How to tell if a engine is good?

[SteveRoll]

Hi all, I got a couple parts trikes kicking around. Just finished working on one my projects. I’d like to have a go at rebuilding a top end of a engine / replacing seals piston and so on for a learning experience. None of the parts trikes run.
Aside from testing for compression, is there anything else I should look at for a good “rebuildable engine “? I’m into atc 200’s myself.
Also on same similar topic, can I make a big bore say up to 250 for example?
Looking to Enhance my mechanical skill:)

[El Camexican]

Aside from the obvious like a rod sticking out of the cases, or a seized piston you can check the condition of the top end of a 4 stroke engine with a leak-down tester. Watch a few videos on how to use one and decide if you want to invest. Unfortunately it can't tell you the condition of bearings and seals, only valves, rings and head gasket.

Because our trike engines are so old and we usually know nothing of their past history it makes good sense to fully tear down any engine that isn't running when you get it. That's not to say that a barn find that looks otherwise to be in good condition should be torn down, but it sounds like your stuff is in less than pristine condition, so you'd be doing yourself a favor to tear one down completely and do the job right.

I don't know your exact bore and stroke, but typically a 200 bored out to the maximum will get you up to about 215cc and you won't be able to notice a gain in performance, but your engine will run a little hotter and if you need another bore in the future you'll have to buy or sleeve a cylinder, so do yourself a favor and bore yours as little as possible.

And if by chance its white knuckle "Big Bore" performance you're after these are not the engines to get your adrenalin fix from. Look for a 350X, or any 250cc 2 stroke for that.


PS. If you do proceed with a rebuild and plan to post questions as you go PLEASE start one thread and add questions to it as you go rather than starting a new thread for every @#%#$*ing question. Thank you in advance. :beer

[SteveRoll]

Yes , makes sense. Big bore is not huge, the little 200s have a nice bit of power for my need, just was curious. Yes the 3 trikes I bought were bought for parts. One has no compression, the other two suppose to run but I’d like to dismantle one to learn about these engines. Ok I’ll post a engine rebuild thread when I go at it. Most likely won’t be touching the bottom end as id most likely be over my head

[El Camexican]

Yes , makes sense. Big bore is not huge, the little 200s have a nice bit of power for my need, just was curious. Yes the 3 trikes I bought were bought for parts. One has no compression, the other two suppose to run but I’d like to dismantle one to learn about these engines. Ok I’ll post a engine rebuild thread when I go at it. Most likely won’t be touching the bottom end as id most likely be over my head

There isn’t any question you’re going to be able to post on here that somebody isn’t going to be able to answer. All you need to do is buy the right tools and not swing a hammer through the cases while attempting to bypass the use of the proper tool in the process of disassembling the engine and everything will be fine. Clear photos, coherent English and a little respect for your helpers are the keys to getting help on this site.

You’ll probably end up being an expert on that particular engine before all is said and done.

If you’ve never opened an engine up before I would suggest you start with the one that has no compression. Get a box of Ziplock bags, a Sharpie and a couple large plastic bins to store your parts and hardware in before you start taking anything apart. Properly labeling and organizing the pieces will allow you to do the job without being rushed, or losing track of any parts.

[danbur55]

There isn’t any question you’re going to be able to post on here that somebody isn’t going to be able to answer. All you need to do is buy the right tools and not swing a hammer through the cases while attempting to bypass the use of the proper tool in the process of disassembling the engine and everything will be fine. Clear photos, coherent English and a little respect for your helpers are the keys to getting help on this site.

You’ll probably end up being an expert on that particular engine before all is said and done.

If you’ve never opened an engine up before I would suggest you start with the one that has no compression. Get a box of Ziplock bags, a Sharpie and a couple large plastic bins to store your parts and hardware in before you start taking anything apart. Properly labeling and organizing the pieces will allow you to do the job without being rushed, or losing track of any parts.

Take lots and lots of pictures maybe even at different angles as you remove pieces so you can refer back for reassembly is something I would add to EL’s advice

[ps2fixer]

Also grab a service manual if you don't already have it.

http://www.oscarmayer.net/atc/manuals/

Once you take apart the no compression engine, it should be somewhat clear why it has no compression, blown head gasket, bent valve, hole in piston, etc.

One tip that I think would help a newer person to engine work is to get some junk cardboard boxes, draw a rough shape of the engine cover, label the front, left vs right etc (as the viewpoint of riding the machine) and push the bolts through the cardboard in order around your drawn shape. It holds the bolts plus tells you where the short vs long ones go. A huge amount of mechanic work is just using common sense, like if you're installing a bolt and it doesn't want to go in all the way... don't just start torquing it down, that's how you end up breaking stuff. The bottom end stuff can scare you, but really it's not bad at all. The most complex part is the transmission and if the bearings are good, you don't even have to take it apart. Careful about thrust washers, they sometimes stick to side covers and such and can fall out after pulling apart. There's also the parts diagrams on http://partzilla.com that can be useful, but the service manual ones should be more accurate for your exact year/model.

