Coguaro problem!

[Morini Rich]

I have a 1989 Coguaro (501 engine / Kokusan electrics) which I bought about a year ago (Steve - If your reading this - any ideas?).
The bike has been great so far (even won 'Best Off Road' at 2005 AGM!) but has recently developed an unwillingness to rev over 5000rpm where it
starts to stutter and lose power. Ease off the throttle and it bursts into life again but won't go past about 5000rpm. Its not possible to 'ride through' this problem.

Over the weekend I checked plugs and major electrical connections, charged the battery, cleaned float bowls and checked/cleaned every available orifice in the carbs - no improvement.

I now suspect electrics but what.....???.

By the way the bike starts on the button every time, ticks over well and pulls clean and strong until the dreaded 5000rpm.

Any advice or suggestions as to where to start looking would be greatly appreciated.

The winning advice wins a pint (at least) if we ever meet!

Cheers

Richard

[cmcwilliam]

Hi Rich - can you rev through when its in neutral?

[Morini Rich]

Hi Rich - can you rev through when its in neutral?

No I still get the same problem. I attached some vacuum gauges at the weekend and revved past 5000 stationary (frightened the neighbours!). The gauge on the front pot dropped as the engine note faltered so I think I've at least narrowed the search a bit. Any tips would be appreciated as I'm starting to run out of ideas. By the way - I don't think I've ever seen a worse designed front end with respect to getting the tank off and gaining access to the gubbins underneath. Congratulations Morini/Cagiva/whoever designed it!

Regards

RIchard

[cmcwilliam]

Have you tried taking off each HT lead in turn and see if one cylinder or the other exhibits the problem? I think that if you loosen the spark plug on the dead one you should be able to rev the engine up enough to get past 5K? (Dont put a rag in the spark plu hole and turn it over as the rag gets sucked in...)

If so, you can swap around the transducers to see if that changes the one that is affected. If os, then you have a faulty transducer and its a quick call to NLM.

If its both cylinders then I am hard pushed to say its anything but the alternator?

If its always one cylinder and never the other and swapping the tarnsducers doesnt do anything then maybe something in the carb or low compression on the cylinder? (Easy to check anyway iin order to eliminate).

Could be faulty HT lead and cap - also easy to change just to make sure.

If it would rev fine in neutral but not under load (ie with wide open throttle) then I woudl have thought maybe fuel starvation.

I have just bought a Coguaro - I was wondering how to get the tank off...

May I ask you a few questions??

* I have carb mounted chokes – are these standard? A real pain to get too – especially when riding…

* Is a parts book available?

* Is there any provision for greasing the rear shock pivots in situ or would that mean stripping it?

* Does the Kokusan alternator use the same puller as the older bikes?

* The front tank mounting bushes - are these supposed to have removable studs? The inner plastic cover fastens on to these at the top and it looks like it should be a nut over the stud to hold on the tank, and then the cover goes over the top and then another nut. is that right?

Sorry for all the questions!

Craig

[Morini Rich]

Hi Craig

Thanks for this I'll give your suggestions a go (but warn the neighbours this time!).

My 501 has handlebar mounted choke lever but not sure if this is standard.

I have a copy of a copy of a copy of a owners manual with some service data (including wiring diagram). If you like I can post a copy if you want to give me your address).

Swing arm pivot - Be careful. I took off the little chrome caps out of curiosity and found the nut underneath was loose and about to come off! Not sure though how to lubricate - let me know if you find out.

Flywheel puller I'm not sure but I have one for my 3 1/2 so will let you know when I try to change cambelt.

Not sure about tank mounting as mine does not look standard.

Cheers

Richard

[stevehod]

Hi Richard,
have an issue originally with this symptom. It seemed to me that the timing was advancing too far. I retarded the ignition a little and it went away. Doesn't sound like it was the correct fix though.

The main difficulty I had was finding a strobe light which was man enough to do the job. Because the timing is crankshaft driven and there's a wasted spark each rev, a cooking strobe light ran out of puff at about 3000rpm, so higher rpm behaviour couldn't be checked.

