Steamer Misfire question (and new member introduction)

[Mustang]

is the cap on the right hand snorkel on the air box ? cuz if it isn't it needs to be !
The tiger should only have 1 snorkel open or it will run just like you are describing .........

[Suitor_Stu]

is the cap on the right hand snorkel on the air box ? cuz if it isn't it needs to be !

 :oops:   :roll:

erm, nope...that whole bit beside the battery bit didn't go back on after I'd had the carbs off this time, just incase they had to come off again...would have thought that it wouldn't mattered that much though being the other side of the filter but will re-fit it tomorrow before testing again.

If it works it'll be a bit of a d'oh moment (although not quite as much as the good ol' kill switch trick!)

[Suitor_Stu]

Right, okay so the snorkel thing didn't work.  Basically to help stop any confusion about how/what the misfire is like I have made a wee video trying to explain the thing;



Sorry about the camera angles and also the 30s of dead footage in the middle, but I couldn't be arsed editing it all down!

The bike will run, but will die when either opening throttle quickly or when it gets too high in the rev range (as shown on the video - watch my throttle hand towards the end).

My thinking now is it's either coils or possibly leaking airbox - didn't think about this one before, but the previous owner switched the stocker to a K&N numer and I damaged a wee bit of the airbox in the process.  I did my best to sort it all with silicone sealer, but this could be the problem?

Anyway see what you think.

[Mustang]

it's got the symptoms of the main jets not being big enuff

quick throttle ..bogs down.....shut throttle some speed picks up = main jet too small
 
won't run good past 5k = too much air getting in and not enuff fuel , needs bigger main jets

k&n filter = more air ........probably needs bigger mains

and the real test will be to road test it ............sitting static in the garage won't help much need to see what it does under load

triumph three cylinder bikes are very fussy about what you do to the air box

is the steel perforated plate still in the box covering the center of the air filter ....it needs to be there .

you may want to get a new stock filter assembly from triumph (just the filter box not the snorkels)

ps . the video didn't help much for diagnosing purposes
and you will never get a perfect idle out of it , thats the nature of the beast , also they are velocity slides in the carbs so they take a sec for vacuum to pull them up they will never be as responsive as a carb that the slide lifts with throttle cable.

[Suitor_Stu]

Right, well I'm gona agree with you there about the lean running thing - mainly because the airbox was in a bit of a mess when I opened it, but as I said K&N was on by last owner and it ran fine on the same jetting (admittedly this was stock jetting so wasn't prob doing it much good).  Perhaps a combination of cleaning it of debris and possible leaks in airbox are contributing.

I'll whack in a new stock airbox and see how things are.  I take your comment on the idle thing, I don't expect a smooth idle but this thing pops every now and again whilst idling which surely isn't normal.

A road test is out for the time being unfortunately, it needs an MOT before I can legally do that.  Don't think they can fail you for an misfire but it sure doesn't fill me with confidence riding the thing to the dealers in this state!  

But aye, if it were coils failing under load what you are saying that wouldn't really show in a garage environment but on the road instead?

[Mustang]

what are you setting the idle speed at ?

1200-1400 rpm works pretty good and an occasional hiccup in the idle is not that big of a deal the road test is what you need to confirm how it's running

getting too much air is going to prevent it from being able to take any throttle past 5000 rpm .

[Suitor_Stu]

I think we may be on to a winner here;

Went to the garage again and dismantled the airbox on it right now, filled every crack and screw hole with silicone sealer (and there were a few blanking plugs missing too so they got filled), put the thing back together and whacked it back on the bike.  

Dropped a fresh set of spark plugs in and bolted together rudimentry bodywork (i.e. a couple of tank bolts and put the seat back on) and took her for a wee spin around the block, private roads of course...for a mile or two's worth just checking out the pull through the range.

As you well know it's a lot easier to tell how a bike is running by using that most unique of diagnostic tester - your arse.  Basically it's running a lot better with the sealant in place.  Running perfectly up to about 2.5-3k (which I can assume is pilot jet) then it starts to get a bit more patchy after that.  The most important thing I feel is that quick openings of the throttle now just result in stumbling rather than the engine giving up completely.

Pulled the plugs on returning to the garage and this was the result.  Now bearing in mind these were fresh plugs when they went in 2 miles before this pic was taken I think I would say that they are denoting an engine running on the bad side of lean, would you agree?

[Mustang]

can't tell much from the pic of the plugs and to get a true reading you need to kill the engine at 4k and coast to side of road and pull the plugs , not easy on tiger .

your bike should have mikunis on it and if everything is stock they should have 105's in it for main jets and be running pretty sweet

not being there to see what is happening makes it hard to diagnose
but if that bike was running anywhere near right the plugs should be a choclate tan color on the ceramic  even black soot would be better than grey or white
if it stumbles hard on a quick throttle pull while riding it and then if you close the throttle back some and it recovers and actually starts to pick up rpm your mains are too small and i would increase them to 110's if they have 105's in there also set the pilot air screws at 2 turns and those mikunis should have the needles set in the middle notch .

[Suitor_Stu]

Okay, just to give a wee update/summation on this thread;

Mustang, although it may be hard to see, those plugs were really white/grey so I knew at once that it was too lean (jetting was all spot on for stock) and since a new stock airbox and the original jetting is less likely to cause a farse-up than non standard stuff that's the way I went.  Fired everything back together and bang - running sweetly once again.  After a wee pre MOT shakedown I found that there was a problem with the bike dying if holding high revs/open throttle for too long, like the bike was running out of fuel - which after a wee bit of searching turned out to be the case.  I removed the nylon socks as per others on this board and fitted an inline filter and that went away.

Took the old girl for her MOT and passed, so went off that day for a wee 250mile odd jaunt to go sign some papers to sell my old flat (not a good day for it mind you - encountered snow on 3 separate occasions...In MAY!).  When I got to my destination and took out my earplugs I noticed that dreaded 'rattlecan' sound coming from the engine - definitely sounded like something that wasn't there before, but I was far from home, no choice but to stick in the earplugs and ride back.  

Parked the bike and went straight to bed, but got around to pulling the alternator at the weekend there and, you've guessed it...

Great buggery-fuck!  This bike is more temperamental than my Enfield!  It's a clutch side break as well, so I'll be reading through the topics linked at the top of the page, but no doubt I'll be needing a wee bit of help with that too...


Cheers again,
Stu

[Sin_Tiger]

Looks like the previous owner/s got lucky. Now you are finding all the usual suspects, should be well sorted soon, just a couple more to go.

Does it ever stop snowing up there, Cockbridge - Tomintool road still closed then