idle rich or lean?

[yamahansolo]

i installed the mikes xs coils the other day and they work great! the only problem i have is that if i am sitting still and i blip the throttle about 1/8-1/4 turns it either stumbles or dies... it never did that before the coils swap.

i think i need a little more gas at idle... any thoughts or tips.

[yamahansolo]

crap i looked at my jet sizes. the pilot airjet is a 210 instead of a 180

and the main is a 140, i have yet to break into the pilot jet to see what it is.

i thought the airjet goes up 1 size for every 3 on the mains???

iether way the combination has been great except for this issue when i changed the coils.

[TopCatGr58]

Hey Chris,

The PILOT JET is the one that's suggested to go up 1 size for every 3 of the main. The Air jet isn't suggested to change in the jet guide. These machines run fairly well in a mild lean condition, that's why Yamaha was able to lean them out in the later years for the EPA and still have decent performance.

However, several of us have put several sizes larger mains, and were able to just adjust the pilot circuit by an extra turn or so out of the pilot screw. IT's been suggested that IF you have to go more than 3 turns out of the pilots that you should go up 1 size instead and then readjust/tune for that. The cheapest thing would be to turn your pilot screws out a 1/2 turn each, test it's performance, try another 1/2 turn if still balking, to see IF you can get it to behave. Just verify how many turns out they are first, and keep track, so IF you get close to 4 turns out, and it's still not behaving, then you will have probably reached the point of bigger pilot jets!? YMMV.
T.C.

[dbeardslee]

Yamahan - I've got the same bike, with basically the same mods. Since the 4/1 and pods will add more air to the mixture you would normally adjust for them with the mains and the pilots. Seems to me that bigger air jets would just screw up the computations for you mains and pilots. I'm at 400' above sea level running 147.5 mains and 45 pilots (genuine mikuni from Mikes XS @ $6 a pair) with the stock air jets, and Betsy seems to like it that way. If you've got access to a colortune, it will tell you pretty quick if your jetting is correct. You should be able to adjust through the entire range of color (yellow, bunson blue, and white/blue). If you can't see the entire range of color, you'll need to adjust your jet sizes. Also, here's an excellent article on CV carb tuning.

[yamahansolo]

thanks!

i have read the article before.... i just never looked at the jets in the throat before. when i got the bike i just pulled the bowls off to see it had 140 mains instead of the 137.5s it already had the jets done when i got the bike and that was with the kerker. it ran awesome. all i did was add the pod filters and i thought i should change jetting but it never stumbled or anything every i have been running the pods for almost 2 years. never a stumble. the only time was two weeks ago when i put the hypo coils on there i will try what tc suggested to see if it's a little better.

the po jetted the bike. i knew it had been jetted when i bought it because he said they had it jetted and in all the extra boxes of parts i got there was a little bag with the 142's in it. i need to get the pilot's out and see what they say.

i read the article where it said that the 11's tuned better by adjusting the screw and not the pilot jet.

i just don't like to mess with it too much because whatever was done to it works. i messed it up by going with the hotter coils!
can't put the old ones back in because the 2 and 3 wires were toast!

[bikerphil]

i installed the mikes xs coils the other day and they work great! the only problem i have is that if i am sitting still and i blip the throttle about 1/8-1/4 turns it either stumbles or dies... it never did that before the coils swap.

i think i need a little more gas at idle... any thoughts or tips.

Did you bypass the ballast resistor?

[petejw]

Also check your connections,
I had a stumble similar to pick up coils,
it turned out to be poor connections.

[yamahansolo]

yes sir bypassed the resistor right away!

all the connectors are solid...

[dbeardslee]

Yamahan - By the 35kv I'm assuming you have the black mikes coils? If you do you might check the feed wires and make sure you have the red/wht going to the positive post on both coils. If you've got the green ones, it doesn't matter which post the red/wht goes to. You might check your primary and secondary resistances with a DMM as well, just to double check your installation and to make sure you don't have a defective coil. Just changing the coils shouldn't cause problems with idle - it should improve it.

[yamahansolo]

red and white is going to positive...

the idle itself is fine it's just if i am sitting and i blip it just a tad. like to 1,500 or so. if i blip it to 2-3k it's fine...???
and they are the black coils.

[dbeardslee]

The only thing I've ever heard of hot coils doing that could be detrimental is that they can cause a slightly leaner condition due to a more complete burn. With the small mains (for your mods) and the over-sized air jets I would think you're already a little lean - maybe the coils just pushed it over the edge. That's what I've heard, but what I've experienced has been different. When I originally installed the black coils on mine it would start faster and idle better and accelerate faster than with the stock setup - didn't cause it to run lean though. When they failed (after 7k miles) the idle was really rough, and it wouldn't do squat before 3k. That's why I would put a DMM on the new coils - just to make sure you don't have a defective unit. If they test OK, I'd be looking at the jetting on the carbs. 140 mains with 230 air jets on a '79 with 4/1 and pods just doesn't sound right. Are the jets that are in it now genuine mikunis?

[yamahansolo]

they look like it??? also when i turned the idle screws out just a tad it seems to work fine. i think it was just too lean at idle. like i said anything above 1500 rpms was fine. just a slight blip would stall it out.