It lives!

Spondon · Post by **Spondon** » Fri Feb 20, 2009 11:29 pm

Hey guys,

I'm back again. It's seems like I log on to this message board like once a year.
Anyway, after some priming of the oil lines and a new pair of spark plugs, my GT500 started up and ran yesterday. It had been sitting for almost 2 years after I rebuilt the top end and it only ran on one cylinder. Out of frustration I gave up on it until now. I eventually mustered up the courage to have another try at it and miraculously, it started right up.
I'm still getting some noise coming from what I think are the big end bearings--but it's difficult for me to diagnose. This was happening before and as far as I know as long as I've owned the bike. I can post up a video if anyone wants to give it a shot as to what the noise is.
Here are some pics for you:

Obviously it's a daily rider, not a museum piece or even close to all original.
Also, I'm now getting intermittent(i.e. not all the time) air bubbles in the left oil line from the oil pump that goes to the left hand cylinder and big end bearing, starting at the junction where it splits into a Y shape and becomes two oil lines. The oil line is New Old Stock, so I'm pretty sure there aren't any cracks in it, but the plastic washers that go on the banjo bolts are NOT original, just some plastic washers I picked up of the approximate size from the hardware store. They do not have the center groove as the original washers do. I'm wondering if air may be leaking in through there???
The engine runs fine as it is; no high revs during idle as is indicative of an air leak but I'm wary of oil starvation and another blown top end if I don't take care of this. I'm running colder NGK B8HS plugs to err on the safe side. A plug chop revealed that the right cylinder is running slightly richer than the left, but not by much. There is more smoke coming from the right pipe as well.
If need be i can take the oil line washers off my spare engine and see if that stops the air bubbles.

Post by **oldjapanesebikes** » Fri Feb 20, 2009 11:37 pm

Nice looking bike !

I would have thought if the washers on the lines were a problem, or indeed if anything down stream of the pump were leaking - you'd have injector oil all over the place. If you don't - then perhaps you have an airlock in the pump and it needs to be bled ? Or possibly a leak on the intake side of the pump ? That's what I'd be checking any way.

Spondon · Post by **Spondon** » Fri Feb 20, 2009 11:44 pm

^ Ah, good idea. I didn't even think of bleeding the pump! There definitely isn't injector oil anywhere it shouldn't be. Do you think a leak on the intake side of the pump would only affect one oil line, though?

Post by **oldjapanesebikes** » Sat Feb 21, 2009 12:13 am

Don't know - and tough to diagnose via email !

I've noticed that after a rebuild, even if I've primed the oil lines and also bled the pump I still usually see bubbles in one or more oil lines for at least a short while. I normally hold the oil pump rod open by hand and watch the oil lines (on first start p I leave the oil pump covers off till I'm happy) and also the exhaust - so long as there is lots of smoke, and I can see the air bubbles being pushed along the lines towards the cylinder, then I'm pretty relaxed about it. If I see new bubbles, then I start looking at the pump and its supply.

Spondon · Post by **Spondon** » Sat Feb 21, 2009 4:24 am

Very true, tough to diagnose via email. I'll report back asap. Thanks.

Spondon · Post by **Spondon** » Sat Feb 21, 2009 2:03 pm

Update:

There's good news, bad news, and odd news...

Bad news first. The threads that hold the bleeder bolt on the oil pump were completely stripped, thus not creating a seal. I believe this to be the source of the air bubbles in the left line.

Good news. I have a spare oil pump. I replaced the entire pump, bled it, and there was enough oil in the lines that I thought I would be able to push out any remaining bubbles. I also replaced the washers w/ OEM from the spare pump.

Odd news. Now BOTH lines are holding air

I rode around for a good 30 minutes and they don't seem to be going away. I re-bled the pump; same story. Now it appears the spare pump may have an air leak!

Nonetheless it runs fine, plug chop looks good, and both exhausts are smoking. I may go back and prime the lines again, but I'm going to have to take a break from this frustrating project for a few days.

johnakay · Post by **johnakay** » Sun Feb 22, 2009 12:02 pm

on your thread damage pump you could try JB weld. .make sure that there is no oil or grease in the threads. bolt it all back on the bike.before you put the banjo bolts in smear the thread(bolts and put the oil line pipe on)with JB weld and just nip it in and leave it for a day or two. it should be fine.

Spondon · Post by **Spondon** » Sun Feb 22, 2009 3:38 pm

I tried again. I primed the lines and I was able to remedy the air leak by tightening the banjo bolts and smearing the threads with gasket sealer. They required a good bit of torquing to get them to stop leaking.

johnakay · Post by **johnakay** » Mon Feb 23, 2009 11:01 am

well that sorted good

Post by **oldjapanesebikes** » Mon Feb 23, 2009 6:59 pm

Spondon wrote:I tried again. I primed the lines and I was able to remedy the air leak by tightening the banjo bolts and smearing the threads with gasket sealer. They required a good bit of torquing to get them to stop leaking.

Glad to hear its working !