handmadematt Posted December 19, 2012 Report Share Posted December 19, 2012 Hello everyone. In the welcome area I was helped greatly with my decision to buy this bike - thank you. I am super happy with it and am thrilled to begin this trials journey. I took the bike out for a proper run for the first time today down the local byways and across a private estate, it rides brilliantly and I am amazed with how capable it is! I'm used to my Royal Enfield which is such a pig! Here are pictures from todays run: I am however having a few problems. I've never owned a two stroke before and I undersand the fine line between the intake and exhaust function, so is flooding a two stroke easier than a four stroke? So the problem: From cold I turn on the fuel, operate the choke (enriching lever) and kick it, it starts beautifully on the first kick. I then run it for half a min and turn the "choke" off. Then off I go. Once warm she ticks over lovely. HOWEVER, if and when she does falter or I stall her I just can't get her started again! I kick and kick and nothing. So the first time this happened I removed the plug and found it was very wet. I held a windproof lighter to the plug hole and it burned all the fuel out the cylinder with a squeaky pop. I then used the blue flame of the lighter to dry and heat the plug. I put it back in and it started first kick.. So I assumed I had flooded it somehow? (I hadn't re-engaged the "choke" or anything, I double checked incase it had flicked on on it's own.) Off I went. (I took the lighter and plug spanner with me.) When it happened again I thought OK, it's flooded so I opened the throttle fully and kicked it a few times to get plenty of air through but no joy. This time the plug was dry (it's a lovely biscuit colour by the way,) there was no popping of fuel in the cylinder with the lighter either. So I put it back together and continued kicking... nothing. Eventually I thought if it's dry maybe I should flick on the "choke" (enricher) so I did and still no joy until I thought, OK I've given it more fuel how about more air... So I held the throttle fully open with the "choke" on and she fired up first kick. (This was after about 15mins of trying on a cold windy day so she had cooled down considerably.) I then enjoyed the rest of my ride not daring to enter "tick over territory." Once I got home I tried and she ticked over beautifully. I left her running whilst I took my kit off and then killed it with the kill switch on the handle bars. Then I thought I'll see if I can start her again and I couldn't... not at all. Even after plug out, pre heat, plug in and every combination of throttle open, throttle closed, choke on and choke off. So dismayed I have wheeled her back in the garage that's that. I've checked the plug and I'm getting a really nice snappy blue spark. What gap should it be? Maybe that'd help? Basically I've experienced a flooding of my engine and also the opposite (I think.) She runs great when she does so I think rather than mechanical error it could be user error. Like I say, I've never owned a two stroke before. Advice welcome please. Many thanks. Quote Link to comment Share on other sites More sharing options...
charlie prescott Posted December 19, 2012 Report Share Posted December 19, 2012 Hi Guy's. Hi, Matt? Just reading through what you have said quickly, It sounds to me as it could be crankcase oil-seals that are at fault? They could well have gone hard and leaking?? Regards Charlie. Quote Link to comment Share on other sites More sharing options...
handmadematt Posted December 19, 2012 Author Report Share Posted December 19, 2012 ...It sounds to me as it could be crankcase oil-seals that are at fault? Thanks Charlie. I don't know how that could be the cause? (I'm no expert though.) Either way, the previous owner said that it's had new crank seals. There's no receipts for this but he was a lovely chap and everything else about the bike and the sale checks out and is/ feels genuine so I have no reason to doubt him. Quote Link to comment Share on other sites More sharing options...
b40rt Posted December 19, 2012 Report Share Posted December 19, 2012 (edited) Needle valve in carb not closing fully ? Causing flooding when stopped ? I would change the plug and condensor as well, cheap and rules them out. I take it its still on points ? Edited December 19, 2012 by b40rt Quote Link to comment Share on other sites More sharing options...
handmadematt Posted December 19, 2012 Author Report Share Posted December 19, 2012 Needle valve in carb not closing fully ? Causing flooding when stopped ? I would change the plug and condensor as well, cheap and rules them out. I take it its still on points ? Thanks mate. The needle valve is on the throttle slide yes? I think it closes fully, it certainly snaps closed when the engine's not running. It is still on points. The spark is good so I don't think it's the condensor or plug. Quote Link to comment Share on other sites More sharing options...
