A forum for owners of Yamaha TTR250 trail and enduro bikes!

Dave · Veteran Member

Cold Starting Issue

Lin · Senior Member

How long since it's had a new spark plug?

TTRfan · Super Guru

Also starting can be affected if the valve clearances are out.

Assuming air filter clean and petrol good.

Brian

PS Welcome to the forum biggrin

Dave · Veteran Member

Cheers for the suggestions guys.

I have checked the air filter this morning, all looks clean to me and the petrol is new as I only filled up on Sunday.

Regarding the spark plug, I haven't changed it since I bought the bike a few months ago, but when I went to inspect it there is quite a bit of dirt & small stones around the opening so I don't want to take the plug out and risk all the dirt falling in the hole when the plug is out - any tips for clearing this out as I don't have access to compressed air!

thanks

Lin · Senior Member

Compressed air is the only way I know of dealing with that. Anyone got an idea?

Cubber · Super Guru

I just poked mine with a small screwdriver (oo-er) wink and flicked the debris out as best I could before blowing. There are small drain holes in the base that should allow water to drain out between the fins.

To prevent crud filling this area after I had cleared it I cut a big wad of sponge and fitted it over the plug and into the void before fitting the plug cap and lead. This prevents the void from filling crud and seems to work. aww

Martyn

Dullthud · Veteran Member

I use a foot pump with one of the little conical attachments that they sometimes come with. Not sure what they're meant to be for. Maybe they are for blowing shate out of the spark plug recess on motorbikes.

I have to pump it by hand balanced on my leg as the pipe's not long enough. Thinking about it I also have an upright bicycle pump that has a really long pipe. That would be perfect but it isn't down the lockup.

Andy

TTRfan · Super Guru

Scratch around best you can and hose it out. When plug is about half way out, hose it out again and mop up any surplus water.

Dave · Veteran Member

Update - A mate has compressed air at work, so I'm headed there tonight to blow out the remnants of the Peak District from the engine. I also have a new plug, so I will fit it tonight and see if the starting problem persists tomorrow morning.

Dave · Veteran Member

I've installed the new spark plug and it started up in roughly a third of the time it was taking before, but it still doesn't feel 100% right. Rather than just turning the motor over until it starts, I've found that trying to start with the throttle cracked a touch for a couple of seconds then repeating until it starts makes it easier. It took around four iterations of this to get the engine started this morning.

Should I be looking at getting the carb cleaned?

TTRfan · Super Guru

Twisting the throttle probably pumps some fuel in from the accelerator pump which makes me think that maybe the choke tube is blocked or the choke not operating properly? Simple enough to get it out to check.

Brian

Lin · Senior Member

The carb's accelerator pump only works after the throttle is more than about 40% open. So try a couple of full open twists before you crank it. If it starts easily following that then I'd suggest lack of proper choke function as Brian suggests, so unscrew it and see that it's working correctly.

Dirty carb symptoms would usually include unstable idle, flat spots, surging at part throttle etc.

TTRMike · Veteran Member

A cheap way to get compressed air is a garden sprayer, the type with the pump on. Usually get one for under thirty quid. I have used a tyre in the past with a pipe from the valve.
I've had similar starting proplems on one of my old bikes and it turned out to be the valve clearances (was a 16 valve bike too confuse ).

I always drain the carb if I think my bike isn't going to get used for a few weeks. Unleaded has a short shelf life and seems to degrade quickly in the carb. If it is the fuel it will usually smoke quite badly when you first get started,

Dave · Veteran Member

This morning, from stone cold, I pulled the choke out fully, petrol on, ignition on, then two full twists of throttle, holding each for one second fully open. Pressed the starter and it fired up first time.

It must be the choke!

Edit - I have got the choke out and the plunger is slightly bent, which I think is the root cause of this.

Does anyone have a choke for sale before I phone Yamaha?

Cheers

-- Edited by Dave on Thursday 6th of October 2011 02:07:30 PM

TTRMike · Veteran Member

Where are you Dave? Might have something in my 'That might come in' box wink

Dave · Veteran Member

I'm in Manchester if you have a choke Mike!

TTRMike · Veteran Member

I'll have a look and let you know tomorrow Dave

TTRMike · Veteran Member

Have located a choke Dave. If you pm me your address I'll pop it in the post next week.

Dave · Veteran Member

Thankyou Mike, that's very kind of you.

I've PM'd my address to you.

Dave · Veteran Member

Thanks very much Mike - the choke was lying on the doormat when I got in this morning.

I've just been looking at fitting it, but I can't seem to get a spanner in to unscrew the choke - do I need to take the carb out to gain access, or is there a method I haven't thought of?

EDIT - I "altered" (blow torch and file) an open ended spanner to form an offset wrench to gain access to the choke. Choke is now fitted and the engine started first time!

-- Edited by Dave on Sunday 16th of October 2011 03:55:23 PM

TTRMike · Veteran Member

Sorry for slow reply Dave. Glad the choke found you ok. Has it cured the problem?

Dave · Veteran Member

It is starting better than before, but it still doesn't seem 100%. I've just tried it from cold (ie not been used for few days) and it still needs a turn of throttle or two with the engine off before it will fire up.

TTRfan · Super Guru

Low float level?

I had a problem starting a bike because of this but I was lazy and discovered that if I leant the bike over until petrol ran out of the overflow, then upright it, and it would then start easily wink

Worth a try as it may identify the problem.

Sometimes closing the plug gap to just a tad less than recommended will aid starting and not affect the overall performance.

Brian

TTRMike · Veteran Member

I agree Brian, if the carb is all clean its the most likely option.

Only other I can think of is valve clearances but I doubt the twist of the throttle would help if this was the case confuse

Lin · Senior Member

I'd agree and check the valve clearances if all else fails. Tight clearances lower intake vacuum at cranking speed and the engine won't pull fuel through the choke circuit. So a couple of full twists on the throttle overcome the fuel delivery issue and it will start...

-- Edited by Lin on Tuesday 25th of October 2011 09:58:41 PM

Dave · Veteran Member

Last night I left the petrol on (I usually turn it off) and it started first time this morning. I tried again just now when I got in from work and again it started first push of the button!

Do you guys turn the petrol off, or leave it on?

I haven't had chance to check the carb/float level yet but will have a look at the weekend just to be sure.

Cubber · Super Guru

I generally turn the petrol OFF when I put the bike away last thing.

I have noticed that mine will start readily but soon stops, before the float bowl empties, if I forget to turn the petrol on. evileye

I endeavour to turn it on as soon as I'm getting kitted up to go for a ride and don't usually have any starting problems. I'm intrigued by the responses so far. confuse

Martyn

TTRfan · Super Guru

I tend to leave my petrol on - just through laziness I think cry

If you usually switch your petrol off then the float bowl would only empty in the space of a few days if there was a leak - however small.

Brian

TTRMike · Veteran Member

I usually turn my fuel off. If I know the bike is going to stand for a few weeks I run for a few minutes when the fuel has been turned off. This is because with every Yam I've had, the fuel goes off quite quickly in the carb. This either causes a starting problem or a lot of smoke. Usually only takes 30 seconds or less for the carb to fill enough to run though. Maybe the float valve is a bit sticky confuse .

shenglu · Newbie

If it starts easily, the following words, I would suggest a lack of proper function of the reactor, Brian suggested, so unscrew it and see it work.

TTRed · Veteran Member

Dave, did you eventually find a definite reason/cure for this starting problem?