Oil Pump Failure

[forkyleigh]

Just wondering if anyone else has had issues with their oil pump?  I believe I am having issues with mine.  I have seen basic Minkuni ones for sale, and racing versions.  Am I better of just blocking the oil pump and premixing?  I had one soft seize issue recently and I have been purposely running rich to try and prevent it.  I just don't think the pump can keep up the the demands of oil that my moped has at high speeds.

Also, what things can I do to help keep engine temps down?  Again, I am running rich to try and help.  Are their different engine cases available?  Do after market fans help?  What about the fan "scoops?"  I am trying to keep reliability and daily driving.

[90GTVert]

I've never had one of mine fail, but did have a customer with a failed pump. I ditch oil injection totally on mine. The convenience of not mixing is kinda nice, but I prefer knowing there's oil and how much over that convenience. I don't think it's such a common problem that we should all be terrified of our stock pumps though.

You could disable your pump for now and try a tank of pre-mix to see if the issue persists. Some just loop a hose from the inlet to the outlet of the pump. I prefer removal, but that would be good for just testing at least. Mix your fuel at 32 to 40:1 with oil intended for pre-mix, preferably synthetic or synthetic blend, and see how it does.

The 90cc style large fans drop temps quite a bit. Some scoots need a different fan shroud to accomodate them and other scoots already have a large shroud. If there's a bunch of clearance between shroud and fan, you can prob fit a 90cc fan. The youth ATVs like Polaris 90s powered by the Minarelli are a good source. You cna find them on eBay or places like kaseaparts.com. A scoop helps a small amount, but not like the fan. A larger carb may keep it cooler. If you've got excessive compression or timing it may increase temps.


49ccscoot.proboards.com/post/41099

49ccscoot.proboards.com/thread/6426/shroud-info-yamaha-vino-shrouds

[forkyleigh]

I have a vento, so according to your links, i should be able to fit a bigger one in there. I drove it about 30 miles yesterday without incident. But I kept cruising speeds about 40-45mph. There were hills, both steep and long. I think the only time I run into issues is at high throttle. I tried a few higher throttle pulls. It seems like there may be some detonation at sustained high rpm and high speed runs. This would lead me to believe it may be lean at high throttle. I am using a #90 jet with my new 70cc cylinder and piston. The last 70cc I was using an 82.5. Could I really need to go bigger? Otherwise I wonder if I am feeding to much oil that there isn't enough fuel for high rpm. I turned the oil pump up as far as it could go by adjusting the cable. There is also some in the gas. I didnt want to ruin the new parts. I just fear trying to run it without extra oil and having it damage the engine.

Note: I did a few high throttle runs last night. But I had no where to pull over to check the plug. I had a drive 3 blocks home after the runs. I also let of the throttle as soon as I heard what I thought was detonation.

This thing really wants to go once I hit about 45mph. it pulls like crazy for a scoot. But the detonation noise makes make back off quickly. GPS was 56mph when I had to let off out of fear.

Do I put in my new fan when it comes and test it a bit? Do I try and do a few hard pulls in a place where I can pull the plug? Also, how long would it take to show its true colors on a used plug?

[90GTVert]

I would decide what you wanna do with the oil pump, whether it stays or goes, and run just that oil mix. Then tune it. Get a selection of main jets. Make WOT passes with them over set distances and record speed, RPM, and any other observations that you feel are useful. You should come up with a jet or two that are working better than the rest. Choose the richest of those to stay on the safe side. Then you know the jetting should be correct. If the detonation persists, you probably have a cooling issue of some sort. Whether that's from oiling or compression or timing or a poor air cooling system needs to be determined. I told you above how to temporarily disable the oil pump, and that could be a good checkup on the oil issue if needed but you have to know what's in the tank. No good to do that and not be sure that you're in a proper range of oil mix.

[forkyleigh]

Good ideas. I appreciate the assistance! Just a bit anxious to see what the top speed is, just know that I am putting the engine at risk at this point.