All Things Moto! Web Forums

Go Back   All Things Moto! Web Forums > Dirt Bike - ATV - Suspension Forums > 4-Stroke Dirt Bike Bike Forums > 4-Stroke Dirt Bikes - Yamaha

     
Reply
 
LinkBack Thread Tools
  #1  
Old 01-30-2005, 08:47 PM
Beginner Class
 
Join Date: Jan 2005
Last Online: 02-08-2005 08:37 PM
Posts: 7
Default YZ450 neutral switch and hard starting

I have grafted a YZ450F motor into a TZ250 GP bike chassis.
One of the problems with this was the fact that the kick start could not be fitted because of the frame position. This did not seem like a big problem because I thought I could bump start the bike.
Starting the bike proved to be much harder than I thought, we must have pushed the bike up and down my street 50 times and only managed to get it started once. When it did start the motor seemed to heat up very quickly, this worried me so I talked to Yamaha about this and was told that it was normal, and that the headers would glow red hot if the bike was left idling.
This got me thinking. Perhaps Yamaha retard the ignition so that it fires after top dead centre when the bike is in neutral.
To test this I cut the neutral wire and connected it to a switch, this switch allows me to tell the CDI that it is in neutral while I try to bump start it.
With the switch on the bike fired up without a problem.
The reason I have posted this message is to make all you YZ/WR450 riders aware of a potential problem.
If you stall the bike and try and kick start it while still in gear you could damage the engine cases, this is because you run the risk of the motor kicking back while the kick start is engaged.
This kick back is caused because the ignition is firing before TDC and may force the motor to rotate backwards. If the kick back is hard enough it can break the engine case around the kick start.
A good idea would be to tee a wire into the neutral switch wire, then take the second wire to a handle bar kill switch. This would allow you to kick it while in gear as long as you hold the button in.
Reply With Quote
  #2  
Old 01-31-2005, 06:46 AM
Semper Fidelis
 
Join Date: Dec 2002
Last Online: 02-26-2014 07:31 AM
Location: Barrineau Park, FL
Posts: 7,291
Take it off entirely

wmc,
Most of the 450 and 426 riders took the neutral switch off and put a cover over the opening (I used a ZipTy cover.) The switch is to keep the revs down in neutral by cahnging the ignition mapping, as the European standard mandates the sound testing be done. Check the archives here and at Thumper talk for some of the posts on this. Some do feel taht they get easier starting with the removal of the switch. Satch had the best idea on his old 426 when he goe the cover with a site glass for oil level.

Taht must be some creation you have. Enjoy the road rashing with that bike. I remember working on TD and TZ 250 Yamahas back in the mid 70's. Great bikes thast were giant killers for a while.

Regards,
Bill
Reply With Quote
  #3  
Old 01-31-2005, 06:35 PM
Beginner Class
 
Join Date: Jan 2005
Last Online: 02-08-2005 08:37 PM
Posts: 7
Default Re: YZ450 neutral switch and hard starting

I think you will find that the neutral switch will make the bike much easier to start.
This can easily be tested by grounding the wire and trying to kick the bike in a lazy fashion. I think you will find that it still starts easily.
Then disconnect the wire and try the same lazy kick. The bike will punish you for the lazy kick.
We found the bike almost impossible to start without the neutral switch grounded (simulates neutral position when grounded). That was with two people pushing on a down hill.
With the switch grounded the bike was easy to start, even with one person on the flat.
The gearing on the bike is 16/36 so even a bump start in first gear does not turn the motor over very fast.
I will put a timing light on and see exactly what the ignition advance is with the switch on and off.
Reply With Quote
Sponsored Ads
  #4  
Old 01-31-2005, 07:20 PM
Satch0922's Avatar
ATM! Addict
 
Join Date: Feb 2003
Location: USA
Posts: 9,220
Default Re: YZ450 neutral switch and hard starting

Actually the "blue wire mod" was recommended "back in the day" on the 426 to IMPROVE starting. The blue wire when disconnected, bypassed the nuetral safety switch. As Florida393 mentioned, alot of us removed the switch and wiring all together with ZERO starting issues. Also, the factory bikes do not run a NS switch either. I think there maybe something else going on with the wiring on your bike.

Reply With Quote
  #5  
Old 01-31-2005, 08:22 PM
Beginner Class
 
Join Date: Jan 2005
Last Online: 02-08-2005 08:37 PM
Posts: 7
Default Re: YZ450 neutral switch and hard starting

When you say "bypassed the neutral safety" do you mean the protection from over rev in neutral?
Reply With Quote
  #6  
Old 02-01-2005, 06:29 AM
Satch0922's Avatar
ATM! Addict
 
Join Date: Feb 2003
Location: USA
Posts: 9,220
Default Re: YZ450 neutral switch and hard starting

I mean removed, no longer there.. not working
Reply With Quote
  #7  
Old 02-01-2005, 04:45 PM
Beginner Class
 
Join Date: Jan 2005
Last Online: 02-08-2005 08:37 PM
Posts: 7
Default Re: YZ450 neutral switch and hard starting

I was asking what you meant by safety not bypass.

