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**Joel** · 06-15-2009, 02:13 PM

^On the RTR for ex, as soon as the revs get past 5000rpm, it switches to a retarded map. On almost all race engines(but there are exceptions to the rule), timing is retarded at peak revs to avoid deto mostly.
However on a bike like a karizma which runs a lazy compression ratio, you can advance the revs if you actually had access to a fully programmable unit. It would make a difference for sure on a stock engine itself. But the moment you go high on comp and increase the dynamic compression courtesy cams, etc you will need to go retard.
In race engines, the only likely way people go for timing advance higher up the band is by switching to high octane fuel. AV gas etc can help in dropping engine temps crazily despite the advance.

For now for your stock zma, just set the TPS for WOT and forget the rest

. get hold of a programmble unit someday and play around man.

**abhijeet080808** · 06-15-2009, 02:21 PM

Originally posted by Joel View Post

^On the RTR for ex, as soon as the revs get past 5000rpm, it switches to a retarded map. On almost all race engines(but there are exceptions to the rule), timing is retarded at peak revs to avoid deto mostly.

That means the turbulence effect is much more in the RTR engine that it effectively reduces flame propagation time at higher rpm, similar to 2 stroke?

Care to explain what exactly causes this? Just head design/valve dynamics/cam profile?

**Joel** · 06-15-2009, 02:44 PM

Originally posted by abhijeet080808 View Post

Care to explain what exactly causes this? Just head design/valve dynamics/cam profile?

You answered your own question

. Its mainly the head and cam.

**Jokerman** · 06-21-2009, 08:58 AM

You have no idea how much better I feel, now that I know how variable ignition characteristics can go on similar motorcycles. I could not understand how people went around with a thumb rule of advance/retard based on the combustion cycle. Did not make sense to me.

@joel
Your suggestions have already been accepted as permanent, as far as the ZMA goes. Am only making other inquiries while I have your attention

@ abhijeet
You are the first person that I have come across with specific information and data, or maybe the first one to divulge it. All due thanks to you, sir. Its a huge help.

Trade secrets apart, I don't know why companies do not print the behavior of their CDI boxes on the manuals. They should. Just like the carb specifics like the main jets, etc. Any one have time for an RTI application?

More seriously, I have to thank the both of you again, I have hugely benefited here.

I guess the thread can be closed here, unless someone is going to come around with more delectable technical data

**Jokerman** · 06-28-2009, 09:57 PM

Theory to Practice

All right, here goes.

Dumped a Mikuni TM28 into the ZMA, left the 165 mains that it came with (I know it sounds too much but I wanted to know that by a plug reading than assume on a theoretical basis and it was indeed rich). Gonna shove in a 140ish soon.

Then I set the TPS on WOT.

It sounded extremely sick from 0 to 1/4 throttle, began to come together from 1/4 to 1/2 and then screams on hard all the way to WOT.

I then put the TPS on a bit above 1/2 throttle and it actually felt much stronger through the rev range though it hits a wall a bit sooner than before.

Maybe it just the tuning, that darned air screw is located in a place that asks me to take the fuel tank off before I can reach it.

Will need another 2 days before I get more time, but I want to know your opinions so that I am a bit more armed with info the next time I wield a screwdriver.

Does no one have specific details as to what Ignition Timing figures go through the rev range?

**atul_astro** · 06-29-2009, 01:52 AM

the TVS victor uses a 3 way tps at the throttle. Costs peanuts. Might be of help. My 2 cents

**atul_astro** · 06-29-2009, 01:54 AM

also, a small tip on the jetting when using a mikuni carb for the zma. try a 1.2mm mains

**Jokerman** · 06-29-2009, 12:23 PM

Originally posted by atul_astro View Post

the TVS victor uses a 3 way tps at the throttle. Costs peanuts. Might be of help. My 2 cents

Question is, does it have a compatibility with the CDI on the ZMA? If yes, how do I introduce the both to each other without any of them getting into seek-and-destroy mode?

Electrical gremlins get quite annoying and I would not mind just running static, just that I'd like to choose what timing the static timing is at, and get a suitable setting!

Someone give me numbers!

**Joel** · 06-29-2009, 02:33 PM

^The RTR and TVS Victor have similar TPS switches. It has only 2 positions. Its more like an On/OFF switch. Switches from one map to the other. Barely makes the CDI work dynamic. I'd rather run a karizma static at one position only for WOT. However soon, Im upgrading to a fully programmable system. So a TPS will make a big deal then.
@Atul - The zma already comes with a 125 main, i.e 1.25mm

**karthik_R** · 06-29-2009, 02:40 PM

I still remember removing the tank of my victor on the very first week after delivery to make the throttle operated switch remain on the POWER mode at low revs..That was something

**Jokerman** · 06-29-2009, 07:46 PM

Originally posted by Joel View Post

I'd rather run a karizma static at one position only for WOT.

Me too. But Joel, its not running all that great at WOT setting. Wants WOT all the time! I need something more street worthy. Am I doing something wrong or have you over estimated the roads of Bombay??

Though that's not the final word. Will revert back after tuning and jetting it accurately. Maybe the WOT setting wont shock the engine like it is doing now.

**Joel** · 06-29-2009, 08:01 PM

These long-stroke motors wont suffer much (although there could be a slight lag coz of the ignition retard) at low revs. The lag could most probably be pronounced coz you are running a larger carb? Whats the dia?

**atul_astro** · 06-29-2009, 08:37 PM

@Atul - The zma already comes with a 125 main, i.e 1.25mm

yea man..but the keihin thread pattern is nothing like the mikuni hex jet. The 160 is tad big for the bike, so a 1.2mm on a TM28 would suffice. hence the heads up

btw..what ignition for the zma?..fully prog? PM me the details if you like

**Joel** · 06-29-2009, 09:02 PM

Originally posted by atul_astro View Post

yea man..but the keihin thread pattern is nothing like the mikuni hex jet. The 160 is tad big for the bike, so a 1.2mm on a TM28 would suffice. hence the heads up

btw..what ignition for the zma?..fully prog? PM me the details if you like

Oh, u talking about the TM28 eh.

Ignition is a fully programmable one and I'm working on the set-up as of now. Will let you know once it comes through

**Jokerman** · 06-29-2009, 09:53 PM

Originally posted by Joel View Post

These long-stroke motors wont suffer much (although there could be a slight lag coz of the ignition retard) at low revs. The lag could most probably be pronounced coz you are running a larger carb? Whats the dia?

Its in fact a smaller carb from the Keihin VE30 that was in there, I put the TM28. I chose a smaller carb - I thought that will help the throttle response. But I guess I thought wrong. Like I said before, let me get it tuned and I will let you know.

Anything before that will only be speculation.

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