Need help! Won't start

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Philbot
Posts: 1
Joined: Sat Oct 01, 2016 11:46 pm

Need help! Won't start

Postby Philbot » Sun Oct 02, 2016 12:06 pm

I have an 81 honda CB 650 and cannot for the life of me get it to start, I've checked the timing, the firing order, I have good spark and fuel. Cleaned the carbs many times. The bike has been chopped up and re wired.

It coughs and sputters but just won't start. I'm at a complete loss...
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Folsoml
Posts: 1634
Joined: Sat Apr 07, 2012 9:02 pm
Location: North Florida

Re: Need help! Won't start

Postby Folsoml » Mon Oct 03, 2016 5:23 am

It is hard to offer advice on a bike so heavily modified. :(
Have a problem with your CB650? Have a technical question? Click here!


My Current Bikes: 2005 HD FLHTCUI Electra Glide Ultra Classic, 2007 Yamaha Vino,

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Kjkenney
Posts: 28
Joined: Thu Aug 04, 2016 7:26 pm

Re: Need help! Won't start

Postby Kjkenney » Mon Oct 03, 2016 8:06 pm

What's the wiring like now? Kill switch hooked up or bypassed to ensure the circuits complete? I've had smaller bikes not start due to dirty solder points on the switches before as well, not sure the standing of the parts you got. Like if they came off a working vehicle and whatnot. But yeah something not stock wiring could be hard to say for sure...
83 Nighthawk 650
85 Elite 150 Deluxe

navydad
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Joined: Wed Dec 16, 2015 9:00 pm
Location: Ohio
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Re: Need help! Won't start

Postby navydad » Tue Oct 04, 2016 5:45 pm

The 81's are a cold natured beast and can be hard to start when everything is working perfectly. You still have the CV carbs installed and these have a bad reputation of not working well with modifications. The exhaust is not stock and the stock airbox has been eliminated. I know this doesn't answer your question, but you are dealing with a bike that can be a stubborn starter without modifications.

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tario
Posts: 166
Joined: Sat Mar 07, 2015 2:26 pm

Re: Need help! Won't start

Postby tario » Thu Oct 06, 2016 8:47 am

I'd consider spraying a little gas in each velocity stack. I assume it's running lean if you have not rejetted yet. If you can flood the engine into running that might give you a starting point. Otherwise those spark plug wires raise my curiosity. I think they need to have a certain resistance and yours look like they could have been bought for the look. (not sure what resistance, i just bought mine from a shop that fixes old hondas)

In general; check valve clearances, check timing, check for spark, test compression, clean all wiring connections, make sure you clean all the wiring connections!, dielectric grease on all wiring connections.

I also found cleaning the ground tabs on the coils helped. You need a good ground to have a good 12V or whatever they run at. (for instance it's "safe" to hang off high power lines if you don't touch anything grounded. Although once you do they tend to vaporize you instantly... so don't..)
1979 cb650
1980 cb650

MEHall
Posts: 403
Joined: Mon Nov 15, 2010 8:25 am
Location: Sweden

Re: Need help! Won't start

Postby MEHall » Fri Oct 07, 2016 6:13 pm

What I learned from everything I read here on the forum is that an airbox is quite necessary.
That is without any change on the carbs you need the source of still air you get from the airbox.
So the reason the airbox is there is to keep down the fuel consumption as low it's possible.
So if you change anything on the carb side you really need to check out how the change will affect the engine. :wink:
The solutions i can see is either change the jets or make a custom made airbox, i have seen pics of some on this forum but cant tell where at the moment. :?




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