Topic: Another oil thread - temp on dipstick gauge - 110C (230F) TOO HOT?? Soon OK!

[PeWe]

I have a feeling of running my CB750-k6 hot.
The valve cover feels hotter than I remember. But I had no temp gauge causing worries 25-35 years ago

The fun gadget I bought when ordering parts from Yamiya, oil dipstick with temp gauge show 110C after a few km's drive.
- Is this in the hotter range?  Or, just normal for a CB750? Ambient temp here was +15-20C.

I checked one sparkplug and that was not white, grey-brownish and clean isolator. Good for me.
- Next that can cause hot engine is if EX valve close too early, right?

Oil now is mineral 20W-40. Will change to 20W-50 after 500km's or earlier if needed.
Engine restored with new pistons, cam, valves, clutch, chains, tensioners, crank bearings. All parts inside washed including the cases.

I bought an used CB750 oil cooler in the middle of the 80's that I never used. Adapter between oil filter and case + cooler. Maybe time for them....

[lrutt]

What does it max out at? If it maxs at 110 (230 F) then that's not too bad. but if you are getting over 130 C then it's getting a tad warm.

I remember reading tests back in the early days that said switching from a 10w40 to a 20w50 actually increased the engine temp due to more friction.

[PeWe]

So far, max 110C. But that was rather short rides. 1:st time ~20km to a friend. There 110 visible. Later in town a few km.s same 110. The red area starts at 120C. I'm not sure if this gauge is absolutely true.
- Interesting to know others experiences of oil temp.

[TwoTired]

Kinda depends on the selected oil's breakdown temp.  Some are higher than others.  230F is near the edge of some, and others will take 260F without breakdown.  Some even go to 300F, but I don't think I'd ever be comfortable with that on a street bike. 

For air cooled motors, the temperature and quantity of air taking heat from the cooling fins/outside surfaces if the engine, matters a great deal.
A stationary engine will overheat the oil and cause it to break down.  Then you need to refresh the oil to keep the engine from suffering.

So, when exactly are you taking the reading?  Is it representative of actual driving conditions, or did it idle stationary for a bit before the reading?  What was the outside air temp?

You know you can test the instrument in boiling water to check it's accuracy.  Water boils at 212F.

[PeWe]

Good idea! Boil it and verify.
110 /230F) reading was at arrival, max 20 seconds idling before off. 2:nd ride was 5 km's to the testing center to get the papers OK. Amb temp 10-15C.  Initially I blamed the 4-1 and silent baffle for passing the audit as I always did before too.
The silent baffles in my 4-1 choke the engine. It run very bad, as it did back in the days.  Same temp with the baffle with much wider and much loader opening.

If others have the same oil temperature it's not a big problem.

[lrutt]

if you only have 10 - 15c ambient temps and are hitting 110c after just a few K's then I'd say you are running lean. I have a temp gauge on my XR and I would only hit 110 - 120 in hot florida temps and after riding for a bit. A good synthetic can easily survive 250 on a regular basis with peak higher. But I change frequently down here in the hot summers.

I'd say you better check your jetting.

[TwoTired]

Does PeWe's bike have a stock engine?

[PeWe]

Does PeWe's bike have a stock engine?

NOt stock
836  (NOS RC with crowns need opening chambers. Discussed in other thread were this kind of piston kissed the head)
CX7 cam
Ported head with bigger inlet valves (34mm) Chambers open to fit bore (increased squish area, decrease CR hopefully compensated by milled head) see photo
Mikuni VM29 carbs that need to be adjusted. Main 120, pilot 17.5. Really not good today. (Floats floaded before, adjusted floats verified with clear tube)

I could not feel any additional resistance/friction when I turned the crank around when timing the cam.
Anyway, the most important thing here to know if it run hotter than it should. I do not want mechanical failures.

I found my old oil cooler not used by me. It does not look that good. Need repair when the adapter has a hole where it should seal against the case. see photos.

Next bigger jets 122.5, 20 to see if oil temp decrease. I can test drive when the bike is a runner and season is here.

[PeWe]

Update:
Problem identified when driving the bike.
I increased the jets when I had identification about too lean.
increased pilot 2 steps 17.5-->22.5, main 120 --> 122.5.
Now much cooler [80C] but bike continued to run bad when driving it which turned to constant state.
Ran on 3 cylinders were rather clear. spitted on all 4 exhaust, 2 was just warm, not hot as the other.

Checked coil and found the problem that have tricked me all the time during the jetting sessions since October last year.
The screw that fasten the wire was loose. That screw should be fastened inside the coil somehow.
That's why the jetting never became OK when the coil for 2:nd cylinder had intermittent issues. I tried all kind of combinations.

I'm mounting my Honda OEM coils instead of the PAMCO Ultimate coils.
I'll contact vintagecb750 where I bought the Pamco ultimate kit. There is no warranty left since I bought it soon 2 years ago, started to use it October last year. But one thing is clear: The coil was bad from the beginning.
Maybe possible to get a special deal and no customs here.
Order one coil + shipping + customs fees + VAT will cost a lot.

[PeWe]

Oil temp still high 110C [230F]
Engine runs very well know with new coils that works. Installed Dyna S, first 3 ohm coils, drained battery so I changed to 5 ohms. Bigger jets did not cool down the bike. My first try was with one bad coil, loose plug wire connections.

It might be natural temp with tuned engine.
This threads picture convinced me to go synthetic.
http://forums.sohc4.net/index.php?topic=98236.msg1094386#msg1094386

I'll investigate more on internet about engine oils temperature working range. Dino oil might be wrong for my engine.
I'll test to advance the ignition if it's too late increasing temperature. My helmet is too insulated, I cannot hear the engine as needed.

It's easier to advance the ignition until I hear pinging when twisting the throttle on 5:th gear and 100-120km/hour. Did the same with old cars but 4:th gear in 50km/h + pedal into the floor

[Lost and Confused]

Pewe, try contacting Pamco Pete directly by email. He is absolutly great to work with!!!!!!  Very customer friendly.



Bob

[PeWe]

Pewe, try contacting Pamco Pete directly by email. He is absolutly great to work with!!!!!!  Very customer friendly.

Bob

Yes, the unit should be possible to repair, warranty or not. A single component or the entire 2-3 card.

I have continued with my oil cooler project I started in the middle of the 80's when I bought a cheap cooler in need of repair.
Last time I drove the bike it reached 105 degrees. No idling direct after the road, 20 km mostly 80-150km/h. I wonder how the temperature will increase when ambient temp is the double, 25C, slow driving in city with red lights?

I checked the temp gauge by boiling it and it was correct, 99-100C, 5 minutes boiling.

Today I filled the hole in the adapter with 2k glue. "Cold weld". I think its like same companies "chemical metal" years ago I used on the leaking scratched alternator cover.
It has to support the o-ring only.
Oil cooler was painted with thick layer of bad paint, not oil resistant and will insulate the cooler. now flooding in paint removal gel.
The cooler will help. It look a little bit ugly. An old cooler.. anybody that know this cooler? type, brand?