ninjette.org

Go Back   ninjette.org > 1986 - 2007 Ninja 250R > 1986 - 2007 Ninja 250R Tech Talk

Reply
 
Thread Tools
Old May 2nd, 2021, 06:33 PM   #1
davenay67
ninjette.org member
 
davenay67's Avatar
 
Name: Dave
Location: Lisle
Join Date: Apr 2012

Motorcycle(s): 2003 Goldwing GL1800, 2002 Ninja 250, 2001 VFR800, 1999 Ducati 996

Posts: 104
250 only starts if intake covered.

The bike is a non running 2007 250 bought at the start of the year as a project rebuild. The tank and bodywork, as well as the rest of the bike in general, is in pretty nice condition for a non-runner.
Other than a good head-to-toe cleaning of the frame, wheels and plastics, I was hoping it would just take a good carb strip/rebuild/clean, new oil, new spark plugs and we'd be good to go.

Not so much. The bike simply won't start. I confirmed that both cylinders are getting good spark, and just to prove it I was able to start the bike on some starter fluid. I pulled the airbox off the carbs and was able to start the bike by placing my hands over the carb intakes. It would die if I moved my hand away completely. It would restart easily if I covered the carbs with my hands again.
I was starting the bike from an auxillary fuel source, so the tank and petcock (which are very clean) are not part of the equation.

So, what do you think I'm possibly dealing with here? I thinking the choke circuit on the carbs could be a problem. Also the pilot jets. I originally cleaned the carbs in an ultrasonic cleaner, and was sure to make sure the all the holes in the main jets, pilot jets, and emulsion tubes were clear by using a fine guitar wire. I've done a few sets of these in the past, so I'm fairly confident navigating my way around these carbs. But there's always a firs time to screw things up....

Planning to pull and strip the carbs again, and pay extra special attention to jets and the choke circuit. Anything else I should really be looking at here?


TIA.
davenay67 is offline   Reply With Quote




Old May 3rd, 2021, 06:51 AM   #2
jkv45
Rev Limiter
 
jkv45's Avatar
 
Name: Jay
Location: WI
Join Date: Jul 2013

Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes

Posts: A lot.
MOTM - Jun '18, Oct '16
Quote:
Originally Posted by davenay67 View Post
The bike is a non running 2007 250 bought at the start of the year as a project rebuild. The tank and bodywork, as well as the rest of the bike in general, is in pretty nice condition for a non-runner.
Other than a good head-to-toe cleaning of the frame, wheels and plastics, I was hoping it would just take a good carb strip/rebuild/clean, new oil, new spark plugs and we'd be good to go.

Not so much. The bike simply won't start. I confirmed that both cylinders are getting good spark, and just to prove it I was able to start the bike on some starter fluid. I pulled the airbox off the carbs and was able to start the bike by placing my hands over the carb intakes. It would die if I moved my hand away completely. It would restart easily if I covered the carbs with my hands again.
I was starting the bike from an auxillary fuel source, so the tank and petcock (which are very clean) are not part of the equation.

So, what do you think I'm possibly dealing with here? I thinking the choke circuit on the carbs could be a problem. Also the pilot jets. I originally cleaned the carbs in an ultrasonic cleaner, and was sure to make sure the all the holes in the main jets, pilot jets, and emulsion tubes were clear by using a fine guitar wire. I've done a few sets of these in the past, so I'm fairly confident navigating my way around these carbs. But there's always a firs time to screw things up....

Planning to pull and strip the carbs again, and pay extra special attention to jets and the choke circuit. Anything else I should really be looking at here?


TIA.
Yes - something isn't right with the carbs.

Did you remove the idle mixture screws and make sure the passages are clear? O-rings can break and get lodged in the passages also.

Float levels correct? Bench sync the carbs, then confirm with vacuum gauges?

Set the idle mixture screws at 2.5 turns out for starters, and tune precisely when running and fully warm.

Make sure the gas is fresh and the tank is clean.

Some tips in this section - https://faq.ninja250.org/wiki/Intake
jkv45 is offline   Reply With Quote


Old May 3rd, 2021, 08:00 AM   #3
davenay67
ninjette.org member
 
davenay67's Avatar
 
Name: Dave
Location: Lisle
Join Date: Apr 2012

Motorcycle(s): 2003 Goldwing GL1800, 2002 Ninja 250, 2001 VFR800, 1999 Ducati 996

Posts: 104
Quote:
Originally Posted by jkv45 View Post
Yes - something isn't right with the carbs.

Did you remove the idle mixture screws and make sure the passages are clear? O-rings can break and get lodged in the passages also.

Float levels correct? Bench sync the carbs, then confirm with vacuum gauges?

Set the idle mixture screws at 2.5 turns out for starters, and tune precisely when running and fully warm.

Make sure the gas is fresh and the tank is clean.

Some tips in this section - https://faq.ninja250.org/wiki/Intake
Thanks for the tips!

Mixture screws and o rings are new, and they should be seated correctly, but it's something to double-check.

Float levels checked with clear vinyl tubing attached to the float drains.

Screws are 2.5 turns out to start with.

Gas is fresh, using auxiliary tank. Gas tank and petcock are not part of the equations at this point.

Carbs are bench-synced, have gauges to accurately sync when the engine is running correctly with the airbox.

I'm leaning heavily to blocked choke pickup tubes at this point, but will inspect everything again when I'm back in the carbs....
davenay67 is offline   Reply With Quote


1 out of 1 members found this post helpful.
Old May 5th, 2021, 08:24 AM   #4
davenay67
ninjette.org member
 
davenay67's Avatar
 
Name: Dave
Location: Lisle
Join Date: Apr 2012

Motorcycle(s): 2003 Goldwing GL1800, 2002 Ninja 250, 2001 VFR800, 1999 Ducati 996

Posts: 104
SOLVED!

In case anyone comes across this post with similar issues, I found the problem was a blocked choke intake tube.

After a thorough cleaning of this tube, I reinstalled the carbs and the bike started and ran like a champ.
davenay67 is offline   Reply With Quote


1 out of 1 members found this post helpful.
Old May 5th, 2021, 04:01 PM   #5
JayVapes
ninjette.org member
 
JayVapes's Avatar
 
Name: Honorio
Location: Rio Grande Valley
Join Date: Aug 2020

Motorcycle(s): Ninja EX250

Posts: 34
i would suggest @ducatiman for any carb work
__________________________________________________
RIDE IT UNTIL THE WHEELS FALL OFF, THEN BUY NEW WHEELS
JayVapes is offline   Reply With Quote


Old May 5th, 2021, 04:02 PM   #6
JayVapes
ninjette.org member
 
JayVapes's Avatar
 
Name: Honorio
Location: Rio Grande Valley
Join Date: Aug 2020

Motorcycle(s): Ninja EX250

Posts: 34
glad you got it running
__________________________________________________
RIDE IT UNTIL THE WHEELS FALL OFF, THEN BUY NEW WHEELS
JayVapes is offline   Reply With Quote


Reply




Similar Threads
Thread Thread Starter Forum Replies Last Post
Intake valve clearance 04 Ninja 250 shaggy 1986 - 2007 Ninja 250R Tech Talk 6 June 7th, 2014 05:54 PM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


Motorcycle Safety Foundation

All times are GMT -7. The time now is 04:31 AM.


remote server monitor
Powered by vBulletin®
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
User Alert System provided by Advanced User Tagging (Lite) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Except where otherwise noted, all site contents are Copyright 2021 ninjette.org, All rights reserved.