ELOSSAM
Senior Member
Posts: 146
Loc: MADRID, SPAIN
Reg: 11-19-01
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 07-23-02 10:02 PM - Post#9264
Hi Bill, as I told you, looking for a better ceramic plug color I tried to increase fuell opening the needles. No matter how open they are, itīs imposible to get more than a grey tone there. Iīve cleaned the internal fuell filter on the carb but there is no difference. with the L at 1+5/8 and H.at 1+3/8 I can climb vertical without problems carrying the 2 kg photographic payload but some times when after a 150 mts climbing at full power the engine makes a cough and seems to die for a fraction of a second doing a big tail shake. If I I donīt shut down the trh, the engine continue running normally (always at full power). I have checked the carb setting with the low at 1+3/8 and moving the H from 1+1/4 to 1+3/4 and only a little lake of power could be appreciate with the max H position but the cough were even there. Also with the H at 1+3/8 and moving the Low fron 1+3/8 to 1+3/4 was checked with same results. do you thing it coul be due to a excess of fuell or due to it was very lean?
At this moment and using the Vario "s" profil blades I was flying with -4/+1.5/.5.5 (yes, hovering at 1.5š at 1300 rpm) and the oil mix was increased till 1/33 in order to get someplug color.
Any suggestion?
Best regards Elossam Hirobbo Eagle II long tail / TAS 24cc
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Billme
Senior Member
Posts: 198
Loc: MS
Reg: 03-26-01
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07-24-02 04:10 AM - Post#9279
In response to ELOSSAM
ELOSSAM
If you have added oil, and changed the needles like that, then I would suspect that your spring on your plunger is not setup right....What you need to do, is find a small engine shop, and take the carb to them, and let them do a pressure test...If it was me, I would go ahead, and put a whole new carb kit in it...Its not uncommon to get a bad setup carb from the factory...
I'm sorry that I don't have much experence with that engine, but it should't be that different ....
I would say the cough, is because of a rich condistion according to your needle settings...But, the ceramic color is not a sign of rich condistion....If your plunger is set wrong, say on the lean side, it would do what you have desribe with the big needle changes, assuming you have no air leaks ,or a plugged filter...That motorcycle oil your using, also the oil additive Metallube may be doing something strange, I don't know....Based on what you have told me, I would put the high at 1 1/8, and the low at 1 1/2, and then lean the low in a hover til it gives you a good smooth run, going into a 4 stroke miss, once every ten seconds or so...
Is that carb you have a 197a Walbro?
Regards,
Bill.
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Billme
Senior Member
Posts: 198
Loc: MS
Reg: 03-26-01
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07-24-02 04:24 AM - Post#9280
In response to Billme
One more comment...
If you have changed something on the pitch curve or blades lately, you may not be loading the disk up enough for the engine. This will cause the engine to cough...Since you are hovering at 1.5 degs, this might be a problem for the engine transitioning during climbout...
Regards,
Bill Meador
Team Vario
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ELOSSAM
Senior Member
Posts: 146
Loc: MADRID, SPAIN
Reg: 11-19-01
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07-24-02 11:13 PM - Post#9294
In response to Billme
Thanks Bill
The only ref I can find o the carb was beside the fuell input and it is something like "WT 486 927"
The fuel filter was cleaned but I can see from time to time a little dirty fuel down the carb at the Thr link.
I have also try different pitch curves and it has the same problem no matter witch one were used. Most of the times when finishing a big climbing but also during a normal flying. If I increase pitch I can get a good hovering but it shits with full power.
With -4/1.5/5.5 I can pass from hover to full power without any rpm changes. Of course when doing it opposite , from full power to hover the engine accelerates but canīt find how to reduce it, now my thr curve seems like a big reversed "S" in order to save the pitch curve as straight and linear as possible and to reduce the engine rpm just below hovering and full pitch.
Taking a look into the cylinder I can see everything is ok, not dry, no scratches and only a little oil residues over the piston head so I must suppose oil and metallube are working right.
Have you ever try to reduce the cylinder joint thickness to increase compresion and power?
