Author Topic: TZR125 4DL TRACK BIKE  (Read 9267 times)

Louis

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Re: TZR125 4DL TRACK BIKE
« Reply #345 on: April 08, 2018, 10:06:07 AM »
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I would say considering you have just fitted the new carb, and still not sure of what jetting is required, it's too lean. Close enough to run ok, but with the little bit of extra advance and spark energy from the zeel, pushing it into detonation.

The more I think off it the more I think it was to lean, but I didn't use any more advance the run was with a stock ignition curve it should be safe.
Perhaps the runs before mounting the zeel did some damage.
I will clean the cylinder and order a new piston, that wont be the problem.
But I will make my dyno sniffer ready to do some measurements before I start testing again ::)
Think this would show up on the screen if it was to lean

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If you're unsure about the oil feed pipe you can use premix, or swap the feed pipe over for a larger one
I would like it a little bid bigger, will change this.

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2stroke

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Re: TZR125 4DL TRACK BIKE
« Reply #346 on: April 09, 2018, 12:46:31 PM »
@Louis:

What a pity to see your engine reduced like this.  :'(

At first glance, I see three possible main causes, two of which are strictly related:

1) Surely, you've had an oil flow/quantity problem : your cylinder is seized everywhere, and not only on the exhaust, the hottest area. You can partly solve by placing a larger nozzle on the carburetor or you can place one nozzle on the intake manifold. But you also need to increase oil flow directly on the oil pump.
2) You had a detonation problem due not only to the advance (+5 degrees on first set of dyno-runs), but also to the too lean mixture. The combination of these two factors has led to an increase in piston's temperature with the signs of corrosion on its top, plus an increase in volume of the piston due to the temperature ... those,  together with the breaking of the veil of oil (already poor for the little oil introduced) has led to seizure. The spark plug  broke for the detonation, and the debris hit the top of the piston in several places.

That said, you know what to work on, so that it does not happen again: so do not give up! ;)
The "good news" are that the cast iron sleeve can be simply rebored and you need just to take a new piston.   :)

I have two curiosities: do you have pictures of the head, to better understand what happened, and where? Which was the tolerance between cylinder sleeve and piston? 8)

Louis

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Re: TZR125 4DL TRACK BIKE
« Reply #347 on: April 09, 2018, 06:35:53 PM »
Hello 2stroke,

Quote
1) Surely, you've had an oil flow/quantity problem : your cylinder is seized everywhere, and not only on the exhaust, the hottest area. You can partly solve by placing a larger nozzle on the carburetor or you can place one nozzle on the intake manifold. But you also need to increase oil flow directly on the oil pump.
Yes, think the problem lies more at the flow off the oil, du to the smaller oil feed intake from the RS125 carb, (its about half the diameter as the Yamaha one)
If I had know that this is the end result I had changed it ::)

Quote
2) You had a detonation problem due not only to the advance (+5 degrees on first set of dyno-runs), but also to the too lean mixture. The combination of these two factors has led to an increase in piston's temperature with the signs of corrosion on its top, plus an increase in volume of the piston due to the temperature ... those,  together with the breaking of the veil of oil (already poor for the little oil introduced) has led to seizure. The spark plug  broke for the detonation, and the debris hit the top of the piston in several places.
I don't think the 5 degrees more is the problem, ones the engine is running again I will push it further then the 5 degrees from the oem CDI
The 5 degrees in combination with the lean setup (as you already describing) is the problem, think most damage is done from the runs before I mounted the Zeel
You can see it, Last run is with the 134main giving a 750rpm more is a bid to much.

Then mounted the zeel witch have probably more spark energy on a already damaged plug gave the ..... result
I just wanted thinks to fast. Made some mistakes.... :)

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That said, you know what to work on, so that it does not happen again: so do not give up! ;)
Never say never, but it wont happen in this same conditions ;D

Quote
The "good news" are that the cast iron sleeve can be simply rebored and you need just to take a new piston
If you dont mind did not rebore the Cylinder, only cleaned it, new piston is ordered ;)
(with a did of luck it is running next weekend)

Will change the oil feed connection on the carb just to be sure, and make my A/F system working on my dyno so I can see how far I was off

Quote
I have two curiosities: do you have pictures of the head, to better understand what happened, and where? Which was the tolerance between cylinder sleeve and piston? 8)
Will update my site for this


« Last Edit: April 09, 2018, 07:20:16 PM by Louis »
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2stroke

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Re: TZR125 4DL TRACK BIKE
« Reply #348 on: April 09, 2018, 08:24:21 PM »
I don't think the 5 degrees more is the problem, ones the engine is running again I will push it further then the 5 degrees from the oem CDI
The 5 degrees in combination with the lean setup (as you already describing) is the problem, think most damage is done from the runs before I mounted the Zeel

As I wrote in my previous post, the problem is a combination of the two : carburetion+advance.
Three years ago, at my very first approach to TDR, I've tried moving the pickup by 4.5 degrees, resulting in an equal ignition advance, original CDI.  I had a first run on circuit, but I noticed immediately that was too lean for that advance...after 2/3kms the spark plug and the piston's top were slightly eroded by detonations. In particular I had to enrich the midrange changing the needle. If you have seen my ignition curves, now the 4.5 degrees are easily exceeded, but with programmable CDI plus an adequated carburetion, and above all : not at any engine rpm speed.  Spark plugs are perfect and so are piston's tops.

Start with a rich carburetion, then refine it, it's the best way to avoid damages. (-P)



Quote
If you dont mind did not rebore the Cylinder, only cleaned it, new piston is ordered ;)
(with a did of luck it is running next weekend)

You have the sleeve in your hands and you are an expert, so you can evaluate the depth of the scratches better than in the pictures you posted. In any case, I would have slightly rebored the cylinder and design the "oil friendly" cross pattern. Just to be sure that everything is perfect. ;) Which piston did you order, cast or forged?


Quote
I have two curiosities: do you have pictures of the head, to better understand what happened, and where? Which was the tolerance between cylinder sleeve and piston? 8)
Quote
Will update my site for this
  (-P)
« Last Edit: April 10, 2018, 07:57:40 AM by 2stroke »

casal-fan

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Re: TZR125 4DL TRACK BIKE
« Reply #349 on: April 12, 2018, 10:06:38 AM »
Oooops Louis... bad luck

Kind of read in a bit of a rush, but think there is no reference to the fuel needlevalve size on the dellorto carb???
In a bike I had (TZR400), I mounted TMX35s I also got from ebay, but in the previous application there was a fuel pump, so the needle valve size was very small. I noticed that after I seized the thing first time I gave it the beans...

Have you checked fuel valve size?

Never had the ground electrode craking, but eroded, gone a few times... usually, I think, only my opinion. Too much advance, too lean, or a combination of both...
Scrapping on 4 sides of piston... also some experience with that. My opinion is, either not long enough warm up, or lean.
Think still have a piston that look much like yours from a seizure with the mito. - Too lean on 320 or 330 main jet size.
My mito with 35mm mikuni,  performance pipe as well as M77s magic on the cylinder was using the high 300 size range main jet with a thin (about 1 cm) thick layer of Automotive ventilation filter materiel for airbox filter.




Louis

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Re: TZR125 4DL TRACK BIKE
« Reply #350 on: April 12, 2018, 09:52:20 PM »
Hi Guys,

Thanks for your advice, I will take it step by step.
Will check the needlevalve size, and start way bigger in mains and build gently my way down.

Piston and V-vorce came in today.



So technical it could run this weekend :)

But I like to make my A/F system work on the dyno, currently constructing that to.
Like the idea to do some runs and see how the mixture is ;D
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Martin77

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Re: TZR125 4DL TRACK BIKE
« Reply #351 on: April 12, 2018, 10:49:48 PM »
You can always test the V force with the 32mm carb initially, at least then you'll know the effect of the reeds with a known baseline. Putting the reeds and carb on together is two things at once and adds extra confusion...

