put the carbs in an ultra sonic cleaner. You cant just spray it down, The ACV cover (I believe) can be and is a bugger to clear

 

I had a Kaw 550 Spectre that did the same thing. It showed good compression and good spark. I rebuilt the carbs to no avail. It turned out that the guy that had it it before me did a valve adjust, (The cams had to be removed to facilitate valve adjust, (Shim under cam follower) and when he reassembled it he had the cam misaligned on the cam gears by 2 teeth. Maybe your cam chain has jumped a few cogs.

 

check that your timing advance unit is not stuck

use a timing light and follow the procedure in the fsm

 

Hi fellas, thanks for the speedy replies! I may try recleaning the carbs if all tests on the ignition system show up good, but without access to an ultrasonic cleaner or money to buy one I'll have to carry on the old fashioned way What would the symptoms of dirty or damaged ACVs be, aren't they there just to prevent the engine from running lean on the overrun?

Murray I had been thinking along similiar lines that the timing might not be advancing, according to the FSM which I've just downloaded the advance is activated by a cam which I assume moves under centrifugal force. But I'm now wondering if that cam being stuck would cause these particular symptoms, if it was totally jammed then the engine wouldn't be able to rev past 5000 regardless of load, or would it? Is it absolutely necessary to advance the timing to achieve higher revs, or does it just help it create more power doing so?

 

When I read read this I am wondering if you cleaned the resistors and put them back???

Did you check them ???

Stuck Atu will cause a very lazy engine and depending on load,
Can limit rpm

Remove the,air cleaner element clean the air box screens

With brake cleaner and try a quick ride with tge,air filter out

 

Hi,
No didn't bother checking the resistors, just replaced them with a piece of brass rod as the bike has resistor plugs in. I also tried it with a pair of resistor-less plugs to no avail. I did try the bike without the air filter which made no noticeable difference but I didn't think to check the mesh screen, i would check it now but its absolutely hoofing it down out there so I think thats a job for tomorow....if the rain ever stops that is
As for checking the timing with a strobe light, how to block the inspection hole and still see the marks? Would a piece of see - through plastic taped on be alright?

 

drain one half a quart only

put bike on the side stand this minimizes oil splashing

 

Update;
So in the absence of timing light or funds to buy one I pulled the engine yesterday to check the spark advancer but it seems absolutely fine, the cam moves freely as do the weights (?) and springs everything looks clean and healthly so I've put it all back together now, only problem I had the exhaust being thoroughly seized together. I had to take it off in one piece, I'll be taking it over to a friends house at the weekend to get it apart, weld new mounting studs onto the silencers and I think I may replace the h - box with straight through pipes while I'm at it. Opinions on h - box removal?
However I think I may have found whats causing the problem, the connector block with 3 yellow wires (from stator I think) was melted to buggery and 2 of the pins were actually touching each other in the block. Not sure what could have caused this (perhaps the year I spent riding around with a van battery on it wasn't such a good idea after all) but it can't have been doing it any good and I'm surprised it was still charging at all

 

well before you put it all back together check the stator it may be burnt

and low voltage will cause the spark igniters to misfire

 

Hahaa! Sorted it!
Turned out to be the fecking air filter after all. I had tried the bike without air filter, but it wouldnt run right without it so I didn't realise the problem. Now this is odd because the last time I had problems with the bike it was running rich and fouling plugs, I ripped the airfilter out there at the side of the road and it ran absolutely fine. So not sure what has changed.
Anyways, theres always a little bit of oil in the airbox due to the crankcase breather and it suddenly occurred to me that it was a paper air filter in there, and aren't paper filters supposed to stay dry? So after trying the bike without air filter again to no avail I decided to rip the paper element out of the filter cage and fitted a piece of foam in there instead. Instantly sorted the problem and the bike runs great again wooooo!

 

I've dealt with your air filter problem several times. So much that I know keep a stock filter in the garage but now use a K&N without problems.