[rsss396]

timing that is to far retarded can cause detonation because of the stuffing effects of the pipe and the extra heat in the pipe from the ign timing being to far retarded.

The reason the the exhaust gases are hotter with timing retarded is because of not enough time for the fuel to more completly burn before the exhaust port opens. Advanceing ignition timing gives the fuel mixture more time to complete the combustion process but will add more heat to the piston. That is why you will see holes in the center of a piston if you have to much ignition timing advance.

This is a important thing to know for people that tune their bikes with EGT gauges, the gauge can read low with to much timing added but yet be have the proper air/fuel mixture and vice versa show very high exhaust temps because timing was retarded

 

[acecarlos]

I am not real sure what I am looking for with this anneal line. I Did put a new plug in and run it wide open down a runway and shut it off and checked the plug. I noticed the brown line on the porcelain was angled going up right toward the bend in the metal strap.. is this what I'm looking for?
Or am I looking for the line on the actual plug strap itself? I'm sure I sound like a moron, but only one way to learn, right?

Need to get some heat into the new plug, 2-3 passes at WOT for 6-8 seconds each pass. The Plug reading guides are just that; guides only. Both have statements made of little use in the real world of 250R tuning/jetting. Do a search on this forum, many times has the proper Plug Chop procedure been posted, should be an easy find for you.

If you don't have a good 2 stroke timing light, get one...makes timing much easier & precise.

PS: what rsss396 about retarded timing is true, however; it has to be to an extreme condition to see it as a noticeable change in an EGT. I have tried to prove this many times on the Engine & RW Dyno's we have, and it is quite difficult to associate retarded timing with engine temperature increases, even on an EGT unless you make major timing changes (IGN retardation), and you are specifically looking for the temperature rise. In 'blind' tests, even the best tuners would miss the temperature rise to retarded timing.

Carlos

 

[rsss396]

I am going off memory back when I use to run gas on my bike but I seam to remember about 100 degrees temp drop at the pipe probe when I advanced my bike allot.

I never experiamented with the extreme retard situation but the theory always seem to make since and have heard of siezures because of it.

In my performance manual for my sleds they use to give temps for differant models and they all were differant but some were in the 1300's while most were around 1200 degrees. so never use EGT numbers as a tuning number until it has been established that is the best exhaust temp for your combination. Then use that number to maintain your optimal tune with weather changes.

One situation I did experience was when detonation is happening EGT temps drop and the spark plug head temp sky rockets

 

[C-Leigh Racing]

Will, which one of the heads did you finely end up using ?.
Neil

 

[hartwill]

I ended up turning the 23cc dome out to 28ccs. The 32cc took me down to about 185psi so by turning the other one out I got it back up to 220psi. I have a Paul Turner woods pipe on it now, I only switched from my sparks mx pipe to make sure some of the dents weren't causing this motor to run funny.. it seems to run pretty strong, I have no problem pulling 3rd gear holeshots with 13/38 sprockets, but it was starting it's deto up around 3/4 throttle.. I am going to switch back to the sparks pipe soon Because it seems to rev out a lot better and have a longer power band.

When this timing was very retarded I kept assuming it was too advanced Because it was radiating heat off of the cylinder. Eventually after retarding it a little at a time it just had no power down low. So I decided there was only one other way to go and I advanced it quit a bit. It gained a ton of power and ran much much cooler.. this was before I bought a programmable 2stroke timing light.. I am thinking that this pickup on the fly wheel must be quite a bit more retarded than the 01 Because I have it set at 20° advanced at 2000rpm and I am almost out of advance adjustment on this stator plate.

 

[hartwill]

Hey Neil, I could use some more head gasket o-rings if you have any.. or know best place to get them.. I had to make my own out of some sheets of rubber gasket maker. some guy at the track came out of his trailer with a box of this stuff, I thought no way is this gonna work, so I tore the whole thing down traced the old o -ring cut it out with leatherman scissors put it back together and started her right up.. these guys next to me were like, Yea that's Why no one runs them two strokes no more, I was like Oh Yea, Well I wanna see you change a head gasket in 15 min.. lol, they couldn't believe it when she fired up and ran.. Oh, it held up for both motos, plus some pit riding but think I better put a real 9-ring back in her..

 

[rsss396]

I ended up turning the 23cc dome out to 28ccs. The 32cc took me down to about 185psi so by turning the other one out I got it back up to 220psi. I have a Paul Turner woods pipe on it now, I only switched from my sparks mx pipe to make sure some of the dents weren't causing this motor to run funny.. it seems to run pretty strong, I have no problem pulling 3rd gear holeshots with 13/38 sprockets, but it was starting it's deto up around 3/4 throttle.. I am going to switch back to the sparks pipe soon Because it seems to rev out a lot better and have a longer power band.

When this timing was very retarded I kept assuming it was too advanced Because it was radiating heat off of the cylinder. Eventually after retarding it a little at a time it just had no power down low. So I decided there was only one other way to go and I advanced it quit a bit. It gained a ton of power and ran much much cooler.. this was before I bought a programmable 2stroke timing light.. I am thinking that this pickup on the fly wheel must be quite a bit more retarded than the 01 Because I have it set at 20° advanced at 2000rpm and I am almost out of advance adjustment on this stator plate.

The 02 flywhee tabl should be about 12 degrees retarded from the 01 flywheel tab according to the kart site info which I believe with your results..

You should do a write up on your instal to help all the guys that have not been able to fiquire this out after purchasing the 02 ignitions it just took someone to put a little effort into it! Nice job

 

[hartwill]

Alright guys, finally ran a whole race without any deto problems.. thanks for all the help.. runs real strong with this ignition once it's set-up right.. pulled a 4th over all on Saturday and a first over all Sunday..
I will try and do a write up on what all I had to do to make it work in the next few days.. thanks again for all the help guys, I may have just gave up without your help..