trouble running
 

so heres the short story.

i bought a wrecked bike from a friend. the bike sat for about a year after it was dropped. right now i have the front end off and ive been trying to tackle the running problems of the motor while waiting for fork seals to arrive.
before i did anything.....
the bike wouldnt start at all, it would just turn over. i took the tank off and started manually adding fuel in the line. got it to start with the choke on. so i put the tank back on and it would idle (very low, like 400rpm) with the choke on, but if you touched the choke or throttle AT ALL, it immediately dies. i maxed out the throttle adjustment and still only had a choked idle around 300 rpms

so i figured, carbs gotta be nasty. i pulled them off and followed the service manual and this sites versions of cleaning them out. even though it was pointless, the carbs had nothing in them. i put them back on the bike. hooked everything back up. and i obviously still have the same problem. only now if i hit the throttle very lightly and quickly let go, it will bog like its going to die, but then rev up once the throttle has been returned. so if i do light quick snaps quickly, i can get it to rev up however high i want, but the revs are only after throttle has been returned to 0%.

any ideas here? hopefully someone out there has some ideas

did you pay very specific attention and detail to the jets in the carbs? especially the idle jet, the one that cant be removed... did you run a small wire or guitar string up and down it several times?

how is your vacuum lines routed, are they in the correct factory posistion? they are very touchy as to how the bike will run.

are the spark plug wires in the correct firing order?

how do your spark plugs look? i imagine they are wet and black. is it backfiring and popping like crazy?

cleaned out the idle jets. vacuum lines are routed the same as i took them apart. if i have the idle adjuster all the way out, bike running on choke, it runs very smooth and clean at the rpms it should be running without the choke...it isnt making any sense to me right now. with the idle set out, even trying to touch the throttle kills it. i started trying to check out the fuel filter and pump. i pulled the filter and ran gas into it, and it came right out the other end. i put my thumb over the input of the pump, and intermittently felt suction. should it have constant suction? i wouldnt think the pump would be bad as my friend said he replaced it prior to the accident....

The pump is working properly, it isnt suppost to have a constant "suction". its a pulse style pump and gets a signal from the coils and ignitier box.
Member IDODIRT is a carb and fuel pump guru when it comes to out bikes. Just search some of his threads and he goes into detail on them all.

I say hands down its those carbs, Mike bike did the same thing to the T. would start with choke, warm up idle without choke then hit the throttle and it would die. I tore my carbs down and they were clean so i thought. Those jets are very tricky. i took mine all apart from each other and took every moving part off and soaked them in a parts washer for a half hour.
Then i used a air tip from my compressor to blow out everything to make sure they were clean. Put them all back together and bam ran good. Just have to sync them

ive been doing some more reading on an old thread. the guy that wrote the forum, (Dissevered) later started talking about the pilot jet. in his 28th post he stated....


"Oh and about the pilot screws, they effect idle and pretty much just initial throttle roll on. Jet needle effects mid range power, main jets effect upper rpm power. Technically, jets don't effect power, they effect air/fuel ratio. In a way I suppose it effects power because if you mess up the ratio, you will lose power.

You would need to adjust them equally. If nothing it wrong with your idle or roll on, then I wouldn't mess with them. "



is this what im looking at? because i tightened everything to the "abouts" of what they were when i took them off. and i know for a fact the pilot/slow jet was completely tight. and the main jet was completely tight against the needle jet. should either of these be tightened, and then backed back out?

Always do a compression test first.
If by chance your compression is low, you will never solve the idle problem with the carbs.
If you do you low compression, try adjusting the valves.

On my bike, the compression turned out good, the carbs were ok, the pump was ok, but all of my intake boots were original and the internal seals were ripped, causing a tiny undetectable vacuum issue, but it was enough to keep my bike from idling.

All new boots and $50 bucks later, my bike idles under 1000 rpm!

GOOD LUCK

if everything else was fine except my idle, i would consider buying new intake boots. but thats not the case. i can get it to run, and stay running smoothly, but its everything else. if i start to move the choke to off.....dies. if i touch the throttle......dies. but sometimes if i snap the throttle quickly, it will start to bog out, but then rev up. like its not able to compensate for the air with fuel.
the carbs have factory jets and needles. im a car guy. i bought this bike from a close friend because he made me a deal i couldnt refuse. so im new to the bike world, but i am mechanically inclined. never really done any carb work before tho. but are the slow jets supposed to have a hole all the way through like the main jet/needle jet? because mine dont. a hole goes halfway in and then stops from both ends, on all four slow jets....

i didnt mess with the "d" shaped pilot/slow jet adjusting screw at all. should i?

Did you get a chance to completely drain the gas tank and put fresh gas in?


I am sure you cleaned up everything from the gas tank, fuel lines, fuel petcock, carbs, etc. Since the bike won't start but only with the choke on, it just means you are not getting enough fuel without the choke. Your AFR is fked.

If you are sure there are no blocked fuel lines and the fuel delivery system is working great, then it has to be something with your carbs.

So clean everything again and double check that the fuel delivery is good. If they are and you can be sure that fuel is definitely reaching the carbs properly, then the carb is most likely failing in it's attempt to correctly/sufficiently provide fuel.

there was only about half a cup of gas in it. it didnt smell like turpentine, smelled like fresh gas. i did add about half a gallon on top of it when i first started messing around with it. uhm. im assuming all the jets are factory. the mains say factory and the slows are 40's.

thinking back to what someone else said....
"did you pay very specific attention and detail to the jets in the carbs? especially the idle jet, the one that cant be removed... did you run a small wire or guitar string up and down it several times?"

i thought the idle jet was the slow jet. i ran a guitar string in it as far as it would let me go...which was only go about 1/4 inch in. should it go all the way through? or is this the one my local tech said that everyone drills out?

Dumb thought but a maybe. Add more gas or make sure its on reserve. You might just be out of fuel.....just a thought