The right tool for the job is another thing, being your first time you'll likely need some special tools. The server manual goes over them, you can see where they are used to see if it's a requirement for what you're doing. Also there's several ways you can go about building an engine, the right way is to check all the specs and wearable items. Some people just check the bearings over and make sure there isn't excessive slop and call it good, people with experience can do this pretty well. Generally worn items are pretty easy to spot, but size specs like wear on shafts etc tells you if you need to replace or just a new bearing is enough. Out of 3 engines, any major parts you should have enough to atleast get one engine going, ideally 2 shouldn't be out of the question. Depending why the one has no compression, you could even luck out and get all 3 going.

Good luck with your adventure, there's nothing quite like hands on experience.

[SteveRoll]

Thanks all. I got another question, I was looking online at rebuild kits with like a piston and cylinder and most of the kits i come across say " unsure if kits older atc 200 before 1986" How would i know which kit to buy? I got a copy of a manual now. I will read through it, excited to start learning to process! I tried watching a few videos however theres not many on 200 atc engines.

[El Camexican]

Don’t buy anything besides tools yet. Do you know what year your engine are?

[SteveRoll]

Don’t buy anything besides tools yet. Do you know what year your engine are?
For sure I agree, I was just trying estimate prices of things like that. No idea what years yet. The parts trikes are rough shape. I’ll get some pics of them. I don’t even know what the gear pattern is on them yet because I read some are all down and some all are up gears

[ps2fixer]

Use this page and type in your frame vin and engine serial to find out what year the machine is, and to validate the engine year (could have been swapped). Frame number is on the front of the frame at the steering neck, engine serial is on a flat section on the crank case down low on the left side (from the viewpoint of riding it), should be under the sprocket area.

https://atvmanual.com/honda/interactive-vin-decoder-atv-and-atc

[BarnBoy]

Late to the party but I'll throw in my 2 cents.

Rule #1: DO NOT FORCE ANYTHING EVER! EVER! if it won't go figure out why. This applies to many many situations, I've found out the hard way.

Definitely bag and carefully label every part like PS2fixer said. I also high suggest you keep track of which bolt goes in which case hole, as often times they are different lengths. This is easily done by drawing a diagram and labelling each bolt.

Manual is a must, goes without saying. If you don't have one don't even touch it....they're so easy to get.

Pay careful attention to thrust washers! Also a dab of grease on the dowel pins, and a very thin film of grease on the gaskets facilitate easy removal down the road.

Inspect the cam bearing in the head for excessive wear. And also the rocker arms.

Good luck with your build!

[BarnBoy]

Thanks all. I got another question, I was looking online at rebuild kits with like a piston and cylinder and most of the kits i come across say " unsure if kits older atc 200 before 1986" How would i know which kit to buy? I got a copy of a manual now. I will read through it, excited to start learning to process! I tried watching a few videos however theres not many on 200 atc engines.

GH Discount ATV should have piston kits, etc.

Check out my thread...maybe it will help you some:
http://www.3wheelerworld.com/showthread.php/187672-Barnboy-s-1984-ATC200M-Rebuild

Also this one is excellent:
https://thumpertalk.com/forums/topic/944043-powroll-218-build/

[ps2fixer]

Oh to add to the above, you don't need anything special on the gaskets for them to seal, but I know it's common to apply engine oil to the gasket faces in the automotive industry (my dad was an auto mechanic). I think the concept is to swell the gaskets up to seal any major imperfections in the matting surface, but if all is in good shape. Ease of removing I think comes more down to how long the gasket has been installed for, like 30+ years, yep it's not coming out in great shape don't matter how it was initially installed lol.


There's a lot of people that enjoy working on engines and such, I bet if you made a craigslist post or a fb market place post asking for help and you provide drinks/beer, dinner or whatever, you'd get atleast someone to help share what they know. You'll have to weed out people that don't know what they are doing, but act like they know everything though.

[SteveRoll]

Well so far I got two of the 200m engines running. They have carb issues, I got them running by priming the cylinder / pouring small bit of fuel in the chamber. The wire harnesses are both toast so I mocked up a test harness for testing that plugs into the cdi. Got two more engines to test!

[ps2fixer]

A test harness isn't a bad idea. I've thought about making a tool to plug into the CDI connector (harness side) and test what it can from there (ignition coil primary, exciter coil, lighting coil, and pulse generator. Might have to look into that some day, can't be too hard to build.

[SteveRoll]

Yes it is simple to build just gotta follow what wire is what for the simple harness. Basically just recreating the ignition / firing circuit only. I tested the third trike 200e and the stator isn’t producing voltage. Has good compression and a slightly better harness. Only one more trike to test, another 200e. Whichever one is best running I’ll be building a frame up trike. The rest I’ll probably part out cause how much space they take up

[ps2fixer]

Yea harnesses aren't that complicated.

My last message was more in the context of making a testing tool that plugs in where the CDI does to test basic issues, basically a multi meter in a box for people that have a hard time with electronics.

[SteveRoll]

Yea harnesses aren't that complicated.

My last message was more in the context of making a testing tool that plugