OK,I work on 4wheelers/snowmobiles part time but the problem I am having right now is very hard on the head.My quadsport smokes EXTREMELY bad,striped the engine down last nite and the piston/cylinder and all gaskets were fine (cylinder still cross hatched a lil), Valve seals were good but I put new ones in just in case.Still smokes the same now as before.When I took the intake valve out there was oil on it,It seemed to be running down the stem of the valve but I am not positive.Do these heads have a casting problem? The only thing really left to change is the valve guide and/or valve but they are both tight.What else can I check and did anyone else have a problem Like This?


BJ White


I have been reading the forums now for a while but this is my first post [img]i/expressions/face-icon-small-smile.gif[/img]

 

i would pull the valve cover off and rotate the engine until both intake and exhaust valves are closed, then just do a leakdown compression test on it. if the compression very slowly leaks down this will tell you if your rings and bore are really good, you can't tell just by looking. if the compression never builds up and stabalizes or if it leaks down very fast then you are looking at a problem in your head. i would check for bend valves or bad valve seats. good luck

 

didnt just look,meaured the clearences of the rings and piston.They are wore a tiny bit (1 thou) but not near enough for it to smoke.Valves are all perfect,compression is good but it still burns oil really bad. How would the seats affect oil burning?

BJ White

 

Mrsector9, I had the exact same problem a month ago, smoking like a mosquito fogger. 86 LT230S. Pulled it down, everything looked perfect. Since it was apart, ordered new std bore piston/ring set, valve seals, had valve job done and honed cylinder out. Just got everything back from the machine shop today. I will put it back together next week sometime. Guides and seats were worn a little bit, seals were mushy but intact. I hope I have covered all the possible causes, but I won't know for sure until I put it back together. I will post back the outcome. I was scratching my head too over this one. I've rebuilt dozens of automotive engines and always found the culprit upon teardown. Not this time. If you find the cause first, post back or email me please. bobcatv8@yahoo.com.

 

That is exactly my problem,rebuilt dozens upon dozens of engine for snowmobiles and ATVs and always the problem jumped out (broken ring,wore out,bad head gasket) but this is unbelievable that it can smoke that much with non of the above wrong.I compounded my valves while I had it apart for good measure.I don't see how a wore seat can make it smoke,wore valve stem or guide maybe but never seen that before because the seal will usually take up the slack.I am probably going to work on mine over the weekend again but I am going to try another head on it (I know it will fix it,I just want to know why this one is doing that). Soon as I find a solution though I will post it. Other reasons for smoking I don't understand either like Worn Rocker Arms shouldn't have anythign to do with smoke because they have nothing to do with oil getting into the intake or cylinder. I am going to call one of the best ATV Mechanics in the maritimes tomorrow to see what help he can offer.

BJ White