Page 1 of 1

Oil Pump Leak question- GT750

Posted: Sun Aug 01, 2010 3:41 pm
by dozoretzp
Hi- I am new to the forum. I recently purchased a GT750 motorcycle and although I have build a ton of four stroke bikes, this is my first 2-stroke street bike. My question is this: The bike seems to run fine. However, after running for a while (5+ minutes), I notice that oil is seeping out of the drain hole on the cover of the oil injection pump. It's not alot and am wondering if this is a serious issue that I should figure out right away or one that I can live with until this winter when I can tear the thing down. The bike hadn't been ridden for about 9 months+ and the last owner didn't do a thing to it. I can't pinpoint where the leak is coming from and am concerned that it could be one of the plastic injection tubes which look like a bugger to get to.

Can any of you please advise me on this? I do want to ride it, but I don't want to cause any unnecessary damage.

Thanks
Paul

Re: Oil Pump Leak question- GT750

Posted: Sun Aug 01, 2010 3:48 pm
by oldjapanesebikes
Is it injector oil or possibly crankcase oil ? What colour is it ?

Re: Oil Pump Leak question- GT750

Posted: Sun Aug 01, 2010 3:55 pm
by Suzsmokeyallan
Hello Paul and welcome to the forum, as to your problem you can check this as well. Look at the oil level in the gearbox, make sure you level the bike on the centre stand and remove the level screw then leave it for a while, 15 mins at least,to see if any runs out the hole.
If its overfilled it will blow the oil out the crankcase breather which is located inside the oil pump engine cover and out the hole you see under the oil pump inspection side cover.
The GT750 has a different make up inside the engine to most bikes, in so much as the oil goes directly into the centre of the cases when you fill the engine from the clutch cover cap, it does not go into the clutch cover then flow to the rest of the engines internals.
To this end getting the level correct is not as simple as pour it in till it flows out the level hole since the oil has to find its level through the inner cases first, therefore most people always overfill the engines.

Re: Oil Pump Leak question- GT750

Posted: Sun Aug 01, 2010 4:49 pm
by dozoretzp
Thanks for the replies! You two raise some good points- the oil is a bluish color (although I am color blind- so take that for what it is worth).. THe guy that I bought the bike from wasn't the sharpest tool in the shed. When I did check the crankcase oil level, it was overfilled. I let it drain for a bit, but I will go back out there and let it drain for a while longer as it appears that it is still overfilled.

I'll reply back with what I find.

Thanks again,
Paul

Re: Oil Pump Leak question- GT750

Posted: Sun Aug 01, 2010 5:19 pm
by dozoretzp
Well I have good news/bad news/good news/bad news

Good news is that you all were right. The crankcase was overfilled. It's still draining after 5+ minutes. Bad news- oil coming out of the drain hole under the inspection cover is the blue-ish color. Good news is that it appears that the leak is coming from the black hose (I believe that this is the oil input?) on the right side of the oil pump and not from the pump itself. The small black hose has a wire clamp that seems to have shifted and the hose is not completely on the banjo fitting. Bad news- it looks like a big pain to get to.

I will play around with it a little but it looks like I am going to have to tear down the bike a bit so that I can remove the cover to the oil pump so that I can reattach the hose and I will most likely safety wire the thing on.

But If you all have any more comments, that would be great to hear. I will think about this one a bit. Unfortunately all I have is an older clymer manual and it's not very good.

Re: Oil Pump Leak question- GT750

Posted: Sun Aug 01, 2010 5:31 pm
by oldjapanesebikes
Sounds like you are the right path to getting it sorted - take a look at this link where you can find some shop manuals which may help you. While you are there, you may want to read a few of the GT service bulletins - this one (GT-2) specifically may be helpful. 8)

Re: Oil Pump Leak question- GT750

Posted: Sun Aug 01, 2010 8:41 pm
by dozoretzp
Thanks for your help- I think I fixed it! I ended up shifting the hose up to its proper location and got rid of the stock hose pinch clamp and safety wired it. I checked for any air bubbles in the lines and I didn't see any thankfully.