Help with overheating
Posted May 08, 2012 - 05:54 PM
Maybe is is too lean at idle? Which jet do I change for this and how do I get at it?
Thinking it might be that as I cannot start it with just a kick, I need to give it a few throttle pumps and it will start one kick...
Posted May 09, 2012 - 02:23 AM
Posted May 09, 2012 - 05:47 AM
Just for fun, try starting the bike with the choke on instead of the throttle pumps. If this makes the bike start easier, you definitely need a larger pilot or to richen the fuel screw if the pilot is proper.
I'd also look through the "Jetting Database" thread to see how others who live and ride in the same elevations and conditions, with the similar amount of mods, have set up their bikes.
Edited by Pooley, May 09, 2012 - 05:50 AM.
Posted May 09, 2012 - 06:14 AM
Posted May 09, 2012 - 08:01 AM
Posted May 09, 2012 - 08:39 AM
Do I also need a richer starter jet since I need to crank the gas to start it?
I am at Calgary elevation
Posted May 09, 2012 - 09:03 AM
Turning the throttle before starting just primes things, and doesn't mean it needs a different size jet. I consider my 426 to be almost perfectly jetted, and when cold, I use the choke and twist the throttle 1-2 times max before starting. The pilot jet is what controls fuel flow at idle, and near idle throttle openings. Once off idle the needle takes over from about 1/4 throttle until the main jet at about 1/2 to full throttle.
What other performance things have you done? Airbox mods, exhaust, etc? All those things add up dramatically when considering jetting.
Check out the following. http://www.thumperta...formance-index/ and you should have enough resources to help you with virtually every question you might have.
Under the "Jetting Database" thread you will find this format, which would be super helpful towards getting you where you won't overheat, increase the durability of the bike, and your enjoyment too.
Model (400 - 426 - 450):
Cam Timing (WR/YZ):
Fuel screw (turns out):
Needle Model/Clip position:
Grey Wire Mod (Y/N):
TPS Connected (Y/N):
Airbox Snorkel/Lid (on or off):
AIS Removed (Y/N):
Degree of Satisfaction (0-10):
Posted May 09, 2012 - 10:39 AM
That being said, the biggest culprit here, at low speeds especially is the pilot and fuel screw. Set those properly now to protect things, and then also after doing anything else. Once the pilot is tuned, you can move on to the needle position, leak jet, AP pump etc. But remember each time you mod something, you should check the jetting as outlined on TT to make sure its proper.
The immediate, quick and dirty fix is the pilot and fuel screw just to keep it cooler when at slow speeds.
Posted May 09, 2012 - 12:43 PM
Posted May 09, 2012 - 12:48 PM
And if mine just shuts of right when I take choke off. I'm guessing go up on the low speed jet Or turn mixture screw out. Btw how many turns out is yours. Just so I have a rough estimate of we're to start
Posted May 09, 2012 - 01:36 PM
Posted May 09, 2012 - 03:03 PM
The pilot jet is the one that is about an inch long, with the upper end a bit tapered with several holes in it.
The info for the grey wire, as well as how to do any other mods is in the stickied posts I linked above. Look through those for the "how-to's" for pretty much everything, including the shop manuals.
Pretty much first and foremost, before any tuning, make sure all jets are clean and not plugged with gunk. The air jets get plugged easily if you over-oil, or don't let your airfilters dry properly before riding. Fuel jets get plugged and varnished by old gas. Clean both air and fuel jets in carb cleaner then blow out with compressed air.
I can see you want to correct this ASAP and I really don't want you to run too lean and risk the bike, but I would highly suggest doing some reading of the FAQ, Jetting Database, Mod Database, Jetting Tutorial, Motoman 393s tech articles for the fuel screw, etc. This will provide you with the answers to most of your questions, and answer them much better than most of us can. After reading this information, please post any questions you may have.
Posted May 09, 2012 - 04:05 PM
Posted May 09, 2012 - 05:30 PM
Posted May 09, 2012 - 08:23 PM
Only question now is I don't know where the jet is located and how to get at it and replace it?
Look at the above links to find the service manual for your specific bike. The manual will show you everything you need to know.
Posted May 10, 2012 - 06:50 AM
Also when my bike turned itself off because it was so hot could that caus any damage? I let it sit for 10 mins and fired it back up fine
Edited by Stealth13, May 10, 2012 - 09:30 AM.