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Struggling To Start The Bike But It Runs Ok?


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Right then a problem seems to have cropped up. When the bike (280 pro) is cold it's very very hard to start, sometimes impossible. When I check the plug it's dry and looks like it running on the lean side, if I put a bit of petty in the cylinder it starts right up and runs fine, when I turn it off it can be hit and miss if it starts again but a drop of fuel in head works? I've not had the bike long and it was like it had never been off road when I got it, the little yellow paint Mark on the gear oil filler had never been broken and the clock said it had only done 14 hours.

Now this is the thing and my worry. I put 80 ml of oil to 5 litres but don't ride 100% trials, I do jog about on it a bit but not to the point I'm screwing the bike and always use 5th 6 gears. I'm worried that I might not be using enough oil and that I might have worn the barrel and piston to where as it can't suck it's own fuel in on such a small stroke?

The carb is cleaned out thoroughly with spray and compressor, plug has a good spark, petty is fresh and I'm using fully synth putoline oil.

Have any of you lot got any ideas or do you think I should just take the cylinder off to inspect for wear?

Thanks again Richie.

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Wear is not likely if its not that much used.

I heard of a trick to put the bike on its side before trying to start, this would put some gas in the cilinder.

You use the choke? is it ok? have you cleaned it. Maybe bigger pilot/choke jet?

Edited by crazybond700
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Yeah mate I've had all the bits out of the carb and gave every component a spray and blow, all holes clear as far as I can see. I use the choke when cold and hot when it won't go, no matter how many kicks that plugs dry? I'm not clued up on jetting so I don't know.

Thanks for your reply.

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A couple of thing to try: New spark plug and gap it to 0.8mm, Check float height in carb is correct, Check flow from fuel tap.

It should start 1st or 2nd kick from cold unless it's been stood for a few weeks.

When cleaning carb, make sure you strip out the choke plunger and make sure choke circuit is clean.

Failing that a chipped reed or them not sealing properly can cause bad starting.

What year is the bike and what carb is it running?

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Is it really cold where you are? In cold weather fuel won't vaporize as easily in a cold engine and can require an even richer mixture. Strange as it sounds sometimes when I can't get an engine to fire cold I'll blow into the tank vent to pressurize the tank and pinch off and hold the line for a bit to force fuel into the engine. It seems to help though it could just be brain damage from gas fumes.

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The easiest way to start it without fixing anything is to lay it on the side with the bars touching the ground. Just a few seconds will do. When you pick it up, make sure a little fuel did leak out. It should start within two kicks. You never mentioned where you are from. So pilot circuit could be plugged. Or larger jets or the float level fixed. I started doing this years ago to bikes that sat too long. I usually would jump up and down on the bike if it was a newbie and add a few four letter words. It was always a good laugh when the bike would start the first kick after the owner had worn himself out trying to kick it to death.

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Try this . Don't use any throttle till it fires. Even when it's hot, if it won't start use the choke and no throttle, just knock the choke off as soon as it fires. Had the same problem with one of the kid's 125 pro racing. I did the float level and iridium plug etc to no avail but this routine sorted it out .

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Thanks for helping us out on this folks.

I live in North west England. Year of bike is 06, carb is dell orto, fuel screw 3 1/2 turns out, can't remember size of all jets but I know the main is 118, I have a 120 I could put in to make it run richer but would that make it start easier? The other week I stopped to move some barb wire (probs turned off for 30 seconds) and it wouldnt go when I tried to re-start it, kicked it till I was sweating bullets then put it in a nose wheelie almost vertical so petty was running out and it went first kick, tried that again on Sunday from cold start but had no luck that time. I've had the choke plunger out and it's all clear, I'm sure that's working because it runs lumpy if left on when running. I'll have some time to have another look tomorrow so I'll let you all know the size of pilot jet. How do you check fuel level in the carb?

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I had exactly same issue with a 300 and recked the kickstart and casing due to frantic kicking. Factor Kev at GasGas put me in the right direction and it was better.

Removed the carb and adjusted the floats by tipping them upside down and measured floats from carb base, cant remember if it was 10mm or 5mm.

Starting had to be from cold choke and no throttle. From warm no choke and some throttle. I think its due to lack of fuel from cold as i did the lay it down and flood it which sometimes worked.

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