2000 honda 400ex top end problem

[graydevil]

I purchased this atv with the valves ticking so i took it in and had the shop fix the problem then it started to smoke (blueish -white)so my assumption was the rings, i had them bore the jug to make it a 405 i think. put a wiseco piston 11:1 comp. new valves new rockers,put about 7 hrs on ot at half throttle changed oil ran it for 6 more hrs start to smoke blue when i first started it up ran good after that .i was on a long straight away 3rd gear shifting to 4th motor dies.. took back in bored it again put 416 kit in dyno jet kit and hmf sport exhaust.new air filter when i got it back i put 2 hrs on it change oil checked and cleaned screen new filter. went riding hit second gear let off the throttle motor dies ..i am not happy dumping money in the motor i need help......

[CJM]

Well first off did it smoke profusely or just a bit? A bit is only valve seals, profusely is rings of course.

Next I pray they had the piston before they even bored it-you need the dang piston to do a proper bore job.

Finally since it just died I would check all the obvious: is everything in time (cam gear line up with head?), is it getting fuel, is it getting spark, does it turn over or just keep on thumping, is the timing chain tight?

FYI: All 400EX valves tick, not to overly loud but its there.

[400exshop]

all so check and see if your jets are still in right. make sure non have came lose.

[graydevil]

i gave the machine shop the piston before they did the bore both times i did check all the simple things first. the last time it died i did a compresson check the psi was 10 now my guy tells me the bottom end might let go

[ridein'red7]

all i know is the machine shop is not doing jack but ripping you off it seems or u like the rev limiter or something or cold seize and keep riding haha

[ridein'red7]

did it have oil in it? and was there any sludge built up and did u clean out the screen? lac kof oil could be i tjust seems like its getting hot and melting the rings

[dalejiw25]

I notice you never mentioned Re-Jetting. With The bigger bores and higher compression, I hope you have been Re- Jetting. If not, I'd say You blew that motor again due to an extremely Lean Condition. Anytime you make any upgrades to a motor you need to re-jet. If this is the case, It's Not necessarily the fault of the machine shop. They did their job, You just didn't follow thru. JMO.

[MtnEX]

Oil starvation or fuel starvation...

[dalejiw25]

One other thing. You mention that after the new piston and ring install you rode around for 7 hrs at half throttle, Not good, Let me explain. In order to seat your new Piston and rings you want to Run it slow for about 5 mins. to warm it up, Then run the piss out of it. You need to pin the throttle for a while, back off a while, and keep repeating this action. Remember, It's air cooled. You don't want it to get real hot during Piston break-in and ring seating by riding it slow. So basically, Take it out to the trails, where you're on and off the throttle to get through them(or the track), and ride That SOB like you stole it, For about 4-5 hrs. or a tank of fuel. That's it, You're rings and piston are broke in Proper. Change the oil and filter and you're good to go. And never use synthetic oil for this break-in period, It's too slippery. Now there's a different procedure for a cam, No need to go there though because you didn't replace it.

[graydevil]

thanks for all your help i did jet it with the dyno kit. spark plug was rich in color i am selling it so i am getting a new one since i am still green with engine reconfigering thanks again for all the input and what is cold sieze?:devil: