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Old 07-03-2006, 05:36 PM   #901
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Thanks, Paolo, got them today...I sure do appreciate it.
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Old 07-03-2006, 06:19 PM   #902
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Quote:
Originally Posted by Paolo M
As promised, here is the report about last weekend test of the DSII.


In the final i had some problem with the glowplugs, cause the engine was flaming out a few time. ( i found out that the problem was the head clearance) The engine come with 0.40mm. I add 0.05 for a total of 0.45mm. This was working good with a 7 cold glowplug. For the final, since was really hot, i had to tune the engine a little bit rich and in order to have a good combustion i went to 7 Hot. Well, for the conditions of this weekend, this combo was on the edge and the glowplug broke. Then i change for a 7 cold, but with the engine on the reach side, it was flaming out. Maybe was also too rich on the bottom end. I think i will be running the engine with 0.50 mm (with 30% Nitro)
For sure i need to play a little bit more with the engine to learn how to use it, but the performance is extremely good. Anyone that was at Ft. Myers can confirm this. We use the Efra 2033 3 chamber pipe, Short conical header and INS Box.


Paolo
What was the out come of this problem? I'll buy this the engine but I don't want the unexplained flameouts. I'm really trying to stay away from the Jp's, 35 plus 21, etc.
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Old 07-06-2006, 11:03 PM   #903
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Previous post anyone? Anyone else running the motor yet?
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Old 07-06-2006, 11:44 PM   #904
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Default "head clearance"

what determines you to "increase" or "decrease" head clearance???

understanding that % of fuel, altitude, glow plug, humidity, etc all play a major factor on this, but "what is the rule of thumb"??????

how do you know when to adjust head clearance????

"anyone"?????
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Old 07-07-2006, 08:59 AM   #905
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Quote:
Originally Posted by ghoppa
what determines you to "increase" or "decrease" head clearance???

understanding that % of fuel, altitude, glow plug, humidity, etc all play a major factor on this, but "what is the rule of thumb"??????

how do you know when to adjust head clearance????

"anyone"?????
This is what I got some time ago from Dennis Richey, hope it helps

AFM

Engine Shim Tuning
By Dennis Richey


Experience dictates that just by lowering the head (more compression) you gain more power especially in lower rpm range, idle quality can suffer, but the engine also runs cooler . Also, that a higher head (less compression) will increase top rpm speed on bigger tracks.

A decrease in head shims (an increase in compression ratio) will increase torque because as the compression ratio goes higher, the actual ignition timing occurs sooner. However there is a point of diminishing returns where detonation occurs or engine temps can soar, and if this happens a colder plug can help.

A colder plug will also increase torque, except in the instance of a colder plug the ignition is slowed until a greater point of compression build occurs.
When you increase head shims (a decrease in compression), top end is enhanced as the ignition timing is retarded and occurs later. Generally a hotter plug is needed to advance the ignition cycle so that timing does not occur to late in the cycle, but at this point you end up over leaning the engine to get it to rev properly and the engine life will suffer dramatically.

On a .12 engine we would only advise going 0.10mm over or under 0.46mm, so that is 0.36mm or 0.56mm of total head clearance at sea level.
Generally on a .12 engine 0.10mm will change the compression ratio about 3/4 to 1 point..

We should also state that the comments with regards to plugs and head shimming are when both are used together. Used alone a hotter plug will rev harder and a colder plug will make more torque.

One last comment. never assume that the head shim that is on the engine is the actual head clearance. When in doubt measure the head button register and the piston to the top of the liner at top dead center and subtract, to determine proper shim. This is the only way to really know. Normally, you can safely use 30% Nitro on the stock head clearance.
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Old 07-07-2006, 01:01 PM   #906
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Quote:
Originally Posted by quietstorm76
Previous post anyone? Anyone else running the motor yet?

Is anyone in the United States running the Mega DS II?

If so, what stores/shops are carrying them?

Will it completley replace the original ZX-21, and are the ZX-21 parts compatible with the newer DS II?


thanks
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Old 07-07-2006, 05:16 PM   #907
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Quote:
Originally Posted by quietstorm76
Previous post anyone? Anyone else running the motor yet?
I'm going to run the DSII this weekend during the 4th round of the Dutch Championship.....
I broke the engine in today (friday) and after 1.5 Liter of fuel, it still binds at TDC, when hot.....
The only thing I can tell you now about the engine is:
- The head, got 8 fins, and is a bit higher then the "DSI", so more cooling,
- Performance wise it has A LOT of bottom power, and the top end I don't know yet, because the engine was still running on the rich side,
- Got no flame out problems.....

Oh, and that it looks nice......
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Old 07-08-2006, 10:24 AM   #908
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Originally Posted by M7H
I'm going to run the DSII this weekend during the 4th round of the Dutch Championship.....
I broke the engine in today (friday) and after 1.5 Liter of fuel, it still binds at TDC, when hot.....
The only thing I can tell you now about the engine is:
- The head, got 8 fins, and is a bit higher then the "DSI", so more cooling,
- Performance wise it has A LOT of bottom power, and the top end I don't know yet, because the engine was still running on the rich side,
- Got no flame out problems.....

Oh, and that it looks nice......

