I have a friend that has a Mach Z that is blowing plugs bad. He bought it used earlier this winter and it has been blowing plugs ever since. It is a 98 that supposedly has a 99 ignition system. It also has Crank Shop pipes, V-Force reads, and it may also have the cylinders shimmed and the head cut (not sure). It runs good at high speeds but appears to blow plugs at about any time during normal riding. It does not seem to run noticably rich but the plugs are dark. The plugs do not blow on any particular cylinder. The other night he lowered the needles one clip position and took it for a ride and it still blew plugs (about 8 in 10 miles!). The carbs have been all apart and cleaned and nothing appears wrong. I am not sure on the jetting but the pilots are #50s. He has also tried BR9 and BR10 plugs. When it does not blow plugs it runs real good (and fast!). Does any one have any suggestions? I have heard that a bad stator can do this but I don't see how this is possible. Is this true?

Thanks

I would check the main jets stock 330-340-330 but might be changed because of the work.I would also check to see if the chokes are working right they might be sticking open.check your oil pump arm there should be a line on the pump and on the arm they should line up at idel sometimes the arm does not close all the way they stick open. you might be able to drop pilot jets 1 size also.

Is he running synthetic? I had to retard my pump slightly when I switched, I have a 99 MachZ. As far as the alignment line on the oil pump and lever goes, they should line up when you take up the slack in the throttle. The throttle typically has an 1/8 to a 1/4 inch free play before the carbs start to open, so lightly squeeze the throttle until you feel pressure which is when the carbs would start to open. Holding the throttle in that position the lines on the lever and the pump should be lined up. When throttle is released the line on the lever will actually sit behind the line on the pump at idle.

I had to set my pump slightly behind the line at zero freeplay in order to stop the fouling with synthetic. I would not recomend retarding it like that unless he's using synthetic.

I have also had the choke cable get stuck right were the lever mounts, the cable got pull and the little rubber boot held the cable out slightly. Check all the rubber protector boots on the cable, its a common spot for hangups

I said it a thousand times befor, get rid of those junk NGK plugs and run the champion powersport 8902 plugs. My mach used to eat NGK's so my mechanic friend turned me on to the champions, problem gone. You can ignore my advice and keep waisting your time fidle farting around cleaning the carbs and playing with the needle hight and swaping jets, or you can try the champions. Trust me i'v been there done that.

my buddy had a 98 with the same problem. It went away when he changed the srator ???

I too had a intermettant problem like that.....stator.

try the ngk br9eya's. my ho was fouling 4 in every ride. one of the guys here told me that his mach used to do that and he put br9eya's in instead of the br9 or br10es. Its worked so far for me. thier not that much more expensive either.

Try using the NGK BR8ES. Thats what I got in my '89 MX462. Makes it run a little hotter. If that dosnt work try the NGK BR9EYA, and as a last resort use the champion. I used to have a '73 Olympic that ate the NGK's but liked the Champions.

My 1994 safari deluxe 377 ran on the original plugs from 1994 up untill the begining of this month i changed from br8es to br9es it idles a bit lower than with the 8es's but it has not problem with any type of plug.
But another story is my 72 olympique 399 :angry: it eats those ngks so easily. when i take them out to change them they are always black i tried to change the jets in the carb but they still turn black when they are in that thing.??????? so who knows :p