Cold start issues

[Durango]

Hi, I'm new to the forum.

It's a 1995 F2 done 27k miles, runs perfect otherwise.

Problem starts when the bike has not been started for a week or two and is more acute in winter temps.
Put on full choke, press starter, engine spins but not a peep, doesn't even try. Solution is to warm up the engine with a fan heater for a couple of hours then she will start in an instant.

So, it's either fuel or spark. I know the battery is not perfect but I trickle charge it on a regular basis. Usually reads 12.5/6v. When ignition is on this falls to 11.6 after 10 secs. I'm not sure how susceptible these models are to slightly lower voltages as regards starting.

Fuel- maybe it's the e10 fuel that is in the tank that's not helping?

 

[Biebs]

1992 750 nighthawk also - these bikes are cold blooded and what you are experiencing is normal.

 

[kirky]

Durango i am in chesterfield and have to give my 1979 750 FZ some warm hairdryer in the air box , once started she is fine the next day if i leave her for a week i get the same problem, i think they they have to be perfectly set up 100% with everything

 

[andyfloyd]

I have the same issue with a 1980 CB750 Custom. Have 2 sets of carbs, had both rebuilt and still have same issue. So annoying. Now got a specialist on the case see if they can sort it.

 

[Biebs]

I have the same issue with a 1980 CB750 Custom. Have 2 sets of carbs, had both rebuilt and still have same issue. So annoying. Now got a specialist on the case see if they can sort it.

Trying to fix a non-problem will cost you $$$ and more problems. If it's not broke Don't fix it!!!

 

[andyfloyd]

I have a set which were on the bike when I got it and didn't run on cylinders No2 hence got another set which is now on the bike and running reasonably after a clean and set up. Still has the cold start problem and a flat spot in 5th and 6th gear around 6k revs. I will see how this other guy gets on with rebuilding the original set. Going to be a long slow process. I do hear it was a common problem with these bikes. The placing of a heater 10 mins before firing up works a treat but you can't always fins a plug in the middle of a bike ride in the wilderness lol

 

[SJ15]

My 98 isn't cold blooded at all as of right now. No choke needed just a touch of throttle when pushing the starter button and fires right up. 82 year old Air Force engineer did the carb work on it

 

[andyfloyd]

Maybe they resolved the cold start issue in later years as mine is a 1980 and has cold start issue. Not tried it with no choke must admit. UK weather issue maybe ?

 

[kirky]

andyfloyd is that your name or have you become comfortably numb , anyway mines a 79 and awkward to start in the winter but carbs are all sorted, i have seen on here that valve gear and lower compression can also make them hard to start.

 

[Fourever]

You can try the following:
1. Replace your spark plugs with Iridium spark plugs. This may improve the starting behavior somewhat.
2. You should also close the fuel tap every time you drive home on the last kilometer or so, so that no more fuel can flow into the carburettor. The flammable components of the fuel volatilize through the air filter during longer times of non driving. When you open the fuel tap again, fresh fuel will flow into the carburetor and the machine should start better.

Hope that helps!

 

[kirky]

red face here , finally got my 750 to start easily in the cold damp, once it was going on tickover i tried the wd 40 trick on the boots and the tickover changed a bit. i found two boots that were put on new as a set of 4 had settled in and were pulling air in. once tightened up she is now starting easily,