Still Running Rough below 4000 Revs !

Thanks Rob - that sounds a simple possibility - crap fuel indeed - that RON10 stuff in Europe was hopeless for my other PD- ran a treat on the 98 though !
Did you make it over to Belgium - I was looking forward to going, but had this problem with the Purple Bike, so had to cancel.
Incidentally - had the coil off today, and got readings of;
Primary =0.8 Ohms
Secondary = 12.5 Ohms - according to Haynes & Clymer, that's not right, so could coil be bad ?
 
I didn't make it over unfortunately. I've torn a ligament in my groin, can barely walk let alone ride. 6 weeks since it happened.

Can you pinch the coil from your other bike to try it?
 
Rob Farmer said:
I didn't make it over unfortunately. I've torn a ligament in my groin, can barely walk let alone ride. 6 weeks since it happened.

Can you pinch the coil from your other bike to try it?
Click to expand...

Other bike is with Steve Scriminger to get the front main bearing locator pin replaced, ( which you recommended I leave as is !!!) and steering head bearings replaced.
Coils on my other bike are the brown 1.5 Ohm Dynacoils (twin plugged), so can't swop them out !!!
Two bikes and both off the road -:blast

Re the groin - I won't ask ..........:D
 
Oooops . . Mea Culpa too then :blast

(That pin was a new one on me; I had a quick flick through the Haynes manual before posting as well - didn't spot it - DOH !)

Bob.
 
Rob Farmer said:
Roger,

I'll be very surprised if it is your ignition module but if you want to check it out I can either lend you one or test yours out with my module tester.

Have a look down into the carb from the air filter end and make sure the slide sits right down on the bottom of the cutouts. I had a similar issue where the I rings at the top of the slide had swelled up, presumably with the effect of modern fuel. Mine had swelled so much the taper on the needle was exposed, felt like I was on choke all the time. New o rings cured the problem.
Click to expand...

Rob
Checked the O rings on the slide, and slide
seems to be seating OK. cleaned up the groove
it sits in too.
So, will order new O rings just in case, but can they
swell up once engine is warm & running?

Any other ideas- I thought you might have solved it
for a moment !
The
 
I'd be surprised if they swell during use. Mine had swelled by quite a considerably amount causing the bike to run rich at lower rpm. Obviously I've no idea if they were the originals. It was quite obvious that they were shot as soon as you looked at them.

I'd be looking to ditch the exhaust recirculation system. Scriminger has the parts for plugging the head. They come from a k series bike and may be the drain bolts for the seining arm - not sure though. A replacement air box shouldn't cost much. At least with that crap off the bike you won't have any unknown quantities.
 
Rob Farmer said:
I'd be looking to ditch the exhaust recirculation system. Scriminger has the parts for plugging the head. They come from a k series bike and may be the drain bolts for the seining arm - not sure though. A replacement air box shouldn't cost much. At least with that crap off the bike you won't have any unknown quantities.
Click to expand...

Hi Rob,
my O rings looked fine, and sliders seat right down on the carb base, so doubt that is the problem.
I was planning on removing the secondary circ system at some point, as all I would need to do is block off the exit point under the front pipe - Steve Scriminger is on holiday at present, as I just spoke to them, so no help there for 2 weeks.
I think what has to be done is to remove the threaded section from the head - I can see that being a struggle, with the risk of stripping the thread in the head !!! but, yes, once that's done, MotoBins reckoned that a sump drain plug would fit, but he wasn't sure which one - needs to be 16mm thread and 1.5mm pitch, and quite short. Or, a blanking off type nut, but all I can find on the web is domed nuts in stainless ( for Harleys or custom bikes ) which would be too bulky and too long.
Carb end is no prob, and airbox holes easily blocked off with rubber grommet/blanking bit - as per my turquoise bike. So, do I risk removing the threaded bit on the head ? - think I'll wait a while on that !!!
So, still no progress- got me beat :confused:
 
If you fancy a trip over to mine we could swap some parts out to eliminate the obvious. Makes it easy with a diner bike to hand. I also have a pukka ultrasonic cleaner.
 
Robs your man Roger

Helped me sort my re-circulation system.

Took it all off and blanked off with bits from Rob and Mworks :thumb2
 
Hi Roger

I have read this thread and I am struggling to offer a diagnosis as there appears to be little information on what the symptoms of your problem are.

Does the bike idle OK? How does the engine respond as you vary the idle and mixture screws when you tune it? Does it run Ok at constant speed and revs and only give problems as you roll off the throttle or do you have issues in other conditions?

Did you check that the advance/retard was working properly as Jimish asked?

Have you tried new plugs or cleaned and examined your current ones very thoroughly?

What have you done to the bike since it last ran OK?

