HONDA 1989 CR250 CHEWING PLUGS

[Mick D]

I have been working on this bike.
It goes like stink!
Starts all day long, no worries.
We bring it home.
Lay it up, for a week.
And it just won’t start.
Wet plug?
We put a fresh plug in it, and away it goes, all day long again ?
Why does it need a new plug after a week lay up?
I know there is a lot of clever people on this forum, and I am stumped, I hate to say it? but as Ned would say, this is becoming a real noodle scracher?
Grateful for any suggestions, or help.   

[bazza]

Could be shit fuel alot of the blended fuel only last a month. Are you using NGK? not champion!!!

[southnztim]

What fuel and oil are you using? I had the same problem. The oil was separating from the the fuel after a period of time, so when you tried starting after a spell, it instantly oiled the plug. I changed the oil I use and that solved the problem.
Cheers, Tim.

[shorelinemc]

when you go to srart the bike after it has sat for a week ,drain the float bowl before starting.CD250 hondas leave a couple weeks wont atart ,drain carb starts straight away dont know why have had a few of them thru the shop all have done the same thing cb250  same thing

[monaro308]

Just a silly thought,before your next ride pull your plug out and check your plug for any water/moisture ie a leaking head gasket ...you never know.

[LWC82PE]

the reason this happens is because of the high volatiles that go off/stale quickly in premium unleaded. Thats all it is. Either drain the carb at end of ride or before you start the next ride a week or so later. Its just a side effect of the higher octance premuim unleaded thats all.

[Lozza]

if the dead plug is grounded out of the cylinder does it make spark?Do the old plugs show any tracking between centre and ground electrodes?

[Mick D]

Lots of great ideas and advise there, thanks everybody. I will have a closer look and get back during the week. Thanks, Mick.

[EML]

Mick-De, I spoke to Caltex help line last week re the same trouble we have with the Wasp. They told me that their fuel-Vortex- doesn't ''go off'' and will store for ever-in steel tanks!! when he asked about the tank and I told hin it was FRP he said the fuel will leech polymers from the tank walls and that these will not burn well. Best to drain the tank after use-that is if it is plastic.
The thing is that once the shit gets onto the plug, it wont come off like carbon, no matter what you do you have to chuck it away and we have thrown plenty out in the last year or so.

[Mick D]

Thanks, I didn’t realise so many had answered thankyou. I will read them now.
BUT FIRST;
Have carby here right now. We have stripped it and found that some one put blue Silastic on float bowl joint, which had then blocked the pilot jet. All cleaned up now, But we have no manual. Keihin Carby.

NEED HELP WITH FLOAT LEVEL ADJUSTMENT SETTING;
   

 

[dalesween]

Is it a leaking fuel tap? A leaking tap can fill the cases with premix over the layoff and next time you try and start the bike get a wet plug in no time.

[Mick D]

Thanks Dale, he says it was very smokey last time he started it. so we will look in to that. Cheers.

But the main thing now is how to set the float level. 

[Mick D]

Mick-De, I spoke to Caltex help line last week re the same trouble we have with the Wasp. They told me that their fuel-Vortex- doesn't ''go off'' and will store for ever-in steel tanks!! when he asked about the tank and I told hin it was FRP he said the fuel will leech polymers from the tank walls and that these will not burn well. Best to drain the tank after use-that is if it is plastic.
The thing is that once the shit gets onto the plug, it wont come off like carbon, no matter what you do you have to chuck it away and we have thrown plenty out in the last year or so.

I THINK THERE IS A HELL OF A LOT TO BE LEARNT FROM EMLs POST, AND NOT ONLY FOR ME.

I never queried the old plastic tank with modern fuel phenomenon, until now, that with the help of EMLs post, the penny has dropped.

I know that if modern 98 RON fuels are left in a vented tanks they will gas of their potency quickly.
I know that if they are sealed in full steel jerry cans they keep very well.
I always run my bikes out and drain tanks immediately, then rid my self quickly of the left overs through the "Guzzlerdore".
I always start my bikes next time with fresh fuel, and I don't have problems with my bikes or plugs(the problematic CR250 belongs to someone else).

But, the penny has dropped. It is highly likely that this thing about leeching polymers out of plastic tanks explains the ongoing problem I am having with my Yamaha two stroke outboard chewing plugs.

I once ran 2/S outboards, with METAL tanks. I put phenominal hours on them without ever chewing plugs.

But, my current 2/S Yamaha outboard. Plastics tanks. I use after market plastic reserve tanks and plastic jerry cans for additional camping fuel. I am lucky to get a few hours of combined use, before I become frustrated with unhappy idling again. I replace plugs, all is well again, but not for long.

The Yammie outboard is a great product, But this plug chewing thing has been irritating me for ages. I am now going to rid myself of all the plastic. Then see if a new set of plugs will have a lasting harmonic idle.

Thanks EML, I will let you know what happens.
And thanks to everyone else, for all the good ideas and advise.

[TT5 Matt]

good read about plastic tanks and polymers so does the leeching weaken/effect the tank

[oldskool]

thanx eml my cr 125 was doing the same thing.when i first bought it it ran fine for a couple of weeks on ethanol blend then changed to bp98 ran great all day take home put in shed week later bit hard to start ride for 10 mins plug would foul put in new plug go hard all day till next ride a week later same thing the only thing i changed was the fuel,and after reading this i think i now know what the problem is.its an 87 cr so has plastic tank and my fuel drum is also plastic.thanx gary