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Pulling my hair out with this engine!

doza28

Well-Known Member
Messages
232
Location
bournemouth, UK
Ive mentioned the issues im having in my build thread for the car, but a lot of people might not have been following that, so i decided to post here.

Im having issues with getting my G230 engine to run as i know it should.

Firstly, im not a newb. Ive had numerous 1/5 scale cars over the years... fgs, Hpis, Mcds

My MCD runs perfectly. No issues at all.

But this engine just will not run cleanly.
Ive had a few cases where i thought i had found the problem- mainly when i found the coil lead had broken. With this fixed, i thought id nailed it. Not so.

Spec

Zenoah G230 (stock as far as i know but apparently has had a new ring)
Compression is the same hot or cold and feels good

Standard CMR7 NGK plug

Fg Big Power Exhaust
Fg Inlet

990 carb.

Symptoms

Car starts fine after 2/3 pulls. Even without choke flap closed
Carb is set to 990 stock settings which i found as
low: 1 and 1/8 out
high: 1 and 5/8


Full throttle from idle : Car bogs low down as if its too rich but suddenly clears as it reaches top revs

If i lean the low speed out slightly (the tiniest amount) it then goes flat as if its too lean. Richen it up from stock position, and the car struggles to accelerate as if it just cant burn the fuel
The idle is stable, but not what i would call smooth.

I understand the H end needle covers the car from 1/3 throttle upwards, so i have also tried tweaking the high end needle by 1/16 and 1/8 of a turn either way. The engine still runs the same.



Other points i`ve noticed.

Gaskets have been replaced. I have still checked for leaks with WD and there are none
There is no fuel tank breather
The fuel does seem to be under pressure as when you disconnect either hose, fuel does squirt out.
The engine will also run with the fuel cap off
If you feed the power in gradually, it seems to behave. Its full throttle from standstill it doesn't like.

Is this a fuel pressure issue by not having a tank breather? The tank is the standard one as fitted to the Marder/F1/ Porsche models. I have seen posts suggesting the stock cap breathes fine as long as the hole albeit a tiny one, is clear which mine is.

Im stumped.
I love this car, but its really testing my patience.
 

mark35

Well-Known Member
Messages
239
Location
Merseyside Uk
Hi doza,
Its a pain in the arse when your engine won't run right.😤
Have you tried changing the carb? Sounds to me like that could be your problem with it being so temperamental when your trying to tune, worth a shot of you've not tried already.👍
 

Basher5iveT420

LSF Plus Member
PLUS member
Messages
249
Location
Florida
I agree with @mark35.
It sounds like a faulty carb. It could also just be dirty or clogged, I would Just replace it with a brand new one And give it a go

It also sounds like someone did a lot of engine work and if they did anything wrong. You’ll be having all kinds of issues.

If the carb doesn’t solve it, I would recommend saving a few bucks and just upgrade to a new engine. That way you’ll know exactly what you have.
Zero issues will save you a lot of headaches
 

doza28

Well-Known Member
Messages
232
Location
bournemouth, UK
Thanks for the replies guys. 👍

The car runs the same on a stock Carb too as that was on the car when I bought it. I've been having running issues for that long I've tried as much fault finding as I can lol

There is a choke flap built into the base of the air filter. As I said mentioned though I don't need to use it. Engine fires easily

I'm beginning to think it could be the engine as well. It was second hand off ebay. As I said it seems to go like stink at the top end but just hates any loading from idle. If the wheels are off the ground it seems to be less of an issue
this is very very weird. does the car run fine and tune fine with the gas cap off?
There's no Noticeable difference to be honest. It's still a pig, 😂
 

lorraine

Well-Known Member
Messages
113
Location
new york
1- walbro part# D10-WAT , RR Kit , 1- walbro part# 34-64-1 notched plate , 1- walbro part# 98-3247 , 13psi pop off- 10psi reseat spring , 1- gizzmo's SS carb shaft upgrade kit..... DONE!!! beyond fixed and low speed lag GONE!!!!!!!!!!!!!!!!!!
1- walbro part# D10-WAT , RR Kit , 1- walbro part# 34-64-1 notched plate , 1- walbro part# 98-3247 , 13psi pop off- 10psi reseat spring , 1- gizzmo's SS carb shaft upgrade kit..... DONE!!! beyond fixed and low speed lag GONE!!!!!!!!!!!!!!!!!!
If the motor starts good COLD with no choke help then there is no vac leaks and compression is good, also check that the shaft and body fit is still in check by a quick small shot of ether and shaft/body interface. DO not use wd-40 for this test as it is too thick, Ether will find leak where WD-40 will not
 
Last edited:

lorraine

Well-Known Member
Messages
113
Location
new york
If your carb body/ shaft fit is off it will pull high speed air right near the jet lines in carb bore and induce eddies around them and raise cain
 

doza28

Well-Known Member
Messages
232
Location
bournemouth, UK
Annoyingly at old job where I used to tune and modify cars, I had a mitivac. Don't have access to one now.

The issue is there whether the stock 668 or the 990 Carb I have is fitted. It doesn't seem to matter

The only consistents that I haven't tried are the fuel tank and the engine. Hence why my thoughts are either the engine has been screwed in the mod process, or there is too much pressure in the tank

I have brake cleaner... This providing I don't get any in the filter will highlight an air leak. I'm sure its OK though. Both gaskets replaced and I Skimmed all surfaces gently

I'm leaning towards a new engine and have been for some time.
 

Z.hb71

Well-Known Member
Messages
3,780
Location
Manvel, Texas
Annoyingly at old job where I used to tune and modify cars, I had a mitivac. Don't have access to one now.

The issue is there whether the stock 668 or the 990 Carb I have is fitted. It doesn't seem to matter

The only consistents that I haven't tried are the fuel tank and the engine. Hence why my thoughts are either the engine has been screwed in the mod process, or there is too much pressure in the tank

I have brake cleaner... This providing I don't get any in the filter will highlight an air leak. I'm sure its OK though. Both gaskets replaced and I Skimmed all surfaces gently

I'm leaning towards a new engine and have been for some time.
i say something got screwed up in the modding process. who modded it?
 

doza28

Well-Known Member
Messages
232
Location
bournemouth, UK
i say something got screwed up in the modding process. who modded it?
Not a clue.
I bought it used from ebay a few months back. Seller allegedly used it for racing and got re-rung.

I've never had this issue before on any of my Rc cars. My Mcd is a beast and will light up all four wheels from standstill. It's tuning is spot on so I know how to get them right and how they should sound.
My 5b ripped along as did my old FG comp that I sold to Renbar.

It just doesn't have that snappy response and crispness it should have when you punch the throttle
 

doza28

Well-Known Member
Messages
232
Location
bournemouth, UK
Ah.... OK. I see where you're going here.
I've actually seen this on a real engine lol.

You saying it could be 180 out?
 
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