Acceptable / normal oil consumption

[350Simon]

What would be considered normal for a 350/400 sohc?

I've done 500 miles of running in new pistons and rings, the bores were properly machined and honed and I know that my valve guides are on the upper end of the serviceable limit.

Oil level is just above the min mark on dipstick after 500 miles. Is this acceptable or should I really get the head reconditioned?

I'll be honest I can't detect any smoke from the exhausts in my mirrors while riding or at idle but my friend said the other day there's a faint haze when I'm giving it the beans.

Cheers
Simon

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[Lobo]

My ex CB400F never burned oil, inc after a full rebuild. In fact no vehicle of mine burns any oil, inc a 50yo Kombi. If you’re using Max-Min quantity over a mere 500 miles there’s surely something wrong?

[taysidedragon]

Try topping up the oil to the mark and see how it goes over the next 500 miles.
It might bed in and oil consumption reduce. If not, I would overhaul the valves and guides.

[McCabe-Thiele (Ted)]

What would be considered normal for a 350/400 sohc?

I've done 500 miles of running in new pistons and rings, the bores were properly machined and honed and I know that my valve guides are on the upper end of the serviceable limit.

Oil level is just above the min mark on dipstick after 500 miles. Is this acceptable or should I really get the head reconditioned?

I'll be honest I can't detect any smoke from the exhausts in my mirrors while riding or at idle but my friend said the other day there's a faint haze when I'm giving it the beans.

Cheers
Simon

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Did you replace the 4 valve stem seals?

It has been my experience that when valve stem seals need replacing on a car engine then you tend to get visible smoke if the engine stands for a while from hot  and you then restart it 5 mins later - the smoke is often just for the first 5-10 seconds then all is good. Again on cars I have found giving it the beans also burns oil & produces smoke at high engine rpm.

I would not be too concerned until you carry out your first oil & filter change then see how it goes on the next 500 miles making sure you check the oil on level ground etc.
I would also check  if there a lot of excess pressure from the crankcase vent pipe system.

[kevski]

With valve guides at the upper end there was always going to be a good chance to burn oil as the valves are likely to wobble and the seals will let by.

[350Simon]

What would be considered normal for a 350/400 sohc?

I've done 500 miles of running in new pistons and rings, the bores were properly machined and honed and I know that my valve guides are on the upper end of the serviceable limit.

Oil level is just above the min mark on dipstick after 500 miles. Is this acceptable or should I really get the head reconditioned?

I'll be honest I can't detect any smoke from the exhausts in my mirrors while riding or at idle but my friend said the other day there's a faint haze when I'm giving it the beans.

Cheers
Simon

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Did you replace the 4 valve stem seals?

It has been my experience that when valve stem seals need replacing on a car engine then you tend to get visible smoke if the engine stands for a while from hot  and you then restart it 5 mins later - the smoke is often just for the first 5-10 seconds then all is good. Again on cars I have found giving it the beans also burns oil & produces smoke at high engine rpm.

I would not be too concerned until you carry out your first oil & filter change then see how it goes on the next 500 miles making sure you check the oil on level ground etc.
I would also check  if there a lot of excess pressure from the crankcase vent pipe system.

I didn't do any of the work I bought the bike as is. It's this one that was featured in this you tube video where the guy had real issues identifying the cause of smoke that turned out to be a loose guide in the head. He said the offending guide was replaced but the other 3 remain. All the stem seals were replaced. All 4 exhaust valves were replaced which brought the stem to guide clearance just within the serviceable limit.

https://youtu.be/YM15Gijr6Ag

It seems like a lot of oil to use in 500 miles, through the guides..... especially when I can't see any smoke at all! There's also no oil leaks anywhere.

Perhaps it isn't actually bedded in yet as someone said above.

Next question would be who could properly sort the head out for me?

Cheers

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[Oddjob]

Guide replacement generally means refacing the valve seats and that's not a skill most people have and does require special tools. Graham (Trigger) has the tools, isn't too far away from you BUT I have heard he's sort of semi retired these days so whether he will still be interested is another matter. No harm in asking.

[350Simon]

Guide replacement generally means refacing the valve seats and that's not a skill most people have and does require special tools. Graham (Trigger) has the tools, isn't too far away from you BUT I have heard he's sort of semi retired these days so whether he will still be interested is another matter. No harm in asking.

Great I'll ask him if he's interested. Cheers

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[McCabe-Thiele (Ted)]

..... especially when I can't see any smoke at all!


[/quote]

The old Mini A series 1275 S engine could burn a quart of oil in 200 miles without a trace of blue smoke!

I would definitely wait & see how much oil you use in the next 200 miles before doing anything hasty.

Another factor is warm weather ups apparent oil consumption for complicated reasons connected with oil additatives.

[350Simon]

..... especially when I can't see any smoke at all!

The old Mini A series 1275 S engine could burn a quart of oil in 200 miles without a trace of blue smoke!

I would definitely wait & see how much oil you use in the next 200 miles before doing antything hasty.
[/quote]Yep will put some more miles on it and then see where I'm at.

Thanks chaps



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[350Simon]

Another quickie sorry guys, are the sohc seats 3 angle

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[Nurse Julie]

Another quickie sorry guys, are the sohc seats 3 angle

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Yes

[Oddjob]

Yes, it requires 3 separate seat cutters.

[350Simon]

So having just giving it a good thrashing home and got it nice and hot, unfortunately I can see now that it is smoking a bit looks like cylinders 3 and four.

I'm going to look at just the head first, assuming that the bottom end has actually been done properly as I'm told it has.

Hey ho the joys of old machines!



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[350Simon]

Yes, it requires 3 separate seat cutters.

Cheers. I'm a machinist by trade so feel i could do the job myself but as is often the way with these things by the time I've invested in the tooling it's probably not worth it.

I'll message Graham and hopefully he will agree to the job.



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