hard start

[gabriel33]

i bougth a chinese car with a vertex .15 engine
it was runing good and i tougth i inderstood the tuning
but it started running bad,
not holding idle, and very dificult to start.
i also noticed that the engine is leaking all over. all bolts tigth.
it think its not building good vacum. how do i check?
how do i know whats normal play on the back plate bush?
how do i diagnose buying only whats necesary?
thanks

 

[andydrew39219]

There is a way to check for leaks but it involves submersing the block in water and soap. I never thought that was a good idea, it might be just fine though. What I would do is seal up the motor. You can keep it simple and just remove the backplate, seal it up and put it back on. Then you seal the carb and needles afterwards. You don't necessarily have to remove the sleeve, piston and rod. A visual inspection should be fine. I am not nearly specific enough so I would recommend watching this.

[ame="http://www.youtube.com/watch?v=6xwDy-I0Z4I"]How to seal an RC engine from air leaks - YouTube[/ame]

Check out the other videos this guy has, you can learn everything you need to learn about nitro from this guy and his videos.

I left out a big part of what I was going to say. If it is starting hard and not holding an idle after running for a while it sounds like it's running lean/too hot. This can be from a couple different problems. Not tuned correctly or an air leak. Where exactly is it leaking from? The backplate? Header/exhaust? The carb? You may just need to seal it and get a new gasket for your header.

 

[Rolex]

There is a way to check for leaks but it involves submersing the block in water and soap.

No way!
Spraying soapy water at the points where it's subject to leaks is what you do. That's how you check for leaks by looking for bubbles. You don't even remove the engine.

 

[andydrew39219]

I thought that you could spray it with wd 40 to check for leaks. Never heard of spraying it with water. Either way, if he can see its leaking stuff then no matter what hes going to have to pull the engine, so it doesn't make that much of a difference.

 

[Rolex]

WD also works, but NO WAY do you submerge an engine in soapy water.

 

[babi_hrse]

wd-40? i was under the impression wd-40 was a big no no where bearings are concerned due to its use as a degreaser? bearings need to be greased do they not? if wd-40s acceptable ill just use that instead of lithium grease?:\

 

[andydrew39219]

WD also works, but NO WAY do you submerge an engine in soapy water.

I'm sure it's bad for the engine. But that doesn't mean I haven't seen a video of it before. Cannot find it now that I'm looking for it.

 

[Rolex]

Neither the WD or the soapy water gets sprayed INTO the engine. It's sprayed lightly where leaks are known to occur.
If your getting a lot of oil on the chassis, then obviously you need to remove the engine to deal with the leak. While it's out you do a complete seal.

https://www.rcnitrotalk.com/forum/showpost.php?p=726317&postcount=6

 

[Greywolf74]

Here is squirrels video on air leak detection. It basically uses the method that Rolex is talking about. He just dabs a little bit of soapy water on the problem area and looks for bubbles.

https://www.youtube.com/watch?v=thEln8jrmhk

 

[gabriel33]

so far didnt have time to look at it, but thanks for your answers