New 185cc engine won't start or run

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johnny650
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Wed Jul 18, 2018 11:27 pm

I fitted a new 185cc engine today and tonight it started second kick and revved really strongly right up to WOT when I blipped the throttle a few times . It sounded perfect so I switched off and got ready to take it for a shake down run ....Since then it has not started even once after nearly half an hour of kicking although it has occasionally coughed and spluttered like it wanted to start.

The engine seems to be starved of fuel yet everything seem to check out ok. Even with choke fully on and using Easy Start in the carb mouth the engine still refuses to start. The plug is not even getting wet like you would expect it would be after using the choke for 20 minutes.

Its as if the engine isn't creating a vacuum to draw fuel from the carburettor because there is a leak somewhere

I have noticed that there is a very small leak from the joint between the crankcase and engine at the base gasket. Its a thin oil and petrol mix ? There is also a very slight smear of oil and petrol mixed on the spark plug electrode.

The only thing I can think of now is one of the new oil seals have failed .. I'm not sure how this might effect starting and running .
The previous engine was a new 200cc small block which had really high compression . It was so high that I could stand on the kick start and sometimes even 17 stone wasn't enough to turn it over. It ran for a few miles but it gradually deteriorated and then the next day refused to start at all which is why I replaced the engine with a 185cc that I knew was sound.

Could the high compression have blown an oil seal ? ................if it has how might a blown oil seal effect the engine ? , bearing in mind that this new 185cc engine has only actually run for a total of 20 seconds since fitting earlier today

There is 600ml per minute flow rate from the tank .
Timing is spot on, triple checked points gap and advance is 19 degrees.
Spark at the plug appears strong and consistant.

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garry inglis
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Thu Jul 19, 2018 5:52 am

Check earth and stater connected in headset check wires haven't come out

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mick1
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Thu Jul 19, 2018 7:08 am

A leak test should identify any blown seals or gaskets.......

Daggs
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Thu Jul 19, 2018 7:59 am

Kick the scooter over (not literally) with your hand on the open mouth of the carb. You should feel suction. If not, your blown (or wrongly fitted) seal thought could be the answer.
The leak at the base gasket is concerning. ( I have experienced two Mugello's blowing the base gasket after less than a thousand miles. It's due to the poor matching of cylinder base/crankcase mouth which can result in a very thin strip of gasket in contact) However, I don't believe this would create your starting problem.

johnny650
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Thu Jul 19, 2018 9:40 am

Daggs wrote:
Thu Jul 19, 2018 7:59 am
Kick the scooter over (not literally) with your hand on the open mouth of the carb. You should feel suction. If not, your blown (or wrongly fitted) seal thought could be the answer.
The leak at the base gasket is concerning. ( I have experienced two Mugello's blowing the base gasket after less than a thousand miles. It's due to the poor matching of cylinder base/crankcase mouth which can result in a very thin strip of gasket in contact) However, I don't believe this would create your starting problem.
Thanks for the advice guys its really helpful. It shows me how exhausted I am with this that It didn't even occur to me last night to test the suction by putting my hand over the carb mouth doh... thanks for that Daggs . Your comment about the Mugellos is very worrying to me . The crankcase is an unknown. I aquired it off ebay so i have no way of knowing if the mouth is out of true and needs machining . I lapped it best I could but didn't test it for square with a piece of sheet aluminium and some Engineers blue .

When I stripped off the 200cc cylinder there was evidence of a slight oil leak but it must be very slight as it had mixed with the fuel and was a very thin smear on surfaces. I cannot believe that such a tiny amount of oil could effect starting either .it would just smoke a little

I know that there has to be something seriously amiss if an engine won't start with Easy Start and a well timed spark. The only thing that makes sense is a leak in the crankcase ......

The prospect of having to completely strip the engine and half the gearbox again to find and cure a seal leak is filling me with dread this morning. I so wanted to get on the damn thing and just ride it . Its been nearly 2 weeks of fecking about now and a whole stack of other pressing jobs are stacking up . I'm so close to just dumping it back in the shed and leaving it to next Winter to sort.

I'll make a troubleshooting sequence this morning and work out a way of pressurizing the crankcase with an old inner tube . I have a DIY smoke tester and tyre compressor I use on the car so i might try that.

Thanks for all your support everyone ...I really need it just now . I'm so close to giving up and thats not like me at all. :(

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Doom Patrol
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Thu Jul 19, 2018 11:55 am

What exhaust are you using? I only ask because I had a standard exhaust fitted on a Casa 185 kit and had trouble drawing fuel.

johnny650
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Thu Jul 19, 2018 1:25 pm

Hi DP. I have an untested 42mm AF Clubman fitted which I bought used off ebay. It doesn't appear blocked and was tested for a few miles with the 200cc engine fitted last week.

Did your problem get resolved just by fitting a larger bore exhaust ?

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Doom Patrol
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Thu Jul 19, 2018 5:29 pm

Basically yes. It was a standard exhaust, bear in mind. The back pressure must have been phenomenal, and although I can't say for sure, my theory was that it was somehow preventing the flow of fuel. And fitting a Clubman exhaust did cure it too. It was just a thought really. Nothing scientific.

johnny650
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Thu Jul 19, 2018 10:05 pm

Doom Patrol wrote:
Thu Jul 19, 2018 5:29 pm
It was just a thought really. Nothing scientific.
well i'll take any advice going at the moment as I still cannot get this engine to start and run tonight...

today I
Emptied the tank and replace with fresh fuel
Replaced the inline fuel filter.
Removed , stripped and cleaned the HiFlo fuel tap and filter.
Adjusted the points closer to 4mm
Removed flywheel & adjusted advance to 17 degrees (no oil leak from seal evident)
Checked the choke valve was seating and returning.

Kicked it over and no start. With full throttle and choke it did cough once or twice like it was trying to start but didn't . had to abandon at 8pm for the sake of the neighbours :D

I have ordered a new condenser and ignition coil as I do not have any spare tested ones .

Tomorrow I'll check all the ignition wiring and the headset and ignition switch .
I may also swop the manifold and exhaust to the original 38mm standard box just for the hell of it.

I'm really running out of ideas now ......there still doesn't seem to be sufficient fuel getting through to the engine . The spark plug and carb should have been flooded with fuel after 20 kicks or so but they wern't ??

Muppet
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Thu Jul 19, 2018 10:07 pm

johnny650 wrote:
Thu Jul 19, 2018 10:05 pm
Doom Patrol wrote:
Thu Jul 19, 2018 5:29 pm
It was just a thought really. Nothing scientific.
well i'll take any advice going at the moment as I still cannot get this engine to start and run tonight...

today I
Emptied the tank and replace with fresh fuel
Replaced the inline fuel filter.
Removed , stripped and cleaned the HiFlo fuel tap and filter.
Adjusted the points closer to 4mm
Removed flywheel & adjusted advance to 17 degrees (no oil leak from seal evident)
Checked the choke valve was seating and returning.

Kicked it over and no start. With full throttle and choke it did cough once or twice like it was trying to start but didn't . had to abandon at 8pm for the sake of the neighbours :D

I have ordered a new condenser and ignition coil as I do not have any spare tested ones .

Tomorrow I'll check all the ignition wiring and the headset and ignition switch .
I may also swop the manifold and exhaust to the original 38mm standard box just for the hell of it.

I'm really running out of ideas now ......there still doesn't seem to be sufficient fuel getting through to the engine . The spark plug and carb should have been flooded with fuel after 20 kicks or so but they wern't ??
Adjusted the points closer to 4mm ?
im not a complete idiot
.
.
s me of the piec s are mis i g

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