Topic: Losing 2 cylinders when warm - CB750K2

[gotorx7]

An update!

It's been quite a while, as I decided to replace the rims and spokes due to their poor condition.  Turned out to be a bit of a faff, but all done now, and very happy with the results, they have given the bike quite a lift in appearance.

Then when that got done and I started to put everything back together I found that I'd thrown out the little rubber exhaust balance tubes, and new ones took AGES to get to me.

When they finally arrived I was just about to head off on a 5-week holiday, and had purchased some more bikes (see my Signature!) which were keeping me busy so I never got around to a test ride.

FINALLY! got back from holidays this week, and got the old girl out for a ride, and WOW!  What a difference from when I got her, and she felt like I remembered a 750 should run, so very happy on that front too.   I have a couple of minor adjustments to do, including some fine tuning on the timing as suggested by PeWe but I'm now confident to get out and ride! 

Thanks for all your suggestions and advice,really appreciated.   I'll get some more pictures up soon, and of the "new" 76 and the others.

Cheers, Dave

[Deltarider]

(sigh) All in all a disappointing thread. We have learned nothing, except that you've spent a lot of money on too many parts.

[gotorx7]

(sigh) All in all a disappointing thread. We have learned nothing, except that you've spent a lot of money on too many parts.

I'm sorry to have disappointed you.

I certainly learned a lot through the process, particularly that the problem was a faulty coil pack, that worked fine when cold, but failed when warm.  As I think I mentioned, I was a bit hampered with testing due to the inconvenience of having a driveway that is WAY too steep to push a bike up (most people struggle WALKING up it!) so was reluctant to road test until I was fairly confident I could get back home again.

But I have a bike that runs great now, and feel like the money I spent was well worth it.

Cheers, Dave

[Deltarider]

(sigh) All in all a disappointing thread. We have learned nothing, except that you've spent a lot of money on too many parts.

I'm sorry to have disappointed you.

I certainly learned a lot through the process, particularly that the problem was a faulty coil pack, that worked fine when cold, but failed when warm.  As I think I mentioned, I was a bit hampered with testing due to the inconvenience of having a driveway that is WAY too steep to push a bike up (most people struggle WALKING up it!) so was reluctant to road test until I was fairly confident I could get back home again.

But I have a bike that runs great now, and feel like the money I spent was well worth it.

Cheers, Dave

I'm sorry you have missed my post on the simple DIY coil tester that anyone can make: http://forums.sohc4.net/index.php/topic,206147.0.html
Maybe it has been moved to 'Electrical' too quick where it may have drawn less attention.

[PeWe]

Good experience to know.
"worked fine when cold, but failed when warm."

[Deltarider]

Good experience to know.
"worked fine when cold, but failed when warm."

That's why just measuring the coils' resistances is a bit trivial. A 10 min. bench test* is a better way to determine whether a coil is still good. The same goes for the condensers btw.
* If you run both coils in such a test - one after the other - you may point an infrared gun, to detect any significant difference in temperature. I have not done this myself yet, but I will in the future.

[gotorx7]

(sigh) All in all a disappointing thread. We have learned nothing, except that you've spent a lot of money on too many parts.

I'm sorry to have disappointed you.

I certainly learned a lot through the process, particularly that the problem was a faulty coil pack, that worked fine when cold, but failed when warm.  As I think I mentioned, I was a bit hampered with testing due to the inconvenience of having a driveway that is WAY too steep to push a bike up (most people struggle WALKING up it!) so was reluctant to road test until I was fairly confident I could get back home again.

But I have a bike that runs great now, and feel like the money I spent was well worth it.

Cheers, Dave

I'm sorry you have missed my post on the simple DIY coil tester that anyone can make: http://forums.sohc4.net/index.php/topic,206147.0.html
Maybe it has been moved to 'Electrical' too quick where it may have drawn less attention.

I didn't see that post, unfortunately.  One of the problems on forums like this is that there is a HUGE amount of information, and unless you know pretty much exactly what to search for, it is easy to miss.  Thanks for taking the time to create that post and I will refer to it in the future, no doubt.

[gotorx7]

Just to wrap this thread up, I spent several hours riding yesterday, and the bike was a delight!

I am so pleased with the way it turned out, both visually and mechanically.

Thanks again, everyone, for all the help and guidance - it really is appreciated.

Now onto my K6 with everything I have learned

Stay safe!

[HondaMan]

That's a beautiful paddock of 750s!

[gotorx7]

Thank you!  And for all your help in particular!