Not running properly on all 4

[IMM]

Need some help here bike not running right i get a spark on all 4 cylinders cant get my head round it 1 2 3 exhaust are getting hot {cant put my hand on them} No 4 is getting hot but i can put my hand on it not for long though, does anyone have any ideas on what might be wrong, any help would be appreciated please
Graham

[joebloggs]

More details required.....
Milage?
Does it run clean at high rpm (think blocked pilot jet/diaphram issues)
If it ticks over poorly try squirting some easy start into the airbox (whilst running) and see if the  other cylinder picks up.

[Buzz]

Mine's been like this with no. 3 for the last 3 years, runs fine under load however.  Think the Pilot jet is a bit blocked but I've still not got round to stripping the carbs...one day perhaps!

[Alexander]

Got the same problem on tick over no. 3 doesn't run, I can hold the downpipe with my bare hand.


Picks up at 4k rpm although bogs down occasionally if really try to pin the throttle. Carbs have been off and cleaned but no difference.
Mystery continues

[limax2]

You could try swapping the spark plugs over from No.2 and 3 and even the plug leads as well to see if the problem swaps over. If not at least it rules out the electrics.
2and 3 high tension leads come from the same coil so swapping them over would normally have no effect on the engine.

[darrsi]

You could try swapping the spark plugs over from No.2 and 3 and even the plug leads as well to see if the problem swaps over. If not at least it rules out the electrics.
2and 3 high tension leads come from the same coil so swapping them over would normally have no effect on the engine.

:agree


You can try these, which are totally fine, and me and quite a few others have them on our bikes, the price is for a set of 4.


http://www.ebay.co.uk/itm/4x-NGK-Resisto...4ac0970d44


Or buy these (number 7), which will do exactly the same job, but you need to multiply the price by 4.  :eek


https://www.yamahamotorcyclespares.co.uk...%201?uID=0

[Alexander]

Spark plugs have also been changed, still same problem. I will try swapping the leads and see if that makes any difference.
Sorry if I have hijacked this thread a little.

[darrsi]

Got the same problem on tick over no. 3 doesn't run, I can hold the downpipe with my bare hand.


Picks up at 4k rpm although bogs down occasionally if really try to pin the throttle. Carbs have been off and cleaned but no difference.
Mystery continues

Doesn't the spark plug tell a story?


If it has fuel on it or stinks of fuel then you're not getting a spark meaning iffy coil, cap or plug, and if it doesn't it's not getting enough fuel which would point to the carb.
Sounds like a plan in my head anyway.  :lol

[joebloggs]

Try the easystart I suggested in an earlier post. If you can squirt it straight towards no 3 if will chime in if its got spark but no fuel. You said the carbs were cleaned but did you also check the diaphram's, I had a split on one on a GPZ600 and it gave similar symptoms. The slide wouldn't lift at lower RPM due to the vacuum leak but would lift as the engine speed increased.
A sticking float can also cause this, flooding the cylinder until the rev's build up although this often causes the engine to bog down then chime in like a twostroke

[IMM]

Ok have done all of the above and still no joy,
Crossed the HT leads over no joy,
carbs off again re-cleaned checked the diaphragms all good,
took off the carbs to head rubber on {No 1 cylinder} no cracks sealed it on instillation,
put the carbs back on started the bike then strangely No 3 cylinder wasn't working, stopped the bike restarted it No 3 now working!
so i do a compression test



Engine Cold

13 turns of the engine gave me these results


No 1 cyclinder
125 psi


No 2 Cylinder
124 psi


No 3 Cylinder
100 psi


No 4 Cylinder
125 psi

So i have compression but still not working properly on No 1
cant understand what the hell is wrong anyone got any more ideas please?

[His Dudeness]

down 25 psi compared to the other cylinders is not good! running cool would suggest a weak spark or running too rich. if a jet was blocked and restricting fuel you'd have a lean situation and the cylinder would be running hot compared to the others so i'd suggest the mixture screw on cyl 4 needs to be turned in a bit to lean it out.

[IMM]

Ok i have had the carbs off again taken the float chamber off changed all the jets form a spear set of carbs re-cleaned all the jets in No.1 carb but it all back together and still the same, ok so i did the easy start and it started to run on all 4 whoop whoop  then back the 3 after it burnt off, while the carbs were off i did check and re check all the diaphragms and all look good with no splits in them, checked the float needle by blowing down the fuel delivery pipe while moving the float and it shut the air on and off  so now i am at a loss as what to do next, just to say i have also readjusted the carbs each one is at two turns from there seats, on No1 i did do a full adjustment while the bike was running and that didn't make any difference to its running on 3 cylinders
I am at a loss with this

[joebloggs]

Me thinks the prognosis isn't good. If your carbs are ok and your down on compression I'd say your looking at a rebuild or engine swap.

Could of course be a burnt out valve but you'll have to pop the head off to check

[joebloggs]

Or run it on easystart  .......

[john 087]

put a couple drops of oil in number 3 and do the compression test again. if it is still down it could be valve trouble. if its up it could be ring trouble.