You will be aware that normal Morini troubles are not really relevant as the Cog, like the Dart, uses a real CDI unit and two coils - not the transducer/pickup affair fro the tre mezzo.

I would check out the timing first; Might also be sensitive to spark plug so worth a try. One dirty carb/fuel starve on that cylinder?
cheers

s

[EVguru]

You will be aware that normal Morini troubles are not really relevant as the Cog, like the Dart, uses a real CDI unit and two coils - not the transducer/pickup affair fro the tre mezzo.

The ignition isn't CDI at all, it's an inductive system, hence the larger coils. With electronic dwell control there's no compromise on top end spark and you get a longer spark compared to CDI.

[steve pegg]

Hi I have had a similar problem with an early Camel . I took it down to a rolling road and they conformed what I could not prove. My problem was that although the airbox and intakes were mechanically well put together somehow air was still able to get in. My solution was to tape up all the joints with an alloy backed sealing tape. This solved the problem with one hit. Try this and let me know it goes. Steve pegg

[steve pegg]

Forgot to mention this. What made me suspect the mixture was the fact that I could "manage" the miss fire by putting a little bit of choke on as it started to stutter. Also make sure the actual air cleaner assembly of many parts is correctly put together. Good luck

[Morini Rich]

Steve

Thanks for the tip I'll try that next. I haven't worked on the problem for a couple of months now (preparing my 3 1/2 for the Manx GP trip). Someone else also advised checking the airbox internals to make sure nothing had moved so maybe this is the answer...........

What do you think would happen if I took the airbox off completely as a test? Would it run too weak?

Best regards

Richard

[steve pegg]

Hi Richard, I do not really now about the wisdom of trying without the airbox, all my running problems have involved one way or the other the intergrity of the induction system. With one intake getting a "ram " air effect and the other not, you could confuse the issue. I got an exploded diagram off George Lane to make sure my airbox assembly was OK. So I would stick with the original set up. When I fixed mine after a few months I did not dare to beleive it. I went home left the bike for an hour and went out again to convince myself it really was fixed it was such a nuisance.
Good Luck Steve

[Morini Rich]

Checked airbox at the weekend and indeed it was not fitted together properly with a big gap where the cylindrical part joins the box that splits to the two carbs. However I also found that some bits of the internals were missing compared to an exploded diagram I have. The filter is there but nothing else!
Anyway rebuilt making sure there was a proper seal and guess what.....it was worse when I test rode it. Back to the drawing board.
I suppose the next step is to try and source the missing airbox internals and try again.
Does anybody know if these airboxes are common with other models (Dart, Kanguro etc)?

Cheers

Richard

[Morini Rich]

To: All who are interested.

I'm a bit late posting this, but a couple of months ago I took the damn thing up to NLM one Saturday to see what they could find (MOT was due anyway!). Alex scratched his head for a fair while and tried several things one at a time taking it for test rides after each try (mainly jetting experiments, timing checks, new ignition components, wiring integrity etc.). Thought for a while we had cracked it when we found the carb balance pipe split. However it wasn't to be, although the tickover and slow speed running were improved no end with a new pipe fitted. By the time it came to close the shop things had improved a bit but Alex still wasn't happy. So I rode it home having booked it in for another session the following week (good job I don't live far away).
This time he found the problem and it was all down to timing.................
Some how the timing belt had been fitted a few teeth out of synch??!! To make it worse there was a pen mark on the flywheel that we we had been using to check the timing and this was in the wrong place aarggh!!!!
Any way after fitting the (new) belt with the right relationship of camshaft to flywheel, re-setting the timing and balancing carbs the job was done.
It now goes like the proverbial, pulls smoothly from low revs and ticks over steadily.
I can only conclude that the flat spot at 5k was caused by the ignition advance moving the timing past the point where the engine could still run ok. Although why it should all of a sudden start playing up is still a mystery- maybe the split balance pipe just took it over the edge. Does that make sense to anyone?
Many thanks to Alex at NLM for his patience and allowing me to stick my nose in to what he was doing and answering all my stupid questions.

Hope this helps anyone else with similar problems and many thanks for those who responded to my initial cries for help.

Richard