Rovan Baja 29CC breaking pull starts along with my arm!

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rayclow

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Well I've reading and breaking my head trying to figure out what else to do since last week...I'm not sure what else to try so i turned to this forum for some guidance. I've had my Baja for a few years now. Last year I didn't run much until recently that i tried to start it and it wouldn't start so i checked the spark plug against the motor and i wasn't getting anything so i bought a new spark plug and still nothing. Comes out to be the coil that was done so i replaced it and got spark back but still wouldn't start....It felt really rough when puling to start, very jerky...removed plug and it felt smooth. Tipped the car over just to make sure i didn't flood the engine and nothing came out. Put the plug back in and felt hard to the point that the plastic part from the pull start broke so i ordered another one. I replaced it and this time i heated up the engine with a heat gun, it felt better when i pulled but still nothing.....i then heated the engine again and held the throttle open and BANG! it starts with a bunch of white smoke, i held it there to get rid of anything left in the engine but when i let go it slowly turned off. I tried it again holding down the throttle open and it turned on again but as soon as i let go same thing happened! I checked the gas cap to make sure the hole wasn't clogged up so that is good. Before i go into trying to break more things i wanted to see if there were any other suggestions i should try....everything that i did was based out of suggestions from other threads i read, at least i got it going holding down the throttle but if i was to go try to turn it on right now the pull start would be rough and jerky unless i heat it up and then hold down the throttle to get it going. Its a learning experience and a lot of reading after work but I'm not trying to give up yet. pheeewww! thank you to whoever reads or replies to this long thread.
 
I was thinking maybe fuel is not getting into the motor? that's why it will only start when applying throttle?
 
few things mate,
1, sounds like its getting too much fuel to me (flooded),
take the car outside, take the air filter off and tip the car on its front bumper and hold the throttle plate open and see if a lot of raw fuel comes out of the engine,
if it does, then let that drain, refit filter, and try to start it from there with a clean/dry plug fitted,
2, did you set the coil gap when you fitted the new coil, coil could be dragging on the flywheel, coil gap should be 0.3 to 0.5mm between the coil and magnetic part on the flywheel,
3, is the fuel old, if you're using old fuel from last year or fuel thats been in the tank for all that time then may be bad fuel,
try fresh fuel mix,
4, check fuel lines for splits etc and replace if its needed,
5, carb may be gummed up, strip and clean the carb out and check the pulse hole is clear and that the diaphram and gaskets are in good order,
if its bad in there get a carb rebuild kit or if you don't feel able to rebuild the carb yourself get a mate to do it for you, or try a fresh carb,
just a few things to try mate, the above isnt really in any right order, try the easiest things first like check lines, coil gap and whether the engines flooded (y)(y)
 
My idle screw was way off on mine but this was brand new from the factory. It's a rovan 30.5cc. It would start with throttle at 50% but not neutral. Once I got it running I adjusted idle screw and got it idling high and just worked my way down slowly till it stalled and that gave it half a turn back to increase it I think I went about a quarter back but it stayed running. Hope this helps
Oh and the plastic original pull start is terrible. I bought the upgraded metal original one and it seems much smoother so far.
 
If it is rough to start on the pull, I would agree with Spends on all that was stated. If you do not have a gap tool for the ignition coil, use a business card or even an index card as a spacer to set the ignition coil position. You want the coil as close to the flywheel without it touching when the flywheel rotates.

If all else seems to be OK, start with the basic tune for the 29cc engine. From the boilerplate document I got with my Rovan engine, the 23cc-30.5cc has the same basic tune settings. Low needle at 1 1/4 turns out, and for the high needle 1 1/2 turns out. You may also want to adjust the throttle stop screw, clockwise will open the throttle plate, counterclockwise will close it. There is a cam lever on the side where the low and high needle settings are. So, when you adjust the throttle stop counterclockwise until the cam lever no longer moves, then turn it clockwise a few turns to get the throttle stop to open the throttle plate. If it is hard to start, adjust the throttle stop screw a bit more. Even though the low, high and throttle stop screws are tensioned with springs, they can still move due to vibrations caused by the engine. Things may shift a bit during the last run. Perhaps the settings were dialed in for the air temperature. If it is colder you may need to adjust for temperature. Not sure how sensitive these engines are to temperatures as I only started in this hobby last October. I live in eastern NC so temperatures have been mild and almost summer like this winter.

You may want to take this time to clean the filter (assuming it is the two-stage foam type). If it is of the fabric variant you can clean those too. Paper type, need to replace those.

I would recheck the new plug you installed, if you got it fired up when applying heat, check for a wet plug condition or any contaminants. Spark plug gap may also matter. Not sure what that needs to be, 0.0030" to 0.032" perhaps. Also if the electrode has any stuff making contact to the prong, chances are there will be no spark generated. Carbon build-up on the plug if it flakes off and makes contact to the tip, it will conduct electricity so it will short out the plug. If there is any other stuff getting pushed into the combustion chamber, metal filings from wear, or varnish parts in the bottom end of the engine or carbon deposits on the piston that may flake off. Other contaminants could be from the threaded spark plug hole, or debris that fell in after the original plug was removed.

