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74 GT 750 leaking injector oil after a good run
Posted: Tue Apr 23, 2013 11:43 am
by T350guy
The Gt seems to run fine BUT when i come back after a 1-2 mile ride and on the center stand it leaks a good amount of injector oil from the left side.
It actually drips from the crankcase bolt. I have looked at the feed lines for leakage and ALL dry even the area around the starter is dry.
Over night it stopped dripping.
I go for another ride and again there is a puddle under the left side and it drips!
Crawl underneath and yet again it drips from the Bolt.I move the SRIS line out of the way, wipe clean, still drips.
Put cloth next opening on Cover where Left SRIS line go in. still drips..everything above the bolt is dry. The left SRIS valve is dry.
I am stumped as I find it impossible for a crankcase bolt to leak fresh injector oil.
No leakage at the pump side.
Ideas?
Pics of the area.
you can see oil on the head

Re: 74 GT 750 leaking injector oil after a good run
Posted: Tue Apr 23, 2013 1:49 pm
by oldjapanesebikes
That looks to be bolt #13 which actually passes through the cooling jacket - I suspect its coolant not injector fluid. Take a look
at page 31 in the shop manual - you likely just need to replace the copper washer (note there is no lock washer used). The Haynes manual also suggests putting some Suzuki bond on the bolt for additional security.

Re: 74 GT 750 leaking injector oil after a good run
Posted: Tue Apr 23, 2013 6:07 pm
by T350guy
Thanks Ian
Well that sure looks like the bolt and explains the drip once running and up to temp.
I'll try and get a copper washer to put on.
I did have this bolt removed once to see if anything came out which was zip. I guess It'll show up once coolant is being circulated.
Re: 74 GT 750 leaking injector oil after a good run
Posted: Wed Apr 24, 2013 7:48 am
by T350guy
After reading the bit how trans or cooland if seeping flows into a cavity then out thru a small hole.
GOD I thought I see some work ahead.Something I did NOT want to do.
This morning I get up early and decide to check the trans oil after reading about over flowing when too full.
Well I removed the level plug , the oil keeps flowing out AND it is the same colour ( Blue/Green) as the injector oil.
I really hope this was the problem .
NO coolant was leaking.
Re: 74 GT 750 leaking injector oil after a good run
Posted: Wed Apr 24, 2013 11:21 am
by T350guy
Ran the bike and it still drips Trans oil from the bolt.
IT doesn't appear to come from the Water pump housing as I understand the vent hole is located there.
Am I correct the vent hole exits at the pump housing? or vents into the case where the bolt goes into?
Re: 74 GT 750 leaking injector oil after a good run
Posted: Wed Apr 24, 2013 2:51 pm
by oldjapanesebikes
T350guy wrote:Am I correct the vent hole exits at the pump housing? or vents into the case where the bolt goes into?
The vent hole is for the space between the crankcase oil seal and the mechanical water seal of the water pump, and if there is a leakage past either, the liquid drains at the rear of the water pump cover - usually all over the joint coupler for the centre pipe. Go ahead - ask me how I know
Have you replaced the copper washer (and removed the lock washer) from bolt 13 ? And why is your crankcase oil blue/green ?

Re: 74 GT 750 leaking injector oil after a good run
Posted: Wed Apr 24, 2013 10:58 pm
by T350guy
Just replaced the washer today with the copper one and NO lock washer.
I'm not sure of the manufacture of the oil but that's what previous owner had put in it.
Center pipe and area is squeaky clean.