handmadematt Posted December 19, 2012 Author Report Share Posted December 19, 2012 UPDATE. I've cleaned the carb out, I didn't notice and blocked jets but you never really know do you? I put a new plug in as well. Started her and let her tick over until she warmed up. Stopped her and then the same problem, I couldn't start her again. I removed the plug and it was harder to see if it was wet being all new and shinny but I burned off the fuel in the cylinder anyway and cooked the plug a big with the blow torch and put it back in. This time I kicked her with the throttle wide open... plenty of air. Instant results! Nice. I then let her continue ticking over whilst I put the fibre glass back on and then hit the kill switch again. Gave her a kick again with the throttle wide open, again instand results! I then let her run for 30seconds (which is a long time when your standing next to a loud bike tapping your foot) and tried again - she started great, and again, and again. Every time she fired up from hot with the throttle wide open. I think that's the knack with this particular old girl, she like lots of air to get her going again from hot. I'm used to my Enfield's where it's a cardinal sin to touch the throttle during starting, all these machines are different personalities and it takes time to forge relationships with them hey? I'll re-post to update how I get on over the next few outings. Quote Link to comment Share on other sites More sharing options...
b40rt Posted December 19, 2012 Report Share Posted December 19, 2012 The needle valve is what the floats act upon to stop the petrol entering the float bowel. If this is sticking for any reason, dirt or damage, the float bowl will flood. Quote Link to comment Share on other sites More sharing options...
old trials fanatic Posted December 19, 2012 Report Share Posted December 19, 2012 Dont know why you have a thing about leaving the bike ticking over ? Best way to oil a plug on a two stroke IMHO. Start it use it give it a good caning often and all is usually ok. Trials bikes are competition machines and like being treated as such. If you dont they gas up and get hard to start and keep running. Quote Link to comment Share on other sites More sharing options...
handmadematt Posted December 19, 2012 Author Report Share Posted December 19, 2012 The needle valve is what the floats act upon to stop the petrol entering the float bowel. If this is sticking for any reason, dirt or damage, the float bowl will flood. This was free and operated nicely but having the the float bowl overfill wouldn't result in running problems would it? Just petrol on the garage floor... There's an "overfill drain" on carbs, just like your bath to fuel out if the float sticks. I thought the needle valve was the thin aluminium "pin" or "needle" that threads down into the carb body from the throttle air slide, it's hight controls the richness of the mix. Thanks anyway though, brainstorming is what it's all about. I think the carb's working OK though, the engine runs really sweet. Dont know why you have a thing about leaving the bike ticking over ? Best way to oil a plug on a two stroke IMHO. Start it use it give it a good caning often and all is usually ok. Trials bikes are competition machines and like being treated as such. If you dont they gas up and get hard to start and keep running. I was keeping the bike ticking over to warm it up and keep it warm having just ridden it around my drive for a few mins from cold. I experienced the problem earlier whilst I was out on a run and all my troubleshooting to try and solve my problem was done hours later in the garage. I felt it was important to have the bike at running temperature especially considering that my problem had been hot starts... If well maintained, adjusted and cared for these bikes will work perfectly nicely. Quote Link to comment Share on other sites More sharing options...
old trials fanatic Posted December 19, 2012 Report Share Posted December 19, 2012 (edited) Each to their own. I NEVER let any of my bikes tick over because i have always found it causes them to gas up. The problem you suggest might be due to fuel evaporation especially as it's more prone when hot or after the engine has stood a bit. If i want to get the engine up to temp just keep bliping the throttle then again what do i know eh? As long as you're happy. Edited December 19, 2012 by old trials fanatic Quote Link to comment Share on other sites More sharing options...
