YX160 hard start, perfect when warm.

[DHXrider]

Hi guys.
Little info: Name is Jonathan from Ottawa Canada area (far I know) haha. I'm mainly a Free-rider and I ride anything with handlebars that goes fast, recently have been using these motors to build custom motos.

ISSUE: Hard starts when cold sitting for a day or two. Takes many kicks but once started and just slightly warm will start within two kicks, also when warm bike runs A1, no issues. Just the hard starts.

***BACKGROUND:
YX160, new style needled gearbox and case, bought from wholesale cycle in US. Motor was bought brand new this is second season on it with possibly 20-30hrs use so far.
2. No MODS except for physical advancement of the timing sensor a to solve kick back issue. This helped. Exhaust has been cut to fit frame, exit pipe angles from manifold a little sharper than stock.
3. Motor has TONS of compression.
4. Valves freshly adjusted .004 and .003 intake.
5. Molkt carb with 25pilot, 110main, needle clip down 1 clip from center, air screw 1-2 turns out. A hint of idle. We are 100-200ft altitude. Carb is sealed tightly on manifold. Nice steady idle.
6. Starting with no choke, no throttle whacking.

It's kinda a PIA cause the bike runs so good when warm but just such a pain to start from cold it is lil discouraging. Only thing I can think of is pilot??????

ANALYSIS: Your reply.

 

[grnman]

get a hair-dryer, heat gun or blow torch and head the barrel and manifold. this starts everytime for me. and is like starting your bike after its been running for 10min.

 

[DHZ_XR8cing]

try mixing it up. some bikes like starting with throttle. some dont.
How do you stop the engine when finished riding? Just hit the kill switch or turn ya fuel off?

 

[DHXrider]

YX160Hardstart Cold, warm OK.

Lol. Joking????

So ghetto but I WILL try it. Kinda hard to bring a heat gun out in the woods if you park your bike for a bit.

Gotta figure out the science behind this. All has to do with jetting, Pilot and fuel screw adjustment. I think turning in the idle screw a bit on cold start might help too. When warm I set mine really low, like almost stalled so I can see how it would gasp for air when warm, I can't stand a racing idle on a bike. I like *clunk.......*clunk............*Clunk.........*Clunk..........*Clunk....BBRRRRRRRRRRRRRRRRRRAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAP.

 

[DHXrider]

Kill switch it. To start I'll whack the throttle a few times to charge the intake but never while kicking. Actually, didn't really mention but some days it WILL start easier than others. Not quite as easy as warm but maybe 4-6 kicks. It's just so unpredictable.

 

[DHZ_XR8cing]

try twisting throttle while starting

 

[The_GDFP]

6=fail:action-smiley-035:

Hey, Hoser! You live at the Arctic Circle, use the choke, eh!

"Wacking the throttle" is like wacking off a moose. Sure, it's fun, but really doesn't accomplish any thing. You don't have an accelerator pump. Kicking with the throttle open makes it leaner. It's not starting COLD, BECAUSE IT'S TOO LEAN, already. That's what the choke/fuel-enrichment circuit is for.

When warm, they prefer a tiny bit of carb opening. That's what the hot-start button on big bikes is for. It cracks the slide open a tad. Turning the idle speed up a little helps hot starts, if you don't have a button.

Correct your technique, then "Take off". lol

You moved the ignition pickup up/CCW, right, to retard the timing?

Shame aboot the Senators. Long live the Rough Riders!

 

[DHXrider]

XY160

As I write this from my igloo,

No, I whack off the throttle a few times before I go to, uh...get her started so as to put a load of....uh....er.....air into her.

Seriously, can't be too lean because with choke it won't start and choke shuts it off while it's in a good running state.

Pickup IS moved correctly to retard timing, otherwise I'd be posting about kickback.

and finally, Sens smenz. Ever hear of this little team called the canucks......I believe they were only a few goals away from the cup :action-smiley-035:

 

[The_GDFP]

How aboot float height? Molkt carbs are moose dung, but it should start. Maybe try upping the warm idle speed to 12-1300 and then use the choke when cold? Could be starved for air. Twisting the throttle without kicking is not "charging the intake", though, but feel free to continue the practice. Air has already seeped in there, despite low slide positioning.

I was only a really good line away from nailing a supermodel once.

I'm only 300km south of you, and we had snow till early May I drive the 70 miles south to see the Red Wings do their thing now and then. Not a bad hockey club, most years.

