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[Sixty-5 Endevour]

Hi Folks

Im considering changing my iron barrel for an aluminum one... I know there are a host of other changes I could make.. do you think just changing the barrel will be worth it.. or do I need to change the piston etc.. what would be your minimum upgrade ?

Cheers all

[Adrian]

A new forged 6.5:1 alloy piston matched to that alloy barrel...



A.

[Sixty-5 Endevour]

Cheers Adrian

[Alan R]

Hi Guys------H & S STRESS WARNING !!!Be prepared that your head will be a B'stard of a job to actually remove when the time comes !!..Usually it'll be the original soft steel washers have spread under loading and wedged themselves into the thread of the head studs..

Yes, as per Adrian's reply......These things aren't cheap and you don't want that OE cast piston ruining your day at a later stage, do you ??....I've had 2 in the past years of Bulleting and would strongly advise you to buy from our hosts if you do not have access to any Engineering or machining facilities for remedial work.........They do several quality and accuracy checks on the ones they sell and guarantee the barrel to be ok...........The "less expensive" one that I bought had a nice inclusion ( A casting blemish ) in one of the push-rod tunnels which weeped through to the outside when at running temp..... A home-made Aluminium liner sorted that out but it's not for the faint hearted to attempt...

First thing is that you'll notice just what a difference there is in the weight !!.......You may also think the engine sounds a little noisier, perhaps ???...........A "Must-do" is measure the height of the spigot on top of the barrel and the matching recess in the cylinder head.........The recess must be deeper than the spigot otherwise the head gasket won't be clamped down !!! ..............Buy a new head gasket OR re-anneal the copper one....In the latter case I usually apply a bead of Welseal around the pushrod tube holes on both sides to help prevent oil weeping but you shouldn't need to do that with the composite types..................As you've just gone to a great deal of time and effort to get this far you might want to consider giving the cyl head assy a strip and check-over as well ??

[stinkwheel]

If I was going to spend £200 on a "virgin" bullet, I'd have a forged piston and a balanced rocker set from out hosts before I had an alloy barrel. I'd invest in a set of hardened head washers and some square-ended engine studs at the same time.

[Sixty-5 Endevour]

Hi stinkwheel

Thats an option I had not considered, I thought overheating was one of the problems linked to engine failure, but if you think the barrel can be left, what are the benefits of the balanced rocker head ? I have a basic understanding of engines, however do not know about such things. Im having the work completed by a great local company, but would like to be as best informed before I get the work started

Kind regards 65

[stinkwheel]

Original rocker on the left, balanced samrat rocker on the right.











So yeah. Enormous amount less moving mass/less inertia = revs quicker and revs higher. Making a moving part weigh less will allow it to accelerate more quickly and will always pay more dividends than reducing non-moving mass. Like with suspension, a reduction in unsprung mass (wheels, brakes etc) is reckoned to be equivalent to saving three times as much in sprung mass (rider, luggage, frame... alloy barrel.



I don;t think overheating is a major cause of bullet engine failures. Someone may correct me but I'd go with primary piston failure followed by oil pump drive failure as the two most common causes of a catastrophic engine failure. With electrics being the number one cause of minor breakdowns.

[Barry_Q]

I actually have an alloy barrel on my Lightning (I also have the Samrat rockers). It's all very much 'Plug & Play'. I bought it to make the Lightning look a little more modern. The only difference that I've noticed is I have to use the choke more often.

[Sixty-5 Endevour]

Cheers again SW.. I will read up on this upgrade, thank you so much for taking the time to reply. This forum is such a fantastic resource, but it’s all down to the generosity of folks like yourself. I will start doing the maths and work out what I can afford to upgrade this time around.

[Alan R]

Hi Guys--------Hi BarryQ, With so much Iron now missing and replaced by a lot less material which is now Aluminium ( which in itself is a great Heat conductor ) then the total mass of Head, barrel and Piston will not only heat up quicker --- but cool down quicker than before....So your observation is spot -on I'd say..