2stroke4stroke Posted December 19, 2012 Report Share Posted December 19, 2012 An overfull float bowl causes rich running (and flooding). The needle in the slide controls the mixture over the middle half of throttle opening. Try this for some advice http://sterlingmotorworks.com/amal_carburetor_tuning_tips Quote Link to comment Share on other sites More sharing options...
handmadematt Posted December 19, 2012 Author Report Share Posted December 19, 2012 Each to their own. I NEVER let any of my bikes tick over because i have always found it causes them to gas up. The problem you suggest might be due to fuel evaporation especially as it's more prone when hot or after the engine has stood a bit. If i want to get the engine up to temp just keep bliping the throttle then again what do i know eh? As long as you're happy. What do you mean "gas up?" An overfull float bowl causes rich running (and flooding). The needle in the slide controls the mixture over the middle half of throttle opening. Try this for some advice http://sterlingmotor...tor_tuning_tips This might well be my problem then... It's funny that it would be out of whack though. I'll see how I get on with giving lots of air on start up. When running I'm getting a nice biscuit colour plug so I don't think my mixture is to rich. Quote Link to comment Share on other sites More sharing options...
woody Posted December 19, 2012 Report Share Posted December 19, 2012 (edited) What carburettor is it as you mention a choke lever and the original Amal fitted to the Cota doesn't have one, they have a 'tickler' to flood the carb to help cold starting. If it is fitted with a Mikuni which is a popular conversion, they are buggers for flooding and yes it will affect starting if too much fuel is leaking from the carb down the intake when warm (despite the overflow that lets fuel escape) If it is a Mikuni and it doesn't have one fitted already, swap the float needle for one with a rubber tip to get a better seal when the float height should shut the supply of fuel off. You can get them from Allens. PS - I really wouldn't hold a naked flame over the plug hole to burn off fuel. Bikes have been set on fire simply by the spark from the plug when checking for a spark. Holding a naked flame over the plug hole with all that vapour is a huge risk - add to that possible leakage from the alloy tank due to age and stress related related cracks.... Your flirtation with 2-strokes could be a brief one if you hold to that practise... Edited December 19, 2012 by woody Quote Link to comment Share on other sites More sharing options...
old trials fanatic Posted December 19, 2012 Report Share Posted December 19, 2012 (edited) What do you mean "gas up?" When a 2 stroke is run but not under load the mixture in the crankcase dosent get fully forced into the combustion chamber via the transfer port and some remains in the crankcase. The air fuel mixture then gets very rich and droplets stay in the crankcase causing the motor to 4 stroke, also happens on the overrun if you dont occaisionally blip the throttle, this then often olis the plug or at least causes the motor to be very hesitant when opened up again.Two strokes like being used on 1/4 plus throttle openings and benifit from occaisionally being revved out. Dont expect a 2 stroke to behave like a 4 stroke. Well that is what i've found over the years. Re the carb if yours is an Amal concentric and has a choke lever then it is probably a Mk 1 1/2 , i have one fitted to my James, which came without a tickler but instead had a choke or more correctly an enrichening lever. If it is a mikuni as Woody says they are very prone to flooding especially if the bike is facing downhill. I have one fitted to an Ossa and it regularly floods when going downhill or off drop offs. BTW be careful you dont break anything on the Montesa as spares are quite hard to come by. Edited December 19, 2012 by old trials fanatic Quote Link to comment Share on other sites More sharing options...
handmadematt Posted December 19, 2012 Author Report Share Posted December 19, 2012 What carburettor is it? It's the Mikuni. If it is... swap the float needle for one with a rubber tip to get a better seal. Once I'm more familiar with the bike I'll decide whether it's still a problem and might go down this route. PS - Holding a naked flame over the plug hole with all that vapour is a huge risk... Fair point. Thanks. Dont expect a 2 stroke to behave like a 4 stroke. Well that is what i've found over the years. I really do appreciate the advice. Cheers mate. BTW be careful you dont break anything on the Montesa as spares are quite hard to come by. You're right about preserving the bike, parts aren't so cheap but I went to visit the chaps at "In Motion" (I live locally) Who supply lots of twinshock parts. Nice guys with a good set up. They have plenty, shelves and shelves of Montesa parts and the 247's are easier to source parts for than say the 123cc. Dave said that as long as my bike is mostly complete they have enough to keep me running. Before I bought it the bike's just had new piston and rings with a rebore. New clutch plates and cable, new brake shoes, crank seals, sprockets, wheel bearings, coil, points and condensor (and now plug.) So I'm in good stead! Quote Link to comment Share on other sites More sharing options...
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