Ongoing '06 Scorpa Problem

[jools]

Recently I had a thread going regarding a problem I was having with my 06 SY250. After months of frustration I eventually had to find the problem for myself and traced it to be a faulty CDI and Rectifier. Having put new ones on, the bike ran better than ever for the three trials I have done on it since.

However, 2 days ago I went out for a ride and the problem appears to have come back. I ran the bike for an hour and a half and the fan was cutting in within 20 minutes of riding, so it was warm.

The bike wont rev past half throttle. Its like 4 stroking at the top end. It was struggling to go up a 2 ft. rock! I took the bike around the field a few times to try and clear it out. Put it in 4th gear, and rode accross the field opened it up to just before 3/4 throttle and it was 4 stroking badly. Had to call it a day.

I've spent months going over this bike last time tracing the problem and i'm incredibly frustrated. Birketts appear to be shut until after new year, but i have an entry for the Vic Brittain trial on the 7th and would like to get it sorted.

Any body have any ideas what to check or look for etc!!??

Thank you.

[yama46]

is it over heating/looseing coolant?

[spud]

Jools, its so fustrating when these things happens. It does sound electrical and assuming the HT cap and lead are working okay it sounds like the stator plate. My bike symtoms were the bike ran fine but started to miss fire (not back firing). The bike would clear but got worse as the ride went on. This kept happening for quite some time until the bike finally died after about half a dozen trials riding the bike with this fault. There was no spark the stator was totally dead. I thought is was the coil first, or the CDI but i didn't have the equipment to trace the fault, so i gave up and handed the bike to my local dealer. I'm not saying it is the stator and especially because its a yamaha engine its highly unlikely it is, but what your saying sounds like the same problems i had with my Sherco.

Edited December 30, 2006 by spud

[boofont]

Think about this, you have changed the CDI and Rectifier, were they both broken or was it just one and you changed the other by mistake? If they were both broken and they've gone again, why? Very unlikely that you got two duff units in a row, but it could happen I suppose. I would speak to NB and ask if you can have a CDI and Rectifier on sale or return. Try each one in turn and see if the problem goes away. If it does with one and not the other then you may have got unlucky and got a duff one, speak to NB and see if he'll let you have a bit of discount, explain why. If it takes both to solve it then I would be looking at a problem deeper within the bike, i.e. something on the bike is causing these two items to fail.

I realise this won't help you as to what part but the next step to go to is 'which is it most likely to be?', you might want to get an auto-electrition to help.

[jools]

Thanks very much for all your feedback

yama46; No the bike has not lost any coolent, the fan is cutting in ok and there is no leak

Spud; it does definatly seem electrical. I'm in a similar problem to yourself as i dont have the equipment to test the electrics either.

Boofont; I know what your saying but i dont really want to get an auto electrician involved at this stage as i believe the bike has had this problem from new and it may complicate matters, if you know what I mean. I was seeing if anybody has had a similar problem and found it to be something stupid like a loose terminal or something. I've checked the bike and have not found anything obvious.

I was searching the internet before and found this article of Jim Snell at trialpartsusa.com. I know it is for a Gas gas, but it said " THE SILVER BOX IS THE "VOLTAGE REGULATOR". IT REGULATES THE CURRENT COMING FROM THE MAGNETO TO A CONSTANT 12V AC. IT'S MAIN PURPOSE IS TO PREVENT HIGH RPM VOLTAGE FROM DAMAGING LIGHT BULBS AND ELECTRICAL COMPONENTS.

COMMENTS: VERY FEW FAILURES HAVE BEEN REPORTED."

It continues "THE BLACK BOX IS THE "IGNITION REGULATOR". IT CONTROLS MANY FUNCTIONS OF THE IGNITION SYSTEM. THE ADVANCE/RETARD, THE TIMING, ECT.

COMMENTS: THIS IS USUALLY THE CAUSE OF MOST ELECTRICAL PROBLEMS INVOLVING THE SMOOTH RUNNING OF THE ENGINE. HOWEVER, VERY FEW FAILURES HAVE BEEN REPORTED. TYPICAL FAILURE SYMPTOMS ARE MISSFIRE AT HIGHER RPM AS THE ADVANCE IS NOT WORKING PROPERLY, OR THE MOTORCYCLE WILL NOT START. TO TEST, EXCHANGE FOR ANOTHER IDENTICAL COMPONENT UNIT AND TEST RUN ENGINE. IT IS NOT POSSIBLE TO RUN DIAGNOSTIC TESTS ON THIS COMPONENT. "

This confirms when I put the new ones on the bike ran fine.

