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TGB Hawk 50 won't run

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radddogg
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PostPosted: 01:28 - 08 Nov 2018    Post subject: TGB Hawk 50 won't run Reply with quote

Hi

Newbie here Very Happy

I picked up a cheap Taiwanese scooter as a non-running project. It's had a hard life. It's a 2010 with 7k on the clock and been off the road since 2014.

When I got it the battery and spark plug were missing so I've replaced these and got fuel but no spark. Upon investigation I found one of the LT terminals loose and the other completed detached. I surmise that this might be the reason it was taken off the road.

With the coil connected it did eventually start with a bit of cranking on full throttle. However it was loud, wouldn't idle and was just trying to cut out even with throttle. Also wouldn't rev freely. The loudness was a very large hole in the exhaust expansion chamber. I've ordered a replacement.

So I stripped down the carb and cleaned it out, it was pretty clean to be honest. I dumped the 4 year old fuel, it was yellow and pretty stinky, and replaced it with fresh fuel. I reassembled the carb and tried to start it. There was no change.

It will start with some throttle but won't rev freely and wants to cut out. The exhaust won't be helping but shouldn't stop it running should it?

Any ideas for what next to check?

Thanks

raddders


Last edited by radddogg on 01:34 - 08 Nov 2018; edited 1 time in total
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radddogg
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PostPosted: 01:32 - 08 Nov 2018    Post subject: Reply with quote

Here is a video of it starting and dying even with throttle.
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jaffa90
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PostPosted: 11:13 - 08 Nov 2018    Post subject: Reply with quote

Did you remove the pilot jet to clean it?
What choke system does it have?


Last edited by jaffa90 on 11:37 - 08 Nov 2018; edited 1 time in total
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radddogg
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PostPosted: 11:37 - 08 Nov 2018    Post subject: Reply with quote

jaffa90 wrote:
Did you remove the pilot jet to clean it?
What choke system does it have?
hi, yes I removed the pilot jet. I screwed it all the way in first (3/4 turn) then all the way out.

It's an electric choke. I tried it connected and disconnected but no difference. I will remove it and feed it 12v to test it though
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jaffa90
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PostPosted: 11:40 - 08 Nov 2018    Post subject: Reply with quote

"""""""""I screwed it all the way in first (3/4 turn) then all the way out. """""""""""
This sounds like the pilot mixture screw and not the jet!
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radddogg
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PostPosted: 12:00 - 08 Nov 2018    Post subject: Reply with quote

jaffa90 wrote:
"""""""""I screwed it all the way in first (3/4 turn) then all the way out. """""""""""
This sounds like the pilot mixture screw and not the jet!
sorry you're right. But yes I did remove the jet and blew solvent through it. I could see a pin prick of light through it too
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bikenut
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PostPosted: 12:03 - 08 Nov 2018    Post subject: 50 Reply with quote

Don't know this bike but it sounds like a 4t, a honda 50 ohc copy ??

Electric choke, so temp dependent.

You have a wiring diagram and parts exploded views which can only help.

Sounds very much fuel related as it does start and run then dies, so fuel supply ??

Fuel all yellow and crappy so gummed up carb and blocked jets ?

try cleaning the carb and tank again, that includes the fuel cap and any vents, filters and taps. Establish good fuel flow to carb, the float bowl has a drain ??

picture of carb and/or parts exploded views??
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jaffa90
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PostPosted: 12:05 - 08 Nov 2018    Post subject: Reply with quote

Ok, the exhaust is part of the tuning/running so have you tried half covering the carb intake to see if it just ticks over/idles?
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radddogg
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PostPosted: 12:32 - 08 Nov 2018    Post subject: Reply with quote

No, it's a 2T. It has a separate oil tank and a 2 stroke exhaust.

The carb was pretty clean inside and cleaning it made no difference. The fuel flow is good. There is good vacuum to the petcock valve. The filter is showing clean fuel. There is oily residue coming from the home in the exhaust so it's getting fuel - maybe too much.
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radddogg
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PostPosted: 12:33 - 08 Nov 2018    Post subject: Reply with quote

jaffa90 wrote:
Ok, the exhaust is part of the tuning/running so have you tried half covering the carb intake to see if it just ticks over/idles?
I have tried yes, didn't really make any difference. It needs open throttle to even run
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jaffa90
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PostPosted: 14:05 - 08 Nov 2018    Post subject: Reply with quote

Well if your happy about the carb and no unwanted air going in or out of the engine then what about the engine seals ?
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radddogg
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PostPosted: 14:23 - 08 Nov 2018    Post subject: Reply with quote

jaffa90 wrote:
Well if your happy about the carb and no unwanted air going in or out of the engine then what about the engine seals ?
you mean the reed valves?
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jaffa90
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PostPosted: 14:30 - 08 Nov 2018    Post subject: Reply with quote

The reed valves (if fitted)should close to enable good low revs.
Also the engine has to be sealed being a 2 stroke.
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radddogg
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PostPosted: 14:38 - 08 Nov 2018    Post subject: Reply with quote

jaffa90 wrote:
The reed valves (if fitted)should close to enable good low revs.
Also the engine has to be sealed being a 2 stroke.
ok will check a few things. What seals are you referring to? Crank seals? Thanks
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jaffa90
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PostPosted: 14:53 - 08 Nov 2018    Post subject: Reply with quote

"""What seals are you referring to? Crank seals? """

