My Bike Won't Start

[inanecathode]

My 81 TT500 was running great the other day, started on the first kick every time. I go to start it today, put on the choke, give it a good kick, it fires once. Never fired again.
I've had this problem again, and a new plug solved it. So i checked the plug, its covered in gasoline, and looks awfully carbony to be 50 miles old, i let it dry out and cranked it over a whole bunch to clear the flood, tried to start it again, and no dice.
Anyone have any ideas why i'm having trouble starting this thing? My first inclination is the plug is carbon fouled but how did it happen so quickly?
Do you think maybe it could be a weak ignition system too? How do i check for that?

Im so close to having this thing starting reliably i can taste it...
Rick g, resident old bike expert, you're (one of my) only hopes!

[h2olawyer]

Able to help you, Obi-Rick should.   ;D

H₂O

[Lucky]

it does sound like a weak ignition, explanes both the carbony wet plug & working only for a little while on a new plug.  also, you might need to lean it out a little..

[inanecathode]

What could be a cause of weak ignition?
Its got a new condensor and perfectly clean/gapped points?

[h2olawyer]

Coil, caps, plug wire.

H₂O

[Rick G]

Inane , the TT500 was a great bike to ride and a real POA to start! I would suggest that you try a spark plug, two ranges hotter, to start it, once its warmed up, you will need to change it back  to the original heat range, to ride it . If you forget to change it back, it will suffer sever degradation of the piston.
You can also try lowering the needle all the way down and since its so rich drop the pilot jet one or two sizes . MY XL350 was running pretty rich ,at small throttle openings, so I dropped the needle and checked the float level , that and the fact that I bobbed the rusted out spark arrestor  off, made it a joy to ride , with one kick starts hot or cold.
I have a friend (fancy that!)  ;D ;D here in Kingman who just sold his ( his back didn't like the effort required to start the thing)  He's a retired wrench like me , so I'll ask him how he had his set up. I'll try to report back tomorrow.
Also cut the last 3/8 of an inch from the plug wire and remove the resistor from the cap (if it has one ) I substitute a piece of brass brazing rod cut to the same dimensions, but a brass machine screw with the head cut off will do too.

[inanecathode]

Changing out plugs o_O?
Whats wrong with the one i have? Jetting you reckon? I might look at the spark plug wire and see if theres corrosion there.
I really dont want to play with hard settings like plugs and jets, it was running fine last week.
Hard to start, dont tell my bike that when its running good. Starts first kick every time most the time.

[Rick G]

Inane , hard to start race bikes were always warmed up on a hotter plug , it won't foul as easily . give it a try, it will help it light off so you can diagnose the problem further.

[Walt_M.]

If the insulator is black, the plug will not fire until you clean the carbon off. I used to get them sandblasted but I have recently tried soaking them in carb cleaner and that is working pretty well. Not sure why you are fouling them though except for too rich jetting. Once upon a time, I did see a main jet come loose and fall out. It would be worth a look.

[Rick G]

Word was in the 60's that sand blasting was bad , in that it stripped the glaze from the ceramic and promoted fouling, especially in two strokes, but also on 4 strokes , to a lesser  degree.

[Shop Rat]

I had a hard time with starting and warm-up on my Honda 4 until I tried going one step hotter. Then it lit right up from cold and ran on all 4 immediately. I looked at the plugs and found no signs of excess heat (all had nice tan insulators) so I've used them ever since.  And, they're the same plugs used in the Vision, so I can buy 6 at a time and never have to worry about mixing them up.  At my age, things like that are important.

FC

Changing out plugs o_O?
Whats wrong with the one i have? Jetting you reckon? I might look at the spark plug wire and see if theres corrosion there.
I really dont want to play with hard settings like plugs and jets, it was running fine last week.
Hard to start, dont tell my bike that when its running good. Starts first kick every time most the time.

[inanecathode]

Well i threw a new plug in it and it started right up, waddayaknow.
I also stripped back a section of wire, the end was lookin a little nasty.
I tried asking the parts kid at checkers which number refers to the heat range on an ngk plug and he just looked at me like a cow looks at an oncoming train. Which number is the heat range? The plug in question is a bp7es, i assume its the 7, but im not sure.
Rick, how do i jet this beasty? I'm pretty sure theres something wrong in the jetting, if you're not accelerating or decelerating it burbles pretty good, plus it doesnt like wfo in 5th. I've heard something about throttle chop tests but i dont know how to do one :o

[Night Vision]

7 is the heat range... D8EA on the vision is medium... 7 is hotter

plug chops: http://www.thumpertalk.com/forum/archive/index.php/t-538197.html

[Rick G]

D is the thread diameter= 12 mm, C is 10 mm B is 14 mm.  The letter E is 3/4  inch reach , (thread length) H is1/2  inch.  The number is heat range 6 being the hottest and 9 the coldest (there are others ,but there not commonly used.A DR8E is a  (resistor plug) .

There are DP8ES,  projected electrode (long nose) don't use them , it your bike isn't designed for them , they can burn a hole in a piston , especially in the hotter heat ranges, there really a car plug.
So a plug one step hotter than the 8 would be a 7, two steps would be a 6
Don't ask what the A is, I forget.  There's is also a D8ES  too , could be a plating on the plug?
The important parts are the reach and heat range , but its best to know how to read them.

To do a throttle chop run the bike as hard as it will go in 3rd or better yet 4 th gear and just as you shut the throttle kit the ignition, you will get an "imprint ' of the condition in the engine at that second. 
Before the powers that be , mandated that our gas be as volatile as Jacks Secret sauce , a proper plug reading was coco brown , bleached or yellowish was lean  and of course black was, as always to be avoided. Now a proper colour is light tan , it all changed in 1970/71 with the introduction of low lead and unleaded gas.