[rocketron]

HI Jools

My 06 Scorpa also had a weird fault.It was fine from new but after about 3 outings it would start fine,then after ten minutes or so it wouldnt rev past half throttle.It would four stroke like mad but then if I let it cool down it ran fine the rest of the day.I am still mystified by this but I had changed my two stroke oil from Belray (80:1 mix) to Castrol 747 (100:1 mix).I also noticed that the carb rubber to manifold was very squashed and it looked like it was restricting air flow.I went back to Belray 80:1 mix and reseated the carb rubber so it wasnt so squashed.No problems since.

Maybe the bike had been partially seizing? I never knew the exact cause as I changed two things at once.

Just my thoughts.

Good luck

Ron

[hoodie2]

Have you removed the lights and the related wiring and if so did you remove the cylindrical regulator, that attaches to the sub frame? The absence of this regulator causes the fan to run okay until you reach higher revs, at which point it cuts out, possibly resulting in overheating and seizing. There have been previous posts on removing the lights and on the importance of retaining this regulator.

[lastplacebrad]

Have you removed the lights and the related wiring and if so did you remove the cylindrical regulator, that attaches to the sub frame? The absence of this regulator causes the fan to run okay until you reach higher revs, at which point it cuts out, possibly resulting in overheating and seizing. There have been previous posts on removing the lights and on the importance of retaining this regulator.

First thing i asked!!!......it happened to me!

[yama46]

same path i was thinking my 06 had same problem last trial poor runing this was due 2 overheating as fan was not cliking in bay passed switch. fan should run constent it did until the bike started moving/reved hard.my bike has lights is orginal and has done only 12 clubmen trials. the problem was a poor blockconecter under tank the greenlupe one had about 5mm play when connected.

[jools]

Thanks for all of your replies. Rocket Ron was right, distorted airbox to carb pipe, Thanks. It has been corectly set up now aswell as the carb by Birketts. Apparently its quite a common problem.

They recomended to heat up the elbow at the top of the carb, bend it straight and run the throttle cable over the top of the frame. That would allow you to loosen the carb, turn it so the slide is facing you, undo it, and slide the carb out with out taking the airbox off, because it seems pretty critical how the tube is aligned to the carb.

Hopefully now it wont go wrong! Thanks again!

[rocketron]

Hey Jools,

Am so glad you found the problem after my post! Being in N Ireland I couldnt go and see NB but I asked him if he had had similar problems to mine with the carb rubber and he said he hadnt. Mine occurred about March last year and to my mind the casting of the airbox was all wrong.I had to trim it with a Stanley knife to get the excess plastic off it before reseating the carb rubber.All 06 Scorpa riders beware! My bike ran better than new once I had cured it,beats me how they let them out of the factory that way........French Quality Control is merde.

I hope your bike is continuing to run well.

RocketRon

[timp]

Rocketron, can you explain which bit you were trimming to get a better fit.

[rocketron]

The airbox is made from two pieces of moulded plastic welded together and the inlet to the airbox (where the car rubber joins) had not been tidied up after it had been made.I used a knife and needle files to smooth off any rough edges on the flange where the carb rubber attaches.

To my mind it is bad design from the very start.Most carburation systems require a clean straight flow of air into the carb and on the Scorpa the carb rubber always distorts and restricts the flow.You just have to play about with it to get it as smooth a flow as possible.It works but it could work better if someone could redesign the whole airbox,carb rubber assembly.The problem is the rear shock absorber,there is so little space because of the room it takes up and that is why the carb is angled out of the cylinder barrel.

Of all the features on the Scorpa this is the one bit that could be better thought out!

RocketRon

[timp]

Thanks for that Rocketron.

I had considered insertind some sort of rigid ring inside the rubber pipe to hold it out to improve the shape of the rubber.

Also I had thought of cutting off the outlet on the airbox and aiming it at the carb better and then welding it back on.

[brutus]

I had a similar problem with the airbox of my TXT280, I bought the bike second hand and before riding it I checked it all over and noticed that the flange of the airbox was squashed. So I wanted to fit in a alloy ring to maintain a nice circular shape but to fit the ring I had to soften the plastic. This I tried to do with a paintstripper (like a high performance hairdryer) and the result was that the plastic flange came back to a perfect circular shape just by heating it up! After that I let it cool down and it's been perfect eversince!