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the baffle itself is fine, it's a "competition" baffle so it is just a tube with louvers punched into it. Maybe I will try some steel wool to dampen it down. I used to use fiberglass house insulation but I don't want to touch that stuff anymore.
Based on my efforts to tame the "mighty" Emgo last year, stick with the glass. Stainless lasts longer, but glass is quieter.
 

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Ya, but Geets and Jag are quick to throw in face that mine is close but doesn't run.:)
I do not think I ever did that. If I did it was not to be mean

Is it getting a fairing?
Nope.

Nah it's cool and you know I'm not a big fan of Hondas. Is that CR750 tank aluminum?
Glass.

For Geeto this was a pretty rapid project. Plus factor in the day to day Dad/Husband/Work stuff and it really seems like a quick project.
Yeah this is really a fairly good pace.
 

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Discussion Starter #784
Quickie update:

I finished rebuilding the rear master, mounted it and started bleeding it. I bench bled it and was working pefectly before I bolted it to the bike, and once mounted started pumping fluid until.....the new shaft seal let go. I think the internal seal may have gotten hung up on something and inverted allowing air to suck in or the seal just failed for defect. Either way. I am done working on this stupid thing and am not going to take it back off or rebuild it at this point.

I let the bike sit for a couple of days and the #2 carb started leaking out the bowl vent very heavily. Once the bike was running and warmed up it didn't do it at all so....maybe it was a piece of dirt. I will drop #2 bowl later this week and inspect.

Still trying to figure out why the bike is running rich in the lower revs and kind of choppy. I went for a 7 mile ride to warm it up and got back and it was still popping out the exhaust every once in a while at idle and hunting for a steady idle. So I looked at the martek and noticed that the pointers were a hair advanced. I loosened the screw and backed the timing back a little and the bike smoothed out considerably. Went for a half mile ride and for the first part the bike was spot in almost all throttle positions. but when I got back it was back to the same and the martek had walked forward. It looks like the screws have worn a depression in the plastic so when I retarded the timing the washers were not in full contact and the ignition walked back to it's old position. Not sure how to cure this other than filing out the depression by filing the whole face of the unit or replacing the unit entirely. I need to think on this one, but I might just get some serrated washers and file the depression out.
 

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Thread locker
 

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Discussion Starter #786
Thread locker
the screw isn't moving, the thing the screw secures is moving because the screw doesn't have even purchase. Threadlocker would be useless. can't tighten it down more either because I suspect that is how the depression was made in the plastic in the first place.
 

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Discussion Starter #788
there are washers there already, and I am hesitant to put RTV on the housing but it might work. I have a points plate from Jag, but aside from being poorly timed, this martek unit seems to be working well and I want to see if I can get it dialed in.

you know every once in a while I would turn the key and it would fire a shot through the exhaust. Not being timed well might explain it.
 

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...this martek unit seems to be working well...
I installed a Martek on my 550 in 1980 and never touched it till I totalled the bike in '87 and stupidly sold it with the wrecked bike (and it was unharmed).

That's the bike I should NEVER have sold. A new crank & forks would have fixed it...
 

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Discussion Starter #790
So, I was a total noob this weekend and I'll explain why.

Saturday I decide to take the F down to our local cars and coffee meet. Wanted to scrub in the tires and get some more shakedown miles. All morning the bike was running like a top, it was fast, it jumped when I whacked the throttle open, it idled beautifully. I park it down there, everyone ohhs and ahhs, I drink way too much coffee, it's a productive morning. On the way home I decide to stop over at the local gas station to check the tire pressures where I realize the guy who mounted the tires didn't pull the valve stem all the way through in the rear and I can't get a gas station compressor fitting on it (more on that later). Halfway between the gas station and home (probably about 2-3 miles) the bike starts breaking up and dropping cylinders to the point where I am WFO and barely holding 30mph. I manage to make it to the road leading to my complex before it dies. I try restarting and no good. I push to the side of the road, wait 5 minutes, try it again and it fires right up and idles and I haul ass down the road only to have it loose power and die 200 yards up. I wait, restart again, and limp to my garage.

