[2 stroke] Twin 350cc development ?

Really looks llike yamaha HH barrels with the casting slightly modified to suit RGV low end , even about the 66.4 bore

But the 50.6 stroke is quite restrictive ....

SEB4LO a écrit:

Really looks llike yamaha HH barrels with the casting slightly modified to suit RGV low end , even about the 66.4 bore

But the 50.6 stroke is quite restrictive ....

True. BUT the longer stroke alternative is added expense if you want to go down that route. I have seen a few talk about stroker cranks already being made but try getting one at a resonable cost. It is not likely and I do not have the spare cash to do a minimum of 10 cranks out of my own pocket to make it affordable. So it is the best compromise if they can be made available to customers. I have a few willing to invest in a project but it has to be an affordable one. The Veronesi route could be good IF he would drop the price. but I dont see that happening soon.

Gordon Jones a écrit:

Frits Overmars a écrit:

I don't know if CPI can supply undersize cylinders, Gordon. But you can ask Calvin Pollet: [Vous devez être inscrit et connecté pour voir ce lien]

Hello Frits - I was hoping you would see this post
Should I take it from your reply - that you are thinking the longer stroke option might yield some good results ?
To expand on my thinking....

The TZ350 cylinder cannot easily be sleeved down to suit a smaller piston (I think) - although I know a man that may be able to cast a new TZ cylinder - which could be left with the correct bore size before plating.

The CPI cylinder - if Calvin is able to cast a smaller bore cylinder - we then have the (advantage ?) of the extra ports - but we would then have to use the YPVS engine bottom end - which would really need a close ratio gearbox - and we would also have the wet clutch - I quite like having the dry clutch on the TZ - much easier to work on / repair...


The +7mm Banshee / YPVS cranks are available in lots of places - but - the thoughts I have are whether any of the aftermarket cranks are up to the job....although - at the price they are selling - they could almost be considered a throw away part - especially when compared to servicing a TZ crank - those are becoming very rare (at least the female inner flywheel is) - unless you buy one of the Hoeckle copies that are available (lucky enough to have a proper Hoeckle in my best engine)

Finding a Piston that's up to the job could also be a problem - the only piston I can find listed anywhere near the size I want - is for a Kawasaki - at 61.5mm - but that has a 14mm Piston Pin...(Yamaha is 16mm)

All of this is what could be termed "research" - as funds are very limited - I would want to have a reasonable hope of this being worth the effort before I do too much more - although I do have 3 x YPVS engines under the bench in preparation...(as well as a couple of Aprilia engines & a box of 66mm Hummel cylinders )

I did send several emails to Calvin a couple of years ago - but had no response - maybe the emails just got lost in space - we'll never know...

I have no first hand experience of the CP cylinders - but have seen some reports on other forums regarding seizures - and the guy running one in our series has been prone to seizures - in fact - he has now had the cylinder lined - a mistake I think - but then I'm not running that engine - I can't help but think that some people like to run their engines a lot weaker than I do....

Hi,I'm new to this forum,some will likely recognize my nick from other 2 stroke forums.

the net browser landed me here,and I red this with interest since I too set about building a competitive 350cc race engine to compete in pre '80s motorcycle class in my country,being 350cc the limit plus a few percent over bore allowed for repair.

Even though the project is on hold due to economics,the plan was to use a banshee/RD cases and have Nova racing supply a c.r. gearbox with an extended input shaft and assemble it with TZ primaries and dry clutch/cover.
As for cylinders,though ypvs or Banshee can be made to have a close performance to a TZ,I suspect most of the oustanding engines like that Banshee you mention are stroked and bored with more CCs.
Ideal would be to have a cheetah cylinder with the large reeds (and power valve for me) in stock 64 54 dimensions.

I did have the opurtunity to ask Mr.Calvin Pollet from CPI (whom I found in Aprilia RS forum)if that would be possible.
Here is his quoted reply pretaining a TSS Cheetah based cylinder):

04-08-2012, 10:50 AM#128

2gofast

apriliaforum prov-nov
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Join Date: Feb 2012Location: OklahomaPosts: 30

Originally Posted by motoholic71:

I say when the valve system is solved will this cylinder be continued in production?.....What would be involved in making a 64/54mm bore version for rz stock cc bound racing class?.....


