Need some help with a stock 150cc 1965 original engine. Issue is as follows:
Engine hard to kick start. Taking 4-5 kicks and a few 'false starts' before the kick that gets it to turn over but never quite catches. I pull the plug assuming flooding but it looks suspiciously dry. I check for spark on the fins - all good. Pour in a bit more petrol and move the tap off the reserve and voila - success in 5 kicks. Idles fine once running. Did a little carb tweaking (mix screw set at 1 turn, idle 2 1/4 turn) and got a clean rev and stable idle. Left to warm for 10 mins and then went for a spin around the block to check all good. Went well - bogged and almost stalled on an uphill section but caught it. Stalled on a flat section where I came off the throttle. FYI Went about 3 miles. Worth mentioning that once warmed, the engine was kicking first time so I assumed all good.
Pulled the plug and looked decent - a little black, not choc yet but was idling for ages and only a short 5 min blast at best, most a 1/2-3/4 throttle. Running a 2% mix. I assumed it needed some fine tuning, went and did some other things and came back later in the afternoon.
Bloody hard work to get it to start again. 6-7 kicks and the it would begin to grumble and then fired away. Gave throttle a blip to check things, bogged, stalled and could I get it started again? Nope. Strange, nothing changed. Checked for spark again - all good.
Reset carb back to 2 1/2 and 1 1/2 turns (http://www.vespamaintenance.com/fuel/carbtune/). Kick, kick, kick. Nothing. I pull spark plug and its black and sooty from a rich condition.
Eventually get it running with the choke after a lot of kicks. Notice here the absence of any flooding? Im regularly pulling the plug, kicking over with it out and putting it back in as I assumed it would be... Leave it to idle and warm up, tweak carb a little again but leave it at 1 1/4 turn air mix, 2 1/4 turn idle to allow for a little extra air. Again, stable idle and revving cleanly.
Drive through the gears for about 1 mile and as I go down a hill the engine bogs and stalls. Won't restart. Im at the side of the road for the next hour trying to get it to go.
Here's the weird bit - Im kicking it enough times that I'm thinking this is going to be flooded. So I kick no more than 10 times at a go, then pull the plug. It's dry... hmm... I slacken off the fuel line from the carb and no residual fuel comes out. I reattach the fuel line and give it a squeeze down the length of it and wiggle it a little. Kick a few more times, get a grumble, manage to catch it with choke (I've reset the carb to 2 1/2 and 1 1/2 turns again by this point I've been here this long - also tried the fully wound idle and 1 3/4 air mix to no avail). However it idles lazily and unreliably then stalls. I pull the plug and its now wet and oily. I give it a good clean down and stick it back in (didn't have a spare on me frustratingly). I pull the fuel line again at the carb and this time I get some residual fuel spillage. Hmm.
I decide to kick the machine with the air filter off and look for spray. Can't see anything - should I be able to see spray onto the slide when I kick it? I also have never seen any spray out the spark plug hole when Im kicking without the plug in - should I?
I'm thinking this is a fuelling issue...
Been sat in a garage for last 10 years by previous owner, adding only 20 mile onto the clock since then. He has regularly dropped fluids and turned over the engine. Thats what I'm working with.
Taken the original SI 20/17 C carb off and realised I couldn't get the correct size jetting anymore. So I have purchased a new SPACO 20/17 D and switched jets to match the stock 150 VBB settings as per scooterlounge.
Setup is this:
- SI 20/17 D
Prior to this mornings events, I had done the following:
Compression 120psi, kicked it a few times and got a consistent number.
Dropped the gear oil, looks fine and no smell of oil.
Im reasonably content the spark is present and in attendance.
Pulled the fuel tank, fiddled and cleaned out the petcock. Interestingly it was full of rubbish and grey gunk and previous owner had over-tightened it causing the tap to be stiff to turn and tearing the rubber. The fuel filter on the petcock looks in shoddy shape as well tbh but couldn't get a hold of a new one today so popped it all back in on a hope and prayer given the tank internally is in good nick, fresh fuel and the carb was brand new with a view to doing it later this week.
Before connecting fuel hose to carb, checked petcock works in all three positions - no fuel at off, dribble at on, slightly less dribble on reserve. New gasket on airbox, new carb gasket (and carb) and everything torqued correctly to 15nm.
Fuel hose is reasonably new by previous owner, 600mm end to end.
Petrol is fresh, 2% mix of putoline classic.
My legs knackered from all the kicking today - really hoping one of you lovely folk give me some pointers where you think it might be going wrong for me/something obvious I've missed.
My thoughts at this stage are that it is an intermittent fuel starvation issue. Im suspecting that petcock - I stupidly forgot to blast the breather hose and dismantle the actual filter itself. If there is debris in either, that guess that may cause the fuel starvation issue. Hoping therefore that a new petcock will resolve it.
If its not that - any insights from anyone?!