CR won't hit powerband

R

Rockey5000

Mod Ban

May 6, 2002

293

0

• Sep 29, 2002

• #1

My friend has a 1990 CR125 that shattered a skirt and needed an expensive repairs, the bike got a new top end also, which my friend never broke in. It ran fine for like 2 weeks but now it won't hit the powerband. Two days later it refuses to start. Seemes to have same compression as usual. Any ideas?

 

H

Hucker

~SPONSOR~

Sep 15, 2000

996

0

• Sep 29, 2002

• #2

Check the powervalves? Could be all gummed up..

 

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Stew312

Member

Jul 8, 2002

162

0

• Sep 29, 2002

• #3

It would most likely start fine with gummed up power valves, you need to check the timing. Pull the Magneto cover and take off the flywheel, make sure your woodruff key is not sheared. The flywheel could not have been tightened down properly (or not have a nut under the washer), causing it to slip a little bit (throwing off your timing enough to not hit powerband), and then slipped a little more causing it to not start. I'm guessing the bike backfires every once in a while when you kick it?

 

S

Stew312

Member

Jul 8, 2002

162

0

• Sep 29, 2002

• #4

*nut under the washer = washer under the nut

 

R

Rockey5000

Mod Ban

May 6, 2002

293

0

• Sep 29, 2002

• Thread starter
• #5

I will check the powervalves and the timing, and yes it does backfire once in a while hile kicking. Thanks for the help and keep the ideas coming.

 

S

Stew312

Member

Jul 8, 2002

162

0

• Sep 29, 2002

• #6

If its backfiring, I'd bet $100 on the timing. I've had powervalves locked in both positions for some periods of time, locked down = bad top end & starts fine, locked up = starts almost perfect, but has bad bottom end. Good luck.

 

W

WorldWideRacer

Member

Jul 12, 2000

78

0

• Sep 30, 2002

• #7

Start on the simple things. Is the spark-plug new? Do you have spark? Then do an actual compression test and see what the reading is. It is pretty rare for the timing to suddenly be incorrect. If anything, you might have a bad connection somewhere in your ignition system.

 

David Trustrum

~SPONSOR~

Jan 25, 2001

1,396

0

• Oct 3, 2002

• #8

WWR, so you’ve never broken a woodruff key then?

More common with trail bikes with larger flywheels but a lesson you don’t forget is to carry a spare taped to something lest you are stuck 5 miles from your truck on a long rocky beach trying to make a new one out a small stone. (PS don’t bother). :(

But yes I would take the bet of the sparkplug as most likely cause. (Not that I’d ever pay up).

 

L

Lespaul20

~SPONSOR~

Jun 23, 2002

62

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• Oct 3, 2002

• #9

I've broken a key before on my 1990 ktm, just got it rebuilt and put it together and it started once and didn't start after that. My flywheel wasn't torqued down and just sheared the key right off. Really sucked. I'd listen to stew and check that.

 

S

Stew312

Member

Jul 8, 2002

162

0

• Oct 3, 2002

• #10

yea, i went through 5 keys before i realized there was no washer under the flywheel nut on the bike i just bought, talk about pain in the ass..

 

David Trustrum

~SPONSOR~

Jan 25, 2001

1,396

0

• Oct 3, 2002

• #11

Good idea to lap the flywheel onto the shaft for a few min with some valve grinding paste so it contacts more evenly.