| Author |
Message |
    
Peter Francey
New member
Username: tinkering247
Post Number: 1
Registered: 12-2012
| | Posted on Saturday, December 22, 2012 - 03:06 am: | 
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Hi all- i am new to blaxlands but my wife is already concerned how much time i am spending with my new red friend. I need some advice on backfiring. getting terrible backfiring on the engine. i thought it was the plugs or mixture but all seem fine. (Plugs are dirty after a short run however). It starts fine, runs a short time, revs, then fires out the air intake. the slight rev made me think it was fuel supply. i cleaned out the glass tube inline fuel filter and had a great 10 minute run. the fuel tank was pretty low by the end and it started backfiring again and stopped on me. Is backfiring related to fuel supply at all? and would a near empty fuel tank play havoc with the gravity supply? any advice on backfiring would truly be appreciated. Pete |
Ross Cook
Visitor
| | Posted on Saturday, December 22, 2012 - 05:54 pm: |
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this a reply to me from Dave Meyers when I was having similar troubles with mine
Ross, Yes... Looks like too much Oil... Modern Oils do not fully burn as did the old Mono Grade oils of yester-year. Most of us run Blaxlands at 40:1 and we even have a couple in our group who run at 50:1 with no problems. I run my 3 HP Hall at 40:1 with a nice straw coloured Spark Plug.
It could also be as simple as the Float level too high in the Carby as well.
There is quite a discussion on this Board in the files section regarding various Oils and problems. Do a search.
Where are you located as I may be able to point you to someone who may have a look and guide you though the problem.
Lets know how you go, |
Peter Francey
New member
Username: tinkering247
Post Number: 2
Registered: 12-2012
| | Posted on Saturday, December 22, 2012 - 08:48 pm: |
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Ross thank you very much for sharing. i was running 30:1. will try a little less oil and take her out later today. will get back to you and let you know how it goes. thanks again. Pete |
Ross Cook
Visitor
| | Posted on Sunday, December 23, 2012 - 12:35 am: |
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I started off running about the same as you, 32:1 now that I have gone 40:1 it runs well all day without fouling the plugs at the end of the day. backfiring can occur when the motor is cold, as mine does or you could have an air leak in your inlet manifold |
Allen
Member
Username: allenf
Post Number: 27
Registered: 02-2011
| | Posted on Sunday, December 23, 2012 - 01:45 am: |
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which carby do you have?
Which motor? |
Peter Francey
New member
Username: tinkering247
Post Number: 3
Registered: 12-2012
| | Posted on Sunday, December 23, 2012 - 05:11 am: |
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I took her out today running at 40:1. it ran very well... it still had a few fires as it got warmer. she had a rest and ran well again for another 20 minutes before a few more backfires. as it got warmer i closed the fuel needle and it ran better. interesting point Ross about the air leak- i will look into that. Allen, I have the below set up with the model D carburettor and the 5/7H.P. TXRR. the only difference with my carby on the below pic is the air valve faces forward... |
Roger DiRuscio
Senior Member
Username: solarrog
Post Number: 532
Registered: 03-2002
| | Posted on Sunday, December 23, 2012 - 12:07 pm: |
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I believe you need to run more oil. 40-1 in a non bearing engine, does not seem like enough.
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Ross Cook
Visitor
| | Posted on Sunday, December 23, 2012 - 04:36 pm: |
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two other things worth checking that were part of my problems. the caps on the leads that went onto the spark plugs were dodgy and making irregular contact, I think if I remember correctly was the reason mine was backfiring. when the engine was warm the caps would expand with the heat so replaced them with ones that are screwed down by the cap of the spark plug. the first ones clipped over the spark plug caps. the other thing to watch is with the timing mark on the flywheel, mine was out a fair bit so checking with a dowel down the front plug hole to find top dead centre and see where the points open, if it was like mine, remark TDC with a punch |
Allen
Member
Username: allenf
Post Number: 28
Registered: 02-2011
| | Posted on Sunday, December 23, 2012 - 06:43 pm: |
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Carburettor is a vital component which requires careful attention to detail.
The sump must have 1/8 pint of SAE 50 mineral oil in it, no more no less.
Don't use modern 2 stroke oils in the fuel because these motors do not have bearings and seals as modern two strokes engines have.
