440 will not hold idle

[HondaOnly]

I have a 400ex that i recently rebuilt the engine, just monday actually. When i rebuilt the engine, heres what i did. Wiseco 440 10.5:1 kit, decked the cylinder, hotcams stage 2, mild port job, 38mm lectron carburetor, LRD pro4 exhaust and modified air box lid. Now that all this work has been done to it, i am unable to get it to hold a steady idle, especially when it heats up. It will idle high, then slowly die down and stall out. This doesnt really pose a huge issue because i never ride around at idle anyhow. But its nice to be able start the quad up and let it warm up on its own with out having to blip the throttle every few seconds to get it back up to speed. My guess is that its loading up on me, but i have leaned the lectron out significantly since is started breakin and there is little differnce. Any ideas?

Also, i have heard the 440's take longer to break in than stock bores do, is this true? And how long should i go before i can ride it normally? Generally i go easy on it for the first few tanks, but i have to go somewhere friday with the quad, so i have to know what the minimum safe breakin time is so i can have it set for the trails. Ive put a gallon or so through it now at no more than quater throttle. I plan to go easy on it for another 3-5 hours or 5 gallons whichever comes first.

Thanks

[JRDrider22]

to break it in. keep the same speed but shift all the way up thorugh all the gears for 30 minutes. thats what i did and my bike pulls off now

[quadmx7]

i know that when we built my cosuins 440 recently he had the same problem as u but we found out he was running way too rich, so we lowered his main and changed the pilot and it solved it.

[MIKE400EX]

I'm not too familiar with the Lectron's, but look for a vacuum leak between the head and carb. Maybe a crack in the manifold, carb is not seated correctly in the boot, o-ring in the manifold, etc...

As for break-in, ride it for a while now varying the speed and engine load. Just don't hang it wide open for any extended period. Another hour at varying loads/speeds, change the oil & filter and go thru everything and it should be good to "go". DO go back and retorque-check the head nuts. Pain in the butt (kind-of) but necessary. One important part of any break-in is to NOT keep the engine at a constant speed for long, keep varying it.
Good Luck!

[HondaOnly]

it is definitly not too rich, infact, i just leaned it out tonight and it still had the same issue. I think there is a vaccum leak somewhere, but not sure where. My guess is the bolts that hold the intake manifold to the cylinder are a little loose. The carb is seated all the way in the manifold, i made sure of it. The 440 really viberates alot. The nuts which hold the header on were only finger tight after about 2 hours of slow riding.

The tip of the spark plug was covered with black carbon buildup, the engine blows a puff of black smoke when i tap the throttle fast, so i know its not lean. The strange thing however, is when i leaned it tonight, i couldnt get it to start back up, it would stutter, catch, the engine would rev a little and pop, sneeze a little out the carb, then stall out. I think maybe i just need to get a different metering rod for my lectron, either that or find an air leak if there is one. Also, what if the machinist took alot off the cylinder when he decked it and it bumped the compression higher than i can run on 93, would that cause an erratic idle?

Last thing, so after another tank or so, its safe to start riding the quad normally? Or should i continue to go easy on it for another couple tanks?

Thanks for the replies

[HondaOnly]

sorry, a little off topic but....

Mike400ex, your in oxford ct, which is right close to ridgfield, like 25 miles away. Ive been looking for some places nearby to ride, but havent found any to close, you know of any?

Also, a friend of mine owns some land up in farmington ct, place called taine mountain, just wondering, you ever been up there before?

[JRDrider22]

also ur carb has to be tilted a little bit to the right under your gas tank. make sure you have gas in your bowl

[HondaOnly]

Having the carb at an angle only allows for the throttle cable to clear properly correct? I know the throttle cable doesnt fit that great if they are straight up but it has plenty of fuel. The float is 3/4ths of the way full, is that normal, maybe its a little low?

[JRDrider22]

no thats good as long as you have gas in the bowl it should start. yes the carb should be tilted.if it isnt the throttle cable wont have any clearence it should have for it to be able to move.

[HondaOnly]

i richened up the lectron needle two turns, it fired right up, but still did not hold a steady idle, but it is getting much better, i think i am getting closer. Im going to finish the breakin and and keep doing periodic plug checks to see how the mixture is. Right now, the most important thing to do is for me to continue and breakin the engine well and get as much driving in as possible. Im going to check a few more things. I gapped my valves today, two were just fine, one was just barely closing all the way and the other had a gap that i would estimate to be close to .020 inches, but probably not that much. After the gapping, it seemed to make better power and hold that idle for even longer, but as soon as i stopped giving blips of the throttle every 20-30 seconds, it would stall. I think i have narrowed it down to an air leak somwhere, possibly in the manifold. After it all cools, i will check it out, and if thats the case, i'll get a new o-ring and replace it.

as always thanks for the help, the idle is getting to the point of toleration. maybe the rings are still pretty tight against the cylinder and it still needs to loosen up some more, but once again, probably not

[MIKE400EX]

If there is an idle air bleed jet or "hole" in the intake end of the carb make sure it is not clogged.

[JRDrider22]

glad u got it goin. i had some problems before with it too i just did everything possible till it started now it pulls

[HondaOnly]

Now that is breaking in, i think the rings are starting to seat, thus creating less resistance and more ring seal, especially when the rpms are low. Man this thing hauls, I put about 4 hours through it today, 3 yesterday and a couple on tuesday, so i think its pretty safe to start running it a little harder than i have been. I read somwhere that it is best to actually run your engine normally, with reason, not beating on it, in the first few hours of break in, that way it your rings seat better while the honing cross hatches are still there. If you want the link i can get it, but is this true?