We finally got one last nice day to ride and last night I could not get the bike running. I have not riden the bike for a week. It has plenty of fuel, stabil in the mixture and has been stored in my garage.

A couple of times while I was cranking it over to start the engine back fired. One back fire was significant to blow a hole (increase the size of the hole) in the side of my muffler. I was thinking I had flooded the bike and let it sit for 10-20 minutes. The next time I tried to start it another rather loud back fire.

Any thoughts as to my issue, as you can tell I am not a mechanic.


Thanks

I had something similar a couple days ago. Those backfires are a pretty good way to diagnose the presence of raw gas in the exhaust. With it there, there is a good chance that the spark plugs are fouled.

I put a set of new plugs in and the bike started right back up.

I probably fouled the plugs by adding too much gas with the throttle while starting.

+1! Throw some new plugs in it and she should fire right up. If you want to check the bad plug issue, spray starting fluid in the box and see if she will light up. It will either clean up the plugs and run or prove they need to be replaced!

I'm having exactly the same problem right now. Plugs don't seem to be corroded, but they're coated back. Bike will turn over, but won't catch, and I got a couple of unholy backfires but that's about it out of her. I'm going to replace the plugs on Saturday to see if she'll catch.

What plugs are you running?

I had a lot of problems with the stock plugs. The bike would fire up and then drop a clynder and run like crap. It wouldn't clear up until it warmed up and I reved the crap out of it. I went up(?) 1 heat range on the plugs and she runs like a champ every time and starts easier.

A note on reading spark plugs.

If they are very light then it is running lean.
If they are tan/dark brown then they are about right.
If they are dark dark brown or sooty then it is running rich.

All 4 plugs should be about the same colour. If they are not then 1 or more cylanders is running differently than the rest. This means you should do carb balance. If this isn't the problem then perhaps a compression test or an electrics test.

Now - this is a slightly special case. What you read from the plugs is how the engine performing when it was last used - not the history of the motor. Meaning you can change the colour of your plugs by running it wide open or by running slow with the choke on.

Really dirty plugs won't spark as well. Fuel won't burn as well meaning they get dirtier. Cleaning the plugs might give you enough spark to start. However, you have to wonder if the bad start was all that cased the fouling - probably not. You are probably running rich and having been slowly fouling them for awhile.

A cold engine with a weak spark is very hard to start - a warm engine with a weak spark will start more easily. Meaning it might have got the point of no return a few weeks ago but the cooler weather and sitting awhile was the straw that broke the camels back.



Recommendations:

Clean the plugs and see if will start.

If not purchase a fresh set of spark plugs - they're cheap and it's probably time for a new set anyhow. I put new ones in once a year. I keep the old ones for emergancy use for one year in my travel kit.

If you get it running take it for a proper run. When the engine is cool enough to work on remove the plugs and inspect them. If they are black then it is time for carb work. You are likely too rich.

If you can't get it running - then start checking all other things - like charging the battery, checking the wiring, checking the fuel, empting the float bowls, and finally as a last resort using starting spray. (I personally fear starting spray - it isn't a tool for everyday use...)

Anyhow - good luck - see what tommorow brings.

Woot.


( One hundredth post !!! :))

congorats woot! :P

>bows< Thank you all

:D

I just had a similar situation. A couple of months ago I lucked into a really nice XJ650RJ Seca. I've been dying to get on the road. It takes ages to get liscenced here in Jersey!

When I got the bike, it purred like the proverbial kitten. It always started on the first crank and idled very smoothly.

Every few days, I would go out to the garage and sit on it and generally play with it in anticipation. This would usually involve firing it up for a moment.

A few weeks ago, I discovered that there was gas blowing out of the ptecock. Nothing serious. I got a rebuild kit off of eBay and installed it in about 10 minutes.

Naturally, the bike would no longer start. This puzzled me because it had been running fine. The only change was the petcock. I verified that the carbs were getting fuel, but I just couldn't get it started.

After reading the posts above, I decided to check the plugs. Not exactly sure why that hadn't occured to me before. They were terrible. Completely black and covered with carbon.

I replaced them and the bike started, literaly, on the first crank. I went for about a 5 mile ride and it just ran great.

Tonight, I'm going to pull the new plugs and see how they look.

I have a theory as to how they may have gotten so bad so quickly. I had been starting the bike regularly and letting it idle. During this time, the choke was usually open. If I'm not mistaken (and I could easily be) that would make it run rich. Do you guys think that could account for the plug condition or do you thinik it's just generally running rich?

I also noticed something else. After riding for a while, when the bike is shut off, the right pipe smokes a little. Is this anything to be concerned about? I do think that there may be too much oil in the bike. I'm going to drain it tonight and get it right. Could that account for the smoke?

Thanks!

Greg

Yup - the worst thing you can do to a bike besides not storing it properly is to start it frequently and do nothing... if you are going to start a bike ride it - something to properly warm it up... Now I realize sometimes this can't be helped like running down to the grocery store and getting a jug of milk but you can avoid the starting it up to hear it run game.

A carb'ed bike is setup to run it's best at road RPM's. If you idle alot you'll see your plugs change colour - in your case dark and fouled from running rich. If you ride your bike frequently at road RPM's and find the plugs discolour then it is a sign that carb maintainance is in order. It's not too hard and will usually improve fuel milage and responsiveness.

As for the smoke - it is very likely water. This is your bike telling you to go out onto a twisty road and run 2 tanks of gas through it as quickly as possible. :) When a bike is properly warmed up all of the water will evaporate and be blown out. If you just start your bike for short rides the condensation will not all evaporate and will be seen as steam when you stop.

Go ride your bike you lucky devil!

Thanks Woot! You are the man. I now see the err in my foolish ways. I guess I just let my complete and total lack of patience get the best of me!

Glad to hear that the smoke (or or perhas steam!) isn't anything to worry about. It was also very cold last night which, I'm guessing, could account for some condensation.

I guess I'm just going to have to get out and do some riding! I hate when I get forced into these kinds of things!

Thanks again,

Greg

LOL - :) - It's painful to have to put some miles on... :)

I've been helping my dad build so I haven't finished my oil change (have to remove filter and reseat the big o-ring as it's leaking)

A stupid question, but one I need an answer to!

I pulled the plugs out of my bike and they are fouled (carbon coated). I am guilty of running the bike with the choke open longer than needed (bad memory until the bike reminds me). I am guessing this would cause the mixture to be rich.

Now the stupid question:

Are the plugs in a bike the same as a car?

Sorry, but I need to know!

They are the same so far as the head size and that they spark - however - you will notice on the plugs a code. This code has a manufacture id and other specifics hidden in it.

I don't have a plug near me right now but I seem to remember NGK BP7s or something like that... the point being is that if you take a plug out and write the info down (or take the yamaha book with you) and go to a store (such as canadian tire) you will be able to get replacement ones the same as you took out.

Spark plugs have a number of variables - the length that they reach into the head is very significant. Get too long a plug and you can ram the piston into them. This isn't good. :) The tempature of the spark plug. This will effect predetionation ( pinging) -- reasoning through on this one too hot would cause early ignition too cool would cause incomplete or late burning (WAG!!!). Some plugs also have resistors which we don't need as our ignition system has the resistance built in.

Other features such as split fire etc are for us just gimics as far as I can tell.

If it helps. My bike had NGK BP7ES plugs in it. I went to Pep Boys and got four news ones for about $8. They seem to be pretty common.


Greg

Thanks,

I will take one of the plugs with me when I buy the new ones.

Those are the ones I use - completely from memory - forgot the E - not bad eh? ;)

Spark plug code=NGK bp7es
B=thread diameter 14mm
P=projected insulator type
7=heat range (2hotter-11colder)
E=(mc2 :P )19mm thread reach
S=standard 2.5mmo center elctrode

There are variations for platinum/iridium plugs that would end in a bp7eix.