T500K question and Keyster carb kit observations

[djc]

My T500 had been doing a bit of the old hunting and surging at low revs so I've been doing a carb clean up and refurb. One question arising that I hope some kind folks round here might be able to help with:

It had been a bit smoky too so I took the oil pump cover off to check the adjustment. Under the pump cover, sitting around the cable, is a large spring. Previously I'd just re-assembled things as I found them without question but as I was ordering some new bits I looked for it in the parts book. Can't find it listed either with the pump itself or the throttle cable. It functions as a return spring obviously enough, although a quick bit of experimenting suggested things would work the same without it. So for now I've put it back as was but I'm curious to know if this is as manufactured or whether some previous owner added it for some reason. It does look a bit crude, it's squashed up at end end (to stop it just sliding right over the pump lever) and makes putting the pump cover on a tad awkward as you have to push it out of the way to allow the cover to seat itself.

Part of the reburb was to replace everything in the carbs and a chap in the VJMC said Keyster carb kits were a good option for this so I ordered some up. By and large they seem OK, but K owners might like to know they might not come with the right pilot air screws. I queried this with the UK supplier, who said their kits were good for all models. So I sent them a pic from the parts manual showing two possible jets listed for the K along with a pic of their version and the one from my bike. After which I never heard from them again! They supply the shorter version which is used for most of the range but not some of the K's, the correct ones are available elsewhere at a reasonable price. I also found that their gaskets seemed a bit too large, instead of dropping in you have to squish them into position, so I re-used the old ones as they were still fine.

[PaulD738]

Keyster kits along with Cruzin Image kits are not the best to be honest. Although a lot more expensive genuine Mikuni is the way to go in my opinion. Allen’s carburettors or our Baz can help you out. As to the oil pump return spring it sounds a bit like a bodge to me but if you can post a pic we might be able to help.

[djc]

Pic of the spring inside the oil pump should be attached assuming I've done that right. More I look at it the less convinced I am that it's OE, the Japanese usually do that kind of thing more neatly.

[PaulD738]

Nope that’s definitely not original? I’ve had a few 500’s both T&GT’s and none of them look like that.

[Alan H]

Probably fitted when someone operated the pump with the engine stopped and the arm didn't return to 'rest' position.
Some pumps do that, and usually return when the engine runs, possibly due to the fact that the oil between pump piston and non-return valve can't get out if the NRV doesn't allow all the oil pressure to drop to a minimum value and as there's some pressure in the oil feed pipe, it stops the pump arm returning. With the engine running, the pressure in the pipe is still there, but as most folks switch the engine off at tickover, it's never a problem.
That's my logic on it anyway.

[djc]

Thanks, I'll remove that and keep an eye on things in case it was put there to fix a particular problem but I reckon it should be fine as just the cable motion alone seems to return the arm back to the minimum position quite easily. It won't be missed as it makes getting the cover on and the cable hooked up a bit of a nuisance. Amazing what you discover when you start these jobs: on the top of the battery area was a U clamp with a bit of tube in it. Turned out the bit of tube was just long enough to disappear out of sight but connected to nothing, the parts book revealed it was supposed to be somewhat longer and hooked up to the oil tank breather. Another little thing to fix. Fortunately the UK is currently going through one of those 'when it's not raining it's freezing' weather cycles so I can take my time without getting too frustrated.