ViragoTechForum.com :: Yamaha Virago XV Forums That Rock!!!

#1:  Time for plugs to color. (SOLVED) Author: webales,  Posted: Fri Aug 06, 2010 2:19 pm 1990 1100 - PO removed baffles from stock pipes, left bugeye and internals and added aftermarket aircleaner. I'm trying to dial-in the mixture at cruise: I rode about 20mi. on my old plugs to warm up the engine, pulled over onto the (deserted) highway shoulder, put new plugs in and then rode at 75mph constant for 10mi, (no surging - ran great) pulled over and checked the plugs, doing the kill-switch, clutch thing. They looked like they were still new! The electrodes were a little grey, but the insulators were as white as when I installed them. I rode another 10 mi. back and same exact result. My question is: is it running super lean at cruise, or does it take more than 20 mi. for the plugs to get their color? If I'm running lean, I guess I should drill the pilot jet to .05mm like so many I've read about? Thanks in advance. I find most of the answers to my questions from reading the site, but haven't found this.

#2:   Author: mark75,  Posted: Sun Aug 08, 2010 8:13 pm try adding a #4 washer under each needle. if they are just white with no glazing or erosion of tips you should be ok. maybe go to next colder plug. what plugs are you using?

#3:   Author: webales,  Posted: Tue Aug 10, 2010 11:12 am Thanks for the reply. I'm using the factory recommended NGK BP7ES plugs. Another thing I noticed is that the plugs were covered with fluffy carbon after about 5mi. riding in town - idling at lights, etc... I didn't drill out the idle air screw caps when I cleaned the carbs, so I guess I should do this and clean the screws/passages out when I take off the carbs to put in the needle-washers. Thanks again for the info.

#4:   Author: mark75,  Posted: Wed Aug 11, 2010 2:20 am run a can of Seafoam (0.5 can per tank x2, then tank of fresh name brand reg) and you'll clean insides up (at least the parts that contact fuel). JMO: sounds like you're close about where you want to be. maybe a tad rich @ low speeds. if idling good and no problem at lower speeds I would leave it alone. if it ain't broke, don't "fix" it. try AutoLite Platinum AP-63, = to next step cooler and plats less likely to foul at your lower speeds situation. might not even need washers then, and they are only ~ $3 each.

#5:  Re: Time for plugs to color. Author: webales,  Posted: Thu Aug 12, 2010 5:46 pm I'm putting the AP-63's in today - thanks. I cleaned out the carbs a couple of weeks ago - they were filthy, as the PO had no air cleaner element installed. I just feel bad about not going all the way and cleaning out those screws! I was dependent on the bike then and I just get a little nervous when drill meets carb! Now I have the car back, so I can get a little more "adventurous". As I understand it, air goes through the idle passages where the screws are (?). The bike runs perfectly cruising at 80mph, but when I pull off the highway for fuel it is like riding a bucking horse. This only starts after cruising for 25mi. or so - the bike runs perfectly when it's cold. Many people here say that drilling the pilot jets to .05mm was the best modification they ever did. Do you think this is a good idea?

#6:   Author: mark75,  Posted: Thu Aug 12, 2010 8:37 pm went with P901 on mine, and have a Hitachi, so I am hesitant to advise since you prolly have Mikunis, but it does sound like that circuit does need attention. have you checked for vac leak at warm idle? air filter element now installed?

#7:   Author: webales,  Posted: Thu Aug 12, 2010 8:51 pm I've seriously considered the single-carb setup myself. The single-carb is attractive to me because the carbs are very difficult to get in and out on my bike, and it would seem to really simplify everything. I found a vac leak at the manifold/head seal, tightened the bolts and it "cured" it - but I will replace the o-rings when I pull the carbs again. I put in a new air filter element as soon as I saw it was missing.

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