White smoke and lower end rattle

[Oscarg]

I just bought a 1981 cb 750 k knowing it was a project. But I could still use a little advise. It smokes a little and has a rattle In the lower end. I ran it and felt the pipes the one on the fer right if you were sitting on the bike is cold the rest are hot. I pulled the plug and it was dry  a little dark but dry. I put a new plug in the boot and held it to the valve cover and it had a real weak spark. Any suggestions..

[Oscarg]

Well the all four pipes are hot now since I put in a new plug. So what now still  has little smoke and lower end rattle at idle.

[TOOLS1]

The rattle sounds like the carbs need to be synced.
TOOLS

[rich]

Is the idle speed around 1100 1200 RPM? Anything lower and it'll sound like it's coming apart. Also, try pulling in the clutch lever and see if that changes the sound. The clutch baskets are known to knock a bit at idle sometimes. Adjust the cam chains, they make all kinds of noises when they're out of adjustment.

The smoke could be from oil getting by the rings, valves, valve guides, or seals or maybe it's just burning off some oil that accumulated. Has it been sitting along time? Is the oil fresh? A compression test will give some idea of the internal condition of the engine. The smoke and rattle could be a busted ring or piston, so you may want to check the compression first before you run anymore.

[Oscarg]

Oil was old and low and it was idling around 600  rpms  I filled the oil added new gas  with fuel additive it is now idling around 1500 rpm and most of the noise is gone. It still smokes but less may three more plugs will help. What's dose it take to sync the carbs? It runs smoother But hesitates as it accelerates.

Thanks Oscar

Sent from my iPad

On Sep 30, 2011, at 7:39 PM, "rich [via Honda CB750'S]" <[hidden email]> wrote:

Is the idle speed around 1100 1200 RPM? Anything lower and it'll sound like it's coming apart. Also, try pulling in the clutch lever and see if that changes the sound. The clutch baskets are known to knock a bit at idle sometimes. Adjust the cam chains, they make all kinds of noises when they're out of adjustment.

The smoke could be from oil getting by the rings, valves, valve guides, or seals or maybe it's just burning off some oil that accumulated. Has it been sitting along time? Is the oil fresh? A compression test will give some idea of the internal condition of the engine. The smoke and rattle could be a busted ring or piston, so you may want to check the compression first before you run anymore.

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[Oscarg]

I put the rest of the plugs and the end of #2 plug wire fell off. So I need a set of wires.  Do I need to pull the tank ? Forget just push into the coils like a car?

[Oscarg]

 I hate to ask you guys to solve all my problems. I just ordered a manual on e bay so I will be able to figure out some stuff on my own

[shinyribs]

There are manuals you can download on the top of the forum for free.I kinda hate to tell you that after you have ordered one. I can't believe your bike would idle at 600 rpms!!That is way low!Ask all you want man,that is what this forum is for.You gotta find info somewhere!I trust info from other riders more than i do interweb info.

Syncing the carbs is not nearly as hard as some guys make it out to be.It takes longer to get the tools setup than it does to actually sync them.You can get carb sync kits for around $60-65 on ebay.All you gotta do is make all the gauges match at the proper vacuum.Not hard at all.I am sure you can handle it with no porblem.I did mine in about 10-15 minutes and had never touched a CB750(or any other bike) until about 3 weeks prior.I'll get you a link to a set of gauges

[rich]

The factory service manuals are available for download on this site. Here's the link http://honda-cb750-s.456789.n3.nabble.com/NEW-Repair-manuals-April-26-2011-Updated-td685918.html

Of course you'd burn up your printer and spend $$ for ink if you tried to print it,  but the online will be handy until your paper one comes in the mail.

Edit: Shiny is faster than me even on the computer!

[shinyribs]

Here are the ones i got.Of course it is the only ones i have ever used,but i am extremely pleased with them.Looks like $75 shipped
http://cgi.ebay.com/ebaymotors/Carb-Synchronizer-Vacuum-Gauge-Carb-Sync-5-6mm-DEAL-/380370514102?pt=Motors_Automotive_Tools&hash=item588fd970b6


Try and keep up Rich

[Oscarg]

My iPad won't down load it

 Sent from my iPhone 

 

   Oscar

On Sep 30, 2011, at 11:50 PM, "rich [via Honda CB750'S]" <[hidden email]> wrote:

The factory service manuals are available for download on this site. Here's the link http://honda-cb750-s.456789.n3.nabble.com/NEW-Repair-manuals-April-26-2011-Updated-td685918.html

Of course you'd burn up your printer and spend $$ for ink if you tried to print it,  but the online will be handy until your paper one comes in the mail.

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