2gofast:

I waited a few days to answer this question simply because I do not want to "seem" as though I am trying to cut TSS out of the "loop". The Cheetah cylinder has been in production since 2002, and I see no reason to change the production process......especially if there is interest in the cylinder "crossing over" into a new marketplace. We have been building the Cheetah line of cylinders since day one for the stock 54mm stroke, (all the way up to a plus 20mm stroke, or a 74mm stroke). While we have built 64mm bore engines for certain class specifications, I feel there would need to be a new internal waterjacket tooling made to allow us to run the 64mm bore "successfully", as the wall between the bore and the water would be thick enough to cause the cylinder to be much slower to expand, and much slower to transfer the heat from the bore to the water due to the wall thickness.....at best it could be a source of "cold seizures" as the piston would heat up and expand much quicker than the cylinder.

If there is a need for a 350cc class engine, we are not opposed to building new tooling to supply a product to fill that demand.

End quote from [Vous devez être inscrit et connecté pour voir ce lien]

This might clear some doubts about what would be involved in reducing the bore.

Off course there are other cylinders makes but in my view a monoblock design,a bigger reed cage,a chrome bore,and in my case,power valves all in the same cylinder are the only worthwhile option.

I also have doubts regarding pressed iron liners ,my understanding is that the reliability will be very dependent upon the quality of the job done.
I heard of engines developing hot spots in the liner due to low contact areas between liner/cast and seizing .

Ian Harrison a écrit:

Hi Gordon

I know it's a bit off your topic, but I thought you might be interested to see a direct back-to-back dyno comparrison between an HPI and Ignitech ignition installed on one our Honda CR250 Superkart engines. The HPI is a 2-curve digital programmable CDI unit, just replacing the stock Honda unit and plugging into the Honda generator and taking the trigger off a raised segment on the rotor periphery. We powered the Ignitech with Lipo battery, rectified and regulated 13V supply off the Honda generator and both (which is actually illegal for us. The regs only allow 1 power source). We also triggerd this in the same manner. As well as the lack opf power with the Ignitech you also see a big rise in the EGT's, which under normal circumstances I would say was due to a retarded ignition. The only other thing I could think was that a low spark energy was taking longer to actually fire the plug.

[Vous devez être inscrit et connecté pour voir cette image]

The curves programmed in are identical and were verified on our ignition rig prior to installation on the motor. After the big difference we also verified the curves on the motor (by strobe).


I did speak with Ignitech and they couldn't shed any light on the difference and we did check everything at least 3 or 4 times. We did also try both coil outputs feeding into the single coil as suggested in Frits' comments, but it made no difference. Shame as it's a well priced and featured box. Perhaps they have sorted it now. Our boxes are about 18 months old.

We have had exceptional results with the RTD (Racetech Developments) EMX-04 (for singles and tandem twins) and the EMX-05 for a 2 trigger system.

Best Regards

Ian

I have taken a look at the Ignitech software (I had one which I sold un-used) and was under the impression that the program allowed to input trigger advancing values greater than the static advance set.
This can only happen if the cdi only fires on the next revolution after getting the trig signal,since is impossible for it to fire before passing over the trigger(which will seems to do)

I think this points out to a slow signal processing speed.
Could it be that a very light and fast rpm climbing flywheel will induce a delay in the spark since the rpm will increase a little with every single revolution?

If true the last rpm sample taken more than 360º before by the trigger will be just a little off on the next rev.
The cdi will actually spark based on the previous rpm reading,which will be a bit off as long as the rpm is changing.

This is just a theory that can be confirmed either by math (knowing the RPM climb rate) or by checking the timing marks for trueness with a strobe on a steady rpm running engine (or rig) with a fixed advance curve(or in this case straight)

If the retard effect error disappear on a steady rpm,then this theory is right which means that the CDI is slow processing,despite all other features like great graphics
if not you have maybe a defective unit?

Nice rig BTW

Hi Motoholic71

Thanks for your input.

