Had a guy drop off a 98 xplorer 400 off this morning that he wanted to sell. Won't run. He said a guy told him that it was a two stroke and it probably fried the piston. Carb and reed cage were pulled and so was the plug. Looked in at the piston and down the sparkplug hole with my bore scope and all looked good. Guy said it was running fine and it just died and wouldn't start. He said the throttle acted funny, like it was real loose. It feels like the cable isn't hooked up. Would a broken cable cause the ETC to not let the engine fire? If this is a bad throttle cable, do you have to buy the while thing, with the oil pump cable and all?

Thanks
Mike

 

I'd still check compression as a first step any way on a two stroke.If it was the oil pump section of the split cable that broke or was loose,it shouldn't affect the etc switch as it would still have the carb spring for cable tension. No harm popping the throttle housing cover and checking the etc clearance though. Plus a simple plug against the cylinder should tell on spark condition.If no spark always pull the black wire from the limiter first,check for spark,kill wire from the cdi next and check.If it then has spark could be caused by other problems such as the switches,wiring. The throttle cable comes as a two piece,haven't seen either throttle or oil pump section of it sold separately unless you block off the oil pump and get a single throttle cable from Aaen Performance or other places.If you do need a new cable,Motion Pro or the Sled parts guy on ebay has some cheaper ones than oem.

 

Thanks OPT,

I pulled the cover off the throttle and pulled the slide out of the carb. The cable moves freely but it acts like the spring isn't strong enough to pull the throttle back. Don't know what I should look at. The other machines I have, the throttle snaps back very easily.
As far as the top end, I'm hoping to bolt the reed cage back on and do a compression test. Hopefully it's good. I bought it assuming the worst so if it needs a rebuild, im not too worried about it. If the top end checks out, im still going to do crank seals because the machine is 20 years old.

Thanks
Mike

 

That's me to..
I'm an either an Optimistic pessimist or pessimistic optimist.. Don't know which one as I always expect the worst that can happen,but relieved when it doesn't.

 

Well my suspicions were confirmed, looks like it will need a top end at the very least. Haven't tore the jug off to check the bottom end yet. Son in law left a bunch of gear oil in my drain pan without cleaning it up so I couldn't drain the coolant. I checked the counterbalance fluid and it was clean so no surprises there. I played with adjusting the throttle cable and it is working fine now. Has spark, just very little compression. I can reach in through the intake and wiggle the piston some so it definitely is a loose bore. Get it apart and see what I will need and send it off to the machine shop for a bore and a wiseco piston., lol

Thanks
Mike

 

Oh well... You've rebuilt enough of em now you can teach the other posters on what to do.

 

Lol, I don't think I've done a fraction of these compared to what you probably have done in your lifetime OPT. Fun little hobby for me and it keeps the wife happy because I am out of her hair for the most part.

Pulled the jug today and got what I expected. Piston was trashed on the clutch side. Didn't chew the cylinder up that bad so I'm hoping maybe the next step on a bore job will do, but worst case is going 20 or 40 over will get the job done. Don't know why the piston went. Looks like it had plenty of lubrication and it didn't look like it ran hot at all. Maybe it was just cheap oil, oh well. Bottom end rolled over smooth and was tight so it looks like crank seals, piston kit and upper rod bearing and this one will be ready to go.

Thanks
Mike

 

That is some nasty scarring. Almost as bad as mine, and I'm not talking about engines.