Honda CT70/ST70 oil pressure gauge

Carlos

New Member
#1
Anyone know roughly how much oil pressure to expect from the Honda high flow oil pump from the 12V engines? I'm going to rig up one of these to match the Marshalls 0-15 psi I use for boost pressure.



It would be cool to see close to full "sweep" when cold, guessing the pressure runs less than 30 warm and maybe a tad over when cold ... If no one has done this before, no biggy, I have an old Smiths 0-100 psi I can run a test with first, then I'll post the findings here. Just wondered if I could save some time rather than rig up a test line and gauge first.
 
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#2
I do not know what you will see but my understanding is that these engines and oil pumps are high volume but low pressure. So my feeling is that you will not see lots of needle movement.

But I'm certainly interested in where you would tap in to get a pressure reading. It seems to be easier to tap into the Lifan 140 clone engines rather than a CT70 mill.

Rick
 
#3
i have one off of an SL70 that is being rebuilt.

it's all new to me but if i figure out where
and why to measure oil pressure i'll let you
know what i learned. how about oil or head
temp? thermocouples are easy!

these engines are cold blooded so we can
assume cooling both air and oil cooling are
more than sufficient.

are you making any mods?
 

Carlos

New Member
#4
Kitaco oil cooler plate modified

...
But I'm certainly interested in where you would tap in to get a pressure reading. It seems to be easier to tap into the Lifan 140 clone engines rather than a CT70 mill ...
Here you go Rick, your right it's not easy to tap into the CT or ST, I chose to make a boss by welding a big blob onto a Kitaco oil cooler plate, filed it to shape, tapped and drilled that for a braided Goodrich brake line.



You can see the boss in these photo's, now plugged with a bolt. reason being this was originally a pressure oil feed to the supercharger (Phil that should answer your question about mods) but I abandoned that idea in favor of a gravity oil feed.

The boss/drilling needs to be angled as shown because it was easier to drill through to the lower port.
 
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Carlos

New Member
#6
I know the 12V engine oil pumps are listed as "high volume" but I don't think they are low pressure. Take a look at this vid ... Hard to tell with that digital tach but it looks like about 7psi @ 1,250 rpm and just over 30psi @ 3,500rpm.

Thinking about it, if that is a linear equation for the pump ... which I would think it is, then the pressure will increase in relation to the rpm, much like a positive displacement pump. (I'll try to work out an estimate for about 10 or 11,000 rpm when I get back from the pub!)

[YOUTUBE]monkey bike oil pressure gauge - Bing Videos[/YOUTUBE]
 

Carlos

New Member
#7
Supercharged ST70 (european version of CT70)

a super charger on a 70cc honda????

pics please.
Here you go Phil, sorry for the late reply, I'm running on a power outage so spent the day dicking around setting up a generator ...

If you like these bikes it's an interesting bike, an original ST70 from France, I bought it in England.

The British ST70 has a cast, body color matched headlamp/speedo bowl unlike the black plastic US ones... This is similar to the British one but it's huge! I'm assuming French law dictated the size of the headlight.

The engine is the original but stretched to 119cc, 54mm forged piston, short con-rod, 52mm stroker crank, supercharger, ported and polished big valve head, semi-down draft intake port, Kitaco camshaft, strengthened clutch, oil cooler, 26mm carb, oil filled front forks and lots of other mods ... I even changed the shift pattern in the gearbox so neutral is up and all gears are down.

The exhaust looks standard but it's from a Honda SS50 which has a larger diameter header pipe, I think I cut 2 or 2.5 inches out of the middle pulled all the guts out of it and welded it back together to look standard. I made the end baffle removable so I could pass the annual British M.O.T test requiring baffles and remove it for a straight through exhaust. :grind::scooter:



 
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Carlos

New Member
#9
[Rick

That vid didn't post so here it is again

YOUTUBE]http://www.youtube.com/watch?v=TpeqfWFXvTs[/YOUTUBE]

Hard to tell with that digital tach but it looks like about 7psi @ 1,250 rpm and just over 30psi @ 3,500rpm.

If the pump is positive displacement and there is no oil pressure relief valve, based on the figures above this is what to expect ...

 
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