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HomeAircraftHelicopterEngines Plugs Mufflers Fuel › OS 91 SX-H Cspec w/pump problems on raptor 90
11-22-2006 05:52 PM  11 years agoPost 1
ghettotige

rrNovice

Weymouth, dorset UK

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Hi got my hands on a used Raptor 90 striped it down and replaced any weathered parts including all the plumbing, went to try to start her but the starter was not man enough so upgraded to a dynatron. Got the engine to start but on removing the glo starter it dies instantly. Replaced the glo plug gave it more revs after starting removed the glo starter and it continued to run then lowered the revs a little. Problem is while ticking over the engine reves will increase for a couple of seconds engaging the clutch and drop off for a few seconds before increasing again and this is how it continues. Not an expert with these things so I cant tell whats wrong.
I have it plumbed in the following way.

1 Quick Header tank centre nipple to in on pump through filter.
2 out of pump to main carb.
3 clunk outlet of main fuel tank to top nipple on header.
4 Mp2 nipple to upper rear nipple on main tank
5 from carb outlet nipple (red one) to bottom front nipple on main tank.
6 Centre nipple on header used for fueling

Not sure if it is event plumbed correctly.
Can anybody help?

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11-30-2006 07:03 PM  11 years agoPost 2
helirecago

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hong kong

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i am no expect i must say but have encountered similar problem as yours with the Cspec. It sounds like it is too rich on idle.

leave the idle screw at 12 o'clock position. you may try turn it clockwise to 1 oclock but probably your engine wouldn't start at all. Forget it.
I thought because of the pump the engine tends to run very rich all over the range if one is to leave the high speed needle at 2 turn as suggested by the manual. The engine just dies after the glow plug igniter is removed like yours For my cspec I have to turn the high speed to 1.5turn before a more stable idle speed is attained. (strange enough when you thought the high speed needle is supposed not to affect the idle speed. Fact is it can affect the fuel delivery all over the range from idle to full speed.

PS with 1.5turn for the high spped needle, it's still very rich and the engine remain stone cold . It's alright during run-in I supposed. According to Curtis Youngblood Q&A, the high speed needle for the C-spec with the perry pump should be somewhere between 1-1.25turn after breakin while the idle screw just a little bit past the 12 oclock mark clockwise.

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11-30-2006 07:11 PM  11 years agoPost 3
helirecago

rrNovice

hong kong

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one more thing....

I believe it's better to connect the carb outlet nipple (red one)to the top of the tank rather than the bottom. 'cause the hydrostatic pressure from the fuel will probably give too much resistance to the excess fuel return from the carb and so its even richer

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11-30-2006 07:23 PM  11 years agoPost 4
TonyTypeS

rrElite Veteran

New Orleans, LA & El Monte, CA

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I had the same problem when I installed a pump on my hyper 50. You just need to lean the engine out. I had to leaned the high speed needle half a turn from my current non pump setup to get the engine running right. Low end needs to be leaned out too. I was suprised how much I had to lean the engine out. Just keep leaning the engine out and keep an eye on the temp.
The carb is no longer having to suck fuel since the pump is doing all the work. You have more fuel flowing to the carb so you will need to lean the engine out.

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11-30-2006 07:27 PM  11 years agoPost 5
TonyTypeS

rrElite Veteran

New Orleans, LA & El Monte, CA

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"I believe it's better to connect the carb outlet nipple (red one)to the top of the tank rather than the bottom. 'cause the hydrostatic pressure from the fuel will probably give too much resistance to the excess fuel return from the carb and so its even richer"

It doesn't matter where the return line is at. If there is "hydrostance" than when you fly inverted you will be rich? (having the return line on top)

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11-30-2006 08:24 PM  11 years agoPost 6
Simon - R

rrApprentice

uk

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don,t forget you need a one way valve on the return to the tank to stop the fuel running in both directions .

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11-30-2006 08:32 PM  11 years agoPost 7
wrobijns

rrApprentice

Swalmen, the Netherlands

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If a plug is too cold the engine will die or run slower when the powerpanel is disconnected.
An Enya#4 or OS#8 would be fine.

And also check the settings as the others said.

Walter Robijns, 3D rules !!!

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12-01-2006 03:59 AM  11 years agoPost 8
Jerry Sudimick

rrVeteran

Connecticut

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don,t forget you need a one way valve on the return to the tank to stop the fuel running in both directions .
Not necessary on the Cspec PS, because inside that red return fitting is a built-in checkvalve.

Jerry

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12-01-2006 09:43 AM  11 years agoPost 9
ghettotige

rrNovice

Weymouth, dorset UK

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Interesting I had the engine running smoother today but it was not responding to needle adjustments after allowing it to tick over for a while I went to pinch the fuel line to the carb but it was already closed it seems the engine was running on the feed from the red valve, I guess it does not have a one way valve built in.
I will try putting a one way valve inline between the red nipple and the lower fitting on the tank and try those needle settings.
Or maybe just sell it and get the SZ Hyper as I have that in a Synergy and it runs beautifully.

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12-01-2006 03:29 PM  11 years agoPost 10
Jerry Sudimick

rrVeteran

Connecticut

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I guess it does not have a one way valve built in.
If it is not there - someone removed it. The entire point of that fitting is to accomodate a one way flapper. It is supposed to be there as delivered from the factory.

Simply unthread the cap of the red fitting and look.

Jerry

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12-02-2006 12:20 AM  11 years agoPost 11
Nitrohuffer

rrKey Veteran

Bloomingburg,NY

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Just chiming in that my cspec is bone stock and runs like a champ. It really took almost 4-5 gallons to see some good power. A lot of people give up on this motor too soon. A sz ps is still in another league.

Lungs transformed to take in water.

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