Won't rev when cold

[Gman2528]

Can anyone help with this odd issue. I have a 2019 300 rr that last week cooked a li-pol battery. After checking everything over (including pulling the starter motor) after bike wouldn't start with a new battery it's now decided to start. However, it absolutely refuses to rev when cold. Symptoms are like a blocked main jet. However, if I let the bike idle for a few minutes it then revs and rides fine through the gears. Same thing happens everytime it's cold but I'm at a loss. Its not the carb but is there some sort of thermal switch somewhere that let's it rev when warm? Any pointers appreciated

[Trail Rider]

Can anyone help with this odd issue. I have a 2019 300 rr that last week cooked a li-pol battery. After checking everything over (including pulling the starter motor) after bike wouldn't start with a new battery it's now decided to start. However, it absolutely refuses to rev when cold. Symptoms are like a blocked main jet. However, if I let the bike idle for a few minutes it then revs and rides fine through the gears. Same thing happens everytime it's cold but I'm at a loss. It's not the carb but is there some sort of thermal switch somewhere that let's it rev when warm? Any pointers appreciated

What do you mean it cooked a battery? The bike would no longer crank? Any clicking from the solenoid/starter? The battery just discharged/dead?

What do you mean the bike wouldn't start with a new battery? Was it turning over but would not fire? Nothing at all?

Not revving when cold, does it smoke & bog down? Will it idle OK?

Seems like a number of issues here, just trying to define it better.

[Gman2528]

Hi. Last week the li-pol battery fried so I started working through things. New battery and the starter relay was tested which proved it to be good. When I tried starting the bike the solenoid would click but nothing else happened. I then connected the live and negative (from the battery) to the starter motor). Still nothing. I took the starter motor off, mounted it to the same earth point as the negstive battery terminal, connected the positive to the starter and it spun up fine. Put it all back together and nothing. I then ran a lead from the negative terminal of the battery on to the starter motor and it cranked so I put the starting down to a bad earth. I then put everything back together and it started first time but wouldn't rev (it would cut out). I tried several times so let it idle for about 5 minutes then it would rev fine. The clock display however was very flaky. Same thing this morning - start first time, wouldn't rev. Let it tick over and few minutes later it would rev fine. After this I cleaned the contacts on the diode this afternoon and the bike seemed better and the clock display was clear when revving (it wasn't before I cleaned the diode contacts). I rode the bike through the gears and all was okay (after the warm up period) . Its definitely not the carb but something electrical. Only thing I can't check are the capacitors. Baffling me
at the moment

[aj_mariner]

I have honestly never tried to rev my bike immediately after starting it cold. Start with choke, close choke after 10sec, let it Idle for another minute and off we go.

If you still feel there’s a problem, my guess is the jetting. How high does the rpm go with choke on starting cold? It should be a very strong higher idle that drops to normal rpm after 15 seconds or so

[Gman2528]

When I say rev the bike I'm taking it just off idle and hardly on to the main jet which comes on at about 1/3rd throttle. This morning it would only bump start and I rode it about a mile and then it died. Bumped again, rode about 1/2 mile, died again. This time the fuse blew on the starter relay. Popped a new fuse in, bike fired, picked up the revs very slightly and bike died. Bike wouldn't start off the button and drained battery this time. . I'm ruling out the carb unless it's fuel starvation which I'll also check. Any electrical based riders on this forum who can offer any ideas? Could something be breaking down under load?

[Trail Rider]

You clearly have an electrical issue & it appears to be the cause of your issues. Only thing I could recommend is a complete grounding/wiring check of everything & possibly a bad CDI unit? Is your battery getting charged with the bike running (voltmeter check)?

[Gman2528]

So here's the latest. Bike now starts off the button again but dies when I try to pick up the revs. I stripped the carb completely and a found a piece of the main jet in the float bowl chamber (WTF?). As the bike runs on the main jet I think (hope) this is the problem. Either way, having a piece of the jet come away (it's sort of half the side of the jet, about 2mm long where the screw driver slot should be. This is the first time I've been in the carb since owning the bike and considering things thus far, this could explain a hell of a lot. - that It blocked the main jet before it ended up in the float bowl and now its in the float bowl, the jet (with the piece missing) is causing the issue. Thoughts please?

[aj_mariner]

I agree with Trail Rider checking battery charging and wiring harness.

Also, under the tank in the cubby where the thermostat is, you’ll find the stator and timing pick-up connections. The stator connections came crushed and brittle on my bike and eventually failed. As far as the fuse blowing, check the wiring bundle by the steering lock. That has been reported as a rubbing point. If you don’t have a multimeter, you will need one for electrical troubleshooting.

Edit: the jet with the slot for a flathead is your pilot, the main jet has a hex head.

[Gman2528]

I need to rule out my previous post about the main jet. Really not happy about the spannering ability of the previous owner. I need to try and get the other jet out, pop a new jet in and try that. My local dealer hasn't had any stator or cdi failures on 2019 rr's

[Trail Rider]

I need to rule out my previous post about the main jet. Really not happy about the spannering ability of the previous owner. I need to try and get the other jet out, pop a new jet in and try that. My local dealer hasn't had any stator or cdi failures on 2019 rr's

All well and good about the carb. But batteries not charging & blowing fuses has nothing to do with that.