Al and 1 Guest are viewing this topic.


Warby

Re: Engine Trouble
« Reply #15 on: Aug 30, 2019, 1:25 pm »
Gaz,
We've all been there, listening to advice!! I actually built a HC about 40 years ago using 2 stroke engines.
I was with the HCGB on a beach near Barmouth when the thrust engine, an Aeriel Arrow 250cc, packed up. There were many theories as to what had happened including a failed crank seal between the two cylinders. I actually stripped the engine to find the seal was ok, the fault was ignition related!!!!aaarrrrgh

Pat Tobin

Re: Engine Trouble
« Reply #16 on: Aug 30, 2019, 2:11 pm »
Really it can only be three things, Fuel, ignition or compression...once you have all three it should work. Timing as well but its fixed. So I will just go back and double check everything one thing at a time.


Heading away on business so it will be a week before I get the chance.


Thanks for all the input


Pat

Nick Flint

Re: Engine Trouble
« Reply #17 on: Aug 30, 2019, 3:02 pm »
By bantering stuff back and forth, we all learn, even the "so called" teachers/ advisers.
Its good to discuss these intermittent hard diagnoses.
Its the energy of this forum IMHO.  8)
Memories are BETTER than Dreams---"Capn" FLINT

Pat Tobin

Re: Engine Trouble
« Reply #18 on: Aug 31, 2019, 9:50 am »
Totally agree. A discussion might spark something in someones mind that eventually leads to the fix.

Al

Re: Engine Trouble
« Reply #19 on: Aug 31, 2019, 8:54 pm »

Really it can only be three things, Fuel, ignition or compression...once you have all three it should work. Timing as well but its fixed. So I will just go back and double check everything one thing at a time.

So what was it Pat?


Jimmy Cooper

Re: Engine Trouble
« Reply #20 on: Sep 01, 2019, 6:33 am »
Had a issue recently with a big block Vanguard 35hp B&S unit.
Long story short, it would run fine until just given a of bit 'extra' throttle.
Then it would die.
Spark plugs looked like a weak running engine.
Turned out to be a diaphragm pump that was just not functioning to its full capacity and of course this only really showed at higher rpm/more fuel required. This did though affect both cylinders so may not be your issue.............but worth a look.
Stripping and cleaning sorted it in my case.
Good luck!!!!!!.
A BHC Marlin and Vortex Sirocco Man

Pat Tobin

Re: Engine Trouble
« Reply #21 on: Sep 01, 2019, 10:17 am »
Really it can only be three things, Fuel, ignition or compression...once you have all three it should work. Timing as well but its fixed. So I will just go back and double check everything one thing at a time.

So what was it Pat?


Al..not sorted yet and wont get to the craft until next weekend.

Gary Firth (Gazza)

Re: Engine Trouble
« Reply #22 on: Sep 02, 2019, 7:02 am »
Iím going to say carb.
I had a 35hp similar issues. Cleaned carb etc no better.
Bought new carb solved problem.


Warby

Re: Engine Trouble
« Reply #23 on: Sep 02, 2019, 10:07 am »
"Bought new carb solved problem"
With the amount of use the average HC gets I can't see why a carb should "Pack up" or wear out.
I know its a simple quick solution to fit new but what are we missing when cleaning a carb?
First off the average "Carb Cleaners" from diy motor stores are not that powerful (health and safety with the general public) I have found "motor trade" cleaners more powerful! AND they are only meant to dissolve produsts of the fuel like "Varnish"
I've had dirt in carbs that has been difficult to remove and after perseverance have managed to clear it.
Whats important to remember is the float chamber has to be vented to atmosphere and this is sometimes a way in for muck. When changing fuel filters, particularly the in line type, when a pipe has to be taken off always check the pipe for bits of rubber breaking off. And use top quallity fuel pipe. I've seen carbs with tiny bits of rubber wedged in a jet which no carb cleaner will dissolve!
Also an airline is a BIG help!! 100/150 psi will shift most things!!
I have had several Motor Bikes which were not used in the winter. I ALWAYS drained the carbs before storing to avoid varnish building up when the fuel evaporated.

Ronnie L

Re: Engine Trouble
« Reply #24 on: Sep 02, 2019, 5:15 pm »
The danger always in this situation, is finding a solution and making the fault fit it.
Investigate, test, eliminate.
The easiest thing to test is ignition.
This is why I suggested a strobe light with an inductive pick up.
You can listen to the engine and watch the ignition system working.
Ignition misses are easy to see.
No misses no problem with that bit.....eliminate...move to next system.

Ian Brooks

Re: Engine Trouble
« Reply #25 on: Sep 02, 2019, 11:16 pm »
Years ago I had the same with the 35 Briggs carb. There seems to be circuit that you just can't get to, despite lots of trying, airline, "proper" ultrasonic at work etc etc I gave up and bought a new one. Problem fixed. Never did find out what was wrong with the carb. I'm not suggesting this is Pat's problem though!
Ian Brooks
Gloucester, UK

Gary Firth (Gazza)

Re: Engine Trouble
« Reply #26 on: Sep 03, 2019, 5:33 pm »
Had a similar issue yesterday.
Ran on one cylinder blah blah.
Thought it was the coil.
Diode had packed in on the earth wire that stops it. Easy to check pull the wire off both coils.

Pat Tobin

Re: Engine Trouble
« Reply #27 on: Sep 08, 2019, 9:11 am »
Update:
Went at it again yesterday. This time I arranged the intake of the carb so as I could squirt petrol down each barrel independently.
Started with the colortune spark plug in and it started albeit missing a little.  Spark is fine. Let it warm up and then the dodgy side started to die but would come back some what if throttle advanced. Tried squirting fuel down the bad side carb barrel and no change in revs and on a few occasions it spat the fuel back at me so I was thinking the inlet valve is not closing properly.


So off with the head. Pushrods are both fine, no bends. Removed the valves and there was some light scoring on the exhaust valve which I clean up but otherwise they were fine. Cleaned up the head and reground the valves and lapped them.


Will stick it back on and see what happens. I was hoping for a eureka moment when I examined the valves but not to be.


Also had previously thought of the diodes but it made no difference.


I have another carb on order. Its not the same as the one in it as they a very expensive. Its one from an intek V twin but  a tenth of the price.


So the saga continues..

tomtilley

Re: Engine Trouble
« Reply #28 on: Sep 08, 2019, 11:00 am »
Just a thought you may have a intermittent fault on the   HT leads swap the leads and plugs over it may be a intermittent brake down on the lead to that side . Tom

Jimmy Cooper

Re: Engine Trouble
« Reply #29 on: Yesterday at 9:52 PM »
Yeah the Vanguard V twin carbs are a terrible price. About 325ukp approx. The Vanguard range of engines (at present. They are supposed to be coming back to the USA manufacture soon) are made in Japan by Daihatsu.
The Intek range are USA built.
Metric v A/F bolts etc.....
A BHC Marlin and Vortex Sirocco Man