Kt100 trashed piston skirt

I've had ground squirrels put acorns in some pipes .
TS racing I think is in Florida .
The trash in the pipe aspect is valid especially if you didn't clean it or had never ran it .
 
flattop1 said:
I've had ground squirrels put acorns in some pipes .
TS racing I think is in Florida .
The trash in the pipe aspect is valid especially if you didn't clean it or had never ran it .
Click to expand...
Ts racing is about an hour from me but I wasn't aware they offer machining services. Thank you!
 
Make sure you check the exhaust pipe for debris, as well as any air cleaner or air box for parts as well. You can probably imagine how I know that. hahahahaha!

Be careful using a hotplate to heat cases -- there should never be a need to get beyond 350F. If you have an IR gun, I'd recommend using that to make sure it doesn't get too hot. When using an oven, hot plate, or any other heat source... it work well to have an aluminum plate that sits in the oven or on the hotplate, and then set the case halves on that aluminum plate. It's a big heat sink that will make the heating of the case halves a lot more "even". An oven or hotplate can have hot spots, and that interim plate will even out the temperature.

If the bearings don't fall out at 350F, it might take just a bit of a tap on them to break them free (especially if the cases weren't squeaky clean when the bearings were dropped in). Have something ready that is just a bit larger than the ID of the bearing (like a short length of wooden dowel or a short aluminum bar) and a plastic hammer. Usually if they are "sticky", you can just grab your little bar you have ready and give them one tap and they will fall out.

Let the cases fully cool and give them a good cleaning (Dawn dish soap in a bucket of very hot water works well if you don't have an ultrasonic tank or anything like that). When you heat them up to install bearings, use the same approach and pre-heat your aluminum plate and then set the halves on there. You shouldn't need 350F to install bearings... usually 300F is more than enough, but going to 350F will buy you a lot more time to drop them in.

Once again: I highly recommend not exceeding 350F.

Never install (or remove) bearings with a press -- it's very easy to damage a bearing bore.

PM
 
Pete_Muller said:
Make sure you check the exhaust pipe for debris, as well as any air cleaner or air box for parts as well. You can probably imagine how I know that. hahahahaha!

Be careful using a hotplate to heat cases -- there should never be a need to get beyond 350F. If you have an IR gun, I'd recommend using that to make sure it doesn't get too hot. When using an oven, hot plate, or any other heat source... it work well to have an aluminum plate that sits in the oven or on the hotplate, and then set the case halves on that aluminum plate. It's a big heat sink that will make the heating of the case halves a lot more "even". An oven or hotplate can have hot spots, and that interim plate will even out the temperature.

If the bearings don't fall out at 350F, it might take just a bit of a tap on them to break them free (especially if the cases weren't squeaky clean when the bearings were dropped in). Have something ready that is just a bit larger than the ID of the bearing (like a short length of wooden dowel or a short aluminum bar) and a plastic hammer. Usually if they are "sticky", you can just grab your little bar you have ready and give them one tap and they will fall out.

Let the cases fully cool and give them a good cleaning (Dawn dish soap in a bucket of very hot water works well if you don't have an ultrasonic tank or anything like that). When you heat them up to install bearings, use the same approach and pre-heat your aluminum plate and then set the halves on there. You shouldn't need 350F to install bearings... usually 300F is more than enough, but going to 350F will buy you a lot more time to drop them in.

Once again: I highly recommend not exceeding 350F.

Never install (or remove) bearings with a press -- it's very easy to damage a bearing bore.

PM
Click to expand...
Thank you very much!!!
 
The rod shouldn't go that far over. I think you have the new style lower rod bearing but no side washers? If you have the new style top rod bearing it can move side to side allot and these things combined with excessive crank side clearance got everything on one side in a turn maybe and cocked your highly tapered KSI piston.

Sundog
 
sundog said:
The rod shouldn't go that far over. I think you have the new style lower rod bearing but no side washers? If you have the new style top rod bearing it can move side to side allot and these things combined with excessive crank side clearance got everything on one side in a turn maybe and cocked your highly tapered KSI piston.

Sundog
Click to expand...
That makes sense for sure! I do believe that the upper rod bearing was the new style, I wasn't in any turns I was on a long straight but hit 13,800 rpm's and then the motor died. I'm taking the crank to TS racing for them to put in a new lower bearing and rod on the crankshaft. I'm going to make sure they set me up with the right parts. Thank you very much for your insight!
 
