91C-spec Non-PS help.

[SteveL]

Ok I have the head shimmed to .016
I have the idle full rich and it still sounds lean at an idle.
I have the main needle @ 1.5 and it seems rich (needs a ton of throttle to develope head speed like over 50% with 0 pitch to get 1900 on 7.92)
I know I need to call James and just have the problem fixed but I was hoping to hold off until late May.
I was watching videos of HC flying and I can tell you I can't make this motor smoke as much as his.
Any suggestions?
BTW I did a search.

[SteveL]

BTW. Mid needle is at 1

[DavidH]

Steve,
Probably need to take carb apart and check for trash in the openings.
Also need to check and make sure the pressure fitting on the muffler is open and providing plenty of pressure to the tank.

HC is using CP30%. That fuel will smoke alot even when the mixture settings are lean.
Can't really judge tuning by the amount of smoke that some fuels produce.

David

[Ivan]

The main needle (called the high end needle) governs the whole range of mixture, the other two needles just tune their range from that base line.

I would definately do as David says and check for trash in the carb.

Then richen the high needle, maybe 2 to 2.5 turns and reset teh idle and mid range. I know you say the high end sounds rich, but it seems on my engine, it needs lots of barrel opening compared to what you woudl normally think. I think my vigor hovers at about 65% opening if I am not mistaken. This is on a bone stock CSpec with teh gold head, no pumps, regulators, fuel injection, superchargers, or tetranitromethane. Not even a headertank or fuel magnet. Seems to run fine this way.

Other than that, I woudl do a good mechanical check on the engine to make sure you don't have any rough bearings, a bad ring or liner, maybe even a different glow plug or fresh fuel, etc. Don't over look any of the small stuff, it will get you confuzzled.

[SteveL]

Well I have had the carb apart 3 times and still no luck. I had the file in my hand but chickened out.
My engine is also the gold head s-spec with no mods other than an additional head shim. I put that in there to try to cut down the detonation at an idle I think my head speed problem may be my unfamiliarity with a 90. With a 30 & 50 you only need about 35% power for 0 pitch.
I do need to change the plug.
Muffler Pressure line (SB-17) is clear.
I got it a little better (the idle part) by installing a uni-flow setup in the tank. Course I filled my muffler up on the second flight. :(
Thanks for your help.

[mevigavant]

i would check the fuel filter also just in case. get the omi carb mod and be done with it.

[SteveL]

Sorry... I did check the filter. I think I will call James and see what his turn around time will be. Now I guess I am going to have to buy the head too :lol:

[DavidH]

Steve,
If you just want the Cline added to the carb. James should be able to turn it around fairly quick. If you want the big bore mod also, that may take him a few more days.

Also need to send the back plate unless your comfortable drilling and taping it for a pressure fitting.

The head you have will work fine once you get the carb sorted out.

Give James a call and he can tell you exactly what needs to be done.

David

[Ivan]

I am fairly sure my vigor hovers just abouve half throttle. It has been a while since I messed with it, but I am fairly sure of it. I thought this to be peculiar, but it seems to fly fine and has plenty of power.

You never said what kind of heli, and what gear ratio. I noticed quite a difference between the time i had my vigor on the 8.7(I think) and the 8.0 ratios. I think the engine likes the load better that is given with 8.0. Just a thought.

[SteveL]

Freya EVO with 7.92. I am actually thinking of changing it to 8.45 so I can run a slightly lower (1900) head speed and still not have it bog. Righ now I am running right at 2000.

David
I think if I send it in I am going whole hog (big bore and OMI dual plug head) :D

[DavidH]

Steve,
The whole hog is going to cost over 3 C notes.

Also I guess you have done the math for rpm and gear change

7.92 X 2000 = 15,840
8.45 X 1900 = 16,055

Your probably going to need to get the 8.45 head rpm down to the 1800-1850 range.

I am turning my C Spec 1900 rpm on 7.91 and it seems to like it. That is OMI BB carb and stock blue PS head.

David

[SteveL]

Hmmm. No I did not do the math
I am trying to learn 3D and know as I get better I would improve on col management. Thought the lower gear ratio might help while I am learning.
I know if I drop the headspeed much below the 2000 mark now it will bog pretty easy. As long as I keep it up she runs like a scalded dog.

You keep your motor down @ ~ 15050 and like the performance?

I thought the head was ~ 130 and the BB was 125. I already have the 60K carb. :dontknow

[DavidH]

Viper Head is $130
Big Bore mod is $125
Cline and installing and modifying jets is $80

So about $335 for the whole deal.

Yes my C Spec is turning about 15050- 15200 and it purrs and produces plenty of power.

I have 95/12 on the Tempest = 7.916 ratio
Head is turning 1900-25 = 15040-15225

On 8.18 ratio. Most I have seen are turning the head 1800-1850 with the C Spec and Big Bore Cline regulator carb. That is 14,700 - 15,100 on the engine.

The new SZ likes to turn a higher rpm for some reason.

David

[SteveL]

I thought the 125 included the cline.

I think I might wait until the new SZH pumps are out for a while and see what people are thinking.

[DavidH]

No,
The Cline alone cost about $70. So James installs the Cline and modifieds the jets for $80 total.

Then the BB mod is another $125.

SZ Hyper runs very well from what I have seen.

David

[Clintstone]

You can get the cline and have really nice power and it will be dependable also.