Buster999 Posted April 12, 2020 Share Posted April 12, 2020 Hi everyone, I'm new to the 1/5th scale petrol engine world but I have a good working knowledge of engines in general, I have recently purchased a Rovan 1/5th scale baja buggy with the 30.5cc engine fitted, I was running it in as recommended by running it on tick over then turning it off and letting it cool down, I repeated this 3 times and on the 4th attempt to start it the pull starter failed so I have replaced it and ever since I can't get it to start, all I have done is change the pull starter and I also drained the fuel out and put some more in using better quality 2 stroke oil, so I am asking for any advice about the problem, I have tried starting it using the recommended method and it will not start, the only time it did fire briefly was when I turned the choke off and held the throttle wide open and tried starting it and it did briefly fire, any suggestions, advice and help would be very welcome, many thanks Paul Quote Link to comment Share on other sites More sharing options...
Mack1 Posted April 12, 2020 Share Posted April 12, 2020 If it was running ok before the pull start broke maybe try a new spark plug. With the rich running in coupled with only tickover it probably fouled up. Quote Link to comment Share on other sites More sharing options...
KORB Posted April 12, 2020 Share Posted April 12, 2020 Hi Paul, Have you managed to get your engine running? Quote Link to comment Share on other sites More sharing options...
KORB Posted April 12, 2020 Share Posted April 12, 2020 By the sounds of it , your throttle needs to be slightly adjusted, if you look at your manual you will see the throttle screw (should be a nice shiny one being a new engine) very slightly and very gently screw it inwards , keep trying to start it . You should keep the choke off until you have primed your engine with the primer bubble ( about 5 or 6 pumps ) then flick the choke on ( make sure the choke is already in the OFF position, check your manual for the position settings),. Your engine should now fire up. Also... Because it's a new engine it's always possible that the spark plug could be a little loose so check that first! Also check the HT cable is securely pushed onto the plug. Once you've primed the engine on the fuel bubble and flicked the choke ON , you need only give the starter one good pull then flick it OFF and pull on the starter again until it fires up Quote Link to comment Share on other sites More sharing options...
Buster999 Posted April 13, 2020 Author Share Posted April 13, 2020 12 hours ago, KORB said: Hi Paul, Have you managed to get your engine running? 12 hours ago, KORB said: Hi Paul, Have you managed to get your engine running? Hi, not yet I have ordered a new spark plug, I did also wonder if when I was having problems with the pull starter that I could have moved the coilpack slightly, I have earthed the body of the spark plug that's in the engine and there is a spark but how good the spark is I'm not sure do you have a measurement of the distance between the coilpack and flywheel, Many thanks Paul Quote Link to comment Share on other sites More sharing options...
Mack1 Posted April 13, 2020 Share Posted April 13, 2020 (edited) Spark Plug gap 0•6mm 0•7mm 0•24 0•27in Edited April 13, 2020 by Mack1 Quote Link to comment Share on other sites More sharing options...
Buster999 Posted April 13, 2020 Author Share Posted April 13, 2020 Hi thanks is that the measurements for the gap between the coilpack and flywheel cos you have said spark plug gap many thanks Paul Quote Link to comment Share on other sites More sharing options...
Mack1 Posted April 13, 2020 Share Posted April 13, 2020 Oops my bad I will change it. It just I had it wrote down on my phone and just copy and pasted it. Quote Link to comment Share on other sites More sharing options...
Mack1 Posted April 13, 2020 Share Posted April 13, 2020 Just checked my plastic gauge I use on the 5ive-T and its •7mm Quote Link to comment Share on other sites More sharing options...
