Engine rebuild

[Old Nick]

Have purchased a running 1098 cc engine to replace mine,(Iwas going down the route of a 1275) but the prices for them,even a claped out one is getting too strong for me and at the end of the day she only goes out on high days and holidays!,Would have been nice tho sigh ...Anyway have partialy striped her down and the bores are are nice and smooth without a hint of a ridge,crank is nice and smooth with no scoring and bearings a nice even gray colour,Even the timing chain and gears seem ok,my question is whilst i have her stripped down would it be wise to replace the rings and bearings,and or anything else? oil pump perhaps ? also the locking tabs on the big end caps are missing,i take it i should replace them ?

[matt1975]

If it were me i'd replace big ends, mains, chain and oil pump then you know its good for the long term. Pack the new pump with vaseline as a dry pump may have trouble picking up on initial start.

[beero]

I would take the rings off and measure the tolerances with the ring in the bore. If they are worn and you replace them you will have to hone the bores. I would do main and bigend shells as well as oil pump while you have it apart.

[bmcecosse]

Chances are you will break the rings if you fiddle with them - so just make sure they are not sticking/jammed with carbon. But yes - new bearing shells and oil pump. You don't need to vaseline it unless you are going to let the engine stand for ages - just prime it with fresh oil. But DO check the base plate and spring are present in the oil filter casing.

[Old Nick]

i know with pistons the oversize is stamped on the top,how do i tell if the crank has been reground,will the size be stamped on back of old shells or stamped somwhere on crank or con rod shells ?

[newagetraveller]

It should be stamped on the back of the old shells. I take the old shells and one of the pistons along to my local motor factors or engine rebuilders and tell them the engine that they have come out of. They get the parts for me.

[jaguar68]

It may not be a good idea to pack the oil pump with vaseline, as it has a moisture content. Grease would be better, cranking the engie over every now and again, if stored, probably wouldn't be a bad idea.

Regards

John

[bmcecosse]

Seriously - it's not a problem - just run some oil through the oil pump - don't put it on empty. Before you start the engine - be sure to run it up with the starter motor until it generates oil pressure - and then keep going for 10 seconds......

[katy]

be sure to run it up with the starter motor until it generates oil pressure - and then keep going for 10 seconds......

Suggest that you leave the spark plugs out for this, easier on the starter and the battery.

[Old Nick]

Thanks,points noted !

[dellerie]

if you remove the plugs, would oil not poor out? i am not too clued up on the mechanicals of these engines

[kennatt]

dellerie no oil will come out if it did the engine is basically done for,the workings of the internal combustion engine are no great mystery do a search on google and there are loads of descriptions of how it works,far too lengthy to discuss here,but good to see that you are trying to get to grips with it,it held my attention from the age of 11 to my now ripe old age of 65, stripped and rebuild my first at 13 and never stopped,good luck