The bushing in these motors require the thicker mixture provided by using mineral oil. Also Modern 2 stroke oils will not mix well with the mineral oil in the sump.
If air can be sucked into the sump via the clearance between crank shaft and the bushing the air fuel ratio mixture will be affected.
Use mineral gear oil only in the sump and the same oil in the fuel @ a fuel ratio of 1/4 pint of mineral oil per 1 Gallon . (Metric equivalent is 32:1.)
You will get all sorts of advise often conflicting but the manufacturers' advise is best.
These guys recondition and still make these motors and provide a waranty with them.
Blaxland Chapman Marine Co
Nyeena Avenue
Bensville, NSW 2251
0265583182 |
Peter Francey
Member
Username: tinkering247
Post Number: 4
Registered: 12-2012
| | Posted on Sunday, December 23, 2012 - 11:38 pm: |
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Thank you all so much taking the time to reply. Allen are you able to recommend a brand of oil that you have had good results with?
Ross, the connection to the spark plugs was one thing i did read about and made sure wasn't a problem- however can you explain in more detail about finding dead centre... im a bit confused with your instructions but intrigued to try...
Roger- thank you for the comment- the previous owner was running at 32:1 and passed that info on to me- i am in the process of a long trial and error game- so all these comments a fantastic! really do appreciate the help-
By the way, is there any one in Qld who can look at these motors? |
Ross Cook
Visitor
| | Posted on Monday, December 24, 2012 - 12:37 am: |
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to find TDC take out the font spark plug, then insert a 300mm length of dowel or similar in the plug hole and slowly rotate the flywheel till the piston pushes the dowell up to it's highest point, that is TDC. Check to see if the timing mark on the flywheel is 57mm behind. to quote from the manual 'when the ignition is all in correct setting, the contact breaker points will open when the straight mark on the flywheel is 2/14" (57mm) of the circumference before TDC' |
Ross Cook
Visitor
| | Posted on Monday, December 24, 2012 - 12:59 am: |
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one other thing I have done on my motor is to attach a strap between the carby and the magneto bracket, this stops having to over tighten the carby to get it level or not have it swinging around on the end of the manifold if it is too loose, just tighten till it is a snug fit with plenty of thread tape then attach the bracket |
neil r jones
Senior Member
Username: senojn
Post Number: 101
Registered: 08-2006
| | Posted on Monday, December 24, 2012 - 01:00 am: |
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Roger ,I go with you even though you are accross the Pacific and in California with the snowing
icon. It's 38 c in Sydney
There are special oils in Australia made to meet this limited market .
All on this site without - going into detail.
Thank you Mr DiRuscio
Oils is Oils !
Merry Christmas from all us Aussies |
Allen
Member
Username: allenf
Post Number: 29
Registered: 02-2011
| | Posted on Tuesday, December 25, 2012 - 10:21 pm: |
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is there any one in Qld who can look at these motors
PM sent.
Caution! Avoid ethanol fuel because it will dissolve the shellac coating on the cork float and it will start sinking,affecting your float level. |
Peter Francey
Member
Username: tinkering247
Post Number: 5
Registered: 12-2012
| | Posted on Wednesday, December 26, 2012 - 07:43 am: |
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i spent most of today trying a few things and it seems the problem is the carby. fuel line is fine and allowing enough flow, but it seems it can not keep up with the fuel demand. not yet sure why- Ross, dead centre was spot on, thanks for the extra info. Allan, thank you for the email- i sent a reply- |
Ross Cook
Visitor
| | Posted on Wednesday, December 26, 2012 - 04:21 pm: |
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that sounds a bit like the float level is wrong. take off the top of the carby, is the fuel up to the top of the float bowl? if the level is too low it won't keep up to the demand |
Peter Francey
Member
Username: tinkering247
Post Number: 6
Registered: 12-2012
| | Posted on Thursday, December 27, 2012 - 06:01 am: |
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The cork is new and works well. i noticed yesterday the screw was lose on the cork for some reason. anyway the level seems fine. I tend to think it is back to your earlier comment Ross about an air leak in the manifold. i will replace the gaskets some time soon and see how that goes. there is a small hole in the exhaust manifold outlet which i will have to get fixed. It turns out the most basic of errors i found today- the bolts were not tight on the manifold. i will take it out tomorrow and report back then... |
Ross Cook
Visitor
| | Posted on Thursday, December 27, 2012 - 02:55 pm: |
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there is a good chance the loose manifold is where the air is getting in then. had a good day out in mine yesterday, she ran perfectly all day. hope yours does too |
Peter Francey
Member
Username: tinkering247
Post Number: 7
Registered: 12-2012
| | Posted on Friday, December 28, 2012 - 02:23 am: |
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well i took her out today and still have the back fire happening. It is fine when it is cold- then after 10 minutes, it coughs and claps and stops. Anchored up and went for a swim, came back and another 10 minute run where it was perfect. as soon as it got warm, the backfire was back. water pump is fine, engine is not hot to touch. fuel flow seems fine-
any one have an ideas???