Did the "rev limit in neutral" info come from Yamaha or was it something that was noticed by riders.
The reason I ask is because I think it is far more likely that the limit is a side effect of the ignition retard rather than the goal.
Retarding ignition in neutral to aid starting is a logical thing to do.
How many people would rev the bike past 7000 in neutral? I doubt that it would be enough to make Yamaha spend money and development time to add a neutral rev limiter. Revving the nuts off it in first gear waiting for the gate to go down is going to be every bit as bad as revving it in neutral, and more likely to happen.
These points should be enough to show that the limit in neutral is a side effect.
That brings us back to the real reason for the neutral switch. To retard ignition to help make the bike easier to start.
Why is everyone removing the switch?
I don't see what is to be gained by removing the switch unless you need a sight glass for the wet sump kit.
Reply With Quote
  #8  
Old 02-01-2005, 04:49 PM
Satch0922's Avatar
ATM! Addict
 
Join Date: Feb 2003
Location: USA
Posts: 9,220
Default Re: YZ450 neutral switch and hard starting

aske team Yamaha. They would never do anything to their race bikes (especially thumpers) to make them HARDER to start. Here is why we all did it and with very good results...I assume the factory riders/mechanics did it for the same reason:


[Only registered and activated users can see links. ]
Reply With Quote
  #9  
Old 02-01-2005, 04:55 PM
Beginner Class
 
Join Date: Jan 2005
Last Online: 02-08-2005 08:37 PM
Posts: 7
Default Re: YZ450 neutral switch and hard starting

Do you think the purpose of the neutral switch is as a rev limit in neutral?
Reply With Quote
  #10  
Old 02-01-2005, 04:59 PM
Beginner Class
 
Join Date: Jan 2005
Last Online: 02-08-2005 08:37 PM
Posts: 7
Default Re: YZ450 neutral switch and hard starting

I cannot get to the link you posted on the blue wire change, just times out
Reply With Quote
  #11  
Old 02-02-2005, 06:14 AM
Semper Fidelis
 
Join Date: Dec 2002
Last Online: 02-26-2014 07:31 AM
Location: Barrineau Park, FL
Posts: 7,291
This mod was a factory race team idea

wmc,
The original modification came form the Yamaha MX, SX and off-road teams. As stated above, per Yamaha, the switch served the purpose of limiting the revs in neutral for European sound testing of consumer purchased bikes (EU requires the bike be in neutral for the test and they are dead serious about sound testing there).

The switch was looked at as more weight and something else to short out there by the race teams so it was reomved. Ty Davis, a Yamaha off-road rider (I.S.D.E. tema member, WORCS, National Hare and Hound series and BITD series) has an accessory company that sells a cover. Several other manufacturers make covers of different designs.

I removed mine in 2003. My '02 426 has started easily and with no kick back since the removal, including hot starts on the track.

Bill
Reply With Quote
  #12  
Old 02-02-2005, 06:30 AM
Satch0922's Avatar
ATM! Addict
 
Join Date: Feb 2003
Location: USA
Posts: 9,220
Default Re: YZ450 neutral switch and hard starting

Quote:
Originally Posted by wmcdonal
I cannot get to the link you posted on the blue wire change, just times out
Just checked...the link works.

Here is the main link.....click on "blue wire mod"

[Only registered and activated users can see links. ]
Reply With Quote
  #13  
Old 03-30-2005, 06:06 PM
Tdub's Avatar
ATM! Pro Class
 
Join Date: Dec 2002
Last Online: 08-19-2014 07:17 PM
Location: The OWB, Kentucky
Posts: 3,026
Default Re: YZ450 neutral switch and hard starting

For what it's worth, our race bikes(8 YZF450&505s) have no neutral switch, no choke and no hot starts, no accel pumps(45 Mikunis). 3 kicks max any time to start...it's a wonder what spot on jetting gets you.
We also have "starter nuts" on the end of the cranks of our Framers(2). Stick the remote starter in and hit the switch...voila! Tdub
Reply With Quote
Reply

  All Things Moto! Web Forums > Dirt Bike - ATV - Suspension Forums > 4-Stroke Dirt Bike Bike Forums > 4-Stroke Dirt Bikes - Yamaha


Bookmarks

Thread Tools


Similar Threads for: YZ450 neutral switch and hard starting
Thread Thread Starter Forum Replies Last Post
hard starting Michael Parker 2-Stroke Dirt Bike Forums 20 01-17-2008 01:48 PM
neutral switch? YZ125motoracer 4-Stroke Dirt Bikes - Yamaha 8 09-06-2006 06:00 AM
Help, hard starting CR CRs4life 2-Stroke Dirt Bikes - Honda 26 02-16-2005 01:06 PM
ZipTy neutral switch cover plate Florida 393 4-Stroke Dirt Bikes - Yamaha 26 02-02-2004 10:37 PM
Neutral switch cover / Site Glass Satch0922 4-Stroke Dirt Bikes - Yamaha 16 08-17-2003 05:39 AM


All times are GMT -6. The time now is 11:39 AM.

Portal Forums Photo Gallery Popular Tags RSS Feeds

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright ©2002-2014, JDub Consulting, Inc. All Right Reserved.