20220204_071501.jpg
 
Thanks for all the inputs! I did check and double check the gap of the ignition coil to make sure it was right and not grinding against the flywheel...like mentioned above....i'll have to do a fresh tune and see where it gets me from there....at least i know im getting spark and it does turn on with WOT so I'll be starting from there. This reminds me when i had NITRO rc's and how a pain in the ass those were too...very sensitive but that's what keeps me in the hobby, i like tinkering with these cars.
 
rayclow said:
Thanks for all the inputs! I did check and double check the gap of the ignition coil to make sure it was right and not grinding against the flywheel...like mentioned above....i'll have to do a fresh tune and see where it gets me from there....at least i know im getting spark and it does turn on with WOT so I'll be starting from there. This reminds me when i had NITRO rc's and how a pain in the ass those were too...very sensitive but that's what keeps me in the hobby, i like tinkering with these cars.
Click to expand...

I would change your plug it sounds fouled if it will only run WOT. If there was excess oil in the case while stored it will make the mixture so rich it will have starting issues. As stated as well check for air leaks on the intake and exhaust
 
If you still have the stock pull start, there are better one's that should fit.

I have this mounted on a ESP-Zenoah G43RC engine. I did have it on my Rovan 36cc engine for a short while. It does stick out a bit.
https://www.detroitperformancerc.com/product-page/rcmax-zenoah-cy-billet-easy-start

Turtle racing has one, may be same size as stock. Looks like a promising unit. Tried to get one but no stock available.
https://www.davesmotors.com/turtle-racing-v2-billet-cy-rc-starter-assembly-?sc=12

Rovan has one too, but you need to buy the kit with the extension ring. I have one of these on my King motor Baja. Workes great with the 30.5cc engine. Probably not so great with the body.
https://www.rovanrc.com/product-rv85277s

Hope you get some resolve on your engine issue.
 
Basically, it sounds of 1 of 2 things (one of which, Spents mentioned) MOST LIKELY. I agree, it most likely is getting to much fuel (as he stated).
Or as another person, hinted on. Get new gaskets, as there is an air leak on the carb (or even better, rebuild carb). Which can do 1 of the 2 things, to much fuel, or no (to very little) due to air leak. But the carb, could even be bad after just, new gaskets. The venturi shaft (o-rings) may have widened, enough to cause (easiest word that comes to me is wobble, but that is wrong word) Granted, is easy to check. Once you get it started with WOT. use some wd-40, or PB blaster, spraying around whole carb, and see if any is getting sucked in. Or is blowing bubbles out.
 
I'm telling you mine would start wot and then I realized the idle screw was way off and it wasn't allowing it to idle so that's why it would start wot and not normally.
 
Tons of awesome info, I remember rebuilding a Nitro engine a while back which was also a pain and it seems like the same concept on this bigger engine so I took the carb off and waiting on a Kit to make sure I can rule that out. Since it has been sitting for a while i wanted to make sure i start fresh. I will post and update. Thanks a lot once again for all the suggestions. It can be frustrating but also a good hobby to relieve stress if that makes sense lol
 
well....i put it a new carb, new fuel, double check the gap for the new ignition coil and new spark plug, also replaced the pull start after breaking another one since its hard to pull sometimes and still nothing :( i open the exhaust side to peak at the piston but it seems like everything is fine....i guess my last resort it to remove the engine completely ? which it wasn't what i wanted to do but i followed everyone's suggestions which i appreciate but still cant manage to start.
 
rayclow said:
well....i put it a new carb, new fuel, double check the gap for the new ignition coil and new spark plug, also replaced the pull start after breaking another one since its hard to pull sometimes and still nothing :( i open the exhaust side to peak at the piston but it seems like everything is fine....i guess my last resort it to remove the engine completely ? which it wasn't what i wanted to do but i followed everyone's suggestions which i appreciate but still cant manage to start.
Click to expand...
Is it starting at WOT or nothing at all?
 
i tried starting it with WOT and nothing, so then I tried what i did before which was to heat the engine with a heat gun and then i tried WOT and it ran....i kept my finger on the throttle to let it run for a minute but as soon as i let go it would slowly died. I tried starting again like a warm engine and nothing....tried WOT and nothing. I am really confused with this thing lol
 
rayclow said:
i tried starting it with WOT and nothing, so then I tried what i did before which was to heat the engine with a heat gun and then i tried WOT and it ran....i kept my finger on the throttle to let it run for a minute but as soon as i let go it would slowly died. I tried starting again like a warm engine and nothing....tried WOT and nothing. I am really confused with this thing lol
Click to expand...
What does the plug look like? Is the plug wet?
 
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