The more information you give, the more likely it is that we can help you

Steve
 
SJRoome said:
Hi Roger

I have read this thread and I am struggling to offer a diagnosis as there appears to be little information on what the symptoms of your problem are.

Does the bike idle OK? How does the engine respond as you vary the idle and mixture screws when you tune it? Does it run Ok at constant speed and revs and only give problems as you roll off the throttle or do you have issues in other conditions?

Did you check that the advance/retard was working properly as Jimish asked?

Have you tried new plugs or cleaned and examined your current ones very thoroughly?

What have you done to the bike since it last ran OK?

The more information you give, the more likely it is that we can help you

Steve
Click to expand...

Hi Steve, appreciate the reply, and I think most of your questions are already answered in my earlier posts - eg
new plugs and leads & plug caps,
timing and compression checked and good,
runs great above 4K revs,
is jumpy/jerky surges below 4K revs,
sooty plugs -
mixture is set to where it should be,
carbs balanced OK-
coil checked and reads 12 Ohms across the secondary - NO hairline cracks visible ( it's the newer black version anyhow),
can set tickover pretty well, albeit a bit erratic
have removed and checked idle jet
new carb diaphragms
have checked Secondary Circ System vacuum pipes

Last thing I did to bike prior to the problem was an engine oil change , and bevel box oil change.

However, the problem does appear to show up on a falling throttle, but above 4K revs, it runs just fine, and accelerates extremely well.

So, don't know if these points help -:confused:

I'm off to see Rob Farmer on Sat, and will hopefully have received the necessary bits to block-off the Secondary Circulation System by then as that is certainly for the chop ! Load of old rubbish seems to me.....

So, hopefully I can report back on Sunday that all is well, and detail how we solved the mystery. :eek:
 
If you changed the oil then presumably you changed the air filter. If so this is a likely the source of your problems ie air leak or pattern filter .... choking flow. Oil and bevel cannot affect fuelling or sparks. You really should only change 1 thing at once. Taking off the air system cannot be a reason since it was ok before. Idle screws should be close to default ie 1 +3/4 turn out I think. Anything significantly different than manual setting points to a fuel problem. It should run fine like this. If it is rough below 4k then I don't see how you can say the carbs are balanced. Forget vac gagues. Only balancing is to check both pots come off idle at exactly the same time. On idle reach undercarbs and nudge throttle lever on each side one at a time. Engine must sound equally off balance with a tiny shove if they are in balance. Also check again with a smidge of throttle to check lift off exactly the same both sides.
 
Thanks Kenny - Rob has UltraSonic cleaner at his place, so carbs will be getting a thorough clean out - choke mechanism sounds like a possible- not messed with it so far just in case I re-assemble it wrongly ! As if .....

Christhemuso (what instrument/s do you play- interested as I run a small studio here !).:guitarist
As a Sound Engineer, I am used to a systematic process of elimination/substitution for audio type problem solving etc, so yes, only change one thing at once - agreed.
I am only too aware that changing engine and bevel box oil will not affect engine running etc ( unless of course you forget to re-fill with oil afterwards)- previous post (SJ Roome) asked me what I did to the bike just before problem arose, so I told him !

Forgot to mention that , having a K & N airfilter, one does not automatically change the air filter every oil change- I have however thoroughly cleaned the K & N with their cleaning kit, so that is not the problem either, but admit it was on my list of possible problems.
What I think is one of the main clues is that problem appears to have occurred on BOTH cylinders simultaneously ( ie very sooty plugs), and leads me towards electrical source, but still guessing/eliminating.

All replies are much appreciated though -:cool:
 
Hi Roger

You said it runs great above 4K revs. I assume from this that you are getting full power so I would expect that the air flow (including the air filter etc etc) and the fuel flow and main jets are fine.

You said can set tickover pretty well, albeit a bit erratic. Sounds like idle jet and air passages are probably OK as well.

You also said it is jumpy/jerky surges below 4K revs. Can you give any more details of this? When it happens and what happens? This could be the advance/ retard mechanism sticking , faulty coil, or a faulty spark plug. However it could also be one of the carb slides sticking or an air leak. I once had an occurence of surging at low throttle openings when riding between 30 - 50 mph and it turned out to be a perished 'O' ring on one idle jet.

You say that the choke levers on the carbs are returning fully so I dont see how they can be anything to do with the problem if you have'nt disassembled them. If you do decide to disassemble them only do one side at a time as getting parts mixed up between the sides will cause all sorts of problems.

The very sooty plugs are a puzzle. However they cannot be caused by an electrical problem. This is usually caused by the chokes (which are actually enrichers) not returning to closed or having the wrong side disks in. If it is running very rich I would also have expected the carbs to respond strangely to adjusting the mixture screws, for example running best with them fully screwed in.

I cant wait to find out what Rob discovers. My money is on the carbs having a blocked airway or a perished 'O' ring :)
 
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