Author Topic: Which Iridium plug?  (Read 14027 times)

lankeeyankee

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Re: Which Iridium plug?
« Reply #60 on: October 19, 2010, 03:20:49 AM »
Also, I had the local kymco mech adjust my carb, I don't think it's lean (plug looks tan, not white, this is a good sign, right?)

I pulled and tested the by- starter, ohm meter read checks out. Put 12 v across it, and it seems to retract fully. If I understand this thing right, it functions some what a choke, only it allows more fuel in through a secondary, smaller jet, rather than restricting air flow. I searched the net, but could not seem to find out much on this   thing.

Hi Tom
Its not very accurate in reading plugs on a scoot to tune. I will explain.
Yes, reading a plug is one way to see if your AF (air fuel ratio) is correct.
This way of tuning came from racers with manual transmissions. This how you can do it on vehichles with MANUAL transmission.
Install new spark plugs. Start the engine, run the engine up to max RPM.
Pull the clutch in at max RPM and kill the engine.
Coast to a stop.
Remove the spark plug and read it.
The problem with trying this tuning method with a scooter is you arent able to shut the engine down at MAX RPM.
I use a dual band AF meter and an O2 sensor on my scoot due to many different carb configurations and Nitrous Jetting with Fuel.
Before I had the AF meter I would just start by finding a long stretch of road and using a road sign, land mark etc as a point and clocking the top speed with a GPS unit.
I would start lean and increase the jet size until the MPH would drop. Then set the main jet that had the best top speed. After I had my main fuel jet dialed in I could set my needle height and spring pressure to my likings and this would usually be a short burst from take off such as 0-35mph or mark out 125 feet and and use a GPS to see what the max speed is within the 125ft from 0.
Reading a plug isnt accurate in jetting on a CVT transmission even more so if its not a brand new spark plug.

lankeeyankee

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Re: Which Iridium plug?
« Reply #61 on: November 08, 2010, 11:43:25 PM »
Take a note of the iridium plug your changing out with your standard NGK plug.
If your piston clearance is tight you may have a change in performance your not wanting to achieve.
« Last Edit: November 08, 2010, 11:45:25 PM by lankeeyankee »

tomheet

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Re: Which Iridium plug?
« Reply #62 on: November 12, 2010, 03:52:55 AM »
Lankeeyankee, whatever iridium plug i have (forget the number) is not the one shown. It is actually the same length as the standard. But, it made no difference, so I just keep it with me as a back up now. Repalcing my main jet with a larger one, and re-tuning has greatly improved the cold weather problem. Not to mention quicker acceleration, really noticed the difference.

oswaldters

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Re: Which Iridium plug?
« Reply #63 on: November 12, 2010, 03:56:43 AM »
How much did you increase your jet size?

I'm thinking of doing the same to help with the poor cold weather performance on my scoot.

Rianna

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Re: Which Iridium plug?
« Reply #64 on: November 12, 2010, 04:06:37 AM »
That's awesome, Tom. Glad it's going better in the cold now!

tomheet

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Re: Which Iridium plug?
« Reply #65 on: November 14, 2010, 05:03:40 PM »
hey OS, and Rianna- sorry about the lateness of this reply. The jet in it (factory) was only a 75. The new one is I think a 90, 0r 92. I found a great mechanic-semi retired guy who  used to sell/ service Kymco at his car lot. It really helped alot, even at 35 deg. it runs good when warmed up. My new procedure is, start bike with thumb in air intake to choke it a bit. Let it idle about 2 minutes, good to go.If it starts to puke while idling, put thumb back in intake.

 Last ride of the season yesterday. Put her in storage.

P.S Os- the acceleration has improved big time! cheap to do, so go for it..

oswaldters

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Re: Which Iridium plug?
« Reply #66 on: November 14, 2010, 10:46:41 PM »
Thanks for the information.

I'm running a #80 jet and probably should be at an #85 I suspect.

No problems with starting it even on the coldest day, but I have to warm it up for at least 5 minutes - and more like 10 min. when it hits the mid- to low 20's and below.  Once it has warmed, it runs great.

Don't know if the bigger jet would help with the warming up part.  Seems like before the scoot is fully warmed up if I try to ride it the thing floods out.  I think my problem may be too much fuel when it's cold due to the auto bypass.

kerllycrueaz

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Re: Which Iridium plug?
« Reply #67 on: May 29, 2012, 05:58:16 PM »
The cheapest and best Is an up jet to an #85 main and a 3/8" hole within the outer cowl of the air box,I place the opening to the carob facet behind the limited flare within the cowl.

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