SOHC.co.uk Forums > CB350/400
Oil coolers
400 Cafe Racer:
--- Quote from: 400 Cafe Racer on December 10, 2022, 08:51:31 PM ---
--- Quote from: Scottish Badger on December 07, 2022, 10:35:27 AM ---
--- Quote from: K2-K6 on December 07, 2022, 10:18:28 AM ---Yes to that type of arrangement, but in agreement with you as to how effective it may be in cooling, I was referring to method of fixing as interesting point. The fit for F2 was this plus larger fins on head and barrels as complete package when they ran into trouble with lubrication on that model and kind of stop gap until the twin cam arrived in market.
Wondering the need for cooling as running oil too cold produces just as many problems as too hot. If you've no definite figures of your running example it may be worthwhile assessment to define this.
Running oil too cold, and especially at high rpm can bring unintended side effects. The pump is protected from hydraulic locking (virtually all engine have this) by a pressure bleed off valve that blows excess to sump effectively startng to starve key points in the lubrication system of supply, that's ordinarily the crank and big end bearing sites.
The flow is optimised for stated viscosity (varying with temp) at 90 degree C to give designed flow as originally tested and researched. You'd need to target this temp range in specifying cooling capacity.
--- End quote ---
I'm going to build a 460 engine for my bike, I have a spare 400 engine as a donor for the project and I now have most of the parts needed for the build, but I've read a lot of older posts claiming oil temp gets marginal with the larger bore size hence the need for additional cooling. I was looking to use an in-line oilstat to regulate the temp, being aware of the pitfalls of overcooling. (I'm an aircraft engineer by trade, spent decades working with both piston and gas turbine engines).
--- End quote ---
Hi,
Having fitted both an oil pressure guage and temp guage to my CB400F some months ago, I can confirm that in normal riding you will easily be running at 95c + with 40ish psi @ 3000 and if you give it the beans for a few miles you will be at 120c with 15psi @ 3000. I suspect the reason a low 4.5psi oil pressure switch used was to prevent worry of riders seeing the light blinking at idle on a hot engine.
IMHO If your seals and gaskets are newish, there is a definate case for synthetically improved oils which wern't available in the day to handle the higher temp better, and I will be running some tests next spring.
I think one of the major reasons for piston ring and groove failures is the deposits and gumming caused by burnt 10w 40 oil which cannot handle the excessive conditions at the top of the piston.
Regards
Dennis
--- End quote ---
Laverdaroo:
Alan, mate, what a thing! ................I'm spent!
The LC looks better every time I look at it, clear clutch window too, what a tart! I love it ;D
Thats a tight squeeze with those barrels but I take it you're running a full fairing, hence the cooling issue? Either way, thats going to be an interesting ride, bet you cant wait? Especially as we all have a 90% 'complete bike' in our headsso have expectations etc. I was lucky when I put the Ducati together a few years ago, I was on garden leave and it was like a full time job and was kind of being paid to build my new ride but that looks like I'd rather be playing with that than working. It must be killing you ;D
That's really coming together though and looking great for it. What are those wheels and do you have a link to that headlight per chance, just for a comparible mooch, yer know ;)
Who's the portly chap wearing yer jacket though? Have you a brother? ;) ;D ;D
allankelly1:
--- Quote from: Laverdaroo on December 10, 2022, 09:16:31 PM ---Alan, mate, what a thing! ................I'm spent!
