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The No Go Climber

Posted: Sun Jul 05, 2020 7:01 pm
by Mudnut
Thanks for allowing me into your forum.

I have recently purchased an 89 aprilia climber. After decades on enduro bikes, I thought I'd give trials a go. The bike test rode well. I thought it needed a clutch but that seemed an easy fix (whole different story there) and I got it cheap. When I got it home i was riding around the paddock when suddenly I heard the grind of the flywheel letting go. This is where my problems started. Turns out the bike had been fitted with a new HPI ignition system. For some reason, the guy who fitted it had tack welded part of the old flywheel onto the new one? I'm assuming he was trying to add weight. Unfortunately it was a stupid, badly done idea and it spun itself apart.

I have since reinstalled the flywheel, as per specs - the extra bit.
The stator is mounted on the cover not the motor, there does appear to be some spacing issues which affect how close stator sits near flywheel. This issue is not mentioned in the manual - nothing that should stop it starting but will need to be sorted. The previous owner appears to have tried to fix with stacks of nuts as packers.

My problem is that I cannot get the bike to start! The best I can get is an occasional backfire.

• The bike has got spark.
• I've checked the disc valve timing. Looks ok, however because of backfires I have rechecked timing several times.
• I have pulled down, cleaned and rebuilt the carb.
• Put in a new plug and fresh fuel.
No result. I have spent days on this. I'm very familiar with motorbike rebuilds etc but have not had a rotax before. I'm at a complete loss as to what's going wrong! Any suggestions appreciated.

Re: The No Go Climber

Posted: Sun Jul 05, 2020 8:12 pm
by David Lahey
Because it ran before the flywheel problem and now doesn't run, it sounds like an ignition timing problem. Have you checked for a sheared flywheel key?

Re: The No Go Climber

Posted: Sun Jul 05, 2020 9:13 pm
by Mudnut
Thanks for your reply. There is no key on this flywheel. Just the tapered shaft. The way the new flywheel/stator setup works is that you line up a mark on the stator cover with one on the stator. There is a mark on the flywheel but without a key to line things up I have been taking a guess that putting that mark at 12.00 position when bike is TDC is roughly the right spot. I still think timing is the issue but haven't been able to find any info to point me in the right direction. The manual i downloaded for the HPI unit is very basic. Can't find anything on the motor......... i have been wondering whether there is a timing mark on the motor that was wiped out when the flywheel ground itself to death?

Re: The No Go Climber

Posted: Sun Jul 05, 2020 10:47 pm
by David Lahey
Can you post up what info you have on the ignition and maybe a photo of what your flywheel setup looks like.
Some brands of aftermarket ignition that do away with the key require you to get it close enough to the right timing so that it runs then use a strobe to get it right. Alternatively you can spin the motor with a drill with the plug out to get the strobe readings.

Re: The No Go Climber

Posted: Mon Jul 06, 2020 12:50 pm
by Mudnut
The ignition is from a Belgium based company Horse Power Ignition. It's the 210 model. I refitted the flywheel again today and managed to get it to fire briefly - very briefly. It is close but just not close enough. The stator lines up ok with indicator marks on the cover ok. The flywheel is still a bit of guess work. I've attached a photo of the setup.