New member - GT500 racer

[Ravivos]

Hi Tom, you have always been very helpful, thanks.

[cyclocrossfool]

made some calls, i can get an EXCEL 18" aluminum rim for a decent price, i assume i should go with WM3? or will the 2.5 will suffice?
what size and length of spokes do i need for an 18" rim with the original GT500 hub?


Thanks.
Raviv.

hows the math skills? http://users.senet.com.au/~mitchell/misc/html/spoke.htm" onclick="window.open(this.href);return false;

[tz375]

Careful with those rim size numbers
People talk WM sizes and others talk inches and they are not the same


WM0 is1.40"
WM1 is 1.60"
WM2 is 1.85"
WM3 is 2.15"
WM4 is 2.50"
WM4.5 is 2.75"
WM5 is 3.0"

[Ravivos]

Hi Tom, TZ.
Thanks for the info, very helpful... will go with EXCEL 2.15 18" rims and have them laced up, one thing is for sure - it isnt going to be cheap...
two rims, lacing them, and new tires should cost approx $650, adding to the money already spent on the front forks and future calipers and master cylinder.
i dont mind spending money on my bikes, as long as it is essential and provide good value.

i am moving to a bigger house in a couple of weeks, and assume that once i manage arrange the workshop, will dig into the bike, currently trying to get the basic parts that are needed.

so, will ask again, how do i handle to old and crispy oil lines? need new check valves?

Ignition - and recommendation for an aftermarket adjustable ignition system ? will a 500 2T engine needs an advanced curve?
if there isn't one, perhaps i can go with MegaJolt and set up my own ignition curve, i have a lot of experience with Megasquirt and Megajolt.

what do you guy think?
Thanks.

[Zunspec4]

Hi Ravivos,

Once you start developing a T500 (or any bike for racing or hot road tune) the effect on your wallet is going to be interesting . As you state even putting a re-built set of wheels on it the total soon adds up.

The HPI fully programmable digital ignition system on my race bike cost over £600, I changed from the PowerDynamo unit to specifically be able to change the ign. curve to allow increased retardation at the top end. So, yes a programmable unit will increase your options.

As regards oil lines you will see from other posts there is someone offering new check valves but you need to successfully adapt these to existing oil lines. I run on pre-mix, eliminating the oil pump but you do need to modify the crank when it is re-built to remove the oil flingers so fresh 2-st mix can reach the outer main bearings (centre bearing fed from g/box).

Cheers Geoff

[Ravivos]

Hi Geoff,
As i said, i dont mind spending money on my builds, as long as it is from a performance point of view...
How is the HPI system interface with the engine? does it uses the same hall-sensor and crank magnet to determine the engine's angle? did you had to install any additional hardware for it? does it have any vacuum advance?
i was thinking of going with Megajolt, that have a fully tunable 15X15 ignition table, vacuum advancing and logging capabilities.

the check-valves on ebay cost approx 60$.. that is a lot for 4 basic valves.
will also need a Y splitter and some tygon hoses.
would sure love to hear any other thoughts and ways how to properly set up the oiling system.

can you further elaborate (link?) on the case/crank modification needed in order to run pre-mix?

thanks.
Raviv.

[Zunspec4]

Hello Raviv,

The HPI system I have replaces all the std Suzuki ignition hardware, think that as a starting point you have the bare crankshaft shaft on the left hand side. Mount the adapter plate, followed by the stator. Set the engine to TDC on the left hand side and mount the rotor on the crank taper, lining up the mark on the rotor to that on the stator. From there you move to the TuneBox software and configure the ignition curve of your choice, download the ignition curve to the electronics. That's it, the ign. advance curve is software controlled, no mechanical adv-rtd involved. How all this electronic magic actually works everything out I'm afraid I do not know

Here is the HPI link to the system I have (although this must be the latest version as my electronic boxes are red in colour and a little bit different).
http://www.hpi.be/item.php?item=068K172

The TuneBox software is available as a free download so you can see what you can do if you install it as an App on your computer (go to "Downloads" on the HPI website)

Oil lines - You will need to search the likes of eBay for genuine Suzuki lines, but, you will be very lucky to find a NOS set and will need to pay a high price for them. I'll ask Pete Odell what is specifically involved to convert to pre-mix (I think it is the removal of "Plate, oil guide P/N 12511-15000, 2 of them) No crankcase mods needed.

Cheers Geoff

[Ravivos]

Hi All,
well, even though i have too many projects, and my bike lift is always occupied, decided to take the GT500 out of the shed and work on it.
Cleaned the carbs, with new seals and all, the jets were completely blocked, so this was a must.
went over the entire oiling system, made sure the oil pump is working, oil lines are good, check valves are good.
when through some of the electrical wiring and manage to get a proper spark...
verified that the pistons are intact, a bit of oil through the sparkplug hole, rotated the engine a couple of times and the compression went up properly, i could hardly turn the kick lever with my hand when the engine is in compression angle (for both cylinders)
so, its time... hooked up a fuel line to the carbs, turned on the switch, flipped the "engine kill" switch and gave it a go...
after a few kicks, the engine fired up!!
a few adjustments, and it idles perfectly, very easy to start and revvs fantastic.
i need to go over the some of the electric wiring, as the voltage regulator output (without load) reached 60V-70V.
other than that, need to do some soldering, and the electricity should be fine.

Anyone replaced the rectifier and regulator to a modern one? (2 phase voltage rectifier/regulator)... it shouldn't be too hard to convert it.

once the engine was running, the oil lines filled with fresh (green) two stroke oil, without any bubbles, and the engine smokes with the familiar scent of two stroke smoke... (gotta love those two strokers).
so, as for the engine part, it looks like its running perfect without any issue... now i need to work on the rest of the bike and get some missing parts.

GT750 front, i managed to get a hold of two SV650 calipers, and need to find some rotors to fit the bolt circumference.

now, some questions -
voltage rectifier/regulator, convert to a modern one?
how about adding some reed valves to the intake? i have the fabrication capability to produce an adapter and reed-valve housing, is it worth the effort? especially if i intend on mildly porting the engine and build the expansion chambers to fit.
Grahm bell's book is on its way to me , should be some mind-opening reading.

Raviv.

[tricky1962]

I can't comment on most of your questions, but a lot of the US guys seem to mention Tympanium for the reg/rec

eg. here : viewtopic.php?f=29&t=7833" onclick="window.open(this.href);return false;

[Ravivos]

I can't comment on most of your questions, but a lot of the US guys seem to mention Tympanium for the reg/rec

eg. here : viewtopic.php?f=29&t=7833" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

Thanks for the info
that's what i was thinking of doing, just not with the Tympanium ...
but since the Tympanium can provide 200w, it should be have a very good margin comparing to the power consumption of the bike...

[Ravivos]

more progress done
after cleaning the carbs and get the engine running perfectly, its time to tackle the front brakes.
fitted a GT550 front forks and made a new aluminum bracket to hold the SV650 front calipers.
the rotors are 310mm NG rotors (from a Suzuki Bandit) that i re-drilled to fit the GT500 front hub.

GT500FrontBrake.jpg

designed my own take on the GT500 expansion chambers, all stainless steel with hand made aluminum mufflers to save weight.
the engine revs amazingly with these, but they are too loud! i need to design a new muffler to help reduce the noise.

GT500Chambers.jpg

still alot of work before i can actually ride it, next step is to build a new aluminum fuel tank and tail , need new rearsets , and get the rim issue done...
any input will be appreciated.

if you happen to be on FB, you are more than welcom to follow my page, as i update it regularly with various vintage motorcycle stuff...
https://www.facebook.com/RMSworkshop/

[Zunspec4]

Great stuff Ravivos,

The front end set-up looks well powerful and respect to anyone who can weld up their own pipes

Cheers Geoff