Yes and casing seals because the fuel/air mixture has to circulate the engine first.
Stick a rubber glove over the carb intake to see if you get a suck not blow when cranking the engine with the plug cap OFF.
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radddogg
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PostPosted: 14:56 - 08 Nov 2018    Post subject: Reply with quote

jaffa90 wrote:
"""What seals are you referring to? Crank seals? """

Yes and casing seals because the fuel/air mixture has to circulate the engine first.
Stick a rubber glove over the carb intake to see if you get a suck not blow when cranking the engine with the plug cap OFF.
I'm getting very good vacuum from the engine as I covered it with my fingers while cranking to prime the carb after swapping the fuel
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radddogg
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PostPosted: 21:43 - 08 Nov 2018    Post subject: Reply with quote

So I checked the carb again and both the pilot and main jets were blocked. Cleaned them out still no better. Checked again and they were again blocked. I noticed some discolouration on the bowl and as the petrol evaporated it dried into a flakey powder. I guess crap from where it was left for 4 years. So I cleaned this all out until it was spotless. Put it back together. No difference Sad

Which circuit does it start on? Cheers
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jaffa90
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PostPosted: 22:49 - 08 Nov 2018    Post subject: Reply with quote

The tank needs inspecting and cleaning out properly.

Is it possible to fit an inline fuel filter in between the tank and carb?

Also what does "Which circuit does it start on? " mean?
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radddogg
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PostPosted: 23:59 - 08 Nov 2018    Post subject: Reply with quote

jaffa90 wrote:
The tank needs inspecting and cleaning out properly.

Is it possible to fit an inline fuel filter in between the tank and carb?

Also what does "Which circuit does it start on? " mean?
there already is a filter between the tank and the carb. I haven't replaced the filter but I wouldn't imagine it is letting anything bad through and it looks clear. The bowl is being filled fine.

There are three fuelling circuits in the carb. The main jet, the pilot circuit and the choke circuit (I think). The main jet only comes in after 50% throttle or something.

I guess I need to just get right into it and strip the whole thing down. I'm obviously missing something.

I wanted to take the reeds out but they won't come out without taking the rear subframe off Sad
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jaffa90
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PostPosted: 00:21 - 09 Nov 2018    Post subject: Reply with quote

Why take the reeds out? Do you have a blow back?
Circuits, pilot / slow jet usually up to 3,000 rpm, main jet as you know, choke jet / plunger, the auto choke / plunger shuts off the fuel supply when getting warm.
What good is that fuel filter?
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radddogg
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PostPosted: 00:36 - 09 Nov 2018    Post subject: Reply with quote

jaffa90 wrote:
Why take the reeds out? Do you have a blow back?
Circuits, pilot / slow jet usually up to 3,000 rpm, main jet as you know, choke jet / plunger, the auto choke / plunger shuts off the fuel supply when getting warm.
What good is that fuel filter?
I wanted to check they were ok. Kinda running out of ideas. I also want to check the gasket on case is drawing in air. There's evidence it's been removed before.
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jaffa90
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PostPosted: 01:06 - 09 Nov 2018    Post subject: Reply with quote

I cannot help any more so it`s over to you.
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Fourte
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PostPosted: 09:13 - 09 Nov 2018    Post subject: Reply with quote

If you're getting flakes into the bowl then that filter isn't working. I seem to remember some fake filters were being sold some time ago which actually had an internal picture of a filter and no actual paper filter inside!
Anyway, new inline filter for starters - very cheap and easy to get. Make sure to get the correct one for the diameter of the fuel line.
Just a question: you sure the filter is on the correct pipe? I've known people put them on a vacuum line. Just saying..

Once new filter is on, re-clean the carb and try.
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radddogg
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PostPosted: 10:06 - 09 Nov 2018    Post subject: Reply with quote

Fourte wrote:
If you're getting flakes into the bowl then that filter isn't working.


Sorry the flakes were from some residue in the bowl I hadn't cleaned out. It's fine now.

If I was to completely remove the carb and just try to start it with easy start straight down the intake, would that work in terms of ruling out an engine issue?
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Fourte
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PostPosted: 12:25 - 09 Nov 2018    Post subject: Reply with quote

radddogg wrote:
Fourte wrote:
If you're getting flakes into the bowl then that filter isn't working.


Sorry the flakes were from some residue in the bowl I hadn't cleaned out. It's fine now.

If I was to completely remove the carb and just try to start it with easy start straight down the intake, would that work in terms of ruling out an engine issue?


But you've already ruled that out in the video you posted near the start of the thread!

Quick explanation: Personally aside from the obvious exhaust hole/noise I can't hear anything wrong mechanically (badly wrong that is).
Electrical problems tend to be hitty missy - engine running then suddenly not then suddenly on.
Fuel problems sound exactly like the video does. Runs and slowly dies is a classic fuel starvation symptom as what fuel is available is slowly used up.
If you remove the carb and spray whatever to make it run then you'll have exactly the same: Same running without hitty missy and slowly dies until you squirt more whatever.

You need to address the carb. They're not something you can simply mess on with - they have incredibly accurate tolerances inside and everything needs to be spot on. Even an eyelash inside will kill an engine!

Try this: Remove the carb. Remove the float bowl. Add the fuel pipe and turn on (place above a suitable catchment container!). Let us know if you have a flow of fuel running in. Might not work if you need a vacuum source if it has that system - anyone?)

Try the above and if it's flowing good. Next we need to see several good 'in focus' well lit images of the insides of the carb. It'll help us massively if you do the photos.
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