All 2st Spark plug cap reminder

I've been chasing my tail on my wr300 for quite a while now. It would foul plugs quite often and I could never get the low/mid to run properly, but the top end always felt fine. After trying numerous jetting changes I figured it had to be electrical. Just before I began stripping all the electrical components off the bike for cleaning and reassemble I figured I should first check the plug cap.

Since I replaced the OEM cap with an NGK cap after I bought the bike I assumed it would not be the problem, but as it turns out the cap was not making good contact with the lead wire. I pulled the cap, cut the tip of the lead to expose fresh wires and put the cap back on making sure to seat it properly.

Problem solved! The bike ran better than it ever has this last weekend. It started great, idled great and had no problems with my little-too-rich jetting all day long. It ran and felt awesome!

In my efforts to avoid problems with the OEM cap I instead created a problem. Luckily it only cost me frustration before being fixed!


Hope this helps someone one day....

Good Point PC! I checked mine a while ago and mine was the same way on my 250. I also added one of those spring clamps where the wire goes in the cap for a water tight seal.

I’m glad to hear you got the problem fixed. In the past I have chased a problem with the motor missing at high rpm. Now I know it is just time for a new plug and the problem will go away.
BTW if you thought my WR was a strong runner before you should try it with the CR ignition. It flat out rips! You are not going to regret starting with the CR instead of a WR. When will you have that bike anyway.

The only reason I even checked the plug cap is cause we talking about it last weekend Mark. Thanks for bringing it up!

And I thought your bike ran great last weekend. I was impressed as-is, but glad to hear you liked the CR ignition... I was worried about it how it would be in the woods, but maybe it'll be better than I think.

I Just talked to Bryon and the new frame is in the states and heading to OR. I'm hoping to have it next week.



Darin,
what's the spring clamp you speak of? Does it go around the plug cap only or both the cap and wire?
A little waterproofing is a great idea.

I never had a problem with the stocker either. I thought I was doing preventative maintenance.
Didn't quite turn out that way though!

I'll post a picture tonight! Just put a new cap on the 06 and clamp. I always did it on past bikes but I think it helps hold the wire in better and keep from twisting.

These are what I use. It makes a tight compression seal also makes the end stiff so the plug wire doesn't work it's way loose. I got this last kit at O'reilly auto parts. They also sell them in various packages. Take your cap in to size the end. I use the small ones on my carb vent hoses and T's to run to air box.

Being in the electrical contracting business I would be concerned about arcing between the clamp and the frame (or other metal parts) in damp/wet conditions or if the dielectric strength cap/wire starts to break down. Why not try a nylon zip ty and some silicon?

On the old bikes I used a zip ty. Some of the old good caps used a clamp and phillip head screw. I went this route because on my RMZ, the 4ST heat would make the wire come out of the cap. It was an old solution to an old problem.