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White Plugs

  • Thread starter Thread starter richardhaggarty
  • Start date Start date
R

richardhaggarty

Guest
I have recently re-jeted the carbs on my 1985 gs700 with a k&n kit. I replaced the exhuast with a 4-2 gsxr 1100 pipe and stock air box with k&n pod air filters.

I followed the directions that came with the jet kit to the letter. Then I balanced the carbs. It was very hard to start and the plugs where white so I moved from the stock NGK plugs to the NGK cold type recommended by the factory service manual.

I rode it the other day for about twenty minutes, the plugs are still very white.

Is it time to start adjusting the air/fuel ratio?

Also, (this may be unrelated but maybe not) the engine has a bad hesitation and lurch all through second gear, but second gear only.

Thanks
 
if they are white, it means that you are running leaner than you should be. try adjustting the fuel mix a little bit by screwing in a bit, and see how it turns out.




poot
 
The "base settings" suggested in jet kits can be way off the mark. I'm assuming this is part of what you mean by saying you followed the instructions to the letter.
When jetting, pay attention to the throttle position. Mark your throttle and grip if it helps you before road testing.
Approximately, 3/4 throttle to wide open will be regulated by the main jet.
There is some overlap with the needle jet right about 3/4 throttle.
Below 3/4 is the needle jet, but as you get closer to closed throttle, there's an overlap with the pilot jet until the pilot circuit regulates completely.
Put back the correct standard plugs.
Chances are, your white plug reads were after "general" riding around? This would be mostly the needle circuit.
If you can do so safely, test for the needle circuit as I do.
Mark the throttle and test for a couple of miles, top gear, at a solid 1/3 throttle position. Should be level ground or uphill is OK. No downhill.
Chop the bike off. (quickly pull in clutch lever/close throttle, turn off the key and coast to a stop.) Along with your tools, bring a rag and a piece of rubber hose to fit over the end of the hot plugs. This will make it easier to remove and install them.
If the plugs are very white, 1 position richer on the jet needle may not be enough. 2 positions may have to be tried. Or "1 1/2" by using a jetting spacer supplied in the kit. Error on the side of rich, if you have to.
After you get the needle right, test for the main jet. (My sequence preference.)
The best main will be the one that provides the highest top speed, WITHOUT creating a "bog" during roll ons. By roll ons, I mean going 60 mph in top gear and "rolling on" the throttle to full open throttle. The bike should not have any noticable bogging. It should pull smoothly and strongly. Plug reads should only be done after full throttle for a couple of miles.
For the pilot circuit, I ride a steady 35 mph in 4th gear and get reads. Reads can fluctuate some, so pay attention to performance more. But the plugs should still have an acceptable color. You want just the minimal throttle opening during this test. You want the bike to start and warm up and idle correctly. Throttle response should be acceptable. Do what the plug reads and performance tell you to do.
The carbs must be vacuum synched well and the ignition timing correct before testing. Be sure the K&N's are oiled correctly.
If your engine is hesitating, that's a classic lean mixture, along with the white plugs.
 
Thanks for the advice poot and KK.

That testing procedure will be a big help KK.

Also, I am planning to install a Air/Fuel mixture gauge. I got a Bosch O2 sensor and a Venom ratio gauge off ebay. I'll let you know if it works. Of course, if it fails miserably I might not bother to say anything.
 
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