I have a 2002 Honda 400EX that has the rev box, open air box with K/N, jetted, and a White Bros exhaust. I installed a hot cam type 2 for top end and when I started it to do the break in it ran extremely hot. The head pipe got cherry hot for the first 8 or 10 inches when it was reved to 3K RPM so I shut it down. I was running rich prior to the cam change so I did not change the jetting but I find it hard to believe that it would be running that lean from the cam change. What else should I check before I light this thing off again and try to do the break in on it. Any ideas would be greatly appreciated.
Jim
Full Version: 400ex Mods
PM 24V. he's our local 4 stroke specialist
With those mods you should have a 145-150 main, and a 45 pilot. The airscrew should be 2.5 turns out.
| QUOTE (desertbound @ Jan 21 2005, 12:38 PM) |
| With those mods you should have a 145-150 main, and a 45 pilot. The airscrew should be 2.5 turns out. |
Isn't a 148 stock for a 400ex? A 145-150 main for his mods sounds extremely lean.
I'm sorry, I meant a 155-160. I am a retodd today. 
I even origianlly put that and edited it.
Edit...I am positive about the pilot and airscrew though.
I even origianlly put that and edited it. Edit...I am positive about the pilot and airscrew though.
I have a Hotcams 2 also. Did you set the valve lash at .006in and .008ex? Don't know if that would make the engine run hot or not...just a thought.
Your main jet should be around 160
SS
Your main jet should be around 160
SS
The new cams could be adding a little extra friction while breaking them in. I would go up a size or two on the main jet to get them broken in. Then drop it back down if necessary after the first trip. It is pretty hard to get a 4 stroke so rich that you will foul a plug, so you should be fine. Also, make sure you are running dino oil, and not synthetic for the first trip. cams should not be broken in with synthetic.
You shouldnt have to re jet after installing just a cam, but if you installed the filter at the same time then you need to. Setting the valve lash is not hard at all. If its like my motor there is the cam and the loab of the cam pushes down on this metal bucket thing called a tappet. Under the tappet there is a little magnet looking part about the diameter of an eraser and that is the shim. You will need to measure the valve lash with a feeler gauge. Then go from there. After braking it in you should check the valve lash again and if it needs adjusted do so if not then pt hte cover back on and go ride. 
| QUOTE (SHOCKER @ Jan 21 2005, 09:53 PM) |
| You shouldnt have to re jet after installing just a cam, but if you installed the filter at the same time then you need to. Setting the valve lash is not hard at all. If its like my motor there is the cam and the loab of the cam pushes down on this metal bucket thing called a tappet. Under the tappet there is a little magnet looking part about the diameter of an eraser and that is the shim. You will need to measure the valve lash with a feeler gauge. Then go from there. After braking it in you should check the valve lash again and if it needs adjusted do so if not then pt hte cover back on and go ride. |
2 things. First, yes you should have to rejet after installing a cam. Some aggressive cams may ever require 2-3 sizes larger on the main. Secondly, your valve adjustment procedure seems ok except you forgot that the engine needs to be at TDC.
I guess its different because everyone who put hotcams(both or just the intake) in their Z didn't have to rejet at all. Only if they put on a filter or exhaust. I didn't have to on mine at all
| QUOTE (SHOCKER @ Jan 22 2005, 10:30 PM) |
| I guess its different because everyone who put hotcams(both or just the intake) in their Z didn't have to rejet at all. Only if they put on a filter or exhaust. I didn't have to on mine at all |
Could have been jetted a little rich in the first place? Have you even tried a richer jet yet? How do you know it does not require it? Your quad may run good now, but for all you know, it could run much better with a different jet. I plyed with my jets quite a few times to get mine dialed in. That is really the only way to do it. There is no number for each bike. they are all different. Your z may require a 165 main, whereas the next guy with the same mods may require a 168. You should swap the jettig a little to be sure you are getting the most power for your $.
I re-adjusted the valves and re-jetted to a 160 main. I also put 15 discs in the white bros pipe that let it breath better and did the break-in. Then we took it out and it runs fantastic. It really brought the bike to life. Thanks to everyone who provided guidance, you guys are lifesavers.
Jim
Jim
HOW MUCH WERE THE CAMS!?!?
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