Here's the deal, I've got my 39mm carbs on the DS and I want to know if they are dialed in. The bike runs well and is strong but the questions is "Does she have more in her?"
So I need an air/fuel meter.
I take my bike to a local emmissions shop and we hook it up to their machine, at idle I have an O2 level of about 13.7-14.3 this looks good to me.
at 1/4 throttle I am now at 10.5
at 1/2 throttle I get 10.5
at 3/4 throttle I have 9.4
and at WOT I have an O2 reading of 10.8
I had to hold each of these positions For about 15 secs for the computer to register the readings.

All of the readings but idle are way rich and this is the way the carb came from Sudco. From about 1/2 throttle and WOT I was getting rich back fireing (light popping)and the tach was pegged at over 10,000 rpms, under normal riding conditions I never hear a backfire and never go over 9500 rpms.

My question is: is this a valid way to test the carb set up seeing that there is no load on the engine, all the instructions say is that the various circuits in the carb are strictly throttle related not rpm related so I'm guessing that it should be a valid test and if so it will be easy to lean out most of the throttle range. Also at WOT my HC (hydrocarbons)levels went thru the roof, and it was missing like crazy, I actually think that my ignition system is simply overwhelmed at these rpms and can't fire fast enough, anybody hear of a better ignition system coming on the market any time soon? If you have any thoughts on this topic please share em.
thanks

 

I think your going to get almost dead on with an emission gas anylizer, they work great but you should still take it out warm it up run it hard for a little bit then shut it off try not to let it idle and read your plugs. I have access to a new 5 gas but I run leaded race gas so I can't use it. Oh Well, I have always done it that way and it works for me and you get really good at ripping your carb apart.

 

Major, I remember reading awhile back on one of these forums that the ground for the CDI is weak and was causing some problems. You might want to try fining it and sanding the frame and put on one of those biting type connectors and make sure your battery connections are in perfect shape. Just a thought. WOW 10K huh awesome!!!

 

Good thought Demon , actually when I was doing the mods I checked the ground to the coils and everything seemed pretty tight and I think it did have the washer type that bites into the frame. Battery connection are clean and tight as well. I'm afraid the ignition system isn't up to the task- I'd love to rock this big single to 11 or 12k[img]i/expressions/face-icon-small-happy.gif[/img] I usually tune by plug color but with higher octane fuel I hear it can be a bit misleading. My plugs are a light tan at WOT but still way rich according to the 5 gas.

Ang- you seem to have some experiance with these machines I've looked everywhere to find the ideal levels for CO and CO2 , what I found says that my CO levels should be less than 2% but I can't find a definate # fo the CO2 level that I should be targeting. Any idea?

 

Ok just another little brain storm here, I remember also hearing someone talk about a MSD or simular ignition that could work, I think it may have been Scooby but cant remeber for sure. If I was still in electronics, I would find a way to put that CDI on roids for ya. 12K hmm I would love to see that!!!!

psssst, Can I take her for a spin? LOL Good luck man!

Demon

 

I talked to MSD about a 2 weeks ago. They said that they are in the works on a new system for the DS!!! This is realy good news for all of us because we will be able to advance or retard the timing on the fly!

Here is there # 1-888-258-3835 Call them and we might get this a little quicker.

James

 

great news! I'll call tomorrow, thanks!

 

oops!

 

Hey majorecho forget tuning for a minute have you noticed a definate difference in your power yet.big or little mine should be arriving tuesday and im anxious.

 

Major, My experience is with the older 4 gas machines which read in PPM. With that said all I know about interpreting the readings is not much but here goes. CO should be under 1 PPM at idle and HC can be around 200 at idle but should drop off significantly as the RPM's go up, I only used 02 to relate to a cat.conv. usually looking for something between 13 to 15. I think my info is good but if someone knows differently I'm open for correction. I also don't know some of the new 4 stroke carbs but I would not worry much about the idle numbers get the upper range dialed in and use the idle and idle air screws to get a good idle that does not load up too bad (they all load up at idle) anyway running bad at the top sounds way fat, leaner is meaner and can turn big parts into little ones.
hope this is helpfull, Scott

msd ignitions are awesome would be great to be able to retard for NX