Fazer rough running...again.

[chickenstrip]

Had this develop a short while back, felt almost like a twin at low revs (2-3k), fine above that. Had the bike serviced (carb balance, plugs, air filter cleaned etc) and was back to it's lovely smooth self again. For a while. 1500 miles later, it's back how it was, like it's not firing on one or two cylinders at those low revs. Get above that to say, 4k, and all is fine.

I have two suspicions, but am not at all sure, and could quite easily be barking up the wrong tree with both.

Firstly, I have never liked the Delkevic tri-oval can it came with - it always sounded a bit rough, uneven, almost like the bike was a triple, although at first, and for several thousand miles it didn't actually seem to effect how the bike pulled. The Scorpion oval can I had on the last one seemed to suit the carb and air filter mods better, and I never had this problem on that one. The same modified carbs and air filter are now on this bike.

The other thing I am wondering is: the Scottoiler vacuum take-off cap sits very loosely on the take-off, defo not an air tight seal, although the oiler itself seems to be working fine. Can this put the carbs out of balance/cause any kind of running issues?

Replacing the can with a Scorpion will be expensive, and then will need to have the carbs rebalanced - one option I'm considering.

But if the problem is something else (Scottoiler fitting as mentioned?), it'll go out again, and will have to fix that and have the carbs rebalanced again. So maybe deal with both issues at once (assuming they are issues), and only need to get carbs rebalanced once.

Or do you think I am completely wrong (not unheard of ) and need to look for something else? What?
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[temeluchus]

Wrap a couple of turns of plumbers tape around the vacuum take off to improve the seal on the scottoiler doofer. See if that improves things.
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Some shite cruiser. Now with guns and FREEDOM!

[chickenstrip]

[P.]

What year is your bike and what year R1 engine did they rob.

[Matt B]

TPS fault, sticky EXUP valve (if it has one)?
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[P.]

My query was to see if the 04/05 engine was used. I've heard of 2 instances now of sticking 2nd butterflies.

[chickenstrip]

[pompousporcup...]

could it be dirty/crudded pilot jets on 2 cylinders ? low speed is crappy but whenst throttle is engage it picks up (sounds like the issue mine has (although not a fazer))

crappy carb rubbers* on 2 cylinders?

[Vincent]

Id be looking at dirty fuel or one of the coils breaking down/loose connecter. May be worth checking that the plug caps aren't worn too....where they attach to the plug.
Rather than fiddle about with tape to check the Scottoiler, just disconnect it, plug the feed back up and try without. You sure it's running on 2 and not 3?
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[chickenstrip]

Used plumbers tape on the vacuum take-off, so now the Scottoiler cap fits much better. Seems a bit better. Hmmm, maybe I'm imagining it. Took it for extensive test ride, seems to be confined to a shorter rev range. It's just off idle to just before 3k that it's apparent, and seemingly only in the lower gears. In top, it pulls smoothly from about 2k with no sign of the problem. Worried I'm going to over-analyse it now though

Pilot jets seem a possible. If coils breaking down, would have thought it'd be more apparent under load, at higher revs?

On the service, the chap said the plugs looked ok, so he left them. So maybe a dodgy plug, or plug cap/HT connection. Could try taking a bit off the ends of the HT leads I suppose.

Why am I still suspicious about that can?
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[Vincent]

[chickenstrip]

[Matt B]

[doggone]

[chickenstrip]

I've wrapped a bit more of the tape around the outside of the cap and over the remaining exposed part of the take-off pipe. Tried the bike today, and it's definitely a lot better. I'll see how it goes for a bit, but going on today's ride, I don't think the carbs will need rebalancing. It's not perfect, I can still detect a hint of the symptom, but only in a very narrow rev band and not nearly as bad as it was.

When my mate swapped the Ivanised carbs and airbox bits from the last one, he test rode it and said it was fine, but he didn't like the Delkevic can - "makes it sound like a triple." On first riding it, I saw exactly what he meant. It felt just a little uneven, like it couldn't quite clear it's throat until over about 3k rpm. So it may be that the remaining symptom is now just due to the can, which is why I asked in my OP if anyone thought this could have an effect.

i've now ordered a Scorpion can, which I know works well with this set-up, as it's what I had on the last one (it got trashed in a Welsh hedge). Once that's on, I'll decide whether or not it needs further work. I wanted this can anyway, so it's not a waste if it doesn't feel better with it, as long as it's not worse.

Thanks for your replies.
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Chickenystripgeezer's Biking Life (Latest update 19/10/18) Belgium, France, Italy, Austria tour 2016 Picos de Europa, Pyrenees and French Alps tour 2017 Scotland Trip 1, now with BONUS FEATURE edit, 5/10/19, on page 2 Scotland Trip 2 Luxembourg, Black Forest, Switzerland, Vosges Trip 2017
THERE'S MILLIONS OF CHICKENSTRIPS OUT THERE!