[sevencyrus]

Alright, this is an age old problem for me, and I have posted 2 threads on this topic. Basically, every once in a while the bike will not accelerate past 5K RPM, this is occurring because the right cylinder is not firing, at least I think. When this first happened I took it to the shop, they cleaned the carbs and rejeted, that was 4 months ago and the problem as came back over and over again. The second or third time I simply changed the spark plugs, it worked, and then the same thing happened again. I then took out the carbs and checked the pilot jets 2 times, thinking they may be dirty, each time they were clean. Basically the only thing that fixes the problem temporarily is changing the spark plugs. I have bought new spark plug caps and wires.

So, the only things left are syncing the carbs or the ignition system. For the ignition system, what do I need to check and change? I have no idea what to look for? What made me think of the ignition was a new side effect of the problem, I noticed when I let go of the throttle, I hear a weird noise coming from the bike, it sounds like something is cranking and its pretty loud and constant, its more electric sounding then mechanical, it basically sounds like the bike is trying to start and it doesn’t stop until I give it throttle again or it stops after time.

What about the fuel mixture? Could the bike be to rich? The bike has lost power, even when its running on both cylinders, how do I adjust the fuel/air mixture? Or does this have nothing to do with it?

I’m trying to fix this once and for all, hope you guys can help, thanks.

 

[fog]

It should be painfully obvious to you, as it is to me, that the "Shop" F ed you up. My biggest complaint about jet kits is they simply throw fuel at the problem. You have a extreme case of fuel fouling the plugs and nothing but proper jetting will fix it. Can you return to stock jets and needles?. Do so if possible or if not go down at least two sizes of main jets.
You have a rat's nest that will need several carb alterations and some level of tuning skill to cure

 

[sevencyrus]

I see, so i need to get it rejetted again!

When i took it to the shop i provided a jet kit, which comes with 4 sets of pilot jets, 2 for stage 1 with stock exhaust, 2 for stage 1 with aftermarket exhaust, then 2 for stage 3 with stock exh and a set for stage 3 with aftermarket.

They used the jets for Stage 1 and for bikes with stock exhaust. So they did use a stage 1 but i have a muzzy exhaust, so should they have used the other stage 1 set for aftermarket exhaust?

So what is wrong? Did they just tune it really bad or is it the jets are too small, which i thought they were too big?

 

[fog]

I would vote for too big, but check the function of the floats and the float levels too. Your plugs sholud never foul. What do they look like when you take the out?
Black?

FOG

 

[sevencyrus]

yea the whole tip is black. So basically the problem is the plugs are fouling from to much fuel, and this is only caused by the size of the jets? They used stage 1 for stock exhaust, which means its pretty much stock right?

 

[fog]

No not at all. Stage 1 mumbo jumbo,BS made to obfuscate what the hell is going on. They deliberately change the size of the jets and needles to complicate matters. Your not anywhere near stock. Check to see which slot in the needles the C clip is in and then try it in the top slot , so the needles protrude the longest into the main jet.
Did you keep the paper with the jet kit instructions? That's the only thing in the box that was worth anything. It might help you tune the thing. Be prepared to pull the carbs repeatedly to make the changes required.

FOG

 

[Mulcibre]

what is the substance fouling the plug? Is it for sure gas?

 

[fog]

Carbon and other various combustion by products. Since your getting good at changing plugs, try a hotter plug or better yet a better one like Bosch Platinimum or one of the other exotic metal ones. they run hotter and may solve the problem.
BTW what kind of gas milage are you getting?.

FOG

 

[sevencyrus]

I PMd Mulcibre and he said it might be a leaky piston ring, "which allows oil into the combustion chamber. This oil slowly coats the spark plug, making the cylinder not fire until the oil has been blasted off." Which makes sense as well, the engine is old and I'm pretty sure the a-hole before did not do any maintenance. It could be both, how would i fix the leaky piston ring? Just buy new rings and replace, any tuning required?

Should i put the stock jets on as well? I still have them but i dont have dyno so is it a good idea to mess with it?

 

[fog]

If you had enough oil consumption to foul the plugs you would notice it in oil usage and smoke. If you have the stock jets and needles .put them in and adjust the pilots . That should run fine and eliminate the fouling problem. I would still go for the platinum plugs though . all Exs need them..

FOG

 

[sevencyrus]

Well i am burning oil, but i cant tell if its normal burn and evaporation. I'll put the stock jets and needles back on i guess and get NGK iridium plugs. Thanks FOG

 

[sevencyrus]

Okay, so does the number on the main jet mean the size? The ones that are on are 122, the stock ones that used to be on were 132....so that means i have been running on a smaller? So was the problem not enough fuel? I'm confused.

 

[fog]

No your comparing horses and apples. I told you the jet kit Mfrs. deliberately use a diffrent size jets and needles that have no comparison to the stock ones. even the numbers on the stock jet don't correspond to any size whatsoever. there just numbers. Although a bigger number means more fuel but not any specific ammount.

FOG

 

[sevencyrus]

Well i put the stock main jets back on with no tuning. The bike started up and both cylinders were firing so i guess it fixed it, however it still has some degree of power loss and after riding it hard for 15 mins the bike lagged a bit at 6K for a sec, but it continued to work, i guess tomorrow while i ride it more we will see if both cylinders continue to fire.

As far as the power loss, what will fix this? Will i have to rejet it professionally with a dyno? Or could other things fix this, like carb sync? Its been so long since I first rode the bike when it worked completely that i forgot how powerfull it should be, but i am basing it on the fact that i cant pop the front from 1st to 2nd, which i used to be able to do all the time shifting at 10K.

 

[fog]

Your power loss is mostly imaginary , but if you say your burning oil , that indicates some compression loss. Compression loss= power loss in a direct relationship. The wheelie test is hardly scientific too.

FOG