Vino no start

[ziptiejones]

A few months back it went down, techs at the local scooter shop won't work on 2t, but diagnosed it as no compression (15psi) bought and installed new 70cc Athena kit, installed yasuni r, went up on main jet but won't start.

I have found both a broken reed and a (new)spark plug that magically has no gap all of a sudden. I regapped, reinstalled, had no clearance issues.

I know it gets spark, it's very bright and it hurts. At first I had around 110 psi for compression but that's gone down now to around 90.

Will not fire with starting fluid. Carb gets gas. What else could I be missing?

[ziptiejones]

Edit to add: It did start after starting fluid ONCE and ran for probably 10 seconds, but had no air box(removed to try starting fluid) and had be at wot, and even then barely idled

[aeroxbud]

Did you check the squish band when you installed the cylinder? It sounds like the piston could be making contact. Some cylinder head require a different length plug.
Did you check compression with the throttle open? It should be higher than that. What was the ring end gap like?

[ziptiejones]

I made this post, then messaged a friend and it started once I put the stock air box back on. Runs okay, but I think lean on the pilot. It's having an issue with hanging rpm after like a 1/4 or 1/2 throttle blip. Friend was saying that it sounds like too lean. I went up to the biggest main jet I have (77) but I can't find pilots. The site that zino has linked me to a few times only has main sizes.

Anyways I really didn't think keeping the air box off would keep it from starting even. I only had it off to give it a bit of starting fluid.

Next I'm gonna get it hooked up on the temp gauge and see what it's looking like so I can tell a little better.

[ziptiejones]

We're idling at about 220F but it's a high idle. Any lower and it starts to die out.

Still has a hard time coming back down to idle.

[classacted]

when you're having trouble like this, you want to eliminate parts that could prevent it from starting and running. I always remove the muffler and the air cleaner.
yamaha qt50 puts the 2 cycle in the carb, but I don't know where vino delivers it. if it's like honda and suzuki and puts it in the block, then you could have a block full of 2 cycle and your plug is getting oil fouled. keep checking your plug and wiping it off. the pump doesn't stop oil from dripping in there when it's sitting.
just an idea, but maybe if you can get it to idle at all, you can squirt water places where you should have no air leaks. I have actually found air leaks that way with both cycles and cars. if you find an air leak you might be able to raise your compression. I think what you have there is border line.

[ziptiejones]

After doing some reading I'm worried about an air leak. I didn't really think of it but the oil looking up makes a lot of sense.

After seeing it idle well for a while I took it on a trip to the end of the block and back. One of the things going wrong before it went all the way down was something in the cvt, and the variator not shifting. It still seemed to have the same problem. I checked and the slide(boss maybe?) was kinda gross from belt dust and was sticking a little. I cleaned it up and everything feels good now.

I'm recharging the battery so I can run it without the cvt cover(in the garage and not in a ride) and get an eye on everything. I guess I'll report back then. I appreciate the help and advice so far.

The only problem is that it still won't start without the help of some starting fluid. Pilot jet I'd assume?

[ziptiejones]

Aug 27, 2024 14:16:59 GMT -5 aeroxbud said:

Did you check the squish band when you installed the cylinder? It sounds like the piston could be making contact. Some cylinder head require a different length plug.
Did you check compression with the throttle open? It should be higher than that. What was the ring end gap like?

Did not check squish, it was the same Athena set up I was running before, all the way to the gasket. Idk what could have caused that with the plug, but it hasn't happened again. I'm wondering if I just didn't notice right out of the box? Throttle wide open for the test, I did not check ring clearance. I've seen it done on car engines, more high end ones specifically, but I've never really had anybody mention it to me as far as building a scooter engine, at least not the Chinese bikes I've been used to in the past. I'm not saying it wouldn't make sense to, I'm just saying it's not been something I've done in the past. It's actually a little embarrassing because it's something small that I could have done much earlier in all of this and had some peace of mind. I will probably learn from this moving forward.

[ziptiejones]

Another update

Still starts from cold only on starting fluid, will only really pick up much speed if you very lightly and finickly ease ever so softly into the throttle. If I just hit wot from an idle it bogs, but if I'm nice and easy it can get up and get going. I haven't confirmed top speed but so far I don't really feel like it's that much faster than my last set up, so I know something's off still.

This is still stock carb and stock air box. Revs out fine when it's on the stand but I have to ease into it when I'm riding. I have not clue.

[ziptiejones]

Here's my plug. Too lean?

[jodaddy]

Yes. Too lean.

[ziptiejones]

Any other advice or tips or thoughts as far getting her tuned goes?

I switched back to the technigas silent pro but it's still not wanting to start(even on starting fluid), but probably cause I'm rich after going up a jet size or two.

Are there even pilot jets available for this carb? Am I overthinking the pilot circuit here?

A polini cp21 was recommended as well, but any other advice or tips on that? I had picked up a throttle cable for the vino just in case I decided to donate carb swap.

[jodaddy]

How many turns out on the air screw? Try a clip richer on the needle.

[ziptiejones]

Aug 29, 2024 16:04:32 GMT -5 jodaddy said:

How many turns out on the air screw? Try a clip richer on the needle.

I screwed it out like a half turn or two but I can reset it at 2 1/2 out and try from there I guess.

[jodaddy]

Pretty sure those are air screws. Turn it in for richer. General target is 1 1/2 turns out. Did you raise that needle? That’ll give you more fuel off the bottom and through the mid range but it’ll be same at WOT.