Ellosam
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Billme
Senior Member
Posts: 198
Loc: MS
Reg: 03-26-01
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07-25-02 02:27 AM - Post#9297
In response to ELOSSAM
Yes, I have done the compression thing...First, can you measure the intake venturi for me on that carb?
thanks
Bill
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ELOSSAM
Senior Member
Posts: 146
Loc: MADRID, SPAIN
Reg: 11-19-01
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07-25-02 12:34 PM - Post#9300
In response to Billme
max diameter 0.75 inch (19 mm) min 0.5 inch (13.5 mm); distance between these points 0.25 inch
If you remember the photo I sent you Iīm using an air intake trumpet about 0.9 inch long with the big diameter of 0.8 inch and the little one about 0.6 inch. May be there is the problem. now I can see there is no difference between using the trumpet or not as the diameter differences are equal (0.25-0.30 inch)
I will remove the trumpet for todays flight.
Elossam
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Billme
Senior Member
Posts: 198
Loc: MS
Reg: 03-26-01
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07-25-02 05:03 PM - Post#9303
In response to ELOSSAM
When I know I have everything right on a machine, and I get the cough.....I go in one hole on the throttle servo arm, and increase the atv's...
Have you talked to Mitch D.? He knows this machine better than I.... I know he is putting a RC230 in his, so he might have a reason why he is doing it...I know I don't like the carb on that engine...You might want to try a 167a on it, and see what happens...
Regards,
Bill.
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ELOSSAM
Senior Member
Posts: 146
Loc: MADRID, SPAIN
Reg: 11-19-01
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07-25-02 10:35 PM - Post#9308
In response to Billme
As I told above, the air trumpes was removed fort the last flight, new needles ajustments were done as your advise and also a new pitch curve was programed increasing a few deg the whole curve and finally the oil mix was increased till 3,5%+ aditive . With all that, hovering at 1200 rpm with a fine smooth engine sound but it loose at least 100-150 rpm as soon as I apply full power.
Only a short flight was done because the engine stops when doing a auto simulation and a blade has impacted with the tail boom when landing but only the tail was damaged.
Back home the plug was checked, it has the ceramic as white as new.
Itīs sure I need more power than the Tanaka is capable to give. A cylinder joint reduction? This engine is not delicate, the first one I owned was ruined using fuel at a 0,4% oil mix (I made a mistake doing the measure) but about 8 liters of fuel at this mixing ratio were needed to damage the piston.
The fuell mix about 3% seems to be right and more oil doesnīt help me to give better colour tone to the plug.
Carb settings about 1+3/8H & 1+1/2L are very lean for me (may be due to a carb failure)
The air intake trumpet has no influence in this case (at least it doesnīt help).
I have appreciate plug color changes only if the air filter was put or not At the beginning, when using the original air filter the plug has black ceramic color and as soon as I removed it the black tone was out. That makes me thing that the air filter forces the carb to suck more fuell because it has more problems to suck the fresh air ŋright?
The last chance I will give to this carb will be open the needles a lot, may be about 2 H and 2 L looking for the opposite side of the story, a richer setting, and start from there leaning the settings. If not, the carb will be replaced and finally the joint redution will be done (must I modify the ignitor advance If the joint was reduced from 0.05mm to 0.03 mm?) If all that fails then I will wait to see the results of Mitch D. with its RC230 adaptation.
Thanks for your patience, Bill. I hope this story can also help you and the all the rest to know more about "when things are going wrong". J
Elossam
I,ve recently saw Mitch D. web and I thing itīs not the best time to talk about helis with him. My condolences from here to you, Mitch.
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Billme
Senior Member
Posts: 198
Loc: MS
Reg: 03-26-01
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07-26-02 03:32 AM - Post#9311
In response to ELOSSAM
ELOSSAM
I just wish I was there to help you...I would do what you said about opening the needles up, although, I wouldn't think you need to on the high, just the low. but do what you think ...
With the needle setting you have been telling me, and what you said about the filter being on, with the color, thats telling me the jets may not be big enough(being open that much and not noticing a change) for your power requirment.My next move would be to try a different carb (167a)Walbro
Then again, if you got it smooth, and it went dead, move the idle up...Some of these carbs, you have to not worry about the idle, because it has to be so rich inorder for the hover mixture to be correct...Like the glow, these carbs are not linear in operation...
Hang in there
Bill.
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