trx42023 0 Posted June 7, 2023 Hey guys I'm stumped and need some help. I have a 2008 420 electric shift that refuses to run. ATV ran fine but had a horrible top end knock. Put a rebuild kit on four wheeler and started it up. Ran quiet as could be but would not idle. Tried starting it again after reinstalling fuel tank and quad would not hit a lick. You can spin it over 10-15 times until it pops through the exhaust like 12 guage shot gun. Will not even sputter on starting fluid despite getting spark at plug. Share this post Link to post Share on other sites
jeepwm69 7,624 Posted June 7, 2023 19 hours ago, trx42023 said: Hey guys I'm stumped and need some help. I have a 2008 420 electric shift that refuses to run. ATV ran fine but had a horrible top end knock. Put a rebuild kit on four wheeler and started it up. Ran quiet as could be but would not idle. Tried starting it again after reinstalling fuel tank and quad would not hit a lick. You can spin it over 10-15 times until it pops through the exhaust like 12 guage shot gun. Will not even sputter on starting fluid despite getting spark at plug. Welcome aboard. If it won't hit on starter fluid you either have no spark (unlikely if it pops through the exhaust), or you have no compression (my guess since you just did a top end). Could have jumped time, might have gotten the top end wrong. That said, with the symptoms you describe, not much you can do other than pull the top end back off and see what you see. Might have to take the front cover off too and see if you've jumped time. Share this post Link to post Share on other sites
trx42023 0 Posted June 8, 2023 I find it odd it ran good before and ran after rebuild then now suddenly won't do anything. I took it back apart and checked to see of maybe a ring broke or something but everything is fine. With the plug out and spinning engine over it has a strong visible spark. It won't backfire like a typical 180 out or something. It will spin and spin and spin with nothing other than sound of compression out the pipe/suction at intake. Then after 15-20 spins it makes a huge boom out the pipe. Share this post Link to post Share on other sites
Fishfiles 20,145 Posted June 8, 2023 Did you try and spray some starting fluid into the engine thru the intake ? That quick test will help shed some light and eliminate fuel as an issue .... I would do a compression test and see what I was working with ---- could be timing is off or a valve sticking or adjusted at the wrong spot = like 180 degrees out 1 Share this post Link to post Share on other sites
trx42023 0 Posted June 9, 2023 I tried starting fluid to no luck, took fuel injection off to spray directly in intake and it will not even sputter despite having spark. Which makes no sense even if its 180 out it should backfire or something. Theres pressure coming out exhaust like it has good compression. Share this post Link to post Share on other sites
trx42023 0 Posted June 9, 2023 I've heard of spark plugs firing outside engine but under compression being bad (or too weak to combust). Would the starting fluid cancel that out though? Being easier to ignite. Share this post Link to post Share on other sites
Fishfiles 20,145 Posted June 9, 2023 2 hours ago, trx42023 said: I tried starting fluid to no luck, took fuel injection off to spray directly in intake and it will not even sputter despite having spark. Which makes no sense even if its 180 out it should backfire or something. Theres pressure coming out exhaust like it has good compression. Apparently if it does have spark and compression and won't pop on starting fluid , then it has to be timing , one way or another , the engine has to be top dead center with the valves closed for it to run , bad timing could be caused by many things , maybe jumped a tooth or two off at the sprocket , improperly adjusted valves , worn out cam lobes , a bent valve stem , a stuck valve , bad valve seats , a bent connecting rod ( from having ingested water ) not allowing it to hit top dead center >>>>>>>>>>>>>I was saying maybe you adjusted the valves 180 degrees out ^^^^^^^ Share this post Link to post Share on other sites
