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half a stelvio

C

Chadlebowski

Cruisin' Guzzisti
Joined
Jul 28, 2015
Messages
149
Location
West Sussex; UK
I carried out a service on my 2008 Stelvio. I replaced the spark-plugs, now something isn't quite right...

Once the bike warms up, it seems like only one cylinder is firing, especially under 3000revs and in a low gear. It made riding through central London on a Saturday evening very interesting! Also, the popping on decel was far more common. At higher speeds, everything seemed fine, although there was one instance of hunting\jerking\loss of power over 60mph, but this was short-lived and temporary.

Any thoughts?

The other thing I should say is that a new air filter was fitted, and I changed the oil (although not the filter - don't shoot me - didn't have appropriate wrench, and will replace filter next week, after another 100miles approx).

Ta!
 
You may have buggered up one of the the plug boots when you pulled them off or they are not on all the way. Do you have the replacement NGK boots on the bike ? If not just do a search here an you will find the replacement part. If you do have the original boots pull it off and look for white marks. That will be where it is arcing. You can put some electrical tape on it for now.

You may have also pulled the other end of the wire off the coil. Easy to do as they are not on there very tight. I cable tied mine on to prevent it from coming off.

Lastly, what torque did you use if any. Do not use the torque value in the book. Think it has it at 22 ft lbs. wrong torque. Many have used this and snapped the plug right off. I just use the angle torque that is on the box. Think it is 180 degrees but that is from memory.
 
Ah right - thanks for getting back to me... I was pretty careful taking the boots off, used an angled pair of pliers and levered them off... The were re-tightened to 20nm... I shall have a look this evening; hopefully the boot just isn't sitting snugly!
 
Right - it seems I went running to the forum far too hastily.

Checked the boot last night, it just needed to be pressed in another click. However, this morning, the RH cylinder was misfiring, although again this was just down to the boot having jumped off again!

I suspect it's all the vibration. I've ordered replacement NGK boots. I'll hang on to them as back-ups.

Can anyone say why this only happens once the bike warms up? And why only in low gears under 3000rpm?
 
Right - had the covers off again, started the engine and noticed sparks seeming to be coming from the underside of the 90degree section on the stock boot. This was intermittent, and explains the issue I'm experiencing.

Will insulation tape help in the interim?

Also, I have purchased the NGK replacements... The tutorial on this page is very thorough, but can I just check that all you need to do is screw the severed cable back into the new boots i.e no stripping or other wiring work necessary?
 
Chadlebowski said:
Thanks canuck1969... I've only been riding for about a year, and the Stelvio's only been mine since May... Lots to learn; requires patient teachers!
Click to expand...

No problem. We were all there at one time.

With the tape it will need a few wraps and will last for a little bit but the heat and water will eventually break it down so keep an eye on it. If you can fine rubber electrical splicing tape it will last longer.

Best to get those new caps on as soon as possible so you can enjoy the ride.
 
Ha nice one! I ended up changing the boot, but pulled the ht lead out and then struggled removing bodywork to get at it! All running smoothly now - valve clearances done too.

Didn't place the bottom seal on the cap - is there not a risk that the cap will pull out and the seal will get stuck in the cylinder?
 
Chadlebowski said:
Ha nice one! I ended up changing the boot, but pulled the ht lead out and then struggled removing bodywork to get at it! All running smoothly now - valve clearances done too.

Didn't place the bottom seal on the cap - is there not a risk that the cap will pull out and the seal will get stuck in the cylinder?
Click to expand...

I ran it for a long time with out the bottom seal as it did not fit. IF it fits, then use it. It will not come out assuming it fits properly. There was a big debate that without it it would allow water to get up to the electrode on the plug...dis-proven. I ran my garden hose, full steam through the opening to the plug tube by the exhaust pipe. Ran the bike for a couple of minutes with the water running and not a hiccup.
 
good advice... given the nightmare that was getting to the other end of the HT lead, from now on, if it ain't broke, don't fix it... Don't even fiddle with it... Don't even think about fiddling with it!

If your garden hose experiment was conclusive that's good enough for me. Realised I've spent longer tinkering with the bike than just enjoying riding it!
 
I had the dodgy Cap syndrome just after getting my Stelvio last month.
I've replaced the Cap, but used the NGK all-rubber type, I prefer them to the Plastic version.
They fit the same way . . . just another option for anyone that hasn't done theirs yet.
sd05fm-p400.jpg

 
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