247 Wont Start

[bambam_n_chunx]

Hi, i`ve come across a real gem of a montesa 247, its been sat in a garage since 82 and is totally original although a little rusty in places and the seat has dried and split. Unfortunately the rear guard snapped at some point but I do have the part to piece it. Its road reg and still has the rob edwards stickers on the tank.

Trouble is I cant get the thing to start. I`ve done everything I already know it will need.

I emptied the tank and filled with fresh premix fuel. Ive checked the points and timing (.40mm gap and opening at 2.5mm btdc). the spark is blue and strong. I`ve completely stripped and cleaned the carb, the choke jet was blocked solid, the main wasnt much better, pilot seemed ok. I`ve blown all the airways out thoroughly but it still doesnt want to fire. Even pouring a little petrol into the barrel doesnt help. I`ve tried a few different plugs, champion L9 and ngk b5hs and that makes no difference, they do seem to be getting a little wet but not as much as id like. The engine has excellent compression so I dont think the seals are a problem.

Any ideas.

I`ve a pic on my phone I can txt if any one wants to put one onto my topic for me.

Edited July 26, 2013 by bambam_n_chunx

[p@ul250]

After sitting twenty+ years the crank seals will need replacing! you could do it now or after you get it started and have a runaway engine as I did.

Take off the air cleaner and put your hand over the end of the carb and hold the throttle fully open . As you kick the engine over feel how much vacuum (suck) there is. If it isn't trying to pull the palm of your hand off the crank seals will need replacing. Good compression is only a sign of good ring/piston seal. Air sucked in past the seals can still make it up to the combustion chamber. Just without fuel mixed with it.

Also check the fuel tap is passing plenty of fuel. The one on my Bultaco (also sat for many years) was totally blocked.

After sitting twenty + years the crank seal's DO need replacing

Edited July 26, 2013 by p@ul250

[charlie chitlins]

Along with the above...

Check compression. You could have a ring stuck in the land.

This could be fixed with a bit of penetrating oil and a couple heating/cooling cycles with propane torch if you don't want to pop the top.

Condensors have a shelf life...replace it.

No reason to put it behind the flywheel.

Stick it up by the coil where God intended.

[bambam_n_chunx]

Thanks for the replies.

I`ll change the old crank seals as it makes sense even though it could suck a golfball up a garden hose, the spark is a fat blue one so why would the condensor be at fault?

It`ll have to wait for a while before trying it tho as i`m waiting for a new kickstart return spring, the old one gave up after being stressed for hours by some idiot not knowing when to say enoughs enough.

I`ve heard that you can boil aluminium parts in household detergents to thoroughly clean them, has anybody tried this and what did you use. I`m a bit worried that bleach might ruin the old amal, even though i`d remove its internals 1st as I`m not confident all the old petrol resin has been removed from the carb passage ways.

[charlie chitlins]

Things can happen to a spark under compression.What looks good outside the combustion chamber might not work inside.

This is why Champion used to make a pressurized plug checker.

For a few squid, you can be sure.

If you want to soak your carb in something, I have a buddy who's a long-time BMW mechanic...he soaks them overnight in lemon juice.

I haven't tried it, but have no reason to doubt it...he's a damned good mechanic.

[feetupfun]

bambam n chunx, I've read your posts and suspect that you may have added too much petrol down the spark plug hole for it to fire. If you have liquid petrol visible on the plug, you have too much petrol in there.

I suggest you drain the carby, leave the fuel turned off, kick it over or push it along with the throttle fully open and the spark plug removed and the plug cap located where it can't start a fire when the excess fuel gets blown out of the engine. When you have dried out the motor sufficiently, refit the plug and have a go at starting it, first with the fuel still turned off

You could also turn the bike upside down with the plug out and turn the motor over with the throttle open to get rid of excess fuel

Carby cleaning in an ultrasonic parts cleaner bath is very effective and the solution you use in it should be chosen for what you are trying to remove. Fuel residue, dirt or corrosion?

You mention a choke jet on the AMAL carby. I take it the carby is a MK2 AMAL, otherwise it would not have a "choke" (enrichment circuit) I've only ever known 247 Cotas to come with MK1 AMAL carbies which only have ticklers

I can post your photos onto the forum via my phone but you might not want to send a text to Australia due to cost!!

I'll send you a PM with my email and phone number

No I can't - your message box is full

Edited July 27, 2013 by feetupfun

[p@ul250]

Wait until the wife is out and use the dish washer It's what I do when I have engine/carb parts needing a damned good clean.

[bestrcpilot]

I to had a Mony 247 that sat for years and would not start. after cleaning everthing to with in an inch of my life. Still would not start. It ended up being rust on the cam on the flywheel that open and close the points. The point were opening two times per revulsion. Something to check.

[b40rt]

I to had a Mony 247 that sat for years and would not start. after cleaning everthing to with in an inch of my life. Still would not start. It ended up being rust on the cam on the flywheel that open and close the points. The point were opening two times per revulsion. Something to check.

The rust also wears the heel of the points very quickly so timing will be out, if the points are opening at all.

[keychange]

David is correct - the Amal has no choke, make sure you tickle and lean the bike to the right.

Also double check your timing - mine is a mongrel if it is the slightest bit out but starts like a dream if all is set right.

Edited July 29, 2013 by keychange

[bambam_n_chunx]

Right sorry for the long time in replying the misses made me go on hol lol.

The bike still wont start despite the fact i`ve changed the crank seals, compression is sound and it does suck your palm off.

Timing is set at between 3.5 and 4.0 mil btdc as this is the figure quoted in the book for my eng number. points gap is 0.35 mil also quoted in the book and there is no rust in the electrics at all. The carb fitted is an amal 627/450 and definitely has a choke system not a tickler. I suspect the carb more than anything else and would be grateful if anyone could help with the jet sizes. I`m fairly sure i`ve got it clean but it still wont fire although it does seem to be trying at last. I`ve also checked the points and condensor. I`ll go and get some new plugs tomorrow and if that doesnt work i`ll park it back up until I can find another carb to try.

[bambam_n_chunx]

[bambam_n_chunx]

[bambam_n_chunx]

Finally managed to upload some pics of the bike, It came with the tax disc last used in 82 and original receipts. The airbox is in the garage, and I`ve put a pic of the carb on to show the choke system. The part in the bowl was blocked solid but i`m sure its ok now.

[keychange]

I can't see where you have mentioned a year, so guessing this a C model >1978. You tested the condensor - did you make sure it is earthed properly - many people remove it from the points area and mount it under the seat ( it worked for me ). Spark can look fine but when under compression it can easy fail. At one stage I replaced the low tension lead from magneto to coil as the insulation had worn where it passed under the engine. At the same time I disconnected the other coils to remove chance of shorting from them ( mine is T model not sure all models have the lighting coils etc). Any slight fault won't show up until the plug is installed and under compression.

Also make sure your plug gap is correct mine is 0.40mm (sounds basic I know) but the spark is not strong and too wide a gap will weaken it quite significantly.

Failing that see if you can borrow a carbie from another owner - I don't have a clue what other bikes us use the 450 model, however I would expect the older 427 would still work, or a Mikuni from someone who has already sorted the jets. You can still get all the parts for the Amal, best to start with a full kit, but make sure it is the correct kit - my first kit had wrong needle.

Don't give up - I nearly burned my Cota after 6 infuriating months of endless silly faults but once sorted it has been terrific. As I write my TLR 200 has the head off, my Yamaha (AG175) needs clutch work and my Cota has been mechanically engine-wise faultless for about 2 years.

Edited August 8, 2013 by keychange