Pete |
David Myers
Senior Member
Username: dave_myers
Post Number: 123
Registered: 11-2006
| | Posted on Friday, December 28, 2012 - 03:28 am: |
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Hi Pete, I have been following this thread since your first post. You are doing ok with the advice already given. Now..Check that you have a breather hole in the fuel cap. If it is blocked you will get the symptoms you describe. The fuel flow may seem fine but is not enough when running. Also... do not run with throttle wide open, it only use's more fuel without any benefit of speed. The boat will only go as fast as hull speed allows. (Usually about no more than 3/4 open). On another track.. If the fuel line is the small copper line it may not be delivering enough fuel under load either. We use 6 mm (1/4 Inch) ID copper or Neoprene line. The fuel line should idealy drop vertically for at least 8 inches (200 mm)from the tank. One last thing... DO NOT use UNLEADED fuel. It is Hydroscopic and will pull in water from the air, and the Ethanol also separates and dries out to a very fine powder which will go through any filter and settle in the jet. I had this trouble with my own until I drained the tank and then changed to Standard unleaded. (I am not the only one to have had this problem). Just a few thoughts that may help. It is a bit hard to put a finger on problems by remote control... Getting them going right is half the fun.. See how you go.
Cheers, Dave |
Ross Cook
Visitor
| | Posted on Friday, December 28, 2012 - 03:33 am: |
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I don't know where everyone is from this forum, must be all on holidays I think, leaving an amateur like me in charge. they would have the correct answer for you by now. you have adjusted the needle valve in the bottom of the carby? turn it all the way in then open it one and a half turns, then when the engine is running adjust it for the best running. |
Ross Cook
Visitor
| | Posted on Friday, December 28, 2012 - 03:37 am: |
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you can also get a manual for the motor from here
http://www.rallybadges.com.au/product_info.php?products_id=822 |
Peter Francey
Member
Username: tinkering247
Post Number: 8
Registered: 12-2012
| | Posted on Friday, December 28, 2012 - 05:39 am: |
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Hi Dave, thank you very much for your input. I did look at the fuel breather as it was my first thought also- there are two very small holes in the cap, i also tried letting the cap of completely with no change. the fuel i have also ruled out- as i have only used regular unleaded. I will take some pictures tomorrow of the fuel line and carby setup, i think it is ok but would love some thoughts on it. i am using a plastic fuel filter (not sure if this is part of the problem), and then it does run through a small copper pipe to the carby.
Ross, (you are doing a fantastic job feeding me chores each day, while i thank you, my wife could possible blame you) anyway, you mention one and a half turns on the needle valve??? i have only had it open half to 3/4. i had no idea it was meant to be so open. what does it normally run at when the engine is underway?
One other thing, when i look down the carby with the top off, should i be able to see a needle come out the fuel jet? |
David Myers
Senior Member
Username: dave_myers
Post Number: 124
Registered: 11-2006
| | Posted on Friday, December 28, 2012 - 07:04 am: |
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Pete, Yes you should see the end of the needle in the Jet. That is normal. I always set the needle to 1 turn out and then adjust from there. The motor, when cold should backfire and be ok when hot. The air valve setting on the top should be about 4 turns out and then adjust slightly when under full load.
