Heat related issue with my '02 426

Thanks Moto2000, I got the harness from your link to the Ebay add. Ten whole bucks! Says it comes off a bike with only 30mi on the odo, hope it wasn't some poor kids first and only ride on a sportbike.

Fastest1, depending on what you find in the way of an entire set or just one cap, I'll part it all out to other TT-ers.

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Did you know that a sport bikes life span is less than 90 days according to the insurance industry? It probably was his first ride and a 600 was too small. You got lucky on the harness, I will check on the coil/s

For you guys that have done this mod I have a question and/or concern about this type plugboot before I install one. Without a rubber stopper built in to the top these streetbike boots won't dirt and water be problematic for the sparkplug hole? There are o-rings built into the sides of these boots but nothing capping over the top. Did you custom fit another seal or just not worry about it?

There are 3 seals, 1 on the collar of the ignitor to seal at the entrance to the valve cover, 1 for the electrical plug at the junction of the ignitor (accordion like seal) and I believe I remember 1 in the tip that seals around the spark plug tip. I have run this set up for at least 3 years and water will not be an issue! It will be replicating the 450's system however the ignitor from a 450 has the sealing ring lower down because the valve cover is shorter than the 426. Cya

hey mark,if it still does it after you change the electrical out. it sure sounds like a jetting issue to me. i have to lean my bike(fuel screw) out in a race sometimes as the bike heats up in the tight stuff,then i'll forget i did it on the next trail ride and its way to lean. but it does exactly what your saying runs rough at constant throttle and has a tendency to stall. might be as simple as too rich a pilot. you need a richer pilot in the colder months but if the bike gets really hot its gonna be too much for it to stomach:excuseme:

hey mark,if it still does it after you change the electrical out. it sure sounds like a jetting issue to me. i have to lean my bike(fuel screw) out in a race sometimes as the bike heats up in the tight stuff,then i'll forget i did it on the next trail ride and its way to lean. but it does exactly what your saying runs rough at constant throttle and has a tendency to stall. might be as simple as too rich a pilot. you need a richer pilot in the colder months but if the bike gets really hot its gonna be too much for it to stomach:excuseme:

I hear ya Bob, but two things kinda shoot down the jetting theory. One that this never happened, regardless of temperature, elevation or tightness of trails before 6mo's ago. And second, I just installed (before this last ride), a JD jet kit with the main going up 4 sizes from stock. I'm betting on the elecrical what with my CDI and coil having close to 400hrs on them. I'll post up when it's conclusive.

if ya went up 4 on the main that would do it,as the bike gets hot it needs to be leaner,the only reason its probly running at all is its cooler this time of yr and it needs richer jetting. it started again after the jd jetting kit right?(just a few days ago according to your 1st post on this thread) the main will overlap the pilot when its real rich on the mj,and if your using the blue needle thats also richer than the red one. which clip?

JD suggested going up 3-4 sizes on the main? That doesnt sound right. Did it run good/well before the JD kit and you were looking for that little extra? Highest point in N. Carolina (Mt. Mitchell?) I think around 5000-5500 at the most. That would require going down in main anyway.

Ok, I guess I'm over confident about this being electrical because (1) it sounds more like a miss-fire than a rich or lean studder, and (2) all the advice I've gotten suggests that electricals are more likely to be effected with increasing engine heat and jetting being dictated more by the time of year or altitude (but not being effected by engine temperatures rising during any given ride.)

But assuming that it could be jetting, here's what I did with the JD stuff right before this last ride. I followed their instuction sheet for my bike ridden at an altitude of sea-level to 4000ft.

