Half-Caf: my '80 cb750f SS cafe project

[Half-Caf]

Hello all! Just purchased my first bike last weekend. I am now the proud owner of a 1980 Honda cb750f Super Sport. Took my MSF course this past weekend and am really anxious to get out there and ride.

I purchased the bike knowing it had some electrical issues: a turn signal bulb was burnt out; the bike's battery would drain rapidly; etc.. I work in the A/V industry and have experience troubleshooting and repairing electronics, so I wasn't too intimidated.  

Also, the bike runs, but it takes a while to start up and I feel like the choke has to be used a little longer than it should. Once it is running, I noticed that the engine runs a little rough and makes a popping noise as well (not quite a backfire). He said that the carbs and plugs had been cleaned recently and they might just need synced.

What I have done so far:
-Some basic electrical troubleshooting. I found that the wiring for turn signals (aftermarket w/ running lights) was all messed up, which explains the burnt bulb. I bought new single-filament signals off ebay and will replace them this weekend. I also found that one or two of the fuses were bad, so I replaced all of them with shiny new ones.
-Purchased new NGK DR8EIX Iridium plugs (will also install this weekend)
-Bought a can of Seafoam to run through the system (tips appreciated with this)
-Got some carb cleaner because I'm guessing I will need to clean out the carbs or at least the jets. I don't necessarily trust the seller on this point...

He said the oil had not been changed this season, but the bike was not used much. I would feel better changing this out as well. I found this thread recommending Shell Rotella T6. I live in Chicago which gets hot in the summer and way too cold in the winter (the bike will be stored in a non-heated garage). Would the T6 work well? I haven't been able to find the filter I need either in my manual or the shop manual on this site.

By the way, I was really excited to find this forum and have already been well-educated as a result!
I attached a couple pictures of the bike that were from the previous owner. I will be sure to put more up when I work on it this weekend.

Oh yeah, and I purchased the bike for $750..
So I think the work I do will be well-worth it (I also really enjoy my little projects).

[TOOLS1]

The iridium plugs will help. Also the little backfire thing could be the carbs needing synced, or the air cut valve on your carbs. I always use Texaco Havolin 10W-40, and change every 3,000 miles. My engine is very clean. I also use Fram CH 6009 filters. You can get them at most auto parts stores, and they come with new O-rings.
TOOLS

[Half-Caf]

Awesome. Thanks, tools! I will post an update once I've swapped a few things out.
Now changing the the oil and filter is on the weekend to-do list as well.

[Half-Caf]

Put on the new plugs today -they really made a difference in how fast this thing started up!
The idle is much smoother now and doesn't need the choke nearly as long. However, the temps across the headers are not even at all: Soon after startup I could rest my hand on the far right one, then burnt my hand on the far left

Also, don't think I have the stock coils (I have 2 different kinds). Will post a pic once I get off work this evening..

[Half-Caf]

Yeah, one of them was definitely one of these guys:
http://www.motorcycle-superstore.com/3/13/123/24683/ITEM/Accel-Universal-Super-Coil-Kit.aspx

Expensive little buggers!

[Half-Caf]

Here's a few shots of some things I encountered today..


The far left spark plug was dry and brown looking compared to the others.


Aftermarket air filter


A shot of the two different coils


Guessing this is for the oil light?


These were the gaskets from the exhaust. Definitely seems off..

Especially being new to the whole motorcycle thing, I definitely feel like I have my work cut out.

Question about the coils: Is it bad to not have a matching pair?

[TOOLS1]

It will not hurt anything, but it might make it hard to sync the carbs since one set of cylinders might be firing hotter.
TOOLS

[Half-Caf]

A little update: So far I have run some seafoam through the fuel system and crankase, changed the oil, put in new signals, replaced plugs and all fuses, and found that I need a new charging rotor. Vacuum gauges are in the mail, so once I get those and the new rotor, I am hoping she will run beautifully.

Other than that, I am looking into making some custom side covers and considering paint options -we'll see what happens with those...

[devildawg712]

I'm actually experiencing this popping noise as well. I assumed it had to do with the carbs since I increased the main jets after moving to pods.  

I also am having that crappy issue when starting the bike. Im not really sure what it is. From what I've read it's a number of things. Starter, rectifier etc.  I'm not sure if my battery drains quickly per se'  but I do know that I have like 2 or 3 chances of starting the bike with the push start before the bike starts to be unresponsive so I turn to my kick start very fast.  have you solved that issue and how so exactly?

Thanks in advance. Love this forum

JR

[Piute]

Hello and Good Morn , Half Caf

   Not sure what issues have been solved,over the week you've been here,
 My 77 f had been setting for 6(?)yrs then 10 before that 1month of being played with .
O.K.
 hook up a I.V. gas tank / car batt. and she fired up
   Didn't sound right after 5-8 min run with Sea Foam,like you ! had 2 cold pipe's #3 being the coldest ,
One of my carbs was gummed up #3 and #3 had a bent pilot scew
  ; had taken each apart and cleane and back together (old parts)
check electrical and coil wires were switched (blu--yel)at stk.splice under carb area.
   Fired her up again (starts just fine)
  Idle wouldn't drop  at all ,;removed 'cleaned ,oiled all cables
and pulled and checked out carbs (just a good look see) and silicon lubed all exterior moving points,
 And removed throttle return cable,throttle working great but idail still not droping fast "to me".

