Trouble starting

[bellison80]

So yesterday I went to get my bike out for the spring and it would not start...grrr. I just installed new rubber between air box and crabs, old ones were torn,  cleaned carbs, new choke and throttle cables and new spark plugs gapped to spec. It ran at the end of the last season but was running rough, it was intermittent, real hard to start and seemed worse when cold or wet. This winter I pulled the carbs and inspected the gas tank only to find that the tank had some rust. I went through the carbs again, pulled all jets etc etc and cleaned meticulously. I also did the 3 part kreem tank liner process which was a pain but cleaned and cleared all rust and got a even protective coating on the inside of the tank, followed there directions to a T. So when I put it all back together, installed the charged battery, tank on and fuel, fuel getting to carbs......nothing. Turns over and wont fire. Tried a shot of starting fluid and just a weak cough. Needless to say I was frustrated. I began pulling the plugs to check for spark. First plug I pulled had spark. I then went to pull the plug from the boot to put back in the engine and the wire fell apart in my hand. They appear to be the stock original wires and in poor condition. I am wondering if the rough running and starting would be linked to the wires beginning to fail and if they would also prevent the bike from starting. Probably a dumb question but I am learning as I go. This is my fourth older vintage jap bike and I have never had the difficulty that this one is dishing out. I ordered new wires and plan to replace the coils as well when I can get some additional funds. Your insight, tips and feedback would be greatly appreciated and helpful. If I have left anything out lemme know, thanks guys.

Brian E

[bellison80]

Oh its a 1979 cb750f all stock

[shinyribs]

I would say you are on the right path. Sounds like you get everything concerning the tank and carbs sorted out nicely. If you got fuel and spark it should run! Yes,dry,cracked or crumbly wires/boots will cause all sorts of starting,running and idling issues. Since it was worse in wet weather I would say it is pretty safe to assume that the wires/boots are to blame. If not,sounds like they need to be addressed anyways. i would try that and then see whats up. I would imagine it will cure what ails ya.Good luck!

[bellison80]

Thanks man, I am hoping so. I am itching to get out there and ride. This is my only ride at the momment. I just let a 78kz 650 go.

[katman]

Get your wires fixed first. I had the same problem on my 77. These guys directed me in the right path.
Did you pull the pilot jets to make sure they are clear. I had my carbs rebuilt and still had to pull these
myself and clear, thanks to the advice here. Cranks and runs great now.

[bellison80]

I did pull the pilot jets. I rebuilt the carbs last fall. I should get the wires by the end of the week.

[bellison80]

Got my wires last night and problem solved. Bike is running sweet. I had pulled the carbs and put the pilot jets back to the stock setting and cleaned them , 1 3/4 turns out, the carb bank is so much easier to pull with a second set of hands! I am following the tuning guide in the Clymer manual which all makes sense to me except I have never heard of a portable tachometer which is used for more exact reading of the rpms while tuning. Is this something that can be picked up at a parts store?

[bellison80]

Or can I use the bikes Tach? Any ideas/suggestions?

[shinyribs]

Just use the tach on the bike and you will be fine.Also,the manual will cal for a really low idle rpm.I think the manual claims the idle speed should be around 850-900 rpm.It won't happen.Everyone I talk to says that 11-1300 is a more realistic idle speed. Good luck

[LukeM]

You can use the bike's tachometer if you like.  It may not be as accurate than a standalone unit, due to the narrower sweep, lack of intermediate markings, and possible less accuracy.

You may have good luck finding one on Craigslist or EBay.  I've bought some older diagnostic auto tools from CL without any drama, and been VERY satisfied with the results. Might be kind of hard to find, but I'll leave that to you.

Luke M

[TOOLS1]

Most old Dwell meters had a tachometer built into them. However I never go by the tachometer when setting idle. I just go by ear, and adjust it to where the engine is idling smooth.
TOOLS  

[Re-run]

The bike tach can average 100rpm off. I use a dwell meter with a tach but any tach the takes its reading from the ignition should work fine. Try to find one accurate to under 50 rpm.

[bellison80]

Thanks for the feedback guys. Much appreciated and I think It will send me in the right direction.