Buster999 Posted April 13, 2020 Author Share Posted April 13, 2020 Hi thanks for that, I am still undecided as to what the problem is, like I said I was running the engine in and when I tried to start the engine for the 4th time the starter failed so I removed it and tried to repair it but after several attempts I decided it was beyond repair so purchased and fitted a new better pull starter so I thought I would just have to try starting the car again and it wouldn't be a problem but it refuses to start I just find it frustrating because I haven't changed anything else the car started fine the first 3 times, did you say that the plug could be fouled, I did take it out and cleaned it and it does spark when I earth the body of the plug, but whether the spark is good enough I don't know, even if it is sparking do you think it could still be a problem with the plug ? or could it be a fuelling issue even though I have not changed anything ? I would be very grateful for any input from you, I am not going to give up on the car but I am confused as to why it will not start again ! Many thanks Paul Quote Link to comment Share on other sites More sharing options...
Mack1 Posted April 13, 2020 Share Posted April 13, 2020 I think we all have had our fair share of frustration whilst owning these type of cars and I know how frustrating it is. Whilst waiting have you got a blow torch or similar you could try burning any residue off the end of the plug. Try looking for air leaks. Loose bolts around carb/manifold. Exhaust bolts are tight. I was stumped on mine once when the head bolts came loose and result was eventually a disintegrated head gasket hence letting in air and becoming a non runner. Wasn't obvious due to exhaust holding it in place. Is the fuel cap properly tightened down. Can you feel pressure build up in the primer bulb when priming the carb. Carb hi and low needles set at recommended settings. Try those first and see how you go. Quote Link to comment Share on other sites More sharing options...
Buster999 Posted April 13, 2020 Author Share Posted April 13, 2020 Hi thanks for all that info, as far as I can tell everything is tight as it should be and as far as I can tell there are no air leaks and the carb needles are set at factory standard like they were when it started before, I have tried heating up the spark plug and it didn't work, I do vaguely remember a good few years ago I had problems with a single cylinder 2 stroke motorbike engine and it was a similar problem there was a spark and fuel I dismissed the spark plug as the problem but eventually I changed the plug and it cured the problem and someone did say it's like the compression was blowing the spark out, so I'm sort of answering my own question really but have you heard of anything similar ? it's just such a puzzle as to why it won't start after I only changed the pull starter, I do wonder if with me pulling on the old starter so many times if I have moved the coilpack ? many many thanks for your time for offering your advice and I am very grateful Paul Quote Link to comment Share on other sites More sharing options...
Buster999 Posted April 13, 2020 Author Share Posted April 13, 2020 Hi, I've got the buggy to start, only thing is I had to hold the throttle wide open with no choke, which isn't ideal but at least it has started so would that suggest a fuelling problem at low rpm ? Many thanks Paul Quote Link to comment Share on other sites More sharing options...
Mack1 Posted April 13, 2020 Share Posted April 13, 2020 (edited) Check the choke lever hasn't slipped out of position in relation to the butterfly disk. You will have to remove air filter to do this. But it could also be flooded and struggling to burn off all the excess fuel. When I flood mine I end up closing off the low speed needle then try to run it till all unburnt fuel is gone then open it back up again. Money is still on the spark plug though. Edited April 13, 2020 by Mack1 Quote Link to comment Share on other sites More sharing options...
mond Posted April 13, 2020 Share Posted April 13, 2020 When the throttle is wide open, is the engine just ticking over or is it at high revs? Quote Link to comment Share on other sites More sharing options...
Buster999 Posted April 13, 2020 Author Share Posted April 13, 2020 Hi Mack 1, choke is in the correct position on relation to the operating lever, it just seems short of fuel when I try to start it and yes as soon as I get the new spark plug I have ordered I will be putting it in, many thanks for your advice Paul Quote Link to comment Share on other sites More sharing options...
Buster999 Posted April 13, 2020 Author Share Posted April 13, 2020 Hi mond no when it fires up with the throttle wide open I have to shut the throttle because it does rev ok, it just takes having the throttle wide open to start it and once it's running it's fine it just seems short of fuel on starting and I have my doubts about the spark plug as well ? Many thanks Paul Quote Link to comment Share on other sites More sharing options...
mond Posted April 13, 2020 Share Posted April 13, 2020 Did you check all the carb settings and put them back to factory? I'd definitely do that. Quote Link to comment Share on other sites More sharing options...
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