Let me know how that goes. I'm also interested if you have any problems with the carburetor not sliding properly and binding/jamming. I've had that happen a few times with my ZX-21's (DSI). Good Luck.
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Old 07-08-2006, 12:13 PM   #909
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Default ZX21 DS1 carb jam

Hi Kendall,
I also encounter the carb jam few times... did u get to solve it?? How??
Mine i think was jam at the idle screw and the slot...
I file it abit and no more jam but cam back again after 2 race day...
Thanks...

ck
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Old 07-08-2006, 12:36 PM   #910
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Quote:
Originally Posted by ck960
Hi Kendall,
I also encounter the carb jam few times... did u get to solve it?? How??
Mine i think was jam at the idle screw and the slot...
I file it abit and no more jam but cam back again after 2 race day...
Thanks...

ck

I had the same thing happen. I completely took the carb off the case. Then I took the carb apart and filed the idle slot to make it just a little bit wider. I also filed a bit around the low end side and used an X-acto blade to scrape the sharp edges. I cleaned all the parts after filing and put it back together. The carb worked much smoother. No issues with the carb since then.

I got smart after the jamming/binding happened the second time. Now I just use the same carb on each ZX-21 I use and this works well.

Where are the DSII's in the USA?
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Old 07-08-2006, 01:43 PM   #911
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Quote:
Originally Posted by Kendall
Let me know how that goes. I'm also interested if you have any problems with the carburetor not sliding properly and binding/jamming. I've had that happen a few times with my ZX-21's (DSI). Good Luck.
You will hear from me after tomorrow.....

No, had no problems with the carb, but before I placed it in the engine, I put some afterrun in it, and "broke in" the carb by hand, while watching television......
Just by moving the slide a couple of times to check the smoothness.......

I also read something on this forum about the headclearance being 0.3 or 0.4 mm.....
Mine came with 0.5 mm.....

To be continued....


Edit: (in your mail you will find my previous explanation )
I measured again to be sure, made a small error, the head button is the same as the "DSI", so the total size of head shims will give you the number of head clearance....
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Last edited by M7H; 07-08-2006 at 02:06 PM.
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Old 07-10-2006, 03:16 AM   #912
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Well, even after a dissapointing race result (all driver errors ), I am very glad with the Mega DSII....
I managed to break my own laprecord and the topspeed is great (our circuit has a speedtrap ), the engine has a lot of bottom, and revs quiet high....

For what it's worth to you, you can check my laptime here:
http://www.mylaps.com/live/showLapti...ponder=6839132


Had no issues with glowplugs, checked the plug after each run and it always looked good.
Due to quiet high temperatures for our country, the engine needed to be tuned on the rich side, which then might give flameout problems, but it never did.
It flamed out only once, but this was when I went of track, lost my INS-BOX (with air filter) and before it was installed again, the engine run idle for about 1.5 Minutes (perfectly), then when I opened the throttle it flamed out, but I have never seen an engine not flameout after idling for more then a minute........

Performance wise, it's a great engine, which can easily keep up with the 2 times more expensive engines, only now time will tell how long it will last......
I drove the engine with 0.5mm head clearance and the Mega 2033 exhaust......

Please note that there are 2 versions of the DSII out there.
1 with a coolinghead like the "DSI", with 7 coolingfins.
And the one I have with 8 cooling fins, which is the same as Paolo M. already posted a few pages back.....
http://www.rctech.net/forum/attachme...hmentid=144574

If they are different internaly I don't think so......
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Old 07-10-2006, 11:54 AM   #913
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I wonder how does it compare to the OS.12TZ with say the best pipe. I'd have to have the LHS order a mega pipe, but I'll try this turbo pipe my lhs has.
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Old 07-10-2006, 01:16 PM   #914
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Quote:
Originally Posted by M7H
Well, even after a dissapointing race result (all driver errors ), I am very glad with the Mega DSII....
I managed to break my own laprecord and the topspeed is great (our circuit has a speedtrap ), the engine has a lot of bottom, and revs quiet high....

For what it's worth to you, you can check my laptime here:
http://www.mylaps.com/live/showLapti...ponder=6839132


Had no issues with glowplugs, checked the plug after each run and it always looked good.
Due to quiet high temperatures for our country, the engine needed to be tuned on the rich side, which then might give flameout problems, but it never did.
It flamed out only once, but this was when I went of track, lost my INS-BOX (with air filter) and before it was installed again, the engine run idle for about 1.5 Minutes (perfectly), then when I opened the throttle it flamed out, but I have never seen an engine not flameout after idling for more then a minute........

Performance wise, it's a great engine, which can easily keep up with the 2 times more expensive engines, only now time will tell how long it will last......
I drove the engine with 0.5mm head clearance and the Mega 2033 exhaust......

Please note that there are 2 versions of the DSII out there.
1 with a coolinghead like the "DSI", with 7 coolingfins.
And the one I have with 8 cooling fins, which is the same as Paolo M. already posted a few pages back.....
http://www.rctech.net/forum/attachme...hmentid=144574

If they are different internaly I don't think so......

Thanks for the report. I'll look for the 8 finned DSII. I had very good performance with my ZX-21 this weekend, never stalled, never blew a plug, it was also equal to the top dollar engines. I think I could have even out performed those engine with a little different setup for gearing. I also had stock clearance for the head shimming. Next time we'll see how it goes.
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Old 07-10-2006, 04:44 PM   #915
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I also took the engine apart tonight, to check the conditions (checked for schratches because of the lost airfilter during the crash) luckily there is no damage done.

It looks like the piston/liner is about the same as the DSI, there is a small change in the angle of the rounding on the bottom of the liner, and the pinch looks to be a little more.....
Didn't really see difference in the crankcase....
The conrod is a bit different, overall it has more material everywhere........
And offcourse the coolinghead is different.....
Even though these engines internally don't look like the high modded expensive engines (like my MAX MF) the performance is really great.

Also my MAX blown out the 2 "separations" in the exhaustports, with small damage to the piston, and this after about 5 liter of fuel. It still runs great, but for how long?......
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