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60cc gas tuning NEED HELP!

Old 05-02-2017, 07:20 PM
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Mudnyrey
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Angry 60cc gas tuning NEED HELP!

I purchased an Un-adentified manufacturer (possibly China brand) 60cc gas engine online used by a guy in his 70's flying target models and getting rid of his fleet and excess, the only marking on the engine are 5-08.
The 60cc is running a Walbro HDA carb that has an extension manifold for reed valves into the block.
Walbro HDA manual suggests a setting of 1 1/4 of and High and Idle needle setting, however when I can get it to run, mainly by flooding it by the choke for a start rotation, then opening the choke to get it to run, the engine will surge at idle or at a higher RPM before dying.
Now note that I had to flood the engine to start by choke, then open to run. My current needle setting are... 3 turn on High and 1 1/8 Low

What would cause the engine to surge at idle or at high rpm?
Not enough fuel?
Timing?

I also noticed that the timing sensor looks like it may have been messed with, but I do not have the tools yet to verify timing or find out what it's setting should be. To be honest, I've never had to set up timing on such a motor yet.

The tank is new and was pressure checked prior to install. I am running regular gas (Yellow) tube. Could it be too small in inner diameter for fuel feed?
I have also removed the carb and cleaned it out, removing the H / L needles, diaphragm and cleaning the internal filter which had some old deposits on it and removed.

Any suggestions would be greatly appreciated.
Old 05-03-2017, 03:11 AM
  #2  
ahicks
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I see what you're asking as a 2 part question. The first is what engine you have, likely most easily answered only after you post a picture.

The 2nd is why it won't run. It sounds like it's lean, and generally if it's not a fuel line sucking air, it's something in the carb. There's a small pencil eraser sized screen in there, and it's often plugged. If not by debris of some sort, then a clear difficult to see slime. Clean that and see if that helps.
Old 05-03-2017, 10:37 AM
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Mudnyrey
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[ATTACH]2213036[/IMG][ATTACH]2213037[/IMG][ATTACH]2213038[/IMG][ATTACH]2213039[/IMG]
Well.. There were a few questions.
Without a proper pic, identifying this engine would be difficult, I totally agree. In the list of picture identifications I have also added a few others including the carburetor and fuel line used. However, as I would like to identify the engine(But not so relevant), my main problem and questions are as follows.

1) What would cause the engine to Surge?
2) At general H/L needle settings I have comprised a start list from adjustments of the needles, not knowing a proper start adjustment... however I did use what Walbro HDA manual had noted as mentioned above. However, even though I am currently running the Low end idle needle at 1 1/4 as well as the High end, the only way the engine wants to start is by closing the choke, thus allowing it to gain more gas and less air mixture to help prime ignition start. But once this happens, I will get one bite from the engine and smoke out the exhaust and then quite. I can turn the prop to start it, but a bite or two is it. Once I open the choke, 1-3 stroke hits from the prop and it may run depending on my needle adjustments and then start pulsating at low and high usually dying out.
Currently right now I have the Low needle set at 1 1/4 and the High end needle set at 3 1/4 at the moment. To me, it seems that the Low end needle is roughly in the right area, but the high end needle seems to be too rich possibly?
The odd thing is, is having to use the choke to generate a flood of gas into the chamber, then having to open the choke to allow enough air mixture for ignition, once running, it still pulses, even though I was able to somewhat get my idle speed down and some what managable, it still surges when the throttle is moved to a higher rpm and or dies out.

3) It looks as though the timing sensor was messed with.. it popped a few times, so I was able to get it as close as I could until I receive my ignition timing set to calibrate it in. However, I have been able to run it without major issues, so I know the timing is very close.

