not firing properly on left barrel

[shane2011]

hi there from a newbie,
i was wondering if i could get some help! i am in the process in restoring a 350lc and im having problem with the left barrel not firing properly ie miss firing, i have tried the following things but know change.
change the barrels from 250cc to 350cc with new pistons and rebore.
changed the carbs and changed the coil, and still have the same problem! any ideas?

cheers shane

[arrow]

Some drastic measures there to correct a misfire!
Sounds like the L/H crank seal is shot, presuming you have checked all the inductoin side of things for leaks.

[shane2011]

thanks arrow for the advice but all the seals were replaced, ive also noticed that the plug on that side is like new were the right side is a nice brown colour? does this help?

[arrow]

Possible leak on the crankcase, L/H side only ?

[higgsy]

I know you have changed the coil and the carbs but you can have the same problem with different components, so:

Swop the plug leads over and see if it still does it. It's a wasted spark so both sides fire at once. If it's still on the same side then it points to carbs, strip and remove all the jets, clean in carb cleaner, don't poke anything through the jets, the cleaner should be enough. Check the float height and carb settings and try again. After that it might point to something more sinister

If it swops to the right hand side it'll be the plug, cap or HT lead, possibly the coil but LC ones are pretty indestructable IMO

[shane2011]

thanks very much for the help will double check induction again and then will split lump if all else fails and check L/h seal. also just started her and there is very little smoke from L/H side!!! the joys of two strokes!!!!!!

[arrow]

Dec 29, 2011 21:14:30 GMT 1 shane2011 said:

thanks very much for the help will double check induction again and then will split lump if all else fails and check L/h seal. also just started her and there is very little smoke from L/H side!!! the joys of two strokes!!!!!!

And it was like that before ?

[shane2011]

thanks butchers, yes i do have an oil leak just checked bottom of engine is very wet with oil, and when the engine warms up the RH side is warm and the left is alot colder! thanks shane

[arrow]

A leak from the crank cases (Induction) will be dark(ish) and stink off petrol, to the front of the crank/to the sides of the crank area, or could be leaking internally into the gearbox. Put your finger over the gearbox breather, check for pulses either way, there should be none. Be careful not to confuse this with a leak from the transmission oil.
Pull off the L/H case, there should be no smell of petrol around the flywheel, thats checking the L/H seal. A warm oily smell is normal. HTH

[higgsy]

In my experience, this sort of thing is normally something simple that you invarably overlook and find after dismantling most if not all of the engine!

I take it you have tried changing the plug before anything else? I had a couple of duff NGK's straight out of the box last season. I now keep a couple of known good used ones in the top of the tool box just in case I need to test anything spark wise.

[Delbert]

Got to agree with higgsy 100 % its probably something stupid that you will want to beat yourself for when you find it . Check things likes rubber balance pipe between carbs / check carb slides are adjusted correctly so you have air gap when fully closed . You say the left plug is clean is it wet or dry ? This would give you a clue as to weather its no fuel or too much ! Are the carb slides the correct way round . Look for these sort of things before pulling the motor again . Good luck

[Norbo]

I was gowing to add something but it looks like everything has been covered , so ill just say welcome to the site mate .