One cause of backfire is worn bearings. Place your hands under the Flywheel and lift. Is there any movement up and down? That indicates worn bearings. A 1/16th play is ok. I have seen worse than that and still run ok. Have you screwed down the grease cups as that will help seal the bearings. Just a thought. It definatly seems like a fuel problem though with it starting easy and running for 10 mins. Keep playing.. you learn by doing.. The filter should be ok. I use one off a ride-on mower with no problems.
Dave |
David Myers
Senior Member
Username: dave_myers
Post Number: 125
Registered: 11-2006
| | Posted on Friday, December 28, 2012 - 07:14 am: |
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Pete, Just a late thought. If you take the top off the carby there should be a round cork gasket about 1 inch in dia where it sits on top of the air gallery. Is that there? If not you will get all sorts of problems. If you need to replace it we use neoprene 'O' rings from Bunnings.
Dave |
Allen
Member
Username: allenf
Post Number: 30
Registered: 02-2011
| | Posted on Friday, December 28, 2012 - 02:47 pm: |
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Schebler model D.
http://www.oldmarineengine.com/technical/carburetor/scheblerD.html |
Peter Francey
Member
Username: tinkering247
Post Number: 9
Registered: 12-2012
| | Posted on Friday, December 28, 2012 - 03:41 pm: |
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this is brilliant everyone- thank you for another day of chores. Allan, that link is great- thank you so much. it goes into much more detail than my manual.
Dave, thanks again for your thoughts. I do have the small washer in the top of the carby. it is probably only about 60% in quality so will defiantly replace that. i will take to the carby today and get back to you. the reason i ask about seeing the fuel needle is that i am pretty sure i cant see mine. i will check again today though- i didnt look at it while winding the adjustment up and down so cant be sure. |
Ross Cook
Visitor
| | Posted on Friday, December 28, 2012 - 04:02 pm: |
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thinking about it overnight I am wondering if it is a fuel supply problem, the 'stopping for a swim' bit does seem like it needed the time for more fuel to make it's way to the carby. maybe worth trying it without the filter and see how you go, I don't think it would hurt for just one outing |
David Myers
Senior Member
Username: dave_myers
Post Number: 126
Registered: 11-2006
| | Posted on Friday, December 28, 2012 - 04:30 pm: |
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Just thinking over night, (as you do). Disregard all I said before. It is definatly fuel supply. The backfiring before stopping is the carby leaning out. The fuel line is either too small (as suggested) or may have a kink or blockage. By stopping after 10 mins it is simply out of fuel. Try a run at 1/4 to 1/2 throttle and see how it goes.
Dave |
Ross Cook
Visitor
| | Posted on Friday, December 28, 2012 - 05:08 pm: |
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David Meyers
'SNAP' |
Peter Francey
Member
Username: tinkering247
Post Number: 10
Registered: 12-2012
| | Posted on Friday, December 28, 2012 - 07:34 pm: |
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i have taken apart the carby and put it back together. i really dont see any problem with fuel flow. it comes flowing out the top of the carby when i had it apart. Float is fine, needles are all fine, clean and functioning. when i wind the needle right in, i can just see the very top of the needle through the jet. Is it possible i have just not had the needle open enough!? i will HAVE to take her out again today to test-
i have really only had it one half turn to 3/4 turn open.
I will certainly see how far i get on 1/4 throttle. if its more than 10 min, then it will be time to replace the fuel line.
i will try and attach a picture of the carby so you can see the fuel line. it goes from the tank, through plastic filter via a copper pipe, then through a rubber pipe back to a copper pipe.
 |
Peter Francey
Member
Username: tinkering247
Post Number: 11
Registered: 12-2012
| | Posted on Friday, December 28, 2012 - 08:02 pm: |
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just had to run back inside and give an update. as i turned the fuel line on after i put everything back together, the fuel started to fill perfectly. nice steady stream. then it got about 1/4 full and stopped. i unscrewed the fuel cap and it came to about half before it stopped. the float kicked in and prevented it from flowing further.
if i push the float down, then the carby continues to fill. is there a way to adjust when the float kicks in?
and i will have to increase the breather for the fuel tank.