170 main (up from a 165 stock) (they recommend a 168 for 3 to 6K feet)

Blue needle with the clip on the 4th from top (they suggest the red needle for warmer months)

the thinner o-ring on the AP lever (they recommend the thicker one for MX)

fuel screw out 1 1/4 turns

Before the bike got really hot she absolutely ripped too. That's another reason why I thought I had the jetting nailed and the problem must have been electrical.

between all of that you really richened it,wiring the ap (what the oring does effectively) richens the bottom considerably,especially in tight on/off throttle. that won't effect steady throttle though,but between the richer needle and richer main it could well be jetting,when my main is too rich it stumbles(say on connector roads) at 1/4 to 1/3 steady throttle,kinda; baaah,buh,baaah,buh,baah etc.. get on or off the throttle and it stops. heat changes it because a hot motor requires a leaner mix (hot air is less dense) the same way it requires richer when its cold. during a HS race i commonly have to reach down and lean it out about 1/2 way thru. a new coil won't hurt and i have a 05 ign if it'll work? but if its still doing it after that my $$ on too rich:thumbsup:

So whay would you try first, going to the red needle, higher clip position or down on the main? Oh and thanks on the '05 ign but they don't cross over to the 426's, I checked.

I hear ya Bob, but two things kinda shoot down the jetting theory. One that this never happened, regardless of temperature, elevation or tightness of trails before 6mo's ago. And second, I just installed (before this last ride), a JD jet kit with the main going up 4 sizes from stock. I'm betting on the elecrical what with my CDI and coil having close to 400hrs on them. I'll post up when it's conclusive.

If you are basing your jetting changes on a stock MJ of 165 you probably are too rich. The stock MJ on an '02 426 is a 162

go back to the 165 1st,then if it still does it move the clip up one,that should be enough until the weather warms up. btw what were the temps and elev where it occurred? it wasn't one of those freakishly warm days we had awhile back was it? have you already changed the coil,because you should try it 1st without changing jetting with the new coil(to see if that was the prob) and bring a 165 with you and the tools to change on the trail:thumbsup:

go back to the 165 1st,then if it still does it move the clip up one,that should be enough until the weather warms up. btw what were the temps and elev where it occurred? it wasn't one of those freakishly warm days we had awhile back was it? have you already changed the coil,because you should try it 1st without changing jetting with the new coil(to see if that was the prob) and bring a 165 with you and the tools to change on the trail:thumbsup:

It was a mid 50deg day at Brushy (3000ft?).

I'll be changing the coil this week and hopefully riding again on Sat. I'll post results, thanks Bob.:lol:

thats cool,i just hate to see ya scratchin' your a$$ raw over it. brushy is 1400-2400 +/- is what richard told me. right now my jetting i'd run there is 42pj 165mj 4th clip 1.5 turns:thumbsup:

I took the coil down to the local shop and they OHM tested it right in front of me and it checked out to spec. Can they check out OK when cold but fail when hot?

Don't know about on a 426 but on KTM 50s, yes this can happen. I don't recall where the coil was on my 426 but if it is close enough to the engine to get some heat, it may be the problem. I was going to say coil (see previous KTM 50 experience) but you already replaced that.

I was going to say coil but you already replaced that.

Not yet, just got the new parts today. I'm gonna try my next ride with just the jetting change first and see what happens. If that was it I'm still gonna do this coil mod just to get rid of the coil on the frame.

Went riding today at the same elevation and same temperature but leaned out the jetting (by lowering the needle 1 clip and going back to the 165 stock main).

Same issues...once warm it's cutting in and out all over the place.

For the next ride I'm gonna change out the coil, after that the CDI box

and if none of that does it I'm gonna take up roller-blading.:ride:

well at least ya ruled that out,it was worth a shot. its more than likely the coil....i heard rollerblading is fun.:ride:

Hey Fastest1 and Moto2000, I was told this is a coil-plug from an '04 R6 from the shop where I got it...does it look like the right one to you?

I could barely get it past the top frame tube (had to really force it) and once it was in it wouldn't insert far enough to seal the top.

coils002.jpg

And as you can see below it's about an inch longer than the stock one plus the stock one's plug top reciever (?) is half way up inside vs. the R6's is right on the end. (the white lines represent how far the plug goes up inside)

coils004.jpg

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