2 stroke engine guru needed

[Knuck]

Seized my 300 last night on the guided ride. I have not torn into it yet so I don't have a clue what it is. It didn't feel like a hot seize.. Anyhow if it is a simple top end issue I can tackle a ring and piston but I still will need the cylinder rebored/honed. Jim Titmus has done one for me before but this was eons ago. If the problems are in the bottom end then I will need help because I don't split cases.

Any recommendations?

[MotorEd]

OUCH! Been there done that....it really sucks Describe what happend, how did you warm up the bike? how were you riding when it seized? Can you kick it over? or is the piston stuck? what jetting you got in there?....need more info to help you out.

You will have to take the jug off to take a look as a starter....not sure what to do if the piston is totally seized though?

If you can get the jug off, be sure to check your ports for cracks...more often than not you will see them inbetween the exhaust port and intake ports. I have heard some guys welding, but really you are looking at a whole new jug, head and top end.

sorry to hear about your luck

[steve-o]

Pull your pipe and have look in there first, then the head if you have to. Bottom end might no be bad unless you were really ringing it out and it stopped very sudenly (don't know how/what happened to you last night, sorry about your luck BTW). If it's just the top, Titmus still does cylinder reconditoning (I'm pretty sure). new is also an option. If there is broken rings in there be careful when you remove the jug so you can try to pick the chunks of ring out of the lower portion.

Check all that first before you worry too much about the bottom. If it is the bottom, I can't really make a recommendation about who to use.

[Knuck]

Here are the details:
Bike was running real strong before the seize. We were climbing up the long cutline heading east on logghopper (after the compressor station). A long hill but not real nasty or anything. I did lay the bike downon a fallen tree about 1/2 up. The bike relit fine but seemed a little boggy. Fot the rest of the climb the bike felt perhaps a little boggy but it was a little loose and slick from the rain. At the top I zinged the throttle a few times and it seemed to clean out. We had a 3 minute break and the bike would not kick over. The kickstarter would not move. The rads weren't all that hot but the jug seemed toasty so perhaps a water pump failed and torched the top? we pulled the plug and it looked good, nice and tan/brown, not looking lean.

I guess I will start by washing her up and moving into the garage. I will start on the exploration on the weekend. Can a 2004 EX/C 300 jug be overbored or is there a nikisil thing going on there?

Thanks for the tips so far.

eric

[steve-o]

Here are the details:
Bike was running real strong before the seize. We were climbing up the long cutline heading east on logghopper (after the compressor station). A long hill but not real nasty or anything. I did lay the bike downon a fallen tree about 1/2 up. The bike relit fine but seemed a little boggy. Fot the rest of the climb the bike felt perhaps a little boggy but it was a little loose and slick from the rain. At the top I zinged the throttle a few times and it seemed to clean out. We had a 3 minute break and the bike would not kick over. The kickstarter would not move. The rads weren't all that hot but the jug seemed toasty so perhaps a water pump failed and torched the top? we pulled the plug and it looked good, nice and tan/brown, not looking lean.

I guess I will start by washing her up and moving into the garage. I will start on the exploration on the weekend. Can a 2004 EX/C 300 jug be overbored or is there a nikisil thing going on there?

Thanks for the tips so far.

eric

Sounds like lien seize to me. Try and turn over the engine with the kick starter today. If it's hot and seizes on the trail like that it might get loose again when it cools. You'll be looking at the jug and such as per Motored's post. Maybe a Titmus job if its not scored to bad or cracked.

Where do you live?

[Knuck]

Signal Hill.

[MotorEd]

Here are the details:
I did lay the bike downon a fallen tree about 1/2 up. The bike relit fine but seemed a little boggy....... We had a 3 minute break and the bike would not kick over. The kickstarter would not move.
eric

sound totally like a lean seize, or lean bog after you put it down....need to figure why it got lean after you laid it down?

The fact it just wouldnt kick over is good...rather than seizing it at WOT. My guess is that you will be able to kick it over tonight....dont fire it up! but you should be safe to pop the head off and take a looky inside the jug for scuffing....then pull the jug and check the pistion and rings.

sounds like it wont be that bad though

Good luck! take some pics and postem with your findings

[trailguy]

So when the bike fell over on the tree was there any chance a stick or branch punched a hole in one of the carb boots, or the carb got hit & it cracked the intake rubber boot.

[Knuck]

Ok I have torn into it. The piston didn't look too bad on the top and the cylinder bore looks ok. I think a new piston/ring/hone is probably in order. The bad news is the engine is still seized with the cylinder head off. Whwere to look next? I think clutch? Kickstart gear?

Here is a couple pics:

[Knuck]

Ok I found the source of the problem. It looks like the missing pieces are in the bottom. Out of my league for now. Need someone to fix this mess.

[steve-o]

Ok I found the source of the problem. It looks like the missing pieces are in the bottom. Out of my league for now. Need someone to fix this mess.

not necessarily, see if you can fish them out and account for all of them! report back.

[cedric]

Chances are there are some bits of that are in your main bearings and that is causing the seizure. How old was that piston? Looks like some chunks came up through the ports and got hammered between the piston and the head too. How does the head look?

Splitting the cases is not too big of a deal, I'm sure if you are willing to go slow and post pics, we could walk you through it on here. Rebuilding the crank requires some special tools and skills however. If you want to go this way, start by getting a good manual and reading it carefully.

I once had a crank rebuilt by a guy with a business called LRX performance in DeWinton. He did a great job and was very reasonable. Jim Titmus could probably rebuild the crank for you too.

Hopefully there is no damage to your cases and the seizure is just in the crank.

[Bruce]

I have a bending scope video camera I could lend you can fish it down into the lower end to see if there's anything obviously "out of spec"
Bruce
403 875-7500

[Knuck]

Thanks for all the tips and offers. The co rod had a little play so it may be time for some big end bearings. The head doesn't look too bad. If the cylinder is still in spec I may be able to salvage it as well. I have split cases before but time is tight and I would like to get this done while I am out of town on vacation.

[steve-o]

Chances are there are some bits of that are in your main bearings and that is causing the seizure.

This could be. However I once had a honda 250 and what cause it to stop was a chunk of ring (or piston, can't remember which) that got lodged between the outer portion of the con rod and the case. I jabbed it out and, cleaned er' up and the crank and rod moved freely. New piston and rings, cylinder service and she was golden.

I'm not saying this will be the case for you but you never know.