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Discussion Starter · #1 ·
Hi All
I've just returned to R/C after a 30 yrs break so any help is greatly appreciated.
I initially purchased a Thunder Tiger which has given me a lot of fun and decided to upgrade to 2 stroke for ease of running etc.
I bought an HSP Bajer 4WD ( I know already but it's just a toy not a race car)
My problem is that it runs great but every time I back off the throttle to fully closed it dies and won't start.
After reading the posts on here I've vented the tank and reset the needles to factory and still it does it.
As a consequence I've only run about 1 tank through it and pulled out most of my remaining hair.
When I start it I let it idle for a minute or so and all is good but after a few minutes it just won't idle and dies.
I've adjusted the idle and when cold all is great.
When it stops the plug (another thing I've changed) is dry and light brown.
I thought it would be reliable like a whipper snipper but apparently not.
Has anyone else had this prob?

Thanks in advance

Phill
 

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Check spark, air and fuel.

Are there any leaks in gaskets?

Tighten all bolts etc

My issue recently was the filter in the fuel tank had fallen off, some thing so simple but took ages to problem solve.
 

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Discussion Starter · #5 ·
Thanks Guys
I have spark , air and fuel at startup.
Thats the bit I don't understand.
Starts great when cold
 

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What type of car by is on it? Almost sounds like the fuel pump isn't working properly.
Only other thing I can think of is choke stuck on a little, kinda contradictory to my first assumption.
What's acceleration like? Is it laggy or super quick.

As far as I know most of the motors in these rigs are the same as km and rovan etc....
I have had a few of these motors and no major problems, also check your bolt tourqe for inlet and head bolts.
 

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My problem is that it runs great but every time I back off the throttle to fully closed it dies and won't start.
This sounds like a hot running problem, maybe back your low needle off a quarter of a turn and see if the problem is better or worse.

Either that or lack of compreession
 

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Discussion Starter · #8 ·
Yep it's laggy
Certainly not as quick as it should be
When I checked the needles the LSN was only out 1 turn so increased to 1 1/2 as the manual says but still the same
I'll try another half and see what happens
Choke seems OK

Thanks

What type of car by is on it? Almost sounds like the fuel pump isn't working properly.
Only other thing I can think of is choke stuck on a little, kinda contradictory to my first assumption.
What's acceleration like? Is it laggy or super quick.

As far as I know most of the motors in these rigs are the same as km and rovan etc....
I have had a few of these motors and no major problems, also check your bolt tourqe for inlet and head bolts.
 

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Discussion Starter · #9 ·
Compression is great
I'll try the needle and see what happens

Thanks

This sounds like a hot running problem, maybe back your low needle off a quarter of a turn and see if the problem is better or worse.

Either that or lack of compreession
 

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Is the fuel bulb empty or full after it stops? If its empty its a fuel supply issue, if its still full i bet its an air leak that shows up when its warm. Try running it with the choke on or half on and see if its any better, if it is then u have a leak somewhere.
 

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Discussion Starter · #11 ·
Hi Creepshow
Fuel in the bowl but not full.
The choke seems an easy solution
I'll let you know how it goes
Thanks

Is the fuel bulb empty or full after it stops? If its empty its a fuel supply issue, if its still full i bet its an air leak that shows up when its warm. Try running it with the choke on or half on and see if its any better, if it is then u have a leak somewhere.
 

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Once the engine warms and parts begin to expand, air leaks tend to become evident, while the engine is running, a light spray of WD40 around the gasket seal points will cause the engine to smooth out or increase in RPM, this happens as the WD40 temporarily seals the leak....it is a sure fire way to find the leaks, then you only need repair of replace the gaskets or parts that are leaking
 

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Im thinking a leak around the insulator block. VERY common with standard insulator blocks. As Towie said. Spray it lightly with WD40. If there's a leak revs should change. Another way is to pull the carby off. Check the gasket see if it looks like it has been leaking. Then check the insulator block bolts. Make sure they are not loose. If loose try tightening them up. Or even take the ins block off to check the gasket. At worst put new gaskets in. Do not over tighten the ins block bolts though. You can crack the block or strip threads in the barrel. See what happens then. Failing that you may need to "face" the ins block to "square" it back up.

If its laggy that could be the tune as well. Standard settings are a base point to get the engine started You need to take into consideration your fuel mixture. Have a look at You Tube regarding the tune of the engine. They can be annoying but usually once they are set you rarely need to alter them
 

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Discussion Starter · #14 ·
Thanks to both of you
The WD seems a really easy test
As soon as the temptation to throw it as far as I can has subsided I'll give it a go
 

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As aza brought up. About fuel mix. You may have too much or too little oil in the mix, or even stale fuel. 2 stroke won't last too long when mixed, try to mix it fresh as possible as in only mix what you can use in a day or two.
 

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Discussion Starter · #18 ·
Hi Baja
That's my thoughts too
I'm new to 1/5 so do you know which Walbro would be the best for 30cc?
I've heard a lot about the 668 on a 26c but don't know if it would be OK on a 30
I'd be looking for one with a choke
Thanks

sounds to me to be more of a carby issue. typical of the clone manufacturers to use a cheaper, crappier carby. Try getting a walbro carby (off a friend on loan if need be) and test it.
 

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what carby is on it. all the Rovan motors i have bought have walbros on them.
 
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