Ducati.ms - The Ultimate Ducati Forum banner
  • Hey Everyone! Enter your bike HERE to be a part of this months Bike of the Month Challenge!

1 - 13 of 13 Posts

·
Registered
Joined
·
198 Posts
Discussion Starter #1
Took my 1995 carbed SP for it's first longish run today after changing the plugs to NGKD8EA ..all went well & for an old bike she's quite feisty!! :) But when creeping back into town & into heavy traffic after a 100Km easy but spirited run the exhaust started to splutter & pop a little @ idle in the traffic ..Doesn't seem to affect the performance whilst riding above idle revs but it's kinda annoying & disconcerting as if its gonna stall..

So i pulled into a garage & filled the tank (took 14 litres) so as to eliminate fuel shortage from the equation ..didn't see a reserve light come on prior but i reckon i must have been close to that point..So back at home i pulled the plugs & they looked alright ..(a bit blackish sooty but what i'm used to seeing ) popped them back in & it was still popping & farting idling ..So just as an afterthought i popped the old NGK DPR6EA-9 's back in & Voila" no popping!!!

Now maybe it's just a coincidence & i'll take the bike for a run tomorrow & see but has anyone ever had a problem with dodgy plugs in particular the NGKD8EA's? Should i throw in a set of Iriduim plugs & eliminate plugs from the equation so i can continue to troubleshoot if the problems still there ?

Also what are the troubleshooting tips if she's still being difficult & popping & spluttering? The bike's previous owner sold it due to illness so it wasn't ridden regularly of late although he assures me it was started @ least regularly..It's got the standard mikuni carbs & Staintune pipes with the restrictors removed..belts & shims were done approx 1000kms / 8 months ago...

Cheers
 

·
Registered
Joined
·
198 Posts
Discussion Starter #3
Hey dave..
umm no reason really i just read in the forums that the NGK D8EA was a pretty reliable & easily obtainable plug for the carbed 900SS..i didnt realise it was a diff temp rating...what bearing does that have on its performance?..
 

·
Registered
Joined
·
198 Posts
Discussion Starter #6
Cheers :yeah: will give that a go tomorrow
 

·
Registered
Joined
·
429 Posts
The plugs shouldn't be black and sooty. Take a meter from the electrode and the anode of each spark plug. The resistance should be near infinite. If not, as I've observed, you have some carbon junk that's shorting your plug(s) causing misfires, and popping. I've experienced this issue on my own '95 SP.
 

·
Registered
Joined
·
7,104 Posts
Sounds like you're running rich. Putting a hotter plug in only masks the symptom. When you replaced them with the correct heat range, they fouled. Try adjusting your air screws, maybe you will luck out. Screw them in and count the turns as you do so. Screw them out 2 1/2 turns to start. If your idle hangs, you're too lean and need to screw them out further. If it runs ok, try screwing them in 1/2 turn at a time till revs hang. Engine should be warmed up when doing this. If this doesn't lean it enough and plugs are still black , you may want to try lowering the needles 1 notch. This means you will put the clip in a higher groove so the needle sits lower in the jet. Make sense ? Running too hot a plug in an air cooled engine can cause problems. It shouldn't be done to avoid rejetting.
 

·
Registered
Joined
·
429 Posts
Also check for signs of oil fouling. These bikes have problems with valve guides failing prematurely. If it's a stock bike there shouldn't be much reason to go to a hotter plug.
 

·
Registered
Joined
·
395 Posts
correct plugs are;
Champion RA6HC
or
NGK DCPR8E

the heat ranges are the same

never substitute heat ranges unless you really, really know what you're doing. (especially hotter. don't ask how I know :( )
 

·
Registered
Joined
·
198 Posts
Discussion Starter #11
Thanks again everybody for your advice & tips...popped the NGKD8EA's with a wider gap back in & also tweaked the idle mixture screws to what was advised & all seems to be well again...

Just as an afterthought i'm wondering if the PO used a hotter plug & 98 octane fuel.. over here in Australia we only have 95 & 98 octane (which equates i think to 91 & 93 in the US) readily available & ive always been told to use Caltex 95 octane in my old dukes with hardened valve seats.. anyway will keep an eye on the plugs & not look for trouble just yet if i don't have too..:rolleyes:
 

·
Registered
Joined
·
155 Posts
I've been using 87 (in the US) in my bike with zero negative results. Change those plugs...
 

·
Registered
Joined
·
2,434 Posts
I use 85 octane in my street SS, at 6,000' elevation. Use the lowest octane fuel that will not pre-ignite, also known as detonate or "ping." More power, runs cleaner. If you don't need the additives that are in high octane fuel to slows down the fuel's burning rate, as you would with high compression pistons, then don't use high octane fuel. These motors stock only have 9:1 compression. I do use 91 octane in my track bike, but it has 11:1 pistons and I sometimes track ride at lower elevations, sometimes near sea level.
 
1 - 13 of 13 Posts
Top