First start up

[Craizeehair]

I am getting close to starting up my CB360 after stripping and reassembling, the top end has been off and rebuilt.

I know this is a basic question but it’s the first engine work I have undertaken.

I know that I need to make sure that I have oil getting to the top end but how long should this take roughly?

I don’t want to panic and convince myself there are problems too quickly but also don’t want to have it running for too long and do some damage.

[K2-K6]

Likely within a minute to 90 sec would be a practical estimate.

But fresh build, plugs out and turn it over with no compression to get the oil distribution competent before starting is worthwhile.

If you don't want to spin too long on starter, then push it around in second gear with plugs out to get oil circulation throughout would supplement this process.

[Craizeehair]

Thank you, as per previous advice I’ve seen here I will put a piece of white paper close to the front tappets and check for splashes.

I presume the amount of oil will be sufficient that there would be no doubt that it’s there?

[flatfour]

My brother owned a CB250 G5 many years ago and, following some top - end work I remember the mechanic slackening one of the nuts above the cam box that, I think had a copper washer fitted under it. As I worked in a car workshop at the time I asked the purpose of this and he said that it was to confirm that oil was reaching the camshaft.

[Craizeehair]

Well I convinced myself that I wasn’t getting any oil to the top end. I tried with the white paper for a couple of minutes but didn’t get any splashes. I’ve whipped the rocker cover off and I did have some oil up there.

As you can see the right hand oil bath has oil covering the bottom all over, the right hand bath has some oil but not as much. There are signs of oil on the tensioner bolt head and the valves but to be honest, I was expecting more, there is oil in the centrifugal filter as well and the rockers have a layer of oil on them.

The bike has probably run for around 3-4 minutes or so I guess, would this be about normal for a short start up after a rebuild?

Is the fact that there is some oil up there a good enough sign to put it back together and run it until winter?

I’m getting myself in a bit of a tizz as I know how weak these engines are regarding the oil delivery and camshaft and journals.

Any opinions would be welcome.

[Laverda Dave]

I would expect to see a bit more oil in the oil bath below the cams if the engine has been running for 3-4 minutes. Did the top end sound rattly when first started and did it quieten down after the oil began to circulate or did it sound the same? I am not really experienced with these engines but if one side of the head has more oil than the other I would be concerned the oil jet on one side is restricted and not delivering the correct amount of oil to that side.

The cam chain is picking up oil from the bottom of the engine as it goes around the crankshaft sprocket and it could be splashing oil at the top end as it comes back up to the camshaft. The oil filter is also in the bottom end where oil pressure is likely to be unrestricted.

It will be very messy but I’d be tempted to run the engine on the starter motor in short bursts with the rocker cover (and fuel tank) taken off and see if the oil is reaching the top end.

[Laverda Dave]

I've just noticed the oil seal is not on the end of the camshaft, did it fall off when you took the rocker cover off?

[Craizeehair]

I've just noticed the oil seal is not on the end of the camshaft, did it fall off when you took the rocker cover off?

Yes, that’s to one side for now

[Laverda Dave]

Is that instant gasket on the rocker cover? There appears to be a lot of gasket debris on the edges of the mating surfaces and into the threads. You didn't use liquid gasket on the crankcase to barrel joints did you because that can be squeezed into the oilways and block them and that could well be your problem. Likewise if loose instant gasket debris floats around in the sump it can be picked up by the oil pump and sent up the oilways and create a blockage at the restrictor jets.

[Craizeehair]

That’s hondabond, I only used it on the rocker cover. If it looks excessive I might have been a little heavy handed but the oil looked ok when I dropped it and the filter screen was ok, so hopefully it can’t do much harm there?

I did crank it with the top off as you said and I’m sure there is oil getting to there as it started to spill over ends by the camshaft. I’m quietly confident that there is some oil getting there but is it enough? 

I’m going to sleep on it but I may go with it for now and do a full rebuild in the winter.

[Bryanj]

If its enough to spill out of the trough its enough, dont forget the starter is not spinning the engine at running speed and the faster the engine turns the more the pump works

[Craizeehair]

Thank you chaps, I will put this back together today hopefully and crack on.

[Craizeehair]

Well, that was a mixed bag. Everything back together and checked the cam chain tensioner, valve clearances and static timing.

The bike started really easily and I thought I had cracked this bike fettling malarkey. Only to find it is firing on the right side only, no heat to speak of all more left exhaust.

Also he bike was idling around 1800rpm and I couldn’t bring it down a lower.

Now to try and find out why!

[Craizeehair]

I’ve ordered some bits and bobs to try and get the bike back up and running, I’ve just received two new air filters and one of them has very poor glue to the rubber, will this be a problem or is it cosmetic only at that end?

[Laverda Dave]

Who did you buy that from? I would be sending it straight back, the engine will be sucking in unfiltered air and you'll probably have a job to get the bike to idle properly. When you buy new spares that is what you should recieve unless this was sold as a 'second'.