[Bigfella966]

Hi, I have 2 questions

We have a Yamaha VXR Pro that is breaking down under load and won't rev above 4000rpm, seems to be electrical, changed plugs but no difference.

Also today we were out on our Yamaha 94 Waveraider 701 after approx 2 hours running my young fella was flat out and it just died and would not start, it cranks over but there is no spark. Could it be the CDI unit?

If anyone can help,
Cheers
BF

 

[Ernest T]

The problem with the VXR sounds more like a mechanical problem to me. If it is starting and running you have pretty much ruled out electrical issues. I'd take a look at the carbs (dirty, etc.), check the compression (you may just have a worn out cylinder as first steps.

The problem with the Waveraider sounds more like an electrical issue. The fact that it happened when the ski was running, would have me looking for a loose wire or bad contact as the first step. It could also be a bad coil, or bad CDI, both problems are fairly common on that ski.

 

[Bigfella966]

Cheers for that, I'm going to pull out the VXR intake and have a gander at the reed valves as well as I've been told they were an issue, I'll give the carb a clean &blowout at the same time.

I'll check the Raider for a bad/loose elect connection, is there an easy way of testing the coil and CDI unit do you know?

 

[Ernest T]

You can check the voltage output from the ignition coil where it connects to the CDI. You just take the wire loose and check between that wire and ground. I don't have a service manual for your skis, but for other models, you look for around 30-50 volts AC (it will vary depending on how good your battery and starter are) while you are cranking the ski. Some guys say you can check resistance to find a bad coil, but I've had bad luck doing that. The only sure way is to check the output voltage while you are cranking the ski.

There is no easy way to check the CDI without a very expensive and accurate meter. If you are getting voltage from the coil, but still no spark, you can pretty much assume you have a bad CDI.

 

[Bigfella966]

I took the carb & reed valves out on the Pro, no broken reed valves, cleaned and blew out the carb, the H & L jets were 2 turns out and set them back to that, but I don't think that is the factory setting for them (I messed around with them a bit before), do you know what the factory settings are for the jets?

I haven't had time to check the Raider's electrics out yet but thanks for the advice and I'll sus it out thursday

Happy Australia Day for tomorrow!

 

[Bigfella966]

The Pro seems cured, not breaking down now and Hi speed jet at 1.5 turns out. I guess it was just a blocked/dirty carb.

Now the Raider!, couldn't get a reading on the voltage for some reason (obviously I was doing something wrong), but with the plugs out and earthed, when I crank it over, the spark fires about 2-3 times then fades to no spark at all. Wait about 30 sec then crank again and the same thing happens. Does this sound like its the coil??

 

[Ernest T]

The Pro seems cured, not breaking down now and Hi speed jet at 1.5 turns out. I guess it was just a blocked/dirty carb.

Now the Raider!, couldn't get a reading on the voltage for some reason (obviously I was doing something wrong), but with the plugs out and earthed, when I crank it over, the spark fires about 2-3 times then fades to no spark at all. Wait about 30 sec then crank again and the same thing happens. Does this sound like its the coil??

Sounds more like a bad CDI, but would be hard to tell for sure if you can't check the output voltage from the coil. Also be sure the lanyard is pulling the kill switch all the way up..............seen a similar problem when someone tried to use an aftermarket lanyard that was not completely pulling the kill switch up.

 

[Bigfella966]

RAIDER is fixed!, I'm not sure what was the actual fault but I found the fuse holder would cut in & out if you twisted it slightly (would not crank over), I soldered the break at the joint. I also pulled the starter switch apart and gave it a clean with elec crc at the same time, so whatever one it was (or both) seems to have fixed it.

Now the bad news - I thought the VXR Pro was fixed when fired up on the trailer & reving it up to 6000-7000 rpm, but when I took the ski's down for a run, the Pro continues to break down over approx 4500rpm, and at times only just got onto the plain.

I previously stripped the carb down (have the mikuni exploded diagram) and cleaned & blew out all the passages, jets etc. Put it back together, both High & low speed jets are set at 1.5 turns out. I tried jet adjustments at the beach to no avail, new spark plugs as well, but she still breaks down (revs very erratically) and won't really rev above 5000rpm. I tend to think it is electrical because of the scattered & erratic revving and the fact that the carb was completely cleaned.

Is there something that could be shorting or breaking down the spark?? it reminds me of my old red motor with a carbon track down the dizzy

 

[Bigfella966]

Still Stumped

I thought the VXR Pro was fixed when fired up on the trailer & reving it up to 6000-7000 rpm, but when I took the her down for a run, the she continues to break down over approx 4500rpm, and at times only just got onto the plain.

I previously stripped the carb down (have the mikuni exploded diagram) and cleaned & blew out all the passages, jets etc. Put it back together, both High & low speed jets are set at 1.5 turns out. I tried jet adjustments at the beach to no avail, new spark plugs as well, but she still breaks down (revs very erratically) and won't really rev above 5000rpm. I tend to think it is electrical because of the scattered & erratic revving and the fact that the carb was completely cleaned.

Is there something that could be shorting or breaking down the spark?? it reminds me of my old red motor with a carbon track down the dizzy

Just wondering if anyone has any ideas re: above
Cheers
BF

 

[joecool1960]

May Help!

I have a '93 vxr pro. They have an overheat feature which limits RPM to Approx 3000 (with mine anyway). If your instruments are working (mine don't) there should be a indicator on the bottom right of the panel - next to to the low fuel warning. this will display if overheating.

All this is secondhand info except that I have experienced the rev limiter after idling down a creek!
Hope this is of help.

 

[Bigfella966]

Hi JoeCool,
I'll sus it out, hopefully it is something simple like that, i ain't got the $$$ at the moment to go replacing DI's or the likes at the moment.
Cheers for that
BF

 

[Bigfella966]

VXR PRO still having problems!
Breaking down at 4000-4500rpm on the trailer and also under load on the water. Eliminated carb/fuel so has to be electrical. Eliminated spark plugs and temp rev limiter cutting in (thanks Joecool60). I gather the only things left are the coils/leads or the CDI unit?? does anyone have any other ideas or know how I can test these without having to replace them. I don't want to buy a replacement CDI or "whatever" and find out it's something else.

Any more ideas?

 

[Bigfella966]

IT WAS THE COIL!!!!!, I found it by swapping each electrical component out of the Raider into the Pro and firing it up and running, and low and behold it was the coil.

Thanks to all for your help and advice

Cheers