Starter Motor "Run-On" - possible cause and remedy

John S. (5594) · Post by **John S. (5594)** » Tue Jul 22, 2003 9:40 am

Hi Folks,

My "new" 79 Z Model is exhibiting what I can best describe as starter "run-on" - I will try to elaborate. When the motorcycle is started (cold or hot), the sound associated with the starter mechanism continues for a few seconds after the engine lights. And aside from starting - this slight "whirring" noise seems to be present at times when the bike is slowed to a stop after a "spirited" ride (hot engine). Without knowing the cause - I would suspect that the starter clutch is not disengaging cleanly.

The bike has 15k original miles on the clock and has been beautifully maintained. I have this bike tuned better than my other two early models - it is really a joy to ride. But the possibility of a starter clutch problem sure dampens my enthusiasm. Something is not quite right and without knowing the cause - I am worried that there may be a serious component failure around the corner.

From what I know - the only motor work that has been performed on this bike was replacement of the OEM clutch plates - the previous (and second) owner said the clutch was "slipping". Short of abuse - I am a bit surprised that the original component(s) would have failed with such low mileage (I have looked at the OEM plates that were replaced and do not see the classic dragstrip signs). And as mentioned - the bike seems to have been serviced correctly and often.

As with my other CBX's - I run motorcycle specific Mobile 1 synthetic oil - changed excessively (at about 3k mile intervals). Since purchasing this bike last November - I have actually changed the oil twice in less than 2k miles. Close inspection of the old oil/filter and the residue remaining in the oil pan and pump screen revealed no metal contamination.

I have read that this starter "run-on" problem has occurred to other owners and could certainly use some help on this from their experience. Splitting the engine cases looks like a chore - but if it is required - I'll do it to correct the only "problem" that this nearly flawless motorcycle seems to have.

As always - thanks in advance for your advice. And all the best to you and yours,

John

San Jose, California

Jim-Jim · Post by **Jim-Jim** » Tue Jul 22, 2003 12:15 pm

Well, I'm certainly no expert but I'll give it a shot. The starter clutch is a version of the 'Sprague' clutch in that it uses little rollers that cam into a pinch point in one direction (giving grip) when the inside hub 'drives' [starter] and roll back away from the pinch point (loosing grip) when the outer hub turns faster [engine]. The first thing I think of, remembering some posts in the past, is that the engine oil is causing the rollers to remain engaged with the outer hub through 'stickiness'. I noticed that you said you were using Mobil 1 synthetic oil. While I have no quarrel with this oil, I have heard others say they have stopped using it. I would try switching to another oil - there is an 'oil thread' elsewhere in the Tech Section; personally, I have decided to use Shell Rotella T Synthetic 5W-40. I would replace the oil, run it through for awhile to flush the Mobil 1 out and then put in a new fill of whatever you choose. I would, though, use one of those discussed that work better in CBXs (non-auto oils). It may be a little trouble but, if it works, would be the cheapest way to solve the problem and the quickest way to see if it IS the problem. If you try it, let us know so we can 'file' it away for future reference.

sr71cbx · Post by **sr71cbx** » Tue Jul 22, 2003 7:58 pm

Dave Ditner · Post by **Dave Ditner** » Tue Jul 22, 2003 11:07 pm

If that were the case wouldn't the starter engage when the key was in the ON position? It would seem that if he turned the key off so that the engine stopped then turned it back to the ON position the starter would immediately run

sr71cbx · Post by **sr71cbx** » Wed Jul 23, 2003 7:36 am

Dave Hansen · Post by **Dave Hansen** » Fri Jul 25, 2003 6:45 am

If you were to put a test light on the starter side of the solonoid while cranking it, that would tell if the solonoid was sticking or if the clutch was sticking. If the light goes out when you release the button but the starter runs on, its the clutch. If the light stays on when you release the button, its the solonoid. Give that a try Dave

Jack Gutshall · Post by **Jack Gutshall** » Sat Aug 23, 2003 7:45 am

I have a similar problem with my '85 FJ1100. In my case it's due to a faulty starter button. It seems that the button spring is broken, so the switch stays engaged for several seconds (up to a minute) after I release it. This causes all sorts of weirdisms, like the ongoing starter, also the oil light stays on.