What's up fellow hawkers?
I went out to change the front brakes on my cage today and I decided I would take the hawk to the "zone" for my new pads and here's what happened.

I was cruising down the road everything runnin' fine when all of a sudden she just starts buckin' like crazy. She would clear up for a minute then start acting up again. It was almost like she was trying to run out of gas but I have a full tank. I could definately tell that I had lost a cylinder and she would not stay running at an Idle at all.

I havn't had the carbs off for a while so I know that I have all the lines in the correct locations. I havn't had any problems from her at all for quite a while. The last thing that I had done was change out the R/R. I had just rode the other day so she hasn't sat for very long but she has just passed the 30k mile mark; therefore I'm figuring it just might be an electrical problem.

My question is "What is the average life expectancy of the ign. coils on our bikes?"

Any opinions on what you guys may think?
I did do a search but didn't really find what I was looking for.

 

I don't know of an average lifespan.. Mine have over 60k miles and 10 years on them..

But Tweety just changed to CBR stick coils and gained horsepower indicating that his OEM ones were getting worn..

I'd say if you are going to be changing the coil, do the CBR stick coil upgrade.

 

I'm not sure about our bikes specifically, but on most bikes, cars and trucks the ignition coil/coils will outlive the vehicle. That is as long as it's kept clean from dust accumulation and dry. They do occasionally fail though.

If yours isn't misfiring at idle, when you can check for spark, it will be difficult to diagnose.

I had a very intermittent misfire starting about a year ago. But it was always running okay by the time I stopped. It turned out to be a plugged pilot/slow jet in #2 carb.

If you suspect ignition, check your plugs first, then check resistance on the coils and plug wires. The specs should be in the service manual, which you can download from the Forum.

 

Sounds like the problem I was having with mine, turned out to be a vacuum line problem. The diaphragm was partial closing, causing the bike to appear to be running on one cylinder.

 

bad coils usually act up when hot and then behave properly again when cooled down.

 

coils can do funny things though. Mine went out at the same time and was probably the direct result of seriously malfunctioning R/r. The coils can easily be tested with a multimeter the specs are in the manual.

My bike would drop a cylinder as soon as I began opening up the throttle.

You mentioned an R/r change, was it because of a serious failure or preventative maintenance?

 

I'd start with the obvious culprit first and check for vaccum leaks... Dry rot in hoses and tears in diaphragms are far more likely to cause those problems than coils...

Did this happen with a basicly full tank, just after fill-up or where you down to half-tank or less?

Have you re-located the overflow/vent lines on the carbs?

BTW I'm not saying it isn't the coils... But in my case the bike was running fine, no issues what so ever... Infact had you asked me 2 days ago, I would have answeared it was running better than ever before... Then I put the stick coils in and I couldn't get the settings to behave like I expected it... Put it on a dyno and found out why and found another 2 bonus hp...

 

yeah it was just PM, I just didn't wanna get stranded out in the middle of nowhere.

 

actually it was a little more than 1/2 probally like 3/4 full.

I'm gonna dig into it tomorrow and look around. I already have the manual so I'm gonna check all that I can.

thanks for all the input.

 

Having been through the routine twice now, I am willing to bet the diaphragm in the fuel petcock is torn....

 

Yup... My money is on the diaphragm too... Full tank would have indicated vapour lock...

 

I had this problem too, it turned out to be the coil.
Swap the front and rear coils and see if the dead cylinders swap, that'll tell you if that's the problem

 

Right on, R/R failure can send high voltage trough the electrical system, damaging components, coils and bulbs are sensitive to high voltage and will fry before the rest.

Since it happened not long ago, I'll bet on the coils.

 

Average life of coils? I've put well over a million miles on the bikes, cars and trucks I've owned. Replaced coils once. 1975. On a '73 TX-500 Yamaha.

 

ok so I just checked the diaphram on the petcock and it's in good shape. No tears, no holes. I did find a small hole in the vacuum line that goes to the petcock though. Don't know yet if that was the problem havn't got her put back together yet.

I did fire her up however, and both slides are opening and I did check the plugs. Neither one was fouled and the looked rather good but it is time for a change though the porcelain is disclored just a bit

I'll give more status once all is back together.

thanks for the input.

 

Ok so I got her all put back together. the only thing i did was replace the vacuum line that had the hole fired her up and ket her run for like 10-15 minutes just to see if she would act up and BAM, nothing. she just purred like a kitty. so I synched the carbs while I was there and took her for a spin. It was like nothing ever happened, ran like, like, like, a superhawk!!!! lol

It's hard to believe that a small hole in a vacuum line will reak so much havok.

thanks for the input on where to start guys, I'm frickin' happy it was an easy fix.

 

Ok... So the diaphragm was OK, we where wrong...

But yeah, it's the small niggly things that matter...

 

Glad you got it running like it should again. Sometimes it's the simple things.

The old GM and Ford automatic transmissions (before computer controls) used a vacuum modulator to control shifting. A small leak in the vacuum hose would cause a lean misfire and late 1-2 upshift. I fixed many with 15 cents worth of hose, or at worst a new modulator cost about $20 or so and 10 minutes to install. However, if a motorist took it to the wrong shop, they could get soaked for a rebuilt transmission.