Louis

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Re: TZR125 4DL TRACK BIKE
« Reply #352 on: April 13, 2018, 06:30:31 PM »
Quote
You can always test the V force with the 32mm carb initially, at least then you'll know the effect of the reeds with a known baseline. Putting the reeds and carb on together is two things at once and adds extra confusion...
Sadly this is not that simple, I needed to shorten the throttlecable for the use off the 34mm carb (same as you)
So going back to the 32mm is a bid tricky.

But don't worry, wont mound it all directly.
First I like to setup the 34mm carb correct and then see what the zeel brings me.
After knowing that, I will mound the V-force so it should give good data (-P)
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Martin77

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Re: TZR125 4DL TRACK BIKE
« Reply #353 on: April 13, 2018, 08:44:22 PM »
I made a new cable from the splitter to the carb for the TMX, so can swap them over at the splitter, then re-adjust the oil pump closed position..

Anyway, we await news as it happens  :)

Louis

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Re: TZR125 4DL TRACK BIKE
« Reply #354 on: April 14, 2018, 06:16:15 PM »
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I made a new cable from the splitter to the carb for the TMX, so can swap them over at the splitter, then re-adjust the oil pump closed position..
Yes that could be a solution, I did just to many things in one day without planning or investigate it.
The more I think off it the more I think what the hell I did.... :-[

Anyway I did some work on the cylinder, I have tried to remove the strange curve from the B transfer.

And I quickly realized that I need to investigate in my porting tools to
Sadly this need to wait as I have planned to upgrade my dyno over three weeks after that my workplace needs a update..

But my little Dremel almost worked perfect.


not as smooth as Martins work but maniched to remove the curve and make it somewhat straight ^-^


Curved the direction a little bid more to the center.


I enlarged the ports so they mach the crankcase and curved the cylinder legs in the hope it would help a bid (not cut them ;D)


Not planning to do more, but could not resist it ones I hade the cylinder in hand.

Waiting on some Carb parts, hope to get here running soon (-P)
« Last Edit: April 14, 2018, 07:13:19 PM by Louis »
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2stroke

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Re: TZR125 4DL TRACK BIKE
« Reply #355 on: April 16, 2018, 07:21:16 PM »

Anyway I did some work on the cylinder, I have tried to remove the strange curve from the B transfer.

Have you noticed if it's just your cylinder that has that strange curve or is a peculiarity of all those in the same series? In the latter case, this would make me think :)

By the way, you're doing a great job with your cylinder, as ever. (-P)

Louis

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Re: TZR125 4DL TRACK BIKE
« Reply #356 on: April 16, 2018, 10:05:33 PM »
Hello 2troke,

Quote
Have you noticed if it's just your cylinder that has that strange curve or is a peculiarity of all those in the same series? In the latter case, this would make me think :)
It looks like they all have the same (problem) have tree cylinder lying here all three the same strange curve :)

Don't know if my ''removed curve'' is a success, as it is difficult to keep the smooth surface. (I'm not a professional tuner) but it feels good.
We will see how she goes ones she is running a gain, hope it wont bring less like my cut cylinder legs ::) as that would be a big setback.
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2stroke

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Re: TZR125 4DL TRACK BIKE
« Reply #357 on: April 17, 2018, 12:47:08 PM »

It looks like they all have the same (problem) have tree cylinder lying here all three the same strange curve :)

As I supposed!  :)  This curve seems to have a specifical productive or functional meaning. In my opinion, it was thought for optimizing the distribution of the charge in different points of the chamber. 8)

But on the other hand, the "newest" series of cylinders didn't show this peculiarity: this could be a sign that Yamaha had rethought the distribution scheme, counting however on a different head.

If things are seen in this perspective, your cylinder rework could bring to an improvement of performances. ;) (-P)