Seeley (replica) Framed Project Road Racer

[Zunspec4]

Well, it was worth a go Pete. Shame it cost me £118

Still waiting for the"new" 5mm GT500 discs, I'm beginning to get worried they promised something they can't deliver.

Still on a quest for a racing self generating ignition. Had JHS pointing me in the direction of Electrexworld and Rex Caunt requesting engine timing/spec. details. This just becomes more complicated, where's that spare points & coil set-up .

Cheers Geoff

[Zunspec4]

Got a little more done in the shape of a Splash Guard for the rear wheel. Still needs a bit of a finish and polish but it fits nice and snugly.



Last week I got my tame machinist to bore a hole for the rear wheel spindle in the caliper carrier, shame I set the centre punch mark in the place for an 11" disc instead of the 9" disc that's actually fitted . I like drilling and filing so Mk2 will be fabricated this week (damn). At least the torque arm could be trial fitted (no adjustments needed) and I think I now have the measurements for getting the spacers for the hub and wheel build.



I also got my "race" rubber. 90/90x18 Avon AM26 front and 110/80x18 Avon AM22 rear. Coo, the stuff is sticky just sitting in the workshop. I have chosen a Scitsu rev counter, mainly because it's just about the only one on the market. Powered by a non-replaceable (factory only) rechargeable battery which IMHO is commercial blackmail. Please note the ultra-light "stealth" rim fitted to the Maxton front end



Cheers Geoff

[Zook-e]

Know about the tach. I have to send mine back to get a new battery fitted.

[Suzukidave]

Still on a quest for a racing self generating ignition. Had JHS pointing me in the direction of Electrexworld and Rex Caunt requesting engine timing/spec. details. This just becomes more complicated, where's that spare points & coil set-up .

Cheers Geoff

https://www.powerdynamo.de/shop/index.p ... 8mbi5hlcsd" onclick="window.open(this.href);return false;

[tz375]

I think that Electrexworld sell the units built by HPI in Belgium.

You could try Pitsch Krober or a simple PVL analogue unit. If possible you want something programmable. Try http://www.HPI.be" onclick="window.open(this.href);return false; and look up kit 068K172. with all the options it's around 1000 Euros.

Rex Caunt used to do some nice programmable ignitions based I think around a PVL core but I have no idea who designed or programmed the ECU.

You could also use a small battery and an Ignitech system or a PVL generator and Ignitech

[Zunspec4]

Thanks for the feedback guys,

I have looked at all of the above systems, via their web pages anyway, and I am still dithering on choice. The PVL is not apparently a good starter (in European format at least). I originally used a krober which started in a blink, but, the Pitsch Krober systems are the best part of £900 so quite expensive.

I have spoken to Rex and his systems (PVL based) are about £500 and he would need data I don't currently have to design a suitable ignition curve.

The Powerdyno looks competitive, but no UK supplier so would have to order directly and therfore no easy available back-up and advice.

I am going to speak to Electrex who are the UK supplier of the HPI set-up (£354) and looks promising.

Decisions, decisions when you are not fully up to the technical needs of your requirements. I can't afford much in the way of my own development program, even if I had the nous to do so.

Anyway, the EBC custom 5mm thick GT discs arrived today, they look OK



Cheers Geoff

[tz375]

I checked the HPI site last night and their stock /base system is analogue with fixed timing. They have options for Digital (programmable) and rev counter output etc all for a little extra. Their site has radio boxes and as you click the options you can see the price changing.

Does Rex's box come pre-programed or can you change it with a laptop? You could start with a TZ350 curve but at lower revs of course. Start at say 28 degrees dropping to 19 at peak and then retard for over rev. I think that Rex's are pretty much linear so I'm guessing that's using a resistor of some sort in the circuit and that's not user programmable but maybe he could supply it like the old Motoplat/Rotax set up on Aprillia 250s with a series of plug in resistors to change timing.

[oldjapanesebikes]

Anyway, the EBC custom 5mm thick GT discs arrived today, they look OK

I did the legwork getting info on the stock EBC replacements sometime ago but decided to invest my pennies in other things, as getting them into Canada is a bit steep. That does look nice !

[Zunspec4]

Hi TZ,

I will admit that "ignition curves" for a 2-st are something I have only just become aware of, the stock T500 system is fixed AFAIK. I always assumed that the Krober system I had before was also Fixed but I have no idea what the electronic "box" actually did, apart from provide a spark.

It sounds as if Rex's systems are basically analog hence his request for data prior to purchase so he could "programme" it, maybe with the appropriate resistor. I don't know that for sure however.

What advantages does a programmable digital system have. It seems that the HPI digi system can be adjusted using a laptop and their software program but what do you achieve. I guess it would have to be done on a dyno with an operator who also actually knew what they were doing. It would be no good seeing 75 bhp briefly if it also fried the pistons There are a bunch of variables to move around (plugs, main jet, pilot jet, needle jet, needle & position, porting, pipes) and then the all singing and dancing ignition.

I think I will first have to get the bike running safely before I go for the killer 80 bhp motor (to make up for my ancient riding abilities ) Dang, this could become a full time job.

Hi OJB,

Is there no Canadian EBC agent you could use?. I can now get a 25% discount on EBC products which would off-set to a degree UK-to-Canada postage costs. Willing to to do the ordering + P&P thing for you if we sort out payment arrangements before hand. I don't have the resources, or desire, to buy items in advance of the recipients commitment. I guess that means payment assured in advance of my placing an order and hitting my own credit card etc. I am not a commercial enterprise but more than willing to help out fellow forumeers

Cheers Geoff

[greasemonkey]

you can use the programmable curve to get every bit of power thats in that engine and also get a smooth power curve witch gives you a bike that has much more traction out of the corner comparing to an engine with spikes in the curve.
I've been working for some time with hpi ignitions and the program is very easy to work with and you can have a switch for 2 separate delay curves.
but if you want 80 hp out of a 500 engine I think you gonna need the programmable ignition and a lof of bench-time.

[Zunspec4]

Hi greasemonkey,

An 80bhp 500cc motor, who would not aspire to such a beast .

I would be ecstatic if the race engine I have bought dialed out to 70bhp + (expectation = unlikely)

Happy as a sand-boy if it dialed out to upper 60's bhp (outside possibility)

Well content if it dialed out to mid 60's bhp (scope for improvement)

Would be rather deflated if it dialed out to low 60's high 50's (but would be determined to make it better)

Absolutely crestfallen it could not make 55 bhp and would consider asking for my money back.

I have at least assembled some good ingredients so the rest is really up to me and how I can optimise the potential of these parts. I hope to speak to the Electrex tech guy tomorrow and gain some further understanding of what a programmable digi ignition can do for me. I do want an ignition that easily bump starts and will not need one of those sets of starting rollers to get it going. If I go for a fully programmable HPI set-up the next task is to find a Dyno guy who can get it set up to go with the hardware I will have available to him. I don't need advice along the lines of "you need to totally re-port the barrels and change the pipes" etc.

All an adventure though and having a good time building the rolling chassis (at least I know what I'm doing there )

Cheers Geoff

[tz375]

A highly developed two stroke requires different timing for different reasons at points in the rev range. Some are very sensitive to changes and others are not.

TZ Yamahas making close to 80HP out of 350cc can use around 30 degrees of advance at low revs where the pipe is not filling the combustion chamber so effectively and where there is more time for the burn. At higher revs, the pipe is making the effective compression ratio higher which generates higher flame propagation rates or more accurately perhaps - a faster pressure rise. We want peak combustion pressure at around about 15 degrees ATDC.

At revs up to the peak, we expect to see more advance than a stock fixed timing at lower revs, dropping back to stock timing at peak revs.

At the very top end, after the peak, a perfectly tuned pipe will go out of tune soon after peak power and by that I mean that the reflected waves start to arrive too late to be effective. Retarding the ignition at that point allows more of the burning mixture to enter the exhaust and that raises the exhaust temperature. That's important because pressure pulses travel at the speed of sound and the speed of sound in a gaseous environment rises with temperature. That allows the pressure waves to return sooner and avoids the lag that I mentioned earlier. Retarding the ignition over the peak allows the pipe to stay in tune longer and that gives a much stronger over rev period.

The trick is to work out how much is just enough. A simple straight line retard will typically work better than a fixed timing in that it provides more torque lower in the rev range, making the bike faster and easier to ride - a rare combination.

In a perfect world you would probably set up your test motor on am eddy current dyno that allows the motor to be held at pre-programmed steps in speed and dial in all the jets at stock timing and then run it at at lower revs and test different ignition timings to determine a base map. Then you would postulate a theory as to what the motor needs in timing and test that hypothesis and continue testing at different engine speeds and full sweep until you have a complete 3D map of engine speed - TPS - ignition advance.

That would probably require a couple of jetting changes along the way until you have the perfect 3D ignition map for that motor/pipe carb/combo. After a few tests for the retard over-rev portion you would probably be deciding that hose pipes were leaving something on the table and so it would continue until you have the best timing curve or you ran out of time cash and interest.

At a lower state of tune many motors are remarkably insensitive to ignition advance - as long as it's not way too far advanced. I suspect that a T/GT500 may be that way until say you have the compression up to around 15:1 it's water cooled and is making huge HP numbers.

As a rule of thumb, most two stroke race bikes can use more than stock advance early and stock or less at peak and that's what Rex is focused on I think. He would have a pretty good idea of what that motor would need and if he can make it adjustable through the use of either an adjustable Pot. or plug ins, that could be a nice solution.

[oldjapanesebikes]

...I suspect that a T/GT500 may be that way until say you have the compression up to around 15:1 it's water cooled and is making huge HP numbers.

Richard - that last part isn't clear to me - perhaps you are missing a comma ? The T/GT500 stock engines are air cooled eh ?

[oldjapanesebikes]

Is there no Canadian EBC agent you could use?. I can now get a 25% discount on EBC products which would off-set to a degree UK-to-Canada postage costs. Willing to to do the ordering + P&P thing for you if we sort out payment arrangements before hand. I don't have the resources, or desire, to buy items in advance of the recipients commitment. I guess that means payment assured in advance of my placing an order and hitting my own credit card etc. I am not a commercial enterprise but more than willing to help out fellow forumeers

Geoff - let me tag up with you via email, but to your first question I am not aware of a Canadian distributor - but may well be wrong. I can order from the USA, but the shipping gets a bit steep. From the UK I suspect it would be worse, but that would need to be confirmed.

[tz375]

...I suspect that a T/GT500 may be that way until say you have the compression up to around 15:1 it's water cooled and is making huge HP numbers.

Richard - that last part isn't clear to me - perhaps you are missing a comma ? The T/GT500 stock engines are air cooled eh ?

The internet is not the place for subtle humor I guess.

The comment was intended to make the point that a lightly tuned T/GT may not need as aggressive a timing curve as say one fitted with a high compression water cooled Hi-Tac, XR05 or other full race top end. There's a limit to power output from an air cooled motor before it melts down or just loses its edge as it runs, so water cooling is a must and that is only available a limited number of ways - all of which are possible and none of which are cheap.