Having rebuilt the Sherpa engine and had it running beautifully I then go and pour 2 litres of Diesel in when refueling.

I gave the tank a quick wash with straight unleaded, kicked over the engine lots, cleaned out the carb and replaced the filter and plug. Still running like ****e.

The video is at half throttle and pic of the new plug.

 

 

I plan on dumping the fuel in the tank as presumably the tank was still coated with Diesel, washing again with unleaded and re-cleaning the carb.

 

Any other suggestion apart from stopping being so stupid?

Should I try and wash the crankcase somehow?

 

Hope this gives you all a good laugh :hyper:

 

Netley.

 

 

 

^{It should clean out of the engine pretty fast without doing any special washing out. I had a two stroke lawnmower that had the tank accidentally filled with diesel and the person borrowing it attempted to start it (until they broke the starter mechanism).}

^{I fixed the starter, drained the tank and carby and put premix in the tank. It started up fine but the exhaust fumes smelled terrible for the first few minutes}

One thing I noticed is your plug gap is too wide. A Sherpa likes a plug gap the same as the points. .40mm. Unless it has a CDI installed then go with whatever the ignition maker recommends. I once had to run a lawnmower engined minibike on diesel and it ran and got me home but it was not happy about it all. Graham.

Sounds like it is running backwards

I have had it running and rode it around briefly and it was going forwards. I am having the fuel tank steam cleaned and thought I'd rig up something temporary to try and flush the crank case out. If I get it running I will drop it into gear to check the direction !!!!

Cheers

Neil

Well it is easier to start and will tick over nicely. When revved it bogs down a little and if held at a constant throttle it seems to miss and sometimes there is a blow back through the carb which tries to stop it. I've put it into gear and it does run forward.

 

 

 

The plug is looking better after a short run now as the pic shows. I've gapped the plug and it was to big.

Things are moving forward but it still is far from ok.

 

Thanks for your help, I'd be jiggered without it.

Neil.

 

 

It sounds like the ignition is busted, but it was running "beautifully" before the diesel treatment. I guess you have tested a new spark plug. Is it electronic or points ignition?

/ Carl

^{It should clean out of the engine pretty fast without doing any special washing out. I had a two stroke lawnmower that had the tank accidentally filled with diesel and the person borrowing it attempted to start it (until they broke the starter mechanism).}

^{I fixed the starter, drained the tank and carby and put premix in the tank. It started up fine but the exhaust fumes smelled terrible for the first few minutes}

 

I've done the same thing but on a 4 stroke mower

 

Drained the fuel out, in with the unleaded, bit of carb' cleaner on the spark plug and fired straight up!

 

I don't think I would steam clean the tank out on the Bully, I would hazard a guess that it may give you more probs than you started with. It's difficult to get everything out of a tank, maybe leave the tank in the boiler room for a while.....I'm writing that assuming everyone like myself has oil fired central heating in a seperate boiler room...sorry.

 

I have on occasion turned a trials bike completely over with the plug out to clear a crankcase...Monty 315R with a failed carb' needle valve that filled the engine. But even that didn't give any starting issues afterwards.

 

It always tempting to try second guessing the issue but if it was 100% before the diesel fuel then, well you know the rest.

 

My guess is she needs a good full load run to clear her out?

 

.....it won't be long before a failed condensor is mentioned

 

 

 

Edited November 9, 20169 yr by iconic558

Hi, It's points ignition and the points and condensor were replaced before the rebuild. New plugs have been put in and cleaned alternatively between startings. Too late for the steam clean and I have gas central heating so no boiler room.

When the tank is back I'll ensure it's properly dry and see if I can give it a run for a few miles........

Try a NGK PB4ES instead of a 5 as lonf as you won't like to do MX with the bike for better plug color aka better spark and plug live as it still seems to be too dark in my personal view.

This may be a long shot, but I had a freshly rebuilt bike do something similar, points, condenser, kill switch all new but I couldn't get it to run correctly. Swapped a carb off another bike but the problem persisted -very similar to the dreaded condenser failure. So out of frustration I decided to replace the brand new condenser, thinking it could have been faulty, with a spare I had. Well during this exercise I uncovered the problem, on the points there is a threaded hole where the two wires are attached, this hole was not threaded all the way through and so the screw was bottoming out without actually putting a lot of pressure on the two wires, so under load all these problems would arise due to this poor connection. I guess I should have picked this up when putting the bike together back I'm blaming old age and not so new eyes.

Cheers Greg

PS I should mention that sometimes the bike would run fine for a short while, so very frustrating and difficult to track down

I just had a thought that though I re-set the timing, I set the points gap when the bearings were shot. I shall re-set it. Tank is back from the cleaners.

Although they will run within a large range of timing settings, it is quite alarming to see how much difference a small adjustment to the points gap can have on  this timing. For the bike to run at its best you really need to make sure the timing is done first before looking for other problems.

cheers Greg

Yup, Good advice. I had forgotten about the actual points gap itself. Could really do with an old magneto to cut up. Really awkward using the little slots and having to take it off every time to adjust.

Nice one.

Neil

Hmm. Seems both timing and points gap were out so have corrected this and it started and ran nicely, from a dry tank, 3rd kick. Ticked over nicely. Have to go out but will give it a short run later if it isn't too dark.

 

Cheers to one and all.

Neil