Crank with difficult starting

Art Johnson art-j at
Sat Mar 24 18:23:25 PDT 2012

Occassionaly have a starting problem, where the gp'r won't fire even tough it cranks fine. turning the ignition off, just momentarily seems to do it. it starts right off after that.

----- Original Message -----
From: "Steve Clark" <clarks at>
To: "Art Johnson" <art-j at>
Sent: Saturday, March 24, 2012 6:10:32 PM
Subject: Re: Crank with difficult starting

Don wrote

> The Geep has been getting harder to start when warm. Cranks strongly, but
> will barely catch and fire (today was a question after stopping for
> fuel...). Cold, it starts up with the first stab almost every time.
> Don in GJ

Things to check - Are your valves in adjustment?  Is the air filter clean? 
Is the thermostat keeping your bike cool as it should?  Is the choke working 
correctly - is it truly shutting off all the way?  Have the low speed carb 
screws been changed to something other than stock?  Are you sure that one or 
more of the carbs does not have a leaking needle valve allowing more gas to 
get to the motor from a over full carb or 2? - this would be good for start 
up in cooler weather.

To state the obvious - you need spark - you have that the bike runs, you 
need air but a dirty air filter can make starting good but can make the bike 
get to much fuel during start up hot.  Valves is really about compression or 
the lack of - again starting a cold motor with less compression is less of 
an issue then when the motor is hot.  You need fuel but not to much or to 
little - if a needle valve is leaking a bit you again can be OK at startup 
but have issues when you try to start when warm/hot as there is extra gas. 
The low speed jet setting helps or hinders warm/hot starting (no choke 
needed starting) not enough fuel evaporates to quickly in a warm engine 
during starting and a little choke can help but that is also a sign there is 
something amiss - to much fuel will make things start good and you may not 
experience riding issues as you run most times on the slope / tamper of the 
carbs needle into the main jet/emulsion tube.

"It doesn't SEEM to be loading up on fuel if I put it on prime"  thats good 
cause it should not - prime is the position
you place the petcock in to flow fuel without the engine running and 
operating the petcock by vacum (this is how to get the carbs full of fuel if 
you have drained them etc).  The needle valves in the carbs control the flow 
and fuel level in the carb.

Hope this helps locate the problem or at least eliminate possible issues.


This is from the GPZList mailing list. GPZList at
You subscribed to this mailing list. Therefore, you solicited all
mail that you receive from this list. Therefore, ANY mail that you
receive from this list is, by definition, NOT Spam, and if you report
it as such, you are violating the terms of service. 

To unsubscribe, you may send email to gpzlist-unsubscribe at
Unsubscribe or choose new options at
You are subscribed at the email address art-j at

More information about the GPZList mailing list