4) Could the diameter of fuel line be restricting fuel to carburetor? I'm using yellow Tygon 1/8 ID.. Should I have used the 3/32 instead and having to used the larger fuel tank tubes for the pick up, fill and vent?
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Last edited by Mudnyrey; 05-03-2017 at 01:22 PM.
Old 05-04-2017, 12:56 PM
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Truckracer
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First, regardless of the settings you may read in a manual, 1 1/2 to 2 turns out on the needles is a much more common setting for initial startups. All your descriptions suggest the engine is lean. Open the needles and try it there. You can't hurt anything by doing that. After you get it running, adjust from there as needed.

Second, your fuel line size is more than adequate. 1/8" line is plenty adequate for much larger engines than what you have there.

Third, why are you reluctant to say what engine you have?
Old 05-04-2017, 09:55 PM
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Mudnyrey
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Originally Posted by Truckracer View Post
First, regardless of the settings you may read in a manual, 1 1/2 to 2 turns out on the needles is a much more common setting for initial startups. All your descriptions suggest the engine is lean. Open the needles and try it there. You can't hurt anything by doing that. After you get it running, adjust from there as needed.

Second, your fuel line size is more than adequate. 1/8" line is plenty adequate for much larger engines than what you have there.

Third, why are you reluctant to say what engine you have?
First paragraph.....
I purchased an Un-adentified manufacturer (possibly China brand) 60cc gas engine online used by a guy in his 70's flying target models and getting rid of his fleet and excess, the only marking on the engine are 5-08.

Thanks for verifying the fuel line, Thats what I thought, but you just never know. I've seen guys run 3/32 and larger on 55cc engines..
On the needles I am currently running at 7/8 Low end and roughly between 2-3 on the High end needle. Walbro seems to recommend 1 1/4 turn on both to start. I think I'm going to make two rubber grommets with a rod to fit over each of the needles, so I can turn with my fingers then trying to fit the screw drive on the slot of a vibrating engine.. This should make matters a bit easier to fine tune once I get the motor running.

I'm also going to order a rebuild kit rebuild it. It's possible I over looked the diaphragm as it did appear to be a bit sagging. So I'm going to start there.
Old 05-04-2017, 09:56 PM
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Mudnyrey
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ALSO..... In the picture of the engine I posted... can ANYONE help identify this engine by make/manufacturer?
Old 05-06-2017, 10:35 AM
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Mudnyrey
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Update....

First of all... Thanks to you all for your suggestions and help! It is greatly appreciated.

This morning I tore down the carburetor and with my new rebuild kit, rebuilt it. The carb is a Walbro HDA series (under HDA is 245 and below is 710 Walbro has a youtube that describes how to read their carb part numbers.... they certainly make it a bit confusing, because most carb series break-downs do not include the full image of the carburetor, but only the BOM parts listing. If you can't take the carb down to your local small engine shop, then take pictures of it. Usually the numbers will be on the needle adjustment end. They then can cross reference the number as needed, however, for your reference, it's cheaper to by the universal kit rather than separate or particular part items. The universal items will come with a few extra items in which you only need to pic out the correct ones for your model carb.

I used a universal rebuild kit 532 (OEP 49-845) which ran $12. Replacing the diaphragm, needle, rocker assembly, filter, gaskets etc. and after flushing and blowing it out thoroughly, removing all needles and internal replacement parts.
Set both High and Low end needle valves to 1 1/2 turns to start. I applied the choke and got my first pop spin to feed the carburetor. Opened the choke and it would cycle a bit again after firing up, then after it went away, slowly finding the adjustment to peak the throttle to max up/down. This surge finally went away and I am now able to tune to peak performance.

My current settings are: Low = 1 1/4
High = 2 3/8

It has a slight hesitation from idle to max throttle wanting to cut out. I keep forgetting what the lean reaction is to rich.... so if someone could help remind me... this would be a great thread to add here..

Mud~
Old 05-07-2017, 08:42 AM
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Looking at this thread I can not believe people give you advise without asking "What prop are you using?

The prop choice is the most important determiner of tuning.

So, what prop are you using?

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