Author Topic: 250R Engine Information - What do I have? (Read 5800 times)

Rider414 · « **on:** October 18, 2014, 02:09:07 PM »

Guys,

First post, long time 2 stroke guy, first 250R. I got a complete 250R that was a mess. I am getting into the engine due to a loose crank bearing on the stator side.

I am alittle confused on what I have.
Frame: 86 per the VIN
Cases: 86 ATC per the #
Cylinder: I believe it was a short rod topend due to the open intake and no intake bridge.

BUT - I opened it up and the crank is a Hot Rods CK 109 on the rod. Alittle "googling" and I see that the 109 is a long rod crank.

Other notes: No Spacer Plate.

How do I find out of this is a long rod or short rod motor?

Matt

Pumashine · « **Reply #1 on:** October 18, 2014, 02:48:56 PM »

A long rod crank just needs to have the compatible piston to work on a 86 cylinder. Take a pic of the top of the piston or google the numbers and you will see the piston pin height has been changed to run on a long rod.

Rider414 · « **Reply #2 on:** October 18, 2014, 06:47:11 PM »

I am getting mixed numbers on the piston.

Its a W5032P4 and has .040 stamped on it. Obviously the over size. But is this a Wiseco or a LA Sleeve piston? I am getting all sorts of different answers.

broken1 · « **Reply #3 on:** October 18, 2014, 07:23:12 PM »

Wosner piston maybe?

Pumashine · « **Reply #4 on:** October 18, 2014, 08:29:08 PM »

Wiseco .040 W5032P4 73.00 is what the LA sleeve catalog says. TRX-295R Big Bore 1987-89. So you have a 73mm Wiseco piston which goes on a long rod. You can see the head studs are going through the sleeve in the pic. This is what happens when you put a 310 sleeve on a OEM 250. Nice motor you got there. Just a heads up as you only have 1 bore left. The OEM big bore is prone to head gasket leaks and warping heads. The OEM cylinder was not designed to handle that much heat

Rider414 · « **Reply #5 on:** October 18, 2014, 10:03:29 PM »

Yes it has a sleeve, wouldn't the .040 mean it's at 67mm?

Rider414 · « **Reply #6 on:** October 18, 2014, 10:12:47 PM »

Never mind I get it now. Wow this is interesting.

Hawaiiysr · « **Reply #7 on:** October 18, 2014, 11:07:19 PM »

looks like you scored on that mess:)

Rider414 · « **Reply #8 on:** October 18, 2014, 11:16:46 PM »

I think I would like to have a builder check this setup out. Maybe suggest solutions on the head gasket issues. I noticed the top of the piston comes out of the cylinder some. The head looks to be rechambered. Anyy suggestions on a builder? I use Halls Precision for my Zilla stuff.

Pumashine · « **Reply #9 on:** October 19, 2014, 09:04:32 AM »

Quote from: Rider414;44723

Never mind I get it now. Wow this is interesting.

The cylinder was re-sleeved as a 295. It probably has some nice port work done and one clue is the pic of the intake. Much material has been removed for more air/gas flow. If you have a builder look at it he could measure the bore to see if you could get by with just honing the cylinder and put a new piston back in. Otherwise you will go to the next bore size. The head can be checked for flatness with a straight edge. The OEM cylinders with a big bore sleeve tend to get much warmer than stack bore. There is nothing that can be done about the head gasket because that is the nature of the beast. You do have to be careful that the head gasket has a big enough I.D. that the piston can travel through it at the top of the stroke. There are 72mm head gaskets and 74mm head gaskets. Most likely you have a 74mm head gasket now. Jerry Hall is a builder who provides much information on this site. He is the one of the most knowledgeable builders we know. That is your best route to go.

Rider414 · « **Reply #10 on:** October 19, 2014, 09:16:14 AM »

Quote from: Pumashine;44735

The cylinder was re-sleeved as a 295. It probably has some nice port work done and one clue is the pic of the intake. Much material has been removed for more air/gas flow. If you have a builder look at it he could measure the bore to see if you could get by with just honing the cylinder and put a new piston back in. Otherwise you will go to the next bore size. The head can be checked for flatness with a straight edge. The OEM cylinders with a big bore sleeve tend to get much warmer than stack bore. There is nothing that can be done about the head gasket because that is the nature of the beast. You do have to be careful that the head gasket has a big enough I.D. that the piston can travel through it at the top of the stroke. There are 72mm head gaskets and 74mm head gaskets. Most likely you have a 74mm head gasket now. Jerry Hall is a builder who provides much information on this site. He is the one of the most knowledgeable builders we know. That is your best route to go.

Yeah Jerry is the best. I will give him a jingle and get this boxed up to send out. In the meantime, I can get the new crank bearings installed and the bottom end reassembled.

I was wondering why it had such a big carb. Its a PWK 39MM bored out to 41MM from what I can measure. Thanks for all of the help on this mystery machine.

Matt