T500 oil pump sucking in reverse

[snorkelfork]

First post on the forum. Just made an even trade my 74' CB450 for a 74' T500. The CB had sentimental value but was so top heavy and a dog that i couldn't pass the opportunity. I've an RD350 that's my daily rider and another RD350 AC/LC hybrid TZ look alike on the bench. This is my first suzuki and first piston port 2 stroke.

last night I noticed the oil lines to the right cylinder and crank were nearly dry, so this morning I pulled the line and filled it with oil before returning it to the bike, then at idle I pulled the oil cable to clear any bubbles. I then rode it about a mile and noticed while at a light that at Idle the right side is sucking oil back up the lines. luckily I left the pump cover off so I just reached down and primed it before the light turned.

I've down loaded the service manual and will read it soon enough but I'd really like to get out on this thing so any help in diagnosis and service would be stellar

[Buffalo-guy]

Be aware that the T 500 oil pump stops pumping when you have the clutch pulled in. When you come to a traffic light, get in the habit of finding neutral, and leave the clutch engaged. The symptoms you describe could be related to that. Check it out. Cheers.
Fred

[snorkelfork]

i spoke to one owner who explained that there is a check valve consisting of a bearing and spring in the line itself and that when they malfunction the case pressure pushes the oil back up the line.

He said it is possible to pull the banjo from the line and clean the valve if done carefully but he wasn't clear if there is one check valve at the pump side or two, one at each end and i'm experiencing both lines going dry.

has anyone done this? any advise?

or where can I buy a new line if push comes to shove.

(edit) alright, spoke to someone else who reassured me that the lines themselves do not have the valves and that it is in the oil pump. can anyone verify this before i tear it down?

[Coyote]

I'm not a T-500 man but looking at the fiche on alpha sports ALL the check valves are in the lines. None in the pump.

http://www.alpha-sports.com/suzuki_parts.htm" onclick="window.open(this.href);return false;

[snorkelfork]

Thanks, you're right. Found some detailed images earlier. Going to try soakng ina mild solvent and see what comes of it

[tz375]

Check ba\\valves crack open at 2-4psi so do not use compressed air to blast the lines clean. They operate as a one way valve to allow oil to flow from pump to motor and to stop crankcase pressure from pushing back the other way.

[oldjapanesebikes]

Sometimes a photo is easier ! This is the check valve unit at the end of one of the GT750 injector lines - it should be similar to what is on a T500.

[snorkelfork]

Stellar, thank you for the Photo

headed out side to dig into it now

[snorkelfork]

no success.

I freed the banjo's as gently as i could, dismantled them and rinsed everything before reassembly but had no luck stopping the back flow.

any other suggestions? are there work arounds? or a better place to hustle for a pair than ebay?

thanks to everyone for your assistance o far

[rbond]

Sounds like you may have an air leak back toward or in the pump itself. It is losing prime at lower engine speeds (maybe?). I would start at the tank and check the filter/ trap, then check the pump. It may need to dis-assembled to be cleaned and new oil seals fitted. To repeat an earlier mention, DO NOT hold the clutch in at a stop or for more than needed to shift into neutral. The pump stops with the clutch pulled in, it is driven by the tach drive that runs off the clutch basket. It takes a little time to adjust to this oddity, but it is most assuredly safer to get into this habit real quick!

[tz375]

no success.

I freed the banjo's as gently as i could, dismantled them and rinsed everything before reassembly but had no luck stopping the back flow.

any other suggestions? are there work arounds? or a better place to hustle for a pair than ebay?

thanks to everyone for your assistance o far

It is possible that the springs are too short or weak or that the "seat" for that ball is too pitted. If the check valves really are beyond repair, go to McMaster's on line site. They have a couple of different options that could work.

[prmurat]

It is possible that the springs are too short or weak or that the "seat" for that ball is too pitted. If the check valves really are beyond repair, go to McMaster's on line site. They have a couple of different options that could work.

Sorry to get back on this old thread.... what McMaster product were you thinking about?
Thanks
Philippe