2 Strokes Down Under

Hi All,
I need some advice / thoughts please on how to correctly adjust the oil pump on my RZ250 83 mod. The manual doesnt make it very clear, and Im concerned its currently set too rich. The manual basically says there should be a small gap of between 0.1mm and 0.15 mm between the little metal boss thing and the large washer/plunger.
Can anyone tell me a better or easier way to do it ?
Ta
Saul

Hi, there is no other way to do it I'm afraid. 0.1mm is not very much at all and will quickly go to zero if the pump is not maintained correctly. The reason for the tiny gaps was to make out the bikes ran cleaner than they actually did! This tiny gap also requires a different adjusting method on the cable, to raise the oil ratio very quickly with just the hint of throttle opening. Instead of using a mark at full throttle and a realistic gap, like 0.25mm, like most Yamaha models of the last 40 years or so.
The gap you mention produces a fuel/oil ratio at idle speed of around 235:1 this will quickly reduce (more oil) as the throttle is opened, providing the cable is adjusted correctly.
If that gap reduces by 0.05mm then the ratio becomes 470:1, not good! The 0.25mm gap will give you an idle ratio of around 90:1, finishing at around 20:1 at full throttle
HTH.

What ratio do people use when running "pre-mix"?

Mmm that's a really sensitive little adjustment isn't it. Nice thing about the pump as opposed to going premix is that the oil/fuel mix varies according to load (ie more oil delivered with more revs).
Sometimes though, you think that at least with premix you can be certain that it's always getting the right amount of oil.
It's compounded by the fact that the Haynes manual illustration bears no resemblance to the actual pump markings.
We'd better get making some shim washers to get that gap perfect rzripper!
(Thanks Arrow for your useful explanation).

Good to see you posting here Gary, your knowledge is invaluable!

Chees Jon, good to be here.

I was just thinking today that 99% of the UK forum guys now run an Arrow Pump, and a few of us are now ordering them, so how long before it's the same is true of Aus I wonder? I just placed an order for another one... LOL

Actually I noticed today that Arrow has rebuilt/tested pumps you can buy outright for sale again, so grab em while you can guys, but be quick they sell out fast! both 250 and 350. Contact him via the PM system here, on RZRD500 and Norbos forum etc.

Jon, what are these Arrow pumps?

Arrow, who posted above, strips, cleans and rebuilds oem LC and RZ pumps and then checks his work and sends them out 'better than new'. His service is very well rated in the UK by the forum members there and a few of us here have started to have him do the work on our pumps or ones we get from uk forums and ebay and have sent to him. After all a 30 yrs old pumps is often dirty, clogged and could be worn out. If you use them you should make sure they are top notch etc.

Im sure he will say more when he chimes back in, and other than a customer I have no affiliation with him so Im just passing on the info of course.

Thanks Jon. As Jon says, I started to offer a full oil pump re-furb service for fellow enthusiasts last year, by total accident really. I have seen many things now with these old pumps, worn out cams, passing valves, no balls in valves, scored main bores, scored pistons, worn out thrust washers, broken thrust washers, worn out springs, worn out/passing seals, wrong seals, wrong pump for bike, corrosion damage, no minimum stroke, unlimited stroke, no shims, shakeproof washers for shims, etc, etc. But some are ok!!!

blimey, sounds like a catalogue of disasters. I got one from Canada, and the new seals from Yamaha, was just going to rebuild it and bung it in as I convert my RZ250 to 350. Maybe I'll have a closer look first.
what forum/website are your services available on Mr Arrow?
Jon, what 'UK' forums are you frequenting, or maybe suggest?

BRG1200 wrote:blimey, sounds like a catalogue of disasters. I got one from Canada, and the new seals from Yamaha, was just going to rebuild it and bung it in as I convert my RZ250 to 350. Maybe I'll have a closer look first.
what forum/website are your services available on Mr Arrow?
Jon, what 'UK' forums are you frequenting, or maybe suggest?

Hi mate, You probably know this but make sure you have the correct pump for the bike and the correct course worm to go with that pump. My services are available on any forum via PM.

BRG, As Arrow says to build a 3fiddy you defo need the correct 350 pump with its coarse worm drive... the 250 is different and has more 'teeth'... the drive gears are the same, but not the worms. Also make sure you have the bush (washer) the worm drive as well, they are often missing, yam still sells those but not easy to track down.

I have rebuilt my own pump before using new seals, worked well but ive no real idea on how well it runs. It was dirty and the NRVs were mostly clogged and it runs way better now its clean and resealed, you can really see it ship oil, but is it adjusted right? and did i do it right? I dunno... these days I just let Arrow do it, then I know its right. He has also built me an uprated pump for my 421.

UK forums, well there are a few, but Norbo's is the most well frequented and thats where I post, its called RDLCCrazy, but as Arrow says you can contact him here as he posts here as well now. Drop him a PM as he says.

When I bought my 250e back in 2009 I had problems with the oil pump. I did not know much about setting the oil pump or other issues (the former is supposed to be an easy affair) so I decided to study the pumps in great detail. I have learned much in 5 years. One issue for example is early pumps were prone to scoring in the bore of the main casting, especially if the engine got hotter than "normal". Yamaha later introduced a mod to prevent this and I incorporate this mod in all the pumps that come my way. I have had to tell some people that their main casting is scrap, so I provide another casting. Once the mod is done the bore is not prone to scoring. Seal fitting is another issue, the tiny 4x9x3 seal is easily dished which makes it a tighter fit on the piston causing rapid wear. I made my own tools for fitting all the seals.

gday Gary, , how you going? you'll have branches all over the world soon, ken