Robins 295 rebuild question

[tplasek]

A few weeks ago I purchased a 2001 Ez Go with the 295cc engine. I adjusted the governor spring and have been toying around the neighborhood. It will run 22mph on the top and this being my first cart it seems like a perfectly good running machine. However, it seems slow to start and seems to be very slow to get from a stopped condition to moving. Today I decided to take closer look to make sure all the linkages were set properly. As far as I could tell they all looked Ok. I also decided to check the plugs and run a compression check. Plugs looked normal but I only measured 120psi in both cylinders. It doesn't smoke or make any unusual noises, but this appears to be low when reading previous posts others have made. I will check the valves clearances tomorrow to make sure that isn't the culprit, but I suspect I need to freshen up the motor.

I have read through several posts on here about rebuild kits this and that but no one mentions if they are buying standard bore rebuild kits or if they are boring to a larger size and buying the oversized piston and ring kits. I am kind of hesitant to rebuild a perfectly running machine, but I always like my stuff to perform to the max and if we are only talking 9 horsepower to begin with, I can't afford to loose any.

How can I tell if i need to bore?

As long as my crank measures to spec, I plan to buy new pistons, rings, rods, gaskets, and belts.

Tim

[ez go go]

I would definitely check the valve lash first. Second, boring cylinders is only need when end gap tolerance on the rings is to much or if there is damage or if the cylinder is egg shaped which would show up with a mic... Even if you have a ridge on the cylinder deck you can trim those off with a ridge cutter without boring if the ridge isn't to bad. All the build specs can be found in the gas tech section in the shop manuals if you need more specs. For me personally on my own machine, if the end gap was in range and nothing but comp. was the issue, I would hone the cylinder and replace the rings and pistons and check the valve condition. The intake valves on these machines are notorious for mushrooming and pulling up into the head.

[tplasek]

WOW!!! What a difference a 10 minute valve adjustment can make! I took the valve cover off pointed the two intake lobes down and sure enough, both intake rockers were tight against the cam with no clearance. I set all valves to .004 and rechecked the compression on the cold engine. 182 and 178 on the other. It now starts much easier, doesn't loose power when it gets warm, and the transition from a dead stop to moving is pleasant. That will save me some bucks.

Tim

[ez go go]

Good deal!!! The intake valves as I said before are notorious for wearing into the head and a power loss due to compression is usually chocked up to intake valve adjustment. Glad it worked out for ya.

[kaolinemine]

Testing inserting photos from my phone

[kaolinemine]

notice the bright wear ring around the top of valve keeper, It had sucked the valve so far up in head the rocker arm could not clear the retainer . I see this alot hear a the chalk plants,Lots of dust being sucked in motors.Really need away to extend the air intake up away from ground level+ like at roof line. I been trying to learn how to upload the photos (im slow with that type of thing.)

[ez go go]

When this condition goes to far, the rocker arm can push the spring cap down and release the keepers. This could drop the valve and the keepers into the cylinder and lead to a really bad day.

[tplasek]

Wow, I can't believe how far that valve worked it's way up into the head. Amazing it even ran like that. In your last picture with the cleaned head and new valve, is this the same head with a new valve, or is the valve casting scrap after a valve works it way up into the head?

Tim

[ez go go]

Just FYI tplasek, the valve is softer than the head by design to keep damage to a minimum at the valve seat. The seat can be cut with a seat cutter and lapped in with some compound. I have done some that looked just that bad and had no problems with the new valve seating. These engines are tough, and I've sanded and polished some worn parts that some would say could not be used and the cart is still going today. I'll never understand why they quit making this engine. It's TOUGH!!

[kaolinemine]

No , no new head , it is the same head and all i did was replace the new intake valve and clean the exhaust valve. I hate to say but I didnt even cut the seat, only lapped the new valve in with compound and made the best looking seat seal you could ask for. after lapping had a good thin seat line dead center of intake valve.