Getting ready to rebuild

[pfcperry17]

I have decided to rebuild my TRX2.5. More cost efficient for me....And I can learn from it instead of putting a new motor in and knowing nothing about it if I need to fix it.

I also need a new carbby. First off, How hard is it to put in a new piston and sleeve and can I keep my old connecting rod, wrist pin and clips?
And second, Can I swap over my carb needles and all to the new body? The carb body seems to come with o-rings & a silver screw. Don't know what it is yet but I'll find out.

Link to carb body: http://h1072966.hobbyshopnow.com/products/description.asp?prod=TRA5234
Link to piston and sleeve: http://h1072966.hobbyshopnow.com/products/description.asp?prod=TRA5230X

 

[Racer 1966]

Most prefer to put a new rod in with a piston/sleeve along with new bearings.Altogether those items usually cost real close to a new engine. If it's not loose on the wrist pin and crank pin,I'd run it. I've got away with it a few times.

Should be fine to swap needles to the new carb body.

Be sure to thoroughly check the crank bearings while it's down.

 

[savage XL]

First off, you'll need to remove the sleeve from the case, this may need some heating of the crankcase, a popsicle stick slipped through the exhaust port and turning of the flywheel may help you to remove the sleeve.

Secondly, when you have the engine torn down to it's basic parts, you'll need to check the crank pin for wear and the big end bush of the conrod for wear/stretching. If anything on the rod looks dodgy, replace it.
It's always best to replace the wrist pin clips.
If all is OK, you need to check the bearings for any vibration, this is best done by spinning the crank with the flywheel in place. If they feel rough or notchy you'll have to replace them.

The easiest way to remove the flywheel is with a gear puller, this will not damage anything.
To remove the bearings, you have to clean the engine thoroughly of all oil. Brake cleaner works very well for this, and blow the crankcase out with compressed air and make sure it's completely dry.
You'll need to heat the crankcase until it is too hot to touch, a spit test will tell you when this is achieved.
A quick flick of the wrist while holding the crankcase with a towel or similar should pop the bearings out easily, if not, a wooden dowel can be used to knock them out.
Once removed, clean again and blow out, then heat again, but not quite as hot, and drop the bearings in place. You may need to tap them in if the case isn't hot enough, but when you re-install the flywheel, it should seat them to their correct depth anyway. Do this while it's still hot! Let it cool with the crank in place.

The carb needles should go straight into the new carb body, and set them up as you would when first breaking in the engine.

The most important tool you need is a micrometer or good quality dial vernier to check for bush/crank pin wear, the rod may look fine, but it could be 'egg shaped' and have too much clearance. A broken rod can do severe damage to your newly rebuilt engine, and the most likely time it will let go is when the piston is tight in the sleeve.

When re-assembling your engine use a few drops of a light machine/general purpose household oil on all parts, including the crank, bearings, rod bushings, piston and sleeve.
I don't seal my engines with silicon! I make proper paper gaskets with .005" gasket paper, this has always worked for me with all my engines.
I do seal the drawbar for the carb with silicon in most cases.

Cheers.
savage XL.

 

[redneck1]

i have a t maxx 2.5r and my motor shuts down when it gets hot.

 

[moe7404]

if you have ez-start dont put any oil on the shaft that goes from the crank to the over running clutch, cause it will migrate to the over running clutch and it will not spin the engine. its in a bronze bushing and it will be ok.

 

[Archer2k]

I also have a Jato 2.5 that I rescently rebuilt. Everything on it is stock escept the a-arms (RPM) and the TRX 2.5 engine, which I ported and polished. It's actually faster than the 3.3.