank to spin up to 6000rpm for overtaking.

Some info for Taurim. The EURO 3 ecu with the PCV it does some weird stuff also. on the 40% and 60% column, with RevXtend enabled. It will still battle the stock rev limiter a little with ignition cut then push through to 6500rpm. But only does it on those 2 throttle precentages. 80% and 100% it will rev all the way to the new set Rev Limiter set by RevXtend.
That's the only issue I've come across with the Euro 3 ECU with the PCV.

Until the next motor rebuild. Which will be years away, when it's due.
  • I'd like to get a new head, use the same valve kit.
  • Weld up and redesign the combustion chamber.
  • Convert to a 36mm Pumper Carb.
  • Add a decompression valve in the head (for kick starting like I've done to my Electra X head build)
  • Ditch the whole Euro 3 fuel injection wiring loom and convert it to the early UCE carburettor wiring loom and run a mappable ignition module.
  • Slightly revise the balance factor on the crankshaft assembly from what I've set at 63% to 65%. Which I think will be on the money

Just waiting on my 650 Bottom yoke to arrive and then I'll machine up a new, longer steering stem and install some classic clip ons.
Cheers guys.
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Reply #41 on: June 02, 2024, 03:39:16 am
Hi Ben,
Interesting reading about the combination of one tooth less at the front to ease the strain on the engine and a larger diameter rear tyre maintaining the road speed.

Early on in your development of your CGT did you consider a Carberry plate (I am due to vibration induced throttle hand grip loss)?
Is there an appreciable difference in handling between your two bikes; obviously due to the CGT having a double downtube cradle frame?

Riding a motorcycle is like life; it's about the journey not the destination.


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Reply #42 on: June 02, 2024, 04:27:31 am
Hi Ben,
Interesting reading about the combination of one tooth less at the front to ease the strain on the engine and a larger diameter rear tyre maintaining the road speed.

Early on in your development of your CGT did you consider a Carberry plate (I am due to vibration induced throttle hand grip loss)?
Is there an appreciable difference in handling between your two bikes; obviously due to the CGT having a double downtube cradle frame?

Its one of the first things I installed. I didn't notice any difference actually. I've had a few UCE crankshaft assemblies on my jig now and all of them have been pretty spot on for truing and run-out.

The Iron Barrel cranks aren't so great.
I can't speak for UCE Bullets. But the ones I've ridden aren't as noticeable as the GT535. But the frame designs definitely work differently when it comes to vibration.

The stressed member frame of the Bullet/Classic definitely soaks up the vibration more. My Bullets crank had pretty poor run out on disassemble. But still rode smoother than my stock GT.

When the time comes again I'll slightly tweak the balance factor to 65%. At 63% there's a little bit of a slow buzz at 2500rpm. Then nothing to 6000rpm. Standard is 57% and the engine feels like it will self destruct after 4500rpm.

The story goes the home market didn't like a minimal vibration engine, because a strong mans bike has to vibrate. Like riding a baby elephant.  ;D
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