[muckshifter]

I have fitted a Honda HR21-5 engine to the remains of an old rotavator of unknown make that I have been given.
The engine starts on choke as it should then almost immediately dies, this happens a few times until the combustion chamber is flooded.
I have stripped the carb, cleaned it in a caustic soda bath, rinsed thoughrely then blown through with compressed air, as I have no information on this engine I have set the mixture needle at 1 1/2 turns open and it still do's the same,even after starting a few times in a row it wont even fire without choke.I think it's a fuel issue but i'm not sure if it's electronic or traditional ignition but even if its points and condenser I do'nt think its getting hot enough for the condenser to play up.
Any advice or information would be much appreciated.     

[Gwiz]

I'm more than a little concerned that you have used Caustic soda. This shouldn't really be used on Aluminium, the substance most carbs are made from. It tends to have a nasty reaction to it. A quick google search will, I think, confirm this.
I think that you may have ruined the carb, If the engine is now flooding, it suggests that perhaps the float mechanism isn't working correctly. This might be caused by a dodgy float, or that the seating for the needle is now either blocked so that the needle isn't seating correctly, or has been disolved partially by the acid.
When you stripped the carb, did you remove the jet from the centre tube?

[muckshifter]

Greetings Gwiz, The caustic solution is mild and I use the bath for cleaning magneto bodies and float chambers when restoring old stationary engines,the needle is seating correctly still, I did remove the centre jet along with all the other removable parts before the bath.
However, I was'nt sure whether to remove the tube that is revealed once the jet was removed ? I've tested and solder repaired brass floats before, I guess the plastic ones are throwaway jobbies?
Thanks ever so for your help thus far, I do'nt envy you chaps working with plant of this size all the time, give me a digger any day Motto- rough and strong dont take long. .

[Gwiz]

The centre tube will remove, you can push it out from the inside-out with a flat bladed screwdriver (at a pinch)
The machining is critical on the float needle seat. We used a ultrasonic cleaning bath with a mild organic detergent in it, I was taught to never use Caustic as it tends to always end in tears......(which it would if it got in your eye I suppose)
The only times I've ever used the caustic soda is when I need to de-carbon a steel exhaust pipe.
The plastic floats are throw away, but I can't remember the last time I've had to do that.
Did the float needle have it's neoprene tip intact? or was it one of the solid steel ones (silver and shiny)?

[muckshifter]

Thanks Gwiz,Will dismantle again and report back later.

[muckshifter]

Oh woe is me, sripped the carb again, the neoprene needle tip is intact, the tube came out exactly as Gwiz suggested, everything soaked in carb cleaner and blown through with compressed air and it still misbehaves same as before I ever took a spanner to it. .
Could I be barking up the wrong tree? would ignition or govenor problems be likely to be behind all this grief?
The float seems O.K, no noises when shook suggesting it's not got fuel in it and has floated in a dish of fuel overnight.
I might put this project to one side to avoid an attack of the screaming addabs and carry on putting my Mk 1 Clifford Cultivator back together, to which end would I be right in thinking that the old Castrol D was a straight 140 gear oil?
Many thanks for all help and advice given.

[Gwiz]

When I've not been sure whether a carb is flooding or not, I've taken it off the engine, fitted a longer fuel pipe to it, and sat it level, on the bench, with the fuel turned on.
If it floods you'll see it!!
There could be any number of reasons the engine won't start, but the fact you said it would start on choke and then stop because it floods does tend to suggest......

[smud6ie]

Turn off the fuel or if there is no tap,clamp/pinch the pipe and  start it.
If it shows the same symptoms as before then there is a good chance that its not a flooding problem.
Any numbers on the engine or can you post a close up pic of the carb?
smud6ie

[smud6ie]

Forget the pics,I have found a spare engine off an HR21-5  mower in the workshop and its got  a GV-200.
http://engines.honda.com/parts/ownersmanuals/gv200

smud6ie

[muckshifter]

Thanks ever so Smud6ie, have printed a copy off, your dead right thats exactly what it is (Ser No GV200-1122075). Let's hope it can be persuaded to perform and be up to the job of running this rotavator (originally fitted with a 3 horse Briggs I think?)

[muckshifter]

I have this evening removed the flywheel to have a look at the ignition system,I've never seen a magneto in such a mess still give a spark,so much rust and muck that there's barely an air gap, points a lovely shade of yuk so tomorrows job is to clean everything,then blow it all out.
The only thing I'm not sure about is the points gap, the manual gives the timing settings but no points gap. Any help much appreciated.     

[smud6ie]

I havn.t looked at the manual for that engine but a gap is not always specified as the point gap has a direct bearring on the ignition timiming ,it may be the only way of adjusting it if the point mounting is fixed and flywheel keyed
The wider the point gap the more advanced the timing and vice versa  try initially at 18 thou and  out with the fag papers to check if the piston is in the specified possition.
smud6ie

[dorimower]

As Smud6ie says Honda did not give a points gap but instead I seem to recall that they were set so the points were just starting to open relative to one of the timing marks on the flywheel being aligned with a mark on the engine block casting.
I have a feeling that there will be a firing point marked on the flywheel as well as a tdc mark.

Long time since I worked on one though....

"Dori"

[smud6ie]

Setting the points..
smud6ie

[muckshifter]

Thanks ever so for advice thus far. Cleaned all the rust and muck from the mag,cleaned and gapped the points yesterday got a lovely spark.
Went and got a new plug, turns out the one in it was completely wrong (same as the one in my chainsaw).
Took the float bowl off with the carb in situ, put a dish under it turned the fuel on, flows o.k and float needle closes when the float is raised.
End result? Starts 2nd or third pull runs for 30 seconds and dies,can do that 2 or 3 times then the plug is wet just like before I did anything to it. .
It seems to have plenty of compression,has a spark and is getting fuel, think I may check the kill switch and its wiring today.