engine decision

[mmjosh]

hi i am wondering wheather to change my engine from a 948cc to a 1098cc reconditioned engine as it already has a 1098cc gearbox what do you think ?[frame][/frame]

[aupickup]

stick with the smaller one and sell the engine to me

seriously put the 1098 in

[mmjosh]

ill put a picture on tommorrow of it and then i am going to degrease it and paint it

[bmcecosse]

You need to record the change with DVLA - and tell your Insurance co.

[deano69]

But isn't the 948cc engine supposed to be a better engine?Most comparisomes between the two seem to conclude this even if theres a 6mph speed differance with the top speeds when new.

[bmcecosse]

It's a smoother engine - because of the shorter stroke - but the 1098 gives a lot more power! Partly because it's 16% bigger - but it also has a much better camshaft - and a better cylinder head. Put that cam and head on a 948 - and it' won't be too far behind - although will have to rev harder to make ultimate top power - which on both engines will be limited to much the same figure by head/manifold/carb. However -for ultimate best economy - the 948 should be better - and the 848 better still! Still looking for one!!

[deano69]

848!Do they exist?

[mmjosh]

added a picture now

[PSL184]

I want to keep the short stroke of the 948 so I'm gonna put a 940 head on the 948 block with a 1098 cam, LCB manifold, 1.5" exhaust system and an HIF38 carb. Should out do a "standard" 1098 I should think

[MarkyB]

There used to be a chap called John who did several MOTs in a 948 4 up and it was hard to keep up with.
ABS (Absolutely Bog Standard) looking under the bonnet but it went a LOT better than any standard 1098.

[bmcecosse]

Hurray! That engine has the necessary rocker cover WITH breather pipe!

[mmjosh]

i have a none breather rocker cover though

[bmcecosse]

Throw it away!

[MarkyB]

Put it on Ebay!

[mmjosh]

what the non breather rocker cover

[bmcecosse]

YES! It's useless!!

[mmjosh]

the thing i dont understand is what is so bad about them ?

[bmcecosse]

They don't allow the crankcase to breathe cleanly - so fumes and oil leaks soon errupt!

[mmjosh]

non breather rocker cover[frame][/frame]

[bmcecosse]

You could braze a breather into it! Any decent competition A series engine has HUGE breathers connected to the rocker cover!