Cold engine starting problem

Hello everyone.

I'm proud to be new owner of Yamaha XJ700N Maxim 1985 (for Canada, thanks to the thread I've read on this forum!). This is my first bike ever, and of course I have some problems

When I start the engine (cold, choke fully opened), on idle - it stops after few seconds. Sometimes, if he's in a good mood, it works without the rev, but with choke fully opened at around 1 x1000 RPM, but with "coughing". If I always give the rev going, it won't stop, hardly works, but works. When I ride for like few minutes (and the ride is pretty hard, 'cause it's not even at all), it starts to work better, and after 5-10min of ride, I can leave it on choke closed, on idle, and it works perfectly. Then the RPM is around 1,5 x1000. BUT. After a good long ride, it levels up to 2,5 x1000 RPM. But rides perfectly.

What's the problem? Carbs?

P.S: I think I'll make a video few hours later. Sorry for my english

 

Sounds like the carbs to me. I had similar problems until the carbs were completely cleaned. Check out the Information Overload Hour for detailed information. Best to go over the parts of the bike related to safety before riding again. This includes the braking system, such as master cylinder rebuild, brake line replacements, caliper rebuild, and rear brake replacement. The previous owner likely didn't keep up the maintenance, even if he or she states it was done.

Edit: Here are a couple links.

Information Overload Hour - http://www.xjbikes.com/forums/threads/the-information-overload-hour.27544/

Rear brakes - http://www.xjbikes.com/forums/threa...r-brake-bike-owners-please-take-a-look.15874/

 

^^^+1 carbs need cleaned and synched , Valves adjusted (shim check ) good chance your carbs fuel enrichment circuit is plugged and needs to be completely cleaned, you will need to pull the carbs remove the float bowls the jet is in bottom soak bowls in carb cleaner for at least an hour , take a nozzle on can of spray cleaner spray jet in bottom of bowl aim away from anything close by see if it sprays a stream , if so this should help enrichment circuit. While your at it take carbs to church .

 

See the links in my signature, as well as those provided above.

 

Thanks for your response!
I just made a video:

 

1. opening and then shutting the choke as you did at first is unncessary.

2. Your pilot circuits are dirty.

3. Take your carbs to church. Stay for the whole sermon, or don't even bother showing up.
IN THE CHURCH OF CLEAN

 

How cold is it right now? choke may need to be on 1/2 way for a minute or 2 until you feel some heat coming off of the engine. Adjust idle up slightly and then choke off and keep adjusting idle until engine fully warmed up. Idle should be 1050 rpm.

But rotten throttle shaft seals will make idle terrible even if you have everything else right.

Pics below are the carbs I did for Xj700n from Paul Howells bike . Made a huge difference after done it will idle even dead cold without choke after 10 seconds.

 

Depending on the outside temp determines if I touch my choke at all, if its below 60 degrees outside I will put my choke on 3/4 and she will fire right up, I let her warm up until the RPM starts to rise then I know I can shut my choke off and ride. On any day above 60 degrees I just get on, start her and go. I will tell you that when I first got my bike she was a cold blooded bitch, however after I cleaned the carbs completely and put new plugs in her now she runs like a champ!

 

that's about what my bike was doing last summer till i got the carbs/choke fixed. then it started doing it all over again but at least started. anyway.. don't want to say anymore than i got different problems right now i think

 

Clean the carbs, and check your rubber carb boots for cracks. Mine had a lot of cracks on the engine side making the idle very erratic and clod starting hard until I sealed them up with some clear RTV, I do need to replace them eventually but that seems to have make idling a lot smoother a lot faster and made cold starting easier

 

Hey, thanks everyone for the help!
Got my precious to a local service, they cleaned the carbs, sinchronized them, and now it runs perfectly!

 

How much did they soak you for ??

 

As carbs were approx. clean, there weren't a lot of cleaning work, I paid really cheap - 40 euros. That's around $45

 

You will find most shops here in the USA don't even want to work on these bikes nor they don't know how.......with this forum.....you are your best mechanic.....

Motorcycle shops will just take your money......only you care more about your bike than anyone else...

Save your money....and starting wrenching and reading.......

These bikes are fun to wrench on....it can be frustrating at times.....but once dialed in......they are a fine tuned running machine.....

 

Yeah, I know I will work on it more by myself on winter. As our season in Lithuania is quite short, I decided to pay for someone else Plus, I don't have any required tools for repair at this time.

 

After getting the carbs cleaned and synced, find a colortune plug and set the pilot screws. At warm idle close the pilot screw until you get a white (lean) flame. Open pilot screw until white disappears and you see blue flame. Repeat for all four cylinders. Install new plugs and ride about 20 miles. Remove the plugs and "read" them. You are looking for a light tan color on the insulation. If they are still white open the pilot screw about a width of a dime and take another ride and read the plug again. Continue this process until you get a nice light tan color. Then if your bike is like my XJ700N it will start easily, idle well and get better mileage.