Misfire and plug cap changes

oldgreybeard · Post by **oldgreybeard** » Sun Mar 27, 2016 8:59 pm

My 3LG had a bit of a misfire problem. Number 2 cylinder was firing back through the carb.
Intending to swap over 2 and 3 which are driven from the same coil - I found that number 2 plug caps was broken a kindly left the remains of itself in the spark plug access hole.

20 minutes later and a carefully filed down and bent 6 inch nail used as a hook we had the remains out.

Swapping over 2 and 3 then had the machine running on all 4 cylinders.

So the question is - where can you get these really long, bent end plug caps from or do any modern replacements fit?

Post by **Stig** » Sun Mar 27, 2016 9:07 pm

I believe NGK do that style of cap

http://www.ngkpartfinder.co.uk/files/NG ... Covers.pdf

oldgreybeard · Post by **oldgreybeard** » Sun Mar 27, 2016 9:14 pm

Cheers Stig!

If I carry on fixing things at this rate - there is a real risk that I might end up with 2 EXUPs on the road simultaneously!

Fatdog · Post by **Fatdog** » Sun Mar 27, 2016 9:25 pm

The one thing to note with the NGK caps is that the resistance of them is only 5k ohms, where as the Yamaha items are rated at 10k ohms.
But they are a hell of a lot more expensive than the NGK items!

exupbloke · Post by **exupbloke** » Mon Mar 28, 2016 2:26 pm

have you looked at the coil stick mod from here http://fzronline.com/wiki/doku.php?id=c ... _plugs_mod i did this a couple of years ago and my exup starts and runs sweet every time even after sitting out in the rain for weeks at a time.

Vagabond · Post by **Vagabond** » Tue Mar 29, 2016 8:25 pm

Same as exopbloke, I did the stick conversion, I had no end of troubles with the bike idling badly and cutting out in the rain.

The conversion did the trick.

oldgreybeard · Post by **oldgreybeard** » Wed Mar 30, 2016 6:19 pm

Thanks guys - I will keep a lookout for a set. In the meantime I have now got a set of NGK plug caps to try.

Back old aircooled RD days I used to slather an obscene amount of silicone grease over everything. It used to work but Oh - what a mess.

odbguy · Post by **odbguy** » Mon Apr 11, 2016 10:24 pm

Can i bring this up again ... iv found some NGK upgrade HT caps. Type 3r ..
Are they easy to change ? I looked at that other mod and it went completely over my head ... so if it's anything like that it doesn't matter !? Hah

Post by **Stig** » Mon Apr 11, 2016 10:37 pm

The caps simply unscrew off the ht leads and the new ones screw back in.

You may need to trim a few mm off the end of the leads to make a decent connection as long as there's a bit of slack to be had

odbguy · Post by **odbguy** » Mon Apr 11, 2016 10:57 pm

Ah sorry ... I ment lead and cap .. to change the cap sounds manageable .. lol
Would it be similar to change the aftermarket lead and cap ?

Post by **nugget** » Tue Apr 12, 2016 8:55 am

I'm sorry odbguy but you've lost me.

odbguy · Post by **odbguy** » Tue Apr 12, 2016 10:40 pm

Have I got something wrong ?? I'm not sure ?? Lol

Iv seen you can get a replacement lead and cap. NGK Type 3r. .

As stig said to replace the cap seems like a simple job just unscrewing the old caps of the existing leads then connecting the new caps with the possibility of trimming the lead to make a decent connection..

However what iv seen replaces both the cap and lead ... so that requires wiring into the ignition coil .. is that still a simple job ?

I'm sorry if I'm still not making sense. As you all know I'm new to all this and don't actually know anything about bikes !!! :/ haha

Post by **nugget** » Tue Apr 12, 2016 11:18 pm

Now I'm on the same page.

Fitting new caps to the ht is a simple job. Fitting ht leads to coils is a different matter. It can be done but it's a bit tricky. The problem lies in getting the old ht leads out of the coil. There's some barbs inside that hold the leads in. If you can get these out then you've done well. It's when you come to fit the new it leads back in that's the tricky bit. Why do you need to change the ht leads?

odbguy · Post by **odbguy** » Wed Apr 13, 2016 12:10 am

Haha thanks ... OK thank you. So probably be best left as they are for now ...

There isn't a problem with the leads or cap .. but it's 1 of the things I wanted to do..
Change them for some new red lead and caps rather than the black what I have.
It's not a necessity so I will delay that one for now.