Starting Difference

J

jbrocks

New Member
#1
#1
I have two identical set up clone engines on my minibikes, light mods (intakes/airfilter/header). Fresh NGK plugs. Both run great. Why does one motor very consistently start with just one pull while the other one takes five pulls? Starts great on the fifth pull, runs strong, no problems or issues. Just curious. I think someone once said anything under ten is good, but I like closer to one if I can:smile:

​
 
CarPlayLB

CarPlayLB

Well-Known Member
#5
#5
OND said:
X-2 on both of the above. ^^^^^^
Click to expand...
Why?
I have the same issues. Both motors were new, same cam, same flywheel, same jet kit, same carb setting. Everything is exactly the same. One motor, hot or cold, first pull, turn choke off, good to go! The other one, 4 pulls, cold blooded, needs attention until it is warmed up. When warmed up, never starts on first pull.
 
minibikin'

minibikin'

Sho-nuff
#6
#6
I agree on the low speed jet. I don't care if they are identical or not, they almost never perform the same.


Sent from my Texas Instruments Speak and Spell...[emoji2]
 
J

jbrocks

New Member
#7
#7
I did adjust my carb, I thought it was in a 'sweet spot' where it purrs idling with no surging or pulsating, doesn't want to take off on me (engage clutch) take off is right there when you twist the throttle, and you feel the full range of power. Well I found another sweet spot about 2/3 clockwise turn (who'd a figgered??) does all the above and now starts on three pulls, which is good! That engine, right outta the box took three pulls to start, the other one took just one pull and still does. Oh the vagaries of small engines.:doah:
 
pirranah

pirranah

New Member
#8
#8
I went to a #38 pilot jet with mine. Wouldn't idle unless I had 3/4 choke. Now even on a cold 30* morning it'll pop off first pull.
 
J

jbrocks

New Member
#9
#9
pirranah said:
I went to a #38 pilot jet with mine. Wouldn't idle unless I had 3/4 choke. Now even on a cold 30* morning it'll pop off first pull.
Click to expand...
I'm up to #41 jets. I'm also at 5000ft elevation. We been having some cold temps too. But I'm still 3-4 pills to start. Runs great, no issues. One pull in the other:shrug:
 
H

Havasu Dave

Moderator
#10
#10
Starting considerations when fuel isn't involved are about timing. As others have said, there is no way any two engines are going to be identical.

You do have a fixed magneto mount. For 99 dollars, no one is setting these things in a jig and getting 100% accuracy tapping the mag threads in the bosses. Are the coil to magnet relationships exactly the same on both engines? Are both engines set with exactly the same air gap? I found it interesting that .006 difference in flywheel key sides results in 1 degree of timing. Has a key or keyway worn a bit? Are the spark plugs set with exactly the same gap? Is one firing hotter or colder than the other?

There are a lot of available variables JB. On start, fuel is fuel is fuel. It's a timing difference, and most likely nothing you can do anything about. Or, in Predator parlance, just toss it in the trash and buy a new one. :laugh:
 
You must log in or register to reply here.
Top