Topic: 750 Missing under load

[754]

 Set my points two days back, 2-3 stopped working, despite recleaning a few times. When I found a file and cleaned the pit  off, it then worked fine.
Next day. I rode it a few hundred miles. A few times it would cough thru carb under load on a hill but worked good for 160 miles.
 Then it started to crap out under load on hills. After 4 k mostly , sometimes it would kick in or out. Pulled over cleaned the points, felt fine at first, then did it again....limped it home.

 Started up this morning, felt fine, revved clean after about 7 miles started acting up , same thing.. Higher the gear..more load..the more it does it..

 I suspected a component failure as it get warmer. I can see a coil failing, completely, then working again after it cools..but this is intermittent .
 Can it be a condenser, I am not sure how they act up when they fail..

 Any ideas ?

[ekpent]

Do you have a different condenser you can pop in there ?  I sold a 75F to a friend that had a bad miss on would fall on its face at 4,000 rpm. He tried bigger slow and main jets and other things then mentioned to me one day it was running great when he swapped out the condensers. Worth a shot and easy swap.

[754]

I got a few spare used point plates.. Condenser wire is a bit loose, that maybe tells me..
First thing i will change is condensor..

[BobbyR]

I got a few spare used point plates.. Condenser wire is a bit loose, that maybe tells me..
First thing i will change is condensor..

When a condenser either fails or loses connection the points can literally arc weld together. That may explain your having to file them after an episode. You are getting a super pit when the connection is lost.

[540nova]

As you described it, the first thing that came to my mind was the condenser. My 1967 Ford truck did the same thing.


1974 CB450, 2006 CBR1000RR

[754]

There was a severe pit, i had sanded it, then it stopped firing till i found a file and got the pit off. The wire moves if you pull it, should tighten it before i do anything..
Looks like condenser problem.

[seanbarney41]

Yeah frank, that sounds similar to condensor failure I have had before

[Garage_guy_chris]

This sounds very familiar, I was having similar issues. I was having to adjust points / timing every couple hundred miles finding it out a few degree's every time. Bike would start running like crap coughing and spitting and dropping cylinders. Finally after a bad bout i went to stick my feeler gauge in the gap and it would only go in a little. I opened up the point and found a spike of metal protruding from one side and going into a hole on the opposite face. completely trashed.  I started looking at the price of the good points (not daichi) and realized it was cheaper and easier to buy a Dyna S. I put the Dyna S in about 2 months ago, recently rechecked the timing and its dead on.

[BomberMann650]

Of all the things that can stop a honda4 from runnin.  An ailing condenser is the one to have.  Simplest little thing 

[Terry in Australia]

What's a condenser? Didn't they go out of fashion with buckled shoes and capes?

[seanbarney41]

He he, yeah terry, only slightly more technologically advanced than the pushrpd v twin

[PeWe]

Single cam and DUAL condensers, that's a CB750 to be proud of!!! Electromechanical wonders from the past still living in the future. It's a time machine!!

[Terry in Australia]

He he, yeah terry, only slightly more technologically advanced than the pushrpd v twin

Ha ha, well I just finished watching "Harley and the Davidson's" (what a great show) and discovered that Harley actually kick started the motorcycle industry in Japan! Of course the old Harley's ran points and condensors 30 or 40 years before SOHC4's Sean, so I guess you guys are all getting misty eyed about Harley technology! Good job!

[BobbyR]

He he, yeah terry, only slightly more technologically advanced than the pushrpd v twin

Ha ha, well I just finished watching "Harley and the Davidson's" (what a great show) and discovered that Harley actually kick started the motorcycle industry in Japan! Of course the old Harley's ran points and condensors 30 or 40 years before SOHC4's Sean, so I guess you guys are all getting misty eyed about Harley technology! Good job!

I was always a fan of real tangible horsepower:

[seanbarney41]

He he, yeah terry, only slightly more technologically advanced than the pushrpd v twin

Ha ha, well I just finished watching "Harley and the Davidson's" (what a great show) and discovered that Harley actually kick started the motorcycle industry in Japan! Of course the old Harley's ran points and condensors 30 or 40 years before SOHC4's Sean, so I guess you guys are all getting misty eyed about Harley technology! Good job!

terry, I hope you know I dont really hate harleys.  I hust realized long ago that its easy to rile harley owners by pointing out their ibvious deficiency s.   All bikes have them, some just cost more than others

[BomberMann650]

Electromechanical wonders from the past still living in the future. It's a time machine!!

The steampunk movement can eat their heart out.

[754]

Hey my Maxi-dwell is modern stuff, has solid state condenders..
I should put that in there..

[ekpent]

Hey my Maxi-dwell is modern stuff, has solid state condenders..
I should put that in there..

And 350 chevy points-got one still in the original packaging also. Only negative I have heard on those is the aluminum backplate the changes with heat.

[Terry in Australia]

He he, yeah terry, only slightly more technologically advanced than the pushrpd v twin

Ha ha, well I just finished watching "Harley and the Davidson's" (what a great show) and discovered that Harley actually kick started the motorcycle industry in Japan! Of course the old Harley's ran points and condensors 30 or 40 years before SOHC4's Sean, so I guess you guys are all getting misty eyed about Harley technology! Good job!

terry, I hope you know I dont really hate harleys.  I hust realized long ago that its easy to rile harley owners by pointing out their ibvious deficiency s.   All bikes have them, some just cost more than others

Ha ha, yeah mate, I know that. My beautiful new (to me) 1999 Honda VTR1000 (with under 30K miles on it's odometer) is in bits in Jeff's shop, with a busted cam chain tensioner, a common problem with this model that Honda was never able to remedy, so they just ignored the problem, discontinued the model, and moved on, not offering a recall for the thousands of bikes that have, or will, need expensive repairs as a result of their poor design.

As Simon mentioned, it's amazing how 30 years after Honda released the mighty CB750, they still couldn't build a decent cam chain tensioner? Can you imagine the field day that the haters would have if Harley built a bike that self destructed in under 30K miles and didn't fix it?

Anyway, once Jeff has repaired the head and replaced the valves, and installed some after-market cam chain tensioners, (it's incredible to me that even China is making cam chain tensioners for VTR1000's, and they're still better engineered than Honda's OEM product?) re-timed the valve train etc, it should be good to go. I'll get him to replace the water pump while the engine's out, they are another problem on an otherwise nice bike.

[John Eberly]

Did the condenser swap fix your problem?

You should probably invest in new points too. Once the surface plating wears off the points are going to corrode, pit, and need frequent adjustment.

[754]

I did not find one of my spare point plates yet, got at least 4.
Ran out of time at the storage place.... So no have not changed it yet.

[Pan1cReaper]

Sounds just like what I have been going through with daichi condensers. Has left me with a weak twin 225cc bike a couple times now. I think Im going electronic either hondaman or pamco. Just cant stand buying them any more, daichi or otherwise. Everything else checks out, condensers just failing whenever they want.

[Terry in Australia]

Yep, don't mess around mate, get an electronic ignition, install it and forget about it. I've had one in my bike since I built it 10 years or so ago and I haven't removed the points cover since then. Cheers, Terry.

[754]

I would put my Maxi-Dwell in before electronic..
 I think I have a complete Dyna 1 , but no desire to use it .
 Rather put my magneto on.
 Found out 74 Pinto condensers fit..

[Terry in Australia]

That's up to you of course Frank, use whatever you like, of course nothing built since 1980 has used points, but if you had an electronic ignition installed, you would never have had to start this thread, you'd be out riding........