SOHC.co.uk Forums > CB750

Pressure gage tripping after 15min ride

(1/5) > >>

mgy66:
Hi,

I have my 750K1 pressure gage tripping after 15min usage (London commute exclusively). The bike was rebuilt with a 850 cc kit. I have checked the oil temp from the side tank... 82C/180F to 92C/200C.  I have put the bike to factory spec (jets, filter box, exhauste 4 in 4, air screw I tried 1 and 1.5 turn).

Anyone has a measure in similar condition (UK is not specifically a climate for high spec oil)...

I have given it for check and oil replacement. My workshop specialist said the oil pump is fine (I suppose he has also checked the valves) and refill with standard 10W30 semi-syntetic, but still tripping after 15min.

I have noticed the earlier discussion on oil selection. Shall I try a more high temp mineral oil? What would be the reference, I always mix up the grades...

Could it be the oil pressure/temp gages?
Thanks for helping

Trigger:
Air cooled bikes always get hotter with hotter weather, especially with London temp.

royhall:
Factory spec on jets etc with an 850cc kit fitted will leave it running lean. Never done it myself but it will need rejecting. Graham will probably have more idea than anyone.

Sent from my GT-I9305 using Tapatalk

mgy66:
Humm... i actually rejetted up... i had upscaled the #40 by drilling at +50mic with main at .120 with velocity stacks bu had black spark plugs like running too rich. I thought that was the cause of my high temp (too much fuel washing up the combution chamber oil film and/or contaminating the oil somehow) and put everything back to standard, jets and filter box and new filter.

Despite standard set up (#40 and 105) on 850cc i have rechecked the plugs and again black as if still too rich... i actually can't get plugs to turn into clean or even white. Needles seems to be fully engaged, only tip is visible from top of the carbs.

I also checked the floats at 25mm from seal to bottom of the float when up (valves closed position). I was told that running with high level would make the mix too rich.

So would be keen to have some measure of oil temps... Is 93C/200F critical? Shall i top up the oil tank in xs of the high level?

Cheers

totty:
I can't guarantee how accurate this is but an oil blender once told me 130c was the upper limit for mineral oil,  with 90 to 110 being ideal. If temps don't reach 90 or exceed 120 they recommended more frequent changes.
I've only monitored an air cooled single,  85 was the norm,  rising to 120 in traffic on a 27c day.

Navigation

[0] Message Index

[#] Next page