Odd starting issue

I don' t know that I'm really looking into how to fix this issue. I'm almost sure it will go away when I do a proper carb cleaning. I'm looking more for a bit of an explanation of what might be happening.

I commute to work about 10 miles every day. Most of it is country driving on a decent paved road cruising about 60-65. When I go start the bike in the morning it fires up right a way. Put the choke on, hit the start button, blip the throttle and she just purrrrs. I come home for lunch every day ride 15 min home, eat/hang out with the family for about 30 minutes then ride 15 minutes back to work.

When I come out to start the bike after lunch (30 minutes after it was last started) it take a little bit to get the bike going. It almost acts as if it is flooded. I hold down the start button and it cranks a while before it finally catches and starts (5 seconds or so). I then have to give it some gas (another 5 seconds or so) and it doesn't want to go about 2 or 3k rpms then all of the sudden the throttle responds like normal and it roars to life and will idle fine (even with the choke off which it won't do in the morning until it is warmed up).

Thing is when I leave work the bike starts just fine. This would be after the bike has sat for 3 or 4 hours. So something is going on when the bike only sits for 30 minutes or so that makes it difficult to start. Its not really much of a problem but it has just been bugging me. I cleaned the carbs quickly a few months back (passed the clunk test and looked pretty clean) but I'm sure they could use a more thorough cleaning and if I did so it would probably fix the problem. I just want to understand what is happening. Any thoughts?

 

Air leak maybe?? Have you got a chance to Colortune the carbs? Mine does the same thing after a bit of riding. My gf and I ride up to 7-11 for gas. Starts fine, ride up there, fill up.
Then i go to start her again and i gotta blip the throttle to start her. Almost like she's flooded. I also have 2 larger pilot jets in two of my carbs so that could be causeing excess gas mix to go in. Who knows!
Lets see what everyone else gotsta say
-Chris

 

Bad petcock maybe? Could be letting fuel flow when there's no vacuum.

 

I have seen similar issues with mine. Stop for gas for 2 minutes everything is fine - we stop for 10 to 20 minutes and sometimes it's the same thing you describe. Cold or after work - fine. Going to lunch fine.

I had suspected that is was actually low bowl levels at the time it happens. My theory was that we come in to a place to stop and I cut it off quick - so maybe the bowls a re a bit low. When getting gas or parking at work it typically idles a few seconds and bowls refill?

If it happens to you a lot try throwing in on prime for a sec - maybe we can get more data.

Clutching at straws because if petcock is right etc the bowls should not get that low. But I can't think of anything else.

 

Interesting ideas. I'll try letting it idle a little when I park it at home for lunch today. If that doesn't work I'll try priming it tomorrow. Like bill I don't have any trouble when filling it up.

I sure hope it isn't a air leak SL kid. I know I need replace my intake manifolds but I don't think they are leaking yet. If anything I'm running a little rich not lean. I just don't have the money to do it and frankly I'm a little scared to do it. So many stories of snapped blots. We only have one car so my bike is all I have to commute. I really don't want to deal with pulling the top end off.

Petcock is on my short list of possible problems grutz. I have been meaning to rebuild mine.

If any one else has other theories I would be very interested. Good to know I'm not the only one dealing with this.

 

Good thing is its a fairly minor annoyance - Bike still start fairly quick just not on first bump.

 

mine is the same way, and I have pinpointed it to the petcock.
I am going on an ordering spree next week. finally have the money to do everything the right way
cant freakin wait

 

Let me know how it goes Helmet.

I tried letting it idle for a little while when I got home from lunch and that didn't seem to help any. I'm going to try putting it on prime on Monday. We will see what that does.

 

Let us know - I know my petcock is working perfectly

 

My xj behaves just like that too :?

 

Mine does the same thing, petcock is fine, bike is dialed in fine, colortuned, synced, and carb-cleaned. Most of the time, I can avoid it by letting the bike idle for a few seconds and then blip the throttle just a touch and turn the key off. Usually it starts up easily enough. However, sometimes it still takes a bit of "holding the button in while the throttle is turned just a bit, wait for it to catch then build rpms" I'm just used to it and don't really think about it. Nor, do I worry about it.

FWIW

Dave

 

I just rebuilt my petcock and it still does it!!!
Shaun

 

Interesting so many are seeing it. Like Dave my bike is right. I only see it once or twice a month but i think that is riding habit - mostly commuting and it sits all day.

 

if it's not the petcock, it sounds like something is plugging the pilot jet. once it sits, it has a chance to settle down to the bowl and it will start.

what kind of plugs is everyone running?
mine are the OEM style plugs. I want to run something hotter because of high octane fuel and compression. I think it will help.

 

Might check the float levels.

 

newer 4 stroke dirt bikes have a hot start lever, i believe it leans the mixture to start them after their warmed up
i've had bikes that you had to kick start and i recall they were always a pain to start in that half warm state

 

*ding*ding*ding* "Bob, tell that contestant what he's won..."

My '83 used to have this problem until I set the float levels correctly.

HOWEVER: If the float levels check OK (using the clear tube method) then the issue is probably more closely related to what Bill suggested, low fuel levels in the bowls when you shut it off.

Try this: When you get ready to restart it after the "short wait" put the petcock on PRI and wait about 30 seconds before you try to light it.

Oh, and Polock; a Yamaha 4-stroke SINGLE has this very problem, it's inherent and nothing you can do will make it not do it. If you stall an SR500 within the first 5 minutes after starting it, you may as well park it and go have breakfast.

 

That's the thing I know my floats are right. But as I said I don't see it a lot it appears gurgietrueshot sees it a lot more than I do.

 

fitz
a TT500 is one of the ones i was referring to, also a little honda 100