Topic: Engine runs great.. ..then misfires as it gets warmer

[Jmon99]

Hi all,

By accident I put the wrong sparks in my bike (i know i know i know it's bad!!!), and it misfired everywhere.. ..as you'd expect.
So I got round to putting new sparks in and also put a new battery in too.

The bike now starts perfectly and runs better cold than it ever has done. Which is great.. ..however as the engine get warmer I loose power and it misfires .. ..back firing from time to time

now what I want to know is what to next?
I'm thinking that if I ran it for a few weeks with the wrong spark plugs in then it could have damaged the condensors.. ..so they're first on my list to replce.. ..

next the timing.. ..it hasn't been done for a while so it won't hurt

then the contact breaker gap


Am I going down the right track here. Could the wrong spark plugs have damaged the condensors at all? could they dmage the coils?

any help greatly appreciated.. ..but please assume that I'm a complete novice.. ..after all , i DID put the wrong sparks in!!!!!

John

[byidesign]

You won't be the last,either,{been there/done that}
     go thru and do a complete tune up.check connectors...
         clean, air filter too..
     make sure you don't have damaged plug wires/ends.
         {from handling them}.
          and fuel is fresh, and bowls clean
              Old gas, or some water,can give fits too
                 Hope it helps
                         Bruce
       
       
     
       

[TwoTired]

Could the wrong spark plugs have damaged the condensors at all? could they damage the coils?

No.

The bike now starts perfectly and runs better cold than it ever has done. Which is great.. ..however as the engine get warmer I loose power and it misfires .. ..back firing from time to time

If you have no tune up history, it is time for a complete one, normally done every 3000 miles.
-Tappet adjust
-Cam chain tensioner
-Spark plugs, properly gapped
-Point gap/ contact reconditioning if not new.
-Ignition timing
-new or  known clean air filter

Has the bike ever run properly as for as you know?
Are there any changes from stock configuration?  (air filter, exhaust, etc.)

[skidpan]

A misfire when warmed up could be a coil breaking down under load. If you can work out which cylinder is misfiring, swap the coils over and see if the misfire moves to the other pair of cylinders. To test for the misfire cylinder, when its running on three pots, pull lead 1 off its plug and see if you go down to 2 pots. If not, pull off number 4 and if you still on 3 pots, it must be 2 or 3 that is misfiring. Then swap the coils over and retest.
You in Preston? I'm in Chorley area.

[KB02]

Almost sounds like it might just be running rich? What do your plugs look like?

I agree with TwoTired, though, do the full tune-up. Just check the plugs first to see if they're running rich or not.

[Jmon99]

.. ..Yeah.. ..a good old tune up is first on the list me thinks.

I also noticed that a couple of you said the air filter.. ..is it that important... ..*thinks about it*... hmm obviously it's improtant. ...!!! aaaand it's not been changed for a bit

Skid pan: coil check: yeah.. ..I'll try that one.. ..think I'll do the tune up first though. Cheers for the info there. And yeah.. ..I'm just round the corner from you.. ..we should meet up. what bike u got mate?

TwoTired: tappet adjust eh? hmmm mnight have to dig out the manual for than.. ..is it tricky doing that?
in answer to your questions: 1) yes it has run OK before but not perfectly.. ..it's always been missing a little tiny bit, especially on start up.. ..although I put that down to the bike being old. in the 9 years I've had it it's had new coils, (with new HT leads) I bought a new contact breaker base plate with new condensors, and contack breakers. 2) it's all as it should be appart from the 4 to 1 exhaust.. ..and I had the carbs synced at a Honda dealer (albeit 8 years ago!!)

KB02: fuel.. . I think it could be running a little rich.. ..the sparks that I've taken out have been a bit sooty.. .what should I do? I'll get it tuned, then how do I monitor the mix? clean a plug, put it back in then see how it fares over the course of a week? is the mix easy to change?


All I need is a sunny day, lots of coffee and I'll be away.
But I am in the UK.. ..we could be waiting for months!!!

Cheers for all the comments

J

[dusterdude]

is the choke hanging on?

[Jmon99]

dusterdude: choke hanging on? hmmm not sure mate.. ..I'll have a look whilst replacing the airfilter


Nice one!!


J

[78_SaltLick]

same thing happens with mine, i believe on mine its because of the 4 into 1 exaust on it. needs to be rejetted.

[Jmon99]

hey saltlick

you get the same thing with engine misfiring?

mine's 4 into one too you see