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[AMCQ46]

100% agree with Tony's comment. And as the bike shop may not know too much about firestorms don't let them fob you off, print out Tony's instructions and ask them to follow them to the letter.

Also make sure they don't put the fuel tap vac hose onto the wrong pipe on the tap when they rebuild... You don't want to have a double whammy of the 2 most common garage errors on your bike in the 1st week of ownership

[Gazfirestormowner]

Thanx guys they gunna look at it beginning of next week so am sure it will get sorted

[tony.mon]

It's ok to ride in the meantime, you can't do any damage, just keep under 5K.

[Gazfirestormowner]

I think I would struggle to keep it under 5k lol

[darkember]

Agreed.
The issue isn't that the timing is wrong, as pulling the cam covers off will reveal the timing marks lining up properly, but the relationship between one cylinder firing and the next, how much the crank turns between firing pulses.
You'll find that the rear cylinder fires, then the front one fires 90 degrees later.
You need it to be 270 degrees later.

All they need to do is turn it to tdc rear cylinder (no need to touch the front one) with the cams pointing up and towards each other, then remove the cam caps and cams, then holding the cam chain loosely to stop it jamming round the crankshaft, rotate the engine anticlockwise one full turn at the crank, until RT is lined up once more.
Then fit the cams, with lobes pointing up and towards each other as before.

Half an hour, tops.

Someone's been taking cams out........probably a failed CCT recently, but possibly just valve clearances done by a numpty.

Suggest you print this out and give it to them.

I love how you say half an hour tops. That jobs without confidence will take ages

[tony.mon]

The only thing that would make it a longer job is undoing the alternator inspection cap, to access the crankshaft end nut to turn the engine over.
But as I'm fairly sure that this has arisen because some work has been done recently, it should still undo easily.

Five mins to take the tank off, another five for the rear cam cover bolts, take off the two inspection caps, rotate engine to RT, lift off rear cam cover and see if cam lobes are up and towards each other or downwards and away, if downwards rotate engine anticlockwise one complete turn back to the RT mark.
Undo rear CCT and remove.
Another five mins, fifteen so far.

Now undo cam cap bolts, nine in all, don't drop the sideways one down the cam chain tunnel.....
Rotate engine one complete turn anticlockwise.
Five more mins gone.

Reinstall cams, CCT, cam cover, tank and ride to pub.

30 mins.

[VTRDark]

It's true though. It's no different from doing CCT's really and would take someone who's doing it for the first time no more than an hour as long as one don't run into problems. What takes the time is all the coffee and fag breaks and double checking things.

(:-})

[lumpyv]

how come it would be ok up to 7 thousand rpm? what happens at 7k to stop it ? I would have thought it would be crap from the startup ?

[VTRDark]

I may be wrong and I'm sure I will be corrected if so, but if one side is 180 degrees out then I think both cylinders will be firing at the same time rather than alternately which would slow the momentum of the crank turning and cause a loss in power. Either that or they are both fighting against each other.

(:-})

[Kev L]

I thought it was due to the airbox having insufficient time to refill prior to the next cylinder igniting.

[VTRDark]

It could be they are both on the downward stroke. Like I say I could be wrong I look forward to Tony's detailed explanation.

(:-})

[AMCQ46]

Kev has got it. It's the fact the airbox can't flow enough air if both pots are sucking in to close together in the cycle.

[tony.mon]

Yep, airbox.
If you set the cam timing 180 out, one cylinder draws air in from the airbox, then 90 degrees of crankshaft rotation later the other one does. Set properly, it's 270 degrees later.
Air can only refill the airbox so fast, and the second cylinder is drawing on a partial vacuum, and so can't reach the correct air/fuel ratio, losing lots of power.

At lower revs, up to 5000 or so, the airbox has enough time between intakes (when 180 out) to still recharge, but over those revs there's just not enough time, and it won't rev out under load.

One day I'll build a split airbox, one airbox for each cylinder, effectively, and see what it feels like as a Big Bang engine, because it feels very good up to 5000.....and sounds great on open cans!

I think you'd need more space than is available in the normal airbox position, probably meaning an even smaller tank.
However, you could then run a single exhaust for each cylinder, without the join, and tuning each cylinder's carb separately would be a piece of piss.
Effectively, you run two 500 singles on a common crank.
Gotta be worth a play, surely?

[Gazfirestormowner]

Quick update the bike has gone into dealers for them to investigate hopefully will get it back in a couple of days.

[fabiostar]

Agreed.
The issue isn't that the timing is wrong, as pulling the cam covers off will reveal the timing marks lining up properly, but the relationship between one cylinder firing and the next, how much the crank turns between firing pulses.
You'll find that the rear cylinder fires, then the front one fires 90 degrees later.
You need it to be 270 degrees later.

All they need to do is turn it to tdc rear cylinder (no need to touch the front one) with the cams pointing up and towards each other, then remove the cam caps and cams, then holding the cam chain loosely to stop it jamming round the crankshaft, rotate the engine anticlockwise one full turn at the crank, until RT is lined up once more.
Then fit the cams, with lobes pointing up and towards each other as before.

Half an hour, tops.

Someone's been taking cams out........probably a failed CCT recently, but possibly just valve clearances done by a numpty.

Suggest you print this out and give it to them.

like how do i know its firing 90% out?