Tomos forum

Hello,

Can anyone please tell me what is the main differences between Flexer 25km version vs 45km version? Do they have different cylinders and pistons?

My 25km version with upgraded carb (14/12), no intake plug, better exhaust, and 28 rear sprocket does now 40km/h... but it's terrible weak. 0-40 km/h takes about 60 seconds!

What upgrades do I need? Should I exchange piston/cylinder/cylinder head?

Thanks!

Edit: Ok, maybe not 60 seconds... but feels like it. Probably around 25s

Sounds like problems similiar to some i had last week.

Sounds like an air leak, if it idles try to spray some deodorant on the cylinder and carburettor, if it reps, you have a leak. Not always if the moped doesnt react means there's no airleak. I found out that I didnt tighten the cylinder head very wel, it could to a quarter of a revolution more, problem was solved after that. So try to fasten ur cylinder head some more.

You can test this. While driving play with the choke, if the moped shoots forward it means you have the problem i describe above.

Yes, they have different pistons. And also the cylinder head is different, but the last one is only a limit for the acceleration.

Sounds like problems similiar to some i had last week.

Sounds like an air leak, if it idles try to spray some deodorant on the cylinder and carburettor, if it reps, you have a leak. Not always if the moped doesnt react means there's no airleak. I found out that I didnt tighten the cylinder head very wel, it could to a quarter of a revolution more, problem was solved after that. So try to fasten ur cylinder head some more.

You can test this. While driving play with the choke, if the moped shoots forward it means you have the problem i describe above.

Hm, sounds like a good Idea. Will check my bolts and such. Maybe 60 seconds was a bit of an overstatement... it probably does 0-40 in ... 25-30 seconds? No idea, but I'm 90kg so it feels very weak, specially uphill

Yes, they have different pistons. And also the cylinder head is different, but the last one is only a limit for the acceleration.

Hm, so then I should buy that piston + cyl.head. It's more acceleration I want.
But the cylinder is the same?

The new type cylinders are the same, from the older types they are different.

As far as I know the Flexer 25 cylinder is not different from the 45 cylinder.

To get more power(compression) you can buy a 45 cylinderhead. Or maybe, what's even better, a Puch High Compression cylinderhead.

Maybe you can adjust the ignition timing. Probably it's still on 25km/h, you must rotate the plate clockwise towards the high notch.

The new type cylinders are the same, from the older types they are different.

Ok, yes I know the Quadro A35 has a different (better) cylinder compared to flexer.

As far as I know the Flexer 25 cylinder is not different from the 45 cylinder.

To get more power(compression) you can buy a 45 cylinderhead. Or maybe, what's even better, a Puch High Compression cylinderhead.

Will order a 45 cylinderhead, thanks

Maybe you can adjust the ignition timing. Probably it's still on 25km/h, you must rotate the plate clockwise towards the high notch.

As far as I know 25 and 45 have the same timing , and its controlled via the CDI unit...

What's the type of your cylinder block?

The older types have different ignition timings.

What's the type of your cylinder block?

The older types have different ignition timings.

On the block it says "A52". The cylinder has a reed valve so it's an A35

Then it may possibly have a different timing

Its a 2006 version. So what could differ is the position of the... stator plate?

You must check if your ignition is equiped with a so called "pickup unit" (black square part). Then you can't change the timing, otherwise you can indeed turn the stator plate. As far as i know only engines of the A55 type have a pickup unit for the ignition timing. You can check that if your flywheel has a bulge inside where the magnetos are positioned and the stator plate has no notch. Correct me if i'm wrong.

Here is a topic of how to change the timing of a 4-spool ignition with CDI. It has nice pics of how to do it, the text is in dutch. For your information, in 1 photo is displayed the position of the notch. The upper line is for 45 km/h, the lower is for 25 km/h. If your engine does not run well, you can turn it more clockwise, but no more as the upper line. And in the lower right side between 2 spools you see a black kind of part, that isn't a pickup unit. The pickup unit looks different. I don't have pictures of it.

Thanks Shadowranger! I will look into that guide this weekend, and post my result!
I found an exploaded view of the A55 engine (wich I don't have), seems the "pickup-unit" is no.4 in this pic. I will make sure I don't have it.

The upper line is for 45 km/h, the lower is for 25 km/h. If your engine does not run well, you can turn it more clockwise, but no more as the upper line.

Strange, it was allready set to upper line. I could see the tiny mark without taking the flywheel off. So it's set to 45 km/h then?

Probably yes.

Probably yes.

Ok, good. Maybe the pre-owner changed it... So I'll just keep it this way. Hopefully the new high comp cylinderhead will do some difference

Did you check your ignition for a pickup unit? Do or don't you have it on there?