 

[DHXrider]

XY160

haha. Good one on the supermodel. Canucks get points for effort in my book. Not a huge hockey freak myself anyway.

*sigh. hehe, as much as I hate to admit, your dead on about charging the intake with air, for sure it's already in there, just makes me think I'm doing something constructive to get her going, I might as well light a fire under it and start chanting

I think I'll definately play with the idle screw. Can't define it to that exactly but it "seemed" to start easier when I upped the idle a few turns from cold. It's easy to bring down when warm anyway. I'm a perfectionist though, it bugs me that I'd have to do that, technically a bike should be easy to start with no gimmicks. Just perhaps some choke sometime. I'd like to think that there solid are physics processes going on in my machines and they aren't just "moody" from time to time.

Here would be my logic, if I turn in my idle screw a few turns opening the slide a crack and she starts alot easier from cold, then this would mean that my pilot is TOO large because I need more air to compensate for the amount of gas sucked in at first intake stroke.

I had a jetting master sheet for my CR125, I had that bike down to a science I could jet it perfectly for any weather, it came so rich from factory, at first it would run for 10min before fowling a plug, ended up making a nice excel spreadsheet covering all the variables. Guess I'll have to do the same.

 

[krazed0451]

I might as well light a fire under it and start chanting

It'll warm it up at least

Just chuck the carby in the bin and move onto something better...

 

[DHXrider]

Meh, the molkt is a descent carb once you get it dialed, no need to pay anymore atm.

Update:

Actually started up from cold on third kick today no issue! While kicking, I held 1/16th -1/8th throttle open sort of like a fast idle setting so it confirms my idle theory. Hopefully this is the trick but I'll have to test for repeat ability. Bike goes like ballz when it's running, the 160's are sooooo fun, I'm about 150lbs so it's all I need to pull me pretty hard. Torque through the roof even with no mods.

 

[sean01]

Hi guys.
Little info: Name is Jonathan from Ottawa Canada area (far I know) haha. I'm mainly a Free-rider and I ride anything with handlebars that goes fast, recently have been using these motors to build custom motos.

ISSUE: Hard starts when cold sitting for a day or two. Takes many kicks but once started and just slightly warm will start within two kicks, also when warm bike runs A1, no issues. Just the hard starts.

***BACKGROUND:
YX160, new style needled gearbox and case, bought from wholesale cycle in US. Motor was bought brand new this is second season on it with possibly 20-30hrs use so far.
2. No MODS except for physical advancement of the timing sensor a to solve kick back issue. This helped. Exhaust has been cut to fit frame, exit pipe angles from manifold a little sharper than stock.
3. Motor has TONS of compression.
4. Valves freshly adjusted .004 and .003 intake.
5. Molkt carb with 25pilot, 110main, needle clip down 1 clip from center, air screw 1-2 turns out. A hint of idle. We are 100-200ft altitude. Carb is sealed tightly on manifold. Nice steady idle.
6. Starting with no choke, no throttle whacking.

It's kinda a PIA cause the bike runs so good when warm but just such a pain to start from cold it is lil discouraging. Only thing I can think of is pilot??????

ANALYSIS: Your reply.

Kill switch it. To start I'll whack the throttle a few times to charge the intake but never while kicking. Actually, didn't really mention but some days it WILL start easier than others. Not quite as easy as warm but maybe 4-6 kicks. It's just so unpredictable.

upon reading i gather #2 is a typo
1st obvious reason is carby.. as said above throw it in the bin. you'll spend a lifetime trying to dial it in. and when/if you dial it in the carb will fail from a different problem..
pwk 28mm or oko 28mm or pe28mm

and yeah molkts carbs aren't pumpers so you just wearing your wrist and throttle cable out lol...

nothing mentioned yet, but what temp is it where you are?

also have you tried a different heat range plug or even checked the gap...

maybe also try and kick the bike over a couple of times holding the kill switch in to get more fuel in to it..

 

[DHXrider]

yx160

Hate to chuck the carb as it does run well when it starts.
like I mentioned in previos post I kicked it over with just a little bit of throttle held on and it started up on third kick. So for anyone reading this, keep that in mind. Gonna start from cold again tomorrow to see if the technique is repeatable.

Weather is summer, hot and humid in the day.
Never really fully understood how a different heat plug range impacts performance. Pretty sure the plug is fine as is though.