The LC looks better every time I look at it, clear clutch window too, what a tart! I love it ;D
Thats a tight squeeze with those barrels but I take it you're running a full fairing, hence the cooling issue? Either way, thats going to be an interesting ride, bet you cant wait? Especially as we all have a 90% 'complete bike' in our headsso have expectations etc. I was lucky when I put the Ducati together a few years ago, I was on garden leave and it was like a full time job and was kind of being paid to build my new ride but that looks like I'd rather be playing with that than working. It must be killing you ;D
That's really coming together though and looking great for it. What are those wheels and do you have a link to that headlight per chance, just for a comparible mooch, yer know ;)
Who's the portly chap wearing yer jacket though? Have you a brother? ;) ;D ;D
--- End quote ---
Thanks Roo
Yes it’s a very tight squeeze so got my frame guy over soon to discuss opening up the trellis in this area to allow for the wider finned barrels
Went the AC route as no place or space for a rad
As for fairing planning it to be a naked bike like a Ducati monster as it would be a shame to hide away that lovely trellis frame and ac engine
Wheels by the way are KTM 390 Duke
Also jacket is a good excuse not to eat too much at Xmas
Best wishes Al
Ps led light on the yellow peril is a eBay item and here is the link
https://www.ebay.co.uk/itm/303960372602?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=nbUfGDNkSn2&sssrc=2349624&ssuid=Na1jx0DbRzm&var=&widget_ver=artemis&media=COPY
Sent from my iPhone using Tapatalk
Scottish Badger:
--- Quote from: 400 Cafe Racer on December 10, 2022, 08:51:31 PM ---
--- Quote from: Scottish Badger on December 07, 2022, 10:35:27 AM ---
--- Quote from: K2-K6 on December 07, 2022, 10:18:28 AM ---Yes to that type of arrangement, but in agreement with you as to how effective it may be in cooling, I was referring to method of fixing as interesting point. The fit for F2 was this plus larger fins on head and barrels as complete package when they ran into trouble with lubrication on that model and kind of stop gap until the twin cam arrived in market.
Wondering the need for cooling as running oil too cold produces just as many problems as too hot. If you've no definite figures of your running example it may be worthwhile assessment to define this.
Running oil too cold, and especially at high rpm can bring unintended side effects. The pump is protected from hydraulic locking (virtually all engine have this) by a pressure bleed off valve that blows excess to sump effectively startng to starve key points in the lubrication system of supply, that's ordinarily the crank and big end bearing sites.
The flow is optimised for stated viscosity (varying with temp) at 90 degree C to give designed flow as originally tested and researched. You'd need to target this temp range in specifying cooling capacity.
--- End quote ---
I'm going to build a 460 engine for my bike, I have a spare 400 engine as a donor for the project and I now have most of the parts needed for the build, but I've read a lot of older posts claiming oil temp gets marginal with the larger bore size hence the need for additional cooling. I was looking to use an in-line oilstat to regulate the temp, being aware of the pitfalls of overcooling. (I'm an aircraft engineer by trade, spent decades working with both piston and gas turbine engines).
--- End quote ---
Hi,
Having fitted both an oil pressure guage and temp guage to my CB400F some months ago, I can confirm that in normal riding you will easily be running at 95c + with 40ish psi @ 3000 and if you give it the beans for a few miles you will be at 120c with 15psi @ 3000. I suspect the reason a low 4.5psi oil pressure switch used was to prevent worry of riders seeing the light blinking at idle on a hot engine.
IMHO If your seals and gaskets are newish, there is a definate case for synthetically improved oils which wern't available in the day to handle the higher temp better, and I will be running some tests next spring.
Regards
Dennis
--- End quote ---
Dennis, thanks for that info, that's exactly what I needed to convince me of the need for a cooler!
Al, love that yellow LC, looks almost as good as an RD400 in the same colours.... I never knew that AC barrels would fit an LC bottom-end, every day's a school day and all that! Back in the 80's I was fitting 350 top-ends onto 250 bottom-ends, porting the barrels and fitting expansion pipes etc, all great fun! Realised the small-end width of the 250 rods was slightly less than the 350 bearings after destroying a couple, so started doing it right by fitting the 350 cranks as well, meaning we had to take the engines out to split the cases and do it properly, haha. Happy days!
Laverdaroo:
Eeryone had to havean LC in bits with 'mods'......it was the law ;D ;D
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