The float functions, but seems to function too well!
and i best check- the float can only go the one logical way up is that correct? with the cut out for the nut on the bottom and flat side facing the sky? |
Allen
Advanced Member
Username: allenf
Post Number: 31
Registered: 02-2011
| | Posted on Friday, December 28, 2012 - 09:13 pm: |
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Carefully bend the pivot arm at this point to establish correct fuel levil
 |
David Myers
Senior Member
Username: dave_myers
Post Number: 127
Registered: 11-2006
| | Posted on Friday, December 28, 2012 - 11:39 pm: |
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DO NOT repeat... DO NOT bend the float arm. It is only diecast and will break. The ball on the needle can be moved up or down with a piece of copper tube and gentle tapping with a hammer. The ball is a friction fit on the needle.
Dave |
Peter Francey
Member
Username: tinkering247
Post Number: 12
Registered: 12-2012
| | Posted on Saturday, December 29, 2012 - 04:15 am: |
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hi all- ok i have some good news- and now need more advice....
I didnt bend the pivot arm, i was actually looking at that ball on the needle wondering how they made that and figured it may move. anyway went out again today.... (i am up in Maleny on holiday, for those who don't know where that is, it is 500 metres above sea level- and a mighty big range in between the coast and home- so a day trip turns into quite an adventure!)
anyway each time the engine backfired i took off the carby lid to check the level- it was empty each time! so you were all right-
what caught me out was the flow- it is fine when i take it off the back of the carby. it turns out i didnt let it flow for long enough. the flow is fine for the first 10 seconds then stops. it is even worse when it is in the water as the level changes.
so i took out one of the inline fuel valves, bent the copper fuel line into place and had my finger on the prime spring to depress the cork. i had a great 30 minute run up the river. but the engine used more fuel than was supplied-
so my next question----
what fuel set up do other people have??? i obviously need much better flow!
thank you all for your help- you were all in the boat with me today! |
Ross Cook
Visitor
| | Posted on Saturday, December 29, 2012 - 04:39 am: |
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holding the float down as you did, sounds to me like there is a problem with the float level, it is cutting off the fuel supply early so it is set too low. you didn't mention what throttle setting you used so that will obviously make a difference to your fuel consumption. my fuel supply is basically the same as yours, just the tank is under the front deck, holds about 8 litres |
Peter Francey
Member
Username: tinkering247
Post Number: 13
Registered: 12-2012
| | Posted on Saturday, December 29, 2012 - 05:43 am: |
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had the throttle at half and then later tried 3/4. i will adjust the float level tomorrow. out of interest, how full should the carby be before flow stops? just short of the top??
even with my finger on the float level, there still wasn't enough fuel flow- took longer but it still ran out. i cant make the tank any higher, so my pressure will remain the same- so i will have to look at changing the fuel lines i guess. or the filter? |
David Myers
Senior Member
Username: dave_myers
Post Number: 128
Registered: 11-2006
| | Posted on Saturday, December 29, 2012 - 06:48 am: |
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Pete, Thats good news that the run went well. The top of the float should be paralel with the top of the bowl. That means it is about 3/16 inch below the top. Run new fuel line of at least 1/4 inch ID or a lot of owners run 5/16 inch. The fuel tap may need changing if the hole is small. Adjust the Mixture screw and the airbleed screw on the horn for best running. The TXRR uses about 1 1/2 litres fuel per hour on average.
Cheers, Dave |
Richard A. Day Jr.
Senior Member
Username: richardday
Post Number: 1040
Registered: 11-2003
| | Posted on Saturday, December 29, 2012 - 03:31 pm: |
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Make sure you have a good gasket or O ring which seals the bowl cover to the top of the throat. Air leakage at N can cause very difficult running problems. |
Peter Francey
Member
Username: tinkering247
Post Number: 14
Registered: 12-2012
| | Posted on Sunday, December 30, 2012 - 10:51 pm: |
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thank you all so much for your help the past week-
I will replace the fuel line and see how it goes. do you just use hose clamps from new pipe to the carby??
looking forward to some great days out in her. I have some questions about maintenance tips and tricks which I might start a new thread about (if people dont mind sharing!!).... |
David Myers
Senior Member
Username: dave_myers
Post Number: 129
Registered: 11-2006
| | Posted on Sunday, December 30, 2012 - 11:12 pm: |
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Yes... use stainless clamps as one day you will want to undo them...
HNY
Dave |