I think to myself: "I've had this happen before, must be the coils since it only happens when it gets hot". I don't check anything other than the plugs which show 1&4 as carbon fouled, and 2-3 as wet but not fouled. So I proceed to dig out a set of really nice cb750 andrews coils jaguar gave to me a while ago. The only down side is that I don't have any plug wires. So I proceed to spend my weekend chasing down plug wires and ends because, shock of shocks, none of the autoparts stores carry plug wire they sell by the foot anymore. I had to either buy a 30 foot roll or 100 foot roll. I manage to get a "kit" from jegs for $30 for a v-8 which is about what a good set of 4cyl wires and ends would have end up costing me ordering online.





I replace the coils, and then proceed to ride the bike to test it. Well guess what - same exact thing happens to me again, this time with the bike semi-cold (not fully warmed up) and I don't even make it a mile from my house. It takes 4 wait and restarts to make it the 3/4 of a mile back to my garage. That's what I get for being a total noob and not running proper diagnostics, well...that and the hoisting of my own petard that is writing this post explaining about it. When I got back to the garage I tested spark and all 4 seem to have spark but cylinders 2-3 are just not getting hot (I was able to grab the center pipes with a gloved hand, something I can't do on 1-4. All 4 are getting fuel, and there are no air leaks I can tell. So....thoughts?
 

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Sounds like a bad coil.
 

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Discussion Starter #793 (Edited)
Sounds like a bad coil.
eat a dick.

I'm starting to think the regulator/rectifier has gone bad. I had this happen on an old cb750F I had where the reg/rect took a shit and the bike would run fine at idle but at highway speeds the battery would discharge and the bike would sputter and die.

Something electrical is going on, I just need to figure out what.
 

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Lol...
 

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you should look at making it run with no battery, like a true cafe racer. then you could get rid of the worthless airbox and open up the center triangle for a true cafe racer style.

- - - Updated - - -

I wound up getting a polaris R+R for my GS750... any similar options for CB750's?
 

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Didn't the same thing happen a few months back?
I thought you posted an ignition problem on your bike with a couple cylinders before and figured it out.

Not much help, but just wondering what got it working then and what you replaced since then.
 

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Discussion Starter #799
Why would only one coil be effected by battery discharge?
as near as I can figure it, because the trigger for 1-4 are leading - (they are what you set timing by) and the trigger for 2-3 are trailing. The way the martek is setup you can really only set timing for the 1-4 coil and you have to hope the 2-3 is lined up. If it is off for whatever reason, the 2-3 coil might not be recovering enough electricity after the 1-4 fires and unlike a stock system there is no way for me to check it (stock points plates have marks for both sets). If the regulator/rectifier was not allowing consistent charging then it might be taking longer for the battery to recover, remember in a cb750 the ignition triggers need to have constant power.


Didn't the same thing happen a few months back?
I thought you posted an ignition problem on your bike with a couple cylinders before and figured it out.

Not much help, but just wondering what got it working then and what you replaced since then.
Well that's the funny thing about bikes is they can sometimes have issues stacked up on other issues, and until you are riding and diganosing, you can think you solved a problem because it has gone away in the garage only for something to surface later once you are actually using the bike. I may have thought I solved a problem earlier, but now that I am riding it, a new problem is emerging or I am finding I delayed the older problem or changed the parameters.

Here is what I know so far:
- Plugs are fouling on 1-4
- center pipes (2-3) are not getting as hot as outer pipes
- spark plug tester shows all 4 plugs getting spark
- When I assembled the wires all wires had continuity
- When I first bought the bike, all plugs showed a rich condition

Here is what I need to know
- Is the bike charging and if so how much? Last checked when I first got it running but not since then.
- what is the resistance in the wires? (should be less than 50 ohms per foot and less than 10 in the caps).
- What is the compression? low compression could cause a misfire.

From there I can start to figure out other things. My guess is that this bike was put away for an issue where it is running rich and I think I am still fighting this problem 25 years on.
 
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