PLUG CHOP PROCEEDURE

Thanks. It's in the filebase now. The only way I could think of to make pdf was to print the page to a file as postscript and then run ps2pdf. Worked but it's looks just like reading the forum

If anyone has anything to add, or dekete, let me know.

Post edited by: Duck, at: 2006/09/10 12:43

EXELLANT REPLY, THANKS DUCK.It does pull hard but how do I know if she is "pulling for all she's worth "if i don't check the plugs.These are not stock carbs so I dont have a bace line.Some data suggests useing 140 mains for a mildly modified 1000cc engine.I started with 132's and worked my way up to 165's and I still have no color on the plugs.The main problem at the moment is my method of testing.After I reach max rpm I back off the throttle,hit the kill switch,and pull the clutch.Is it posible that when I pull in the clutch that I am removeing the engines load and causing the rpm to over rev ? I am looking for a reason for spinning the rotor on the crank and shearing the woodrif key.

As you increase the main jet size you'll reach a point where there is no improvement in pull at WOT. This is jet you want.
What you've done is no different than setting you idle for max RPM exept at the WOT end of things.

If you want to read color, start with the jet you found above. You're gonna be fine tuning at this point and IMO a dyno setup with exhaust gas and cylinder head temp readouts is worth the $ here. Still want to DIY?

Here is an article I found related to drag racing.
reading-spark-plugs


Another article with photos. Full load spark plug reading

Yet another article . Selecting plugs and the importance of ignition timing. This one is from cylce magazone.


Hit the kill switch at the end of your run.

The referenced article suggests that a number of runs may be necessary to get a reading.

-Duck

Post edited by: Duck, at: 2006/09/10 13:46

My guess is that when you hit the kill switch the engine speed drops rapidly. The rotor still has lots of momentum and wants to continue spinning, so it shears off the key. We used to call this type of thing "sudden stoppage" damage (which usually happened when a plane crashed with the engine running and the prop hit the ground, causing the engine to come to a stop very quickly) in aircraft school. What you are doing is not a normal operating regime for the engine. Normally when you slow down you shut the throttle, but the bike is still in gear and the engine speed drops slowly, so there is not as much stress on the key. I would recommend not doing that procedure anymore unless you want to keep changing the keys. Good luck.

mark1122 wrote:

Is it posible that when I pull in the clutch that I am removeing the engines load and causing the rpm to over rev ? I am looking for a reason for spinning the rotor on the crank and shearing the woodrif key.

Sorry, I didn't answer your other question. When you've run as long as you like at WOT, hit the kill switch before you do anything else. Throttle and clutch are not going to affect reading once the ignition has been killed. You won't over-rev the engine this way.

Also read the articles to make sure you're looking at right stuff for your reading.

-Duck

Post edited by: Duck, at: 2006/09/10 14:51

Thanks guys.The more I read,the more I think I had better star with timeing.The book I have says I should read the porcelin tip and these articals say to read the bace .This is confusing.I do think I should find a locktite product of some kind to secure the rotor to the crank before I go any further.Any suggestions?

Can you tell me how to tell if the main jet air jet is the correct size?

I think I used the green Loctite to secure the rotor to the crank on the 79 750 twin. Just look at the back of the package and get the one with the greatest strength (I think silver, but they had none in stock so I used green).

Post edited by: steell, at: 2006/09/10 17:01

Will I have trouble getting it back off If I need to?

mark1122 wrote:

Will I have trouble getting it back off If I need to?

Not if you have an acetylene torch to get it hot enough to break the bond of the Loctite

The stronger the bond (higher strength) the higher the temp required to break it.

Sounds like some serious stickum.Thanks

Great post duck! Very informative. Where you active in the thread I posted awhile back about needing to change jetting for big bore kits (or actaully not needing to). I forget why exactly it wouldn't be needed, but I must say, the bike pulls pretty damn hard with the dynojet supplied jet for pods and 4-1. It seems a little weak in the midrange though at less than full throttle, so I think the the prescribed 4th clip groove may need to be adjusted.

But anyway, yea I agree with the plug chop not being needed. Maybe if the bike doesn't pull well and you aren't sure if it is rich or lean.. but otherwise, you will know if the jetting is right, because it runs hard!

I wonder how a 134 or a 138 would run (my bike has a 136) but I don't have access to either, and I know it pulls hard with that one.

I don't want to hijack the topic, but if you are blasting up through the gears at WOT.. 1st WOT, shift 2nd WOT, shift 3rd WOT, shift 4th and half or 3/4th throttle and it was pulling really hard at WOT but then when shifting into the next gear and opening the throttle part way and the engine stutters.. Is that possibly to do with my theory of the needle height being off?