Topic: Symptoms of a skipped tooth?

[Broseph]

Hey everyone!

At the end of last season my bike started to bog down in traffic and loose power. I was able I ride home  but was not running on all cylinders. Checked cylinders when home and it looks like cylinder 1 was not running and  3 is running intermittently. Parked it for winter as I ran out of time. Been doing tests to find cause or to eliminate options such as switch spark plug, plug wires, new spark plugs, compression, tappets and cleaned carbs. I noticed the cam chain tensioner bolt was backed off. I am hoping someone can tell me what would be the symptoms if the cam chain skipped a tooth while riding. I feel like I’m going around in circles now and feel like I’ll end up restarting process after an oil change and spark plugs to have a baseline to start from. If tooth has been skipped could a bike still run? Anyway to do a test before pulling engine? Thanks in advance!

[bryanj]

Never heard of a cam chain jumping a tooth unless it was very loudly clattering before and it woud affect all cylinders not just 2

[Broseph]

Thank you for the quick reply. Makes me feel better knowing it probably isn’t the cause as two cylinders have been running fine. I guess I’ll go back through testing after cleaning the carbs again and see if I find anything. Thanks again

[70CB750]

What cylinders are not running?  The ignition pairs 1 with 4 and 2 with 3.  Try to swap the blue and the yellow wire at coils.

[RAFster122s]

Pull your spark plug caps and put a good ohm meter on them. Bet they are shot.

[BenelliSEI]

+1 to the above. Replace your plugs and caps (snip 3/16” off the plug leads to get a clean, new connection to the caps) before you do anything else

[Broseph]

What cylinders are not running?  The ignition pairs 1 with 4 and 2 with 3.  Try to swap the blue and the yellow wire at coils.

Looks like it’s #1 not running and #3 intermittently. If 2 and 4 are running could it still bee coils?

[Broseph]

Pull your spark plug caps and put a good ohm meter on them. Bet they are shot.

+1 to the above. Replace your plugs and caps (snip 3/16” off the plug leads to get a clean, new connection to the caps) before you do anything else

Thank you for your ideas. I’ll have to look up how to test and start with that and cut of a little bit at the ends. Thanks again

[schwartzstuart6]

Here to read ,comments and learn

Sent from my SM-A107F using Tapatalk

[70CB750]

What cylinders are not running?  The ignition pairs 1 with 4 and 2 with 3.  Try to swap the blue and the yellow wire at coils.

Looks like it’s #1 not running and #3 intermittently. If 2 and 4 are running could it still bee coils?

Thats not typical but make sure to eliminate electrical problems befor you dive into carburetors. 

If you have shop manual, do the 3000 miles msintenance. 

[robvangulik]

What cylinders are not running?  The ignition pairs 1 with 4 and 2 with 3.  Try to swap the blue and the yellow wire at coils.

Looks like it’s #1 not running and #3 intermittently. If 2 and 4 are running could it still bee coils?

Did you put the plug leads in the right order?
As said above, the left coil services 1 and 4, the right side coil the middle cylinders, 2 and 3....

[Broseph]

Thank you all for your info! I’ve checked the plug leads and it checked out. Did continuity test on capes and cylinder one, that wasn’t firing, didn’t give me a reading at all!The other three were between 5k and 5.5k. Will replace dead cap. Do I have to replace all caps at once or should be fine leaving the other three? Will trim some off leads when reinstalling, add new spark plugs and do an oil change. I don’t have a shop manual but I should buy one to have all info in hard copy easily accessible. Could there be anything else in the electrical system I should check that could be a culprit on intermittent running cylinder 3? Thanks again to everyone.

[david 750f]

It’s fine to just replace the one spark plug cap if the others check out OK.
Swap 2 & 3 wires as they use the same coil. If the problem follows the wire it is electrical, if not then it’s usually in the carbs.

[70CB750]

Thank you all for your info! I’ve checked the plug leads and it checked out. Did continuity test on capes and cylinder one, that wasn’t firing, didn’t give me a reading at all!The other three were between 5k and 5.5k. Will replace dead cap. Do I have to replace all caps at once or should be fine leaving the other three? Will trim some off leads when reinstalling, add new spark plugs and do an oil change. I don’t have a shop manual but I should buy one to have all info in hard copy easily accessible. Could there be anything else in the electrical system I should check that could be a culprit on intermittent running cylinder 3? Thanks again to everyone.

Shop manual is available for download here, on this forum.

[Broseph]

It’s fine to just replace the one spark plug cap if the others check out OK.
Swap 2 & 3 wires as they use the same coil. If the problem follows the wire it is electrical, if not then it’s usually in the carbs.

Thanks I’ll do that as soon as I get the parts in.

[Broseph]

Thank you all for your info! I’ve checked the plug leads and it checked out. Did continuity test on capes and cylinder one, that wasn’t firing, didn’t give me a reading at all!The other three were between 5k and 5.5k. Will replace dead cap. Do I have to replace all caps at once or should be fine leaving the other three? Will trim some off leads when reinstalling, add new spark plugs and do an oil change. I don’t have a shop manual but I should buy one to have all info in hard copy easily accessible. Could there be anything else in the electrical system I should check that could be a culprit on intermittent running cylinder 3? Thanks again to everyone.

Shop manual is available for download here, on this forum.

Oh that’s great! I’ll have to print it off! Thank you