Is the Zeeltronic worth it?

[Calum]

So just go with the stock settings. You can't go too far wrong.

The easiest way go get started with learning is by having a play with the powervalve timings. You won't run the risk of detination and damaging your engine, so it's a safe place to start

[Strike78]

I ordered one with the connectors already installed
Everything went smoothly and Borut was very helpful throughout the whole process.
Thanks for the help guys!

[Calum]

Aww nice! I've just received another Zeel for my RD yesterday. I've got to wire the plugs myself mind you as it's going into a Cagiva Mito.

[Strike78]

I have another question
Ever since my bike came back from the mechanic a few years ago, it has had very poor low-end power and it never felt the same again. His excuse was that the bigger piston is heavier, but honestly I’m not convinced.

My DTX is noticeably slower than my friends’ DTRs/DTRE, especially in low RPMs. To be honest, I never went back to that mechanic after that. I already adjusted the YPVS before, but the problem still persisted. I also cleaned the carburetor and installed a new spark plug.

Right now I’m waiting for the new CDI to arrive so I can properly tune the power valve again and see if that changes anything.

Has anyone experienced something similar? Could the bad CDI cause such a big loss in low-end power?

Current setup:
Firebox expansion chamber
Firebox silencer (I think)
Original carburetor
18T front sprocket
51T rear sprocket

[Calum]

This is most likely the squish.

If someone built that top end for you, they probably used too thick a base gasket reducing the compression ratio. The cylinder head could sit be marginally higher than what it was before, meaning the squish is off.

I am not saying this definitely the case, but would explain why you'd lose bottom end. I am not sure about the heavier piston, sounds like a cop out, but if a different dome was used, different profile, then same answer. The squish is affected.

A vast majority of power on a two stroke is made in the head, so it could be that the squish band isn't correct. This is a very simple and easy thing to fix and measure. All that is needed is a set of vernier calipers and some 1.2mm thick solder wire, with a dab of grease to stop it falling into the bottom end.

Could be this, especially as you say, it was fine before the top end rebuild, noticeable after.

I once went from the stock 3MB00 cylinder, to the TZR R Belgarda 3MB00P which has a raised exhaust port by 1mm and as a result, greater over-rev (ideal for the TZR) loss of bottom end (less ideal for the DTR).

I went from lifting that front end up with ease (no small feat on my heavier setup) to having to work for it.

Now I run a ported Athena 170cc kit and I love it for the low-rev grunt. I have my RS125 which is lightening fast so I enjoy both aspects now

I am by no means an expert and please someone else chime in and correct me, but based on what you've just articulated, this could explain it.

[Strike78]

Thanks for the explanation, that really helps.

Would fitting a new gasket kit (especially base and head gaskets) potentially restore the correct squish/compression? or should I consider getting a new top end altogether?

I just want to make sure we’re looking in the right direction before replacing parts and not waste money on it.

(I realy dont know anything on the mechanical side).
Thanks once again!

[Calum]

Well, you need to figure out whether this is indeed the problem. Obviously I can't be certain having never seen the bike, you'd need to take some measurements.

You don't need to get a new top end, correcting the squish is standard practice on two strokes.

[Rallyfinnen]

You can take a piece of soldering tin and bend it and stick it through the plug hole to get a rough measurement of the squish. If the solder is not pinched you can 'double twist' it to get a reading. This should give you an idea if it's the cause. A good value should be 1mm or slightly less IMO. You can find different thickness base gaskets in some places, like here: https://www.motorsportgoetz.com/Cylinder-Base-Gasket-03mm-Yamaha-DT-TDR-TZR-125

[Strike78]

Sooo... a lot has happened, and it turns out things are worse than they first looked.

My Zeel finally arrived and I've already installed it. While working on the bike, I found that the cylinder head is warped and it's leaking coolant into the cylinder, so I've taken it to be skimmed.

I also found that the air screw on the carb is completely stripped and there's no way I get it out

[Calum]

Oh that's pretty standard on those Mikunis sadly. Very common.

Jeez how bad is the head to have warped that much? Depending on how much they skim it by you may need go offest with a thicker base gaaket.