Here is an image and instructions regarding setting the "base advance" for the Ignitech.
[Vous devez être inscrit et connecté pour voir cette image]

As you can see the Ignitech calls for the angle of the heel of the trigger from the pickup at TDC and it takes the trigger off that heel. Let's say that angle is 10 deg. In other words that pickup will trigger and the spark will be generated at 10 degrees BTDC until digital control of the curve starts.

I believe that it then simultaneously measures the length of the trigger by sensing the time it takes to pass the sensor and dividing this by the time for a full rotation. This gives it the angle of the trigger.

In our case the trigger is 30 degrees. This means that the front edge of the trigger passes the sensor at 40 degrees BTDC. I had assumed that once the ignition had digital control it then took the pulse off the leading edge of the trigger and could fire any advance up to 40 deg BTDC (less an increasing allowance for "thinking time" as the rpms rise and the engine ravels further in that time).

However, you are suggesting that it always takes the firing trigger off the heel and delays the spark by the time for the engine to rotate say 360 degrees, if we want to fire at 10 degrees BTDC or the time for the engine to rotate say 340 degrees, if we want to fire at 30 degrees BTDC.

On all the other ignitions I have used then (HPI, RTD and Zeeltronic), we tell the ignition the "Tooth Value" or "Static advance" which is the measurement from the leading edge of the trigger to the pickup at TDC. So in the case above 40 degrees. We can see that and the maximum useable advance line, in red, on the HPI graph below.
[Vous devez être inscrit et connecté pour voir cette image]
This means that the pulse is always taken off the leading edge of the trigger, but I believe only after digital control. I believe that before digital control takes over the trigger is again taken from the leading edge of the trigger (i.e.) 10 degrees BTDC in our example.

So we are either telling the ignition the same thing in diffeent ways or as you suggest, the Ignitech works on the "spark for the next rev" (to put it crudely) principle.

If you are correct and this is the case then I don't think that the acceleration of the engine is high enough to affect the timing by a measureable amount as particularly towards the end of a dyno run in top gear and at a high dyno loading the increase of engine rpms is very slow (in electronics terms) and compared to the overall rpms.

I believe that the poor results could be due to increased opportunity for disturbance caused by EMI (remember that at anything less than 10 degrees BTDC the spark for the current revolution would occur after the trigger for the subsequent revolution) and that is hard to get your head round (in fact is it possible??)!!

I will attempt to find out! Unless someone out there can educate me further!!

Best Regards

Ian

The logical used by ignitech to decide when to fire is depending on the trigger set up on page 1

Sometimes the results are quite strange and even the traduction from Cz to english is

But at the end , with a lot of Volt input in the ignitech ( 13 to 16 v ) it's by far the best "bang for the bucks" option

Even on a tuned Rs125 honda i get after only one day on dyno a much stronger curve compared to the stock Ecu ( whatever the static timing used .... )
And as extra gift , i have the shifter controled by the ignitech


I don't trust at all products made by HPI .....

zeeltronic is a bit better than ignitech in every sequence ... but it's much more expensive and i'don't feel the extra price is paying the extra possibilities of the box

Look at the new 25V Seb has variable spark intensity 100% is 70mJ to the plug

I 've seen it Lozza , but with TRS1225 cap plug and 7282A plugs , there is no issues..... at least until 14 000 rpm with the Ignitech ( if used it 16.4 V lipos .... )

Ian Harrison a écrit:

Hi Motoholic71

Thanks for your input.

Here is an image and instructions regarding setting the "base advance" for the Ignitech.
[Vous devez être inscrit et connecté pour voir cette image]

As you can see the Ignitech calls for the angle of the heel of the trigger from the pickup at TDC and it takes the trigger off that heel. Let's say that angle is 10 deg. In other words that pickup will trigger and the spark will be generated at 10 degrees BTDC until digital control of the curve starts.

I believe that it then simultaneously measures the length of the trigger by sensing the time it takes to pass the sensor and dividing this by the time for a full rotation. This gives it the angle of the trigger.

In our case the trigger is 30 degrees. This means that the front edge of the trigger passes the sensor at 40 degrees BTDC. I had assumed that once the ignition had digital control it then took the pulse off the leading edge of the trigger and could fire any advance up to 40 deg BTDC (less an increasing allowance for "thinking time" as the rpms rise and the engine ravels further in that time).

However, you are suggesting that it always takes the firing trigger off the heel and delays the spark by the time for the engine to rotate say 360 degrees, if we want to fire at 10 degrees BTDC or the time for the engine to rotate say 340 degrees, if we want to fire at 30 degrees BTDC.

On all the other ignitions I have used then (HPI, RTD and Zeeltronic), we tell the ignition the "Tooth Value" or "Static advance" which is the measurement from the leading edge of the trigger to the pickup at TDC. So in the case above 40 degrees. We can see that and the maximum useable advance line, in red, on the HPI graph below.
[Vous devez être inscrit et connecté pour voir cette image]
This means that the pulse is always taken off the leading edge of the trigger, but I believe only after digital control. I believe that before digital control takes over the trigger is again taken from the leading edge of the trigger (i.e.) 10 degrees BTDC in our example.

So we are either telling the ignition the same thing in diffeent ways or as you suggest, the Ignitech works on the "spark for the next rev" (to put it crudely) principle.

If you are correct and this is the case then I don't think that the acceleration of the engine is high enough to affect the timing by a measureable amount as particularly towards the end of a dyno run in top gear and at a high dyno loading the increase of engine rpms is very slow (in electronics terms) and compared to the overall rpms.

I believe that the poor results could be due to increased opportunity for disturbance caused by EMI (remember that at anything less than 10 degrees BTDC the spark for the current revolution would occur after the trigger for the subsequent revolution) and that is hard to get your head round (in fact is it possible??)!!

I will attempt to find out! Unless someone out there can educate me further!!

Best Regards

Ian

Hi thank you for the input.

I was though pretty sure that the P-2 race Ign. trigger could only see the trailing edge of the lobe.

That's how most other CDIs work,at least all the analogs do. It's simply less susceptible to EMI that way.

we had a home brew ignition with a p-2 race CDI and we had to machine a part of the trigger lobe to help balancing the flywheel and about 10mm were cut from the leading edge and after timing was re checked with no visible change.
The last comment on the static advancing screen instruction regarding "at idle the rpm is changing too much,set it at end of lobe(zero degrees) to assure adv. stability" is suspect too.
The rpm is changing because at idle the momentum is low and the compression stroke will decelerate the crank and the power stroke will accelerate,causing RPM oscillation,making time base flywheel indexing inaccurate,so they basically recommend "to shut off time processing" by making fire at lobe end.

I have a Wolf factory (suzuki) race CDI and 1 of the options the software allows is to change trigger edge as a means of choice to each end of the lobe the triggering is desired,with a recommendation however that the leading edge is more sensible to EMI and generates a weaker signal.

I have no experience with other brands.

I'm getting the Zeeltronic with 2 channels (the RGV version) as it's the only able to drive the A/F solenoids with duty cicles on the newer bikes and I can vouch for it's accuracy but will certainly like very much to know how good the Ignitech actually is as all the extra features will worth nothing if it's unable to do it's principal job with accuracy,which is to provide correct timing and stable spark energy.
Specially with Extra light flywheels.

What i would say is to use Resistiv plugs and caps

Both ignitech and zeeltronic have quite strange signal output when you use non resistiv plugs or/and caps

Both deliver a precise ignition , i 've NEVER had any precision issue ....
Don't even try to get a stable ignition at iddle , it's impossible as the rpm is not stable ... But if you are in a flat part of the ignition curve you have a stable ignition point ....

Hi Guys

Once again thanks for the info and input.

Of course with any digital ignition I always use resistor race plugs and NGK 5K ohm resistor race suppressor caps to minimise the effects of EMI.

SEB4LO a écrit:

The logical used by ignitech to decide when to fire is depending on the trigger set up on page 1

Thanks for drawing me back to the trigger setup. This has gone on for awhile and some of the setting details I had forgotten about as I set them so long ago. I am currently using the "special setting" and not selecting the "calculate maximum advance off the 2nd (trailing) edge" of the lobe. So it is already calculating off the 1st (leading) edge in common with the other ignitions mentioned. As you can see the initial advance is calculated off the 2nd (trailing) edge as assumed:
[Vous devez être inscrit et connecté pour voir cette image]

I guess that I should try setting the max advance to be calculated off the 2nd (trailing) edge of the lobe and see what happens!!

Which edge are yourself and Lozza using to calculate max advance?

I can understand your comments regarding HPI in some respect. At times their customer service is not the best in the world (on accasion I have had the reverse of that), and I have heard reported that their ignition coils are not so good (we don't use them). However, in terms of the plug-in Honda CR250 programmable ACCDI box they set the standard. OK the indexing is 5 degrees off and when I point this out to them, they don't appear to care, but once you know that, every box is 100% consistent, you just programme accordingly and we have never had a box failure in 5 years (I sell about 30-50 per year), winning many Championships around the world in that time.

That the Zeeltronic produces identical results to the HPI is a great tribute. I now have an option to sell my large stock of new Honda CR250 '02 generators/rec/regs/condensers and give customers a superb ignition system into the bargain.

Anyway, at least I've got one more thing to try before I finally give up
I would like to use this lot if possible!!
[Vous devez être inscrit et connecté pour voir cette image]

Best Regards

Ian

Zeeltronic only ever uses leading edge. That is the 'static advance' figure and the maximum amount of advance you can program.

Institute of TwoStrokes a écrit:

Zeeltronic only ever uses leading edge. That is the 'static advance' figure and the maximum amount of advance you can program.

Hi Lozza

Thanks for your reply, but what I was really asking is which option you use on the Ignitech (I think you said that you use or have used the Igni?) and the base advance and rotational lobe length (in degrees) if you have that to hand?

However, I believe that in common with all the other digital programmable CDI's the Zeeltronic reads the trailing edge to trigger for initial advance prior to digital control, Otherwise with a long lobe (say 50 degrees) you might end up with say 60 degrees of initial advance which would be no good for starting. The max programmable advance will be subject to a diminishing value based on the "tooth" (static angle for Zeel) as rpm increases to allow for a fixed "thinking time".

I will check that out on the rig tomorrow just to be 100% positive.

Anyway, for the Zeeltronic I'll report:

1. Static advance, determined by either leading or trailing edge
2. Min rpm that digital control starts
3. Max possible programmable advance (for my 40 degree front edge) at 2,000 and at 10,000rpm - points inbetween and beyond will just be a straight line relationship, same as with the HPI

I'll also test the Igni with max advance calculated off the trailing edge. If this seems to work on the rig (which I'm very doubtful about), I'll proceed to the dyno test on Thursday.

Best Regards

Ian

A DT200 I ended up with 70deg static angle(leading edge) and a 20V has no problems reading 15deg to start at 500rpm. I use base advance with the Ignitech(trailing edge to TDC).
Zeel won't allow you to program more advance at any point than static angle.

Perfect Lozza , nothing to add

Just that ZEELS are nice units , i think i used half of the 10 first ever built units and as there was nothing against them at this moment , they were by far the best option

Now , it depends a lots , for a road bike , i would use them without hesitation

For a race bike , i would choose Zeel or ignitech depending on the budget only , but thinking that Ignitech NEEDS a battery in the circuit to run fine , Zeel can deel with a capacitor and a regulator , Ignitech can't as they need a lot of Volt all the time , as soon as the got low voltage , they go crazy .....

I conclude many engines failures result from wrongly set ignitions,like a tunned up bike I saw on youtube full of expensive aftermarket goodies,and the first attempt to start the engine resulted in a backwards run,and the owner scratching the head

Hi Lozza/SEB4LO

After testing on the rig, I can now give you the facts regarding the Zeeltronic:

1. Initial advance is fired directly off the trailing edge as I suspected (in my case 10 degrees BTDC)
2. Min rpm that digital control starts is 2000 rpm. So you can program in any setting you like at anything from 100 - 1900rpm and that figure will have no effect and the ignition which will only fire at the initial advance until you hit 2000rpm
3. Max possible programmable advance (for my 40 degree front edge) is as follows:

40 degrees BTDC at 2,000rpm
38 degrees BTDC at 6,000rpm
36 degrees BTDC at 10,000rpm

Again you can program anything in you like up to 80 deg BTDC but the advance will stop at the figures defined by a straight line through the above points.

As you have both said the Zeeltronic is a great ignition. It's just good to know how it actually works and it's characteristics.

As far as the Ignitech goes, as I expected, it dosen't operate correctly if you try and calculate the max advance from the trailing edge. so I can dispel Motoholic71's theory that the Ignitech triggers for the following revolution, it's just that the Ignitech detecs and measures the lobe and sets it's own "static advance" or "tooth" from it's measurement of the lobe, added to the programmed in base advance. However, why we have the poor performance with the Ignitech remains a mystery. We still get the same results when running off a 14.8V LiPo or the rectified, regulated and smoothed output of the generator.

So it looks like we stick with the HPI as our AC CDI of choice for use with the CR250 '01 generator and the Zeeltronic for DC operation off our '02 Honda Generator/reg/rec/capacitor.

I hope the above information will help a few regarding the operation/choice of various programmable ignitions and thanks for joining me on the "voyage of discovery".

Anyone want to buy 6 x cheap Ignitechs?

Best Regards

Ian

I need some more units , you can Pm me

But i do suspect that ignitech doesn't works the same way when using different triggers , i do use the Yam set up ( small trigger ) as much as i can and on rs125r NX4 the strange special set up made in the soft ...
On the rs125r NF4 ; it's something close to the Yam set up , a small trigger .... and it works like a dream .... ( much , much stronger that stock unit )

It works , however we still have trouble on an aprilia 250 to get the same power as a stock Cdi but as i'll have a dyno at home in the next days , developements will go much more faster now


I beleive too that ignitech fires on the next revolution based on the time/rpm fonction between to trigger detected .... ( as it is able to fire more advance than the static advance .... )

Hi SEB4LO

You slightly miss the point.

I can definitely 100% say that the Ignitech triggers for the current engine revolution. In common with all the ignitions discussed here it cannot fire more advance than the leading edge position of the lobe (less thinking time). It's just that the Ignitech calculates that position for itself from the base advance figure programmed-in and the detected lobe length.

Of course if you run a short lobe (say 12 degrees long) and if you want to programme in a max advance of 27 degrees at 6,000rpm you would require a base advance as follows:

27 degrees (required max advance) - 12 degrees (length of lobe) + 2 degrees (ignition thinking time at 6,000rpm) = 17 degrees (Base Advance).

In this instance you will have an initial advance of 17 deg BTDC until digital control begins

PM sent.

Best Regards

Ian

Interesting info Ian I was like Motoholic and thought the Ignitech was working off the previous cycle, but nice to know it sets it's own static angle.
Have you had HPI AC v's DC/DC Zeeltronic cage fight ?
Send me a MP or a email about the Ignitechs

Lozza , i asked for the units already

I dont really need 6 but we can see that together my friend , i would need 3 units ...

Avez-vous une unité de même sur votre vélo

If there are any surplus I'll take them. Send me a pay pal request.

3 FOR EACH THEN

Institute of TwoStrokes a écrit:

Have you had HPI AC v's DC/DC Zeeltronic cage fight ?
Send me a MP or a email about the Ignitechs

Yes, I have and you couldn't seperate them. I'll post the dynographs tomorrow from work.

I'll also sort out the sale tomorrow. Already had a cash sale from someone beating down my door, so I'll split the remainder between SEB4LO and Lozza. Watch your PM's.

Ian

Hi Guys

Here is the "dyno shootout" HPI vs Zeeltronic.

Same engine, all settings the same and both runs within the same hour.

They are really too close to seperate. The slight differences are only enough to be attributed to the normal variation that you can see run-to-run.

[Vous devez être inscrit et connecté pour voir cette image]
Very happy with the performace of both.

Best Regards

Ian