Kt100guy85 said:
Ya I split the cases already, that's why there's the massive gap. The pipe is a c4 I believe, almost comical since I blew the engine lol. I only found pieces of skirt in the case and accounted for about 90% of the skirt with the exception of the pieces that became powdered aluminum that destroyed the head. I didn't think about something coming back from the exhaust but that is a very valid point. Thank you!
Click to expand...
Is there any thrust washers on either side of the rod, in one picture I don't see a thrust washer or was the rod captured on top.
 
michael collins said:
Is there any thrust washers on either side of the rod, in one picture I don't see a thrust washer or was the rod captured on top.
Click to expand...
To be honest I don't know, I'll look when I get home. The last guy who owned this motor Jimmy rigged pretty much everything. So I wouldn't be surprised if there wasn't thrust washers. When I rebult it I didn't take the time to split the case and I learned a valuable lesson. I'm sure TS racing will get me going again. I should have just bought a used shifter kart lol. I paid 450 for the kart, I habe about $800 into it and now I'm looking at another 350-400 to get it right...... I can tell you with certainty that the rod has a lot of side to side play
 
Here's another question, will the new style head work with the old style cylinder? The kt100 that I have is one of the originals I'm assuming from the 70's.
 
20201110_162321.jpg
 
Last edited:
Just curious, have you ever checked the crank play in the main bearings? I'm not saying that piston couldn't fail, but the possibilities increase if the piston is hitting the head or the bearings are knocked out a shape. I've seen it happen on a KT100.
 
Kt100guy85 said:
Here's another question, will the new style head work with the old style cylinder? The kt100 that I have is one of the originals I'm assuming from the 70's.
Click to expand...
Yes, you can interchange the old head with the new or vice versa. Looks like you might have had something inside the engine that wasn't supposed to be there.

Oh, and BTW, your rod will either be captured on the bottom or on the top. Never both! If you look closely at the crank assembly, it might have thrust washers on either side of the big end. But, like Mr. Collins noticed, it doesn't look like it does in your picture. Did the top end (small end) of the rod have aluminum washers on each side of the rod, against the piston? If you had no washers on either end, you may have had excessive piston rock from side to side. How much piston to wall clearance did you have? Too much clearance will let the piston rock back & forth too much and results in broken piston skirts.

Brian #89
 
phantomkartracer said:
Yes, you can interchange the old head with the new or vice versa. Looks like you might have had something inside the engine that wasn't supposed to be there.

Oh, and BTW, your rod will either be captured on the bottom or on the top. Never both! If you look closely at the crank assembly, it might have thrust washers on either side of the big end. But, like Mr. Collins noticed, it doesn't look like it does in your picture. Did the top end (small end) of the rod have aluminum washers on each side of the rod, against the piston? If you had no washers on either end, you may have had excessive piston rock from side to side. How much piston to wall clearance did you have? Too much clearance will let the piston rock back & forth too much and results in broken piston skirts.

Brian #89
Click to expand...
No aluminum washers up top and nothing on the bottom either.... I just tried to get a feeler gauge between the piston and cylinder but .002 is the smallest I have and that won't hardly fit.
 

Attachments

  • 20201110_172227.jpg
    20201110_172227.jpg
    142.9 KB · Views: 16
phantomkartracer said:
Yes, you can interchange the old head with the new or vice versa. Looks like you might have had something inside the engine that wasn't supposed to be there.

Oh, and BTW, your rod will either be captured on the bottom or on the top. Never both! If you look closely at the crank assembly, it might have thrust washers on either side of the big end. But, like Mr. Collins noticed, it doesn't look like it does in your picture. Did the top end (small end) of the rod have aluminum washers on each side of the rod, against the piston? If you had no washers on either end, you may have had excessive piston rock from side to side. How much piston to wall clearance did you have? Too much clearance will let the piston rock back & forth too much and results in broken piston skirts.

Brian #89
Click to expand...
 

Attachments

  • 20201110_172241.jpg
    20201110_172241.jpg
    122.5 KB · Views: 14
  • 20201110_172227.jpg
    20201110_172227.jpg
    142.9 KB · Views: 14
The damage on the right side of the case looks like collision damage be it forgien Material or piston skirt contact .
i don't think the piston could ever reach there , though I'm no expert .
several of the others posting are .
 
Kt100guy85 said:
No aluminum washers up top and nothing on the bottom either.... I just tried to get a feeler gauge between the piston and cylinder but .002 is the smallest I have and that won't hardly fit.
Click to expand...
The KT100 was designed to have either a top locating rod (the old style) or a bottom located rod (the new style). If you don't locate either end of the rod, it is just flopping around from side to side, trying to locate itself. I can't say 100% but, it is more than likely your culprit. Looks like, you have the old style crank assembly. You will either need to obtain the proper top bearing & two aluminum washers to locate the rod properly or swap the crank assembly for the newer bottom located one. BTW, better get that rod checked before you reuse it. It might be bent. They are a little soft & can bend easily, especially when you have a catastrophic failure like yours.

Unless you have some good mechanical knowledge of 2-cycles, better take it to an engine shop or just buy another engine. They can be bought for less than a major overhaul.

Brian #89
 
You must log in or register to reply here.
Back
Top