   Paul (my tech guy)looked inside carbs and said my first squirt gas(Accelerator / diaphragm) wasn't working
 replaced that ,and just gauge synced carbs ( to get back close fer now)
 No more pop,stuck throttle, all pipes even temp
    ,
 
     
Just thought I'd share with you derectly seem these are common probs. and mostly a matter of time cleaning and double checking your own work,(I was the one that switch the blu--yel wire ?)
 Take your time and enjoy >>>Piute<<<N>>>judose<<<

[Half-Caf]

Devildawg, I would look further into the charging system before I messed any more with your carbs.
These bikes actually need the charging system in working order to run properly.

This post by cheesehead is a great place to start:

"As for the charging issue, fire it up and make sure it's at 2000+ RPMs and put a volt meter/multimeter on the battery and see how many volts you're getting. You should be getting approx. 13.5-14.5 volts. If it's in the 12 volt range, you definitely aren't charging.

If it's NOT charging, it can be one or more of 4 things, the battery, stator, rotor, or regulator/rectifier. To check your stator, follow the fat wire that comes out of your stator cover up until it plugs into the wire that comes from your R/R and unplug it. On the stator end you should see about 6 holes with 5 wires in them, 3 yellow, one black, and one white. Set your volt meter to test OHMs. Stick your red and black lead on your meter in ALL combinations of the YELLOW wires (4 total combinations, I think). I read that it should read .5-.6 OHMs in each combination, but in reality it may read .8-.9, mine all read .9 when I checked it, which verified that my stator was good. If that's good, remove the stator cover and you will see the rotor staring at you. On the rotor are 2 copper rings, one large and one smaller. Again set your meter to OHMs and stick one lead on each ring, then reverse it and check the leads on the opposite rings (All of this with the key removed, by the way). It should read somewhere between 4-6 OHms, I think the 4.2 range is the norm. Mine read 1.1 when I tested it, verifying that my rotor was in fact my problem. I had my battery checked at autozone and they said it was still good, but old, so I bought a new one anyway. If your stator, rotor, and battery are all good, the only thing left would be the R/R, so it is more than likely bad. Unfortunately, I'm not 100% sure how to check it so I'm not going to give you bad info on it. But if all else is good, it has to be the problem, assuming all terminal/battery connections/ground wires are good.

You can refer to my link here for a couple pictures and maybe a little info.
http://honda-cb750-s.456789.n3.nabble.com/1981-CB750k-not-charging-the-battery-td3144722.html

Brian"

Sorry, if that's a lot, but If found it very helpful. The original thread can be found here.

[Half-Caf]

Thanks for the tips, Piute. Like I said to devildawg, I am waiting to get my new regulator in to see how that effects things before I begin with the carbs.

However, when I replaced the plugs with the new iridium's ans cleaned all the coil connections, that seem so help, if not resolve, the uneven heat distribution.

Verifying that the plugs are hooked up in the proper sequence is also good advice, as my coils have been changed.

Will keep you guys posted!

[Piute]

opps i did put those plugs in .,plugs and batt. is atoumatic on any ride

[TOOLS1]

Did, you say "automatic"?
TOOLS

[Half-Caf]

So, its been a while since my last update. In shopping for a new rotor, I found a few places that actually rebuilt them. So, being the mechanically minded individual that I am (not to mention thrifty), I decided I would just repair the rotor I already have.

Long story short, I repaired the rotor and fired up the bike to find it ran WAY smoother than before. So, Devildawg and others who have both charging and other suspected issues, I definitely recommend resolving the charging problems first.

I did notice that the bike idles differently than is did before the rotor was repaired. The bike used to idle around 2k once it was warmed up. Now it runs much smoother, but the idle is much lower. So low that when the throttle is not applied, the bike will just die (even in neutral).

Going to check the obvious solution of the idle adjust screw first and go from there.

[Half-Caf]

Also, some other happenings:
-got my new license, plates, and registration yesterday!
-went for my first real ride last night (dark out, rain, and urban highway)
-got my vacuum gauges in and going to sync the carbs this weekend

[shinyribs]

Awesome!Glad you are up and riding.I cant wait to get on mine and ride.It's killing me

[Half-Caf]

Took it for a brief spin today and noticed it was running very rough again. There was an uneven idle and even a lurching when in first gear.
Scratching my head because it was so smooth last night

Hopefully the charging system is all working properly now, but maybe it just needs a full day on the trickle to give it a good foundation.

Also just found out that I have off tomorrow! Maybe I will take the carbs off and soak them until Saturday.

[Half-Caf]

Tools, how would I know if the air cut valve is bad on the carbs? Going to pull them tomorrow most likely and I want to check as much as I can while they are off.

[Piute]

\
 Alright Half Caf,Good to no that good chargeing sytem can make that much difference,
  Waiting on lic N Ins. my self,cause I'll ride it I no(thinking I wont get caught)