Just bought a modded non-running Tomos A3 - Trying to sort out

Hi All,

I just picked up a non-running Tomos. Tags say 1978. It's missing a few things like the carb, and as I'm looking for parts I'm noticing that it appears to have had an A35 swap at some point. The cylinder head says A5. Most research says that means it's an A35, but there are a few posts of people claiming that it could also be an A55. It looks like an A35 to me, but any confirmation from you pros?

I may kit this bitch eventually, but for now I'd like to keep it stockish. It has an aftermarket exhaust from what it looks like (I exceeded the photo limit here) . What is the opinion on buying a stock carb? Sounds like it should be a Dellorto 14.12 SHA correct? Am I missing out on anything by not going a little larger? Since I have no carb at all there's basically no cost difference.

On that note, WTF is up with this intake? Appears to have an oil injection line hooked-up (not connected to anything on the other end though). It looks like it's stamped either TOMOS 012 or TOMOS 912, hard to read. Am I crazy or is that an oil line? If so, why?

Anything else I should be weary of before I start assembling an inventory of parts? The ignition coil wire has been spliced a few times so I'd like to replace that, but if there's an upgrade over what's on there I'd love to hear about it. It's a CEV MOD 6309.

Thanks in advance!

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Re: Just bought a modded non-running Tomos A3 - Trying to sort out

Not crazy. It is an a35 cyl/head on the a3 case.

They probably just moved the intake from the cylinder over which came off an oil injected bike. You can remove the tube and plug up the hole, or replace it with a better intake. Those are just the worst intakes.

The stock carb on an a3 is an encarwi. Garbage. The stock intake for an a35 is a sha. Maybe 12:12, maybe 14:12. Since you have to buy one anyway, get a 15:15, or 16:16. This way when you start upgrading other parts of the engine you wont need to worry about a carb. Grab a range of jets. Probably a full 60's range will get you where you want.

Be sure to drain the tranny fluid and put in some fresh ATF. You can read up on your bike via the wiki here which will give you specific fluid amounts. Or just utilize the oil check plug and fill the case until it leaks out the check hole.

Have fun, tomos sure are a blast to ride!

Re: Just bought a modded non-running Tomos A3 - Trying to sort out

Thanks for the insight. Makes sense they just swapped the intake with the head.

Can I ask what's so lousy about this intake, other than having to plug it? The Dellorto 15.15 comes with a 1.5mm shim from Treats. Is 12mm choking it with just the 50cc head? Or are they prone to leaks and all other crap?

Re: Just bought a modded non-running Tomos A3 - Trying to sort out

Those intakes are fine, get a stock 14:12 used off buy sell forum and slap it on, assuming everything was done right adding the a35 cylinder that will be a nice bike.

Back in the day i built several of them, using the a3 10mm wrist pin piston in the a35 jug. Even with a stock pipe they run strong, 35+ mph. If the intake windows weren't cut in the piston, it will help to do that.

Ignition is always problematic on them, the 'key' is a little alignment dowel that has a tendency to waller out the keyway in the flywheel. If you have spark, compression, and fuel but it won't start, check that.

Re: Just bought a modded non-running Tomos A3 - Trying to sort out

Graham is not wrong, I just find that they are not great for fuel flow. They are shaped like a z with hard right angles. It is also 12mm which then negates the need for the 15sha. The 14:12 would be adequate. If you upgrade the intake to one that has better flow and is at 15mm then the 15:15 will make more sense. I prefer the shorty intakes for tomos but I am not sure you will be able to run one of those with an a3 bottom end. There is probably not enough room, the a35 barely has enough room, you actually have to drop the engine a bit to remove the carb easily. But it is a straight shot of fuel. And yeah a little porting work on that stock just and you can end up with over 40mph easy peasy.

Re: Just bought a modded non-running Tomos A3 - Trying to sort out

Awesome, thanks.

Follow-up, how are the bottom/ends and clutches on these historically? I'm 200lbs and live in a hilly area. I'm thinking about the power adding, would be nice, but power + resistance doesn't always go well on stock bottom ends and clutches.

Re: Just bought a modded non-running Tomos A3 - Trying to sort out

They are what they are. The a3 bottom end is not going to have much replaceable parts for the tranny. Just not a lot of aftermarket items available. An a35 and a55 have a lit more available even some interchangeable. The a3, not so much. Just keep the tranny with the right amount of fluid and it will help it last as long as possible.

Re: Just bought a modded non-running Tomos A3 - Trying to sort out

Thanks for the advice, I'm going to pop the case open, clean it, and probably change the fluid 2x after running it a little.

Follow-up: the handlebars have a few extra limbs. Are these the attachments for a windscreen?

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Re: Just bought a modded non-running Tomos A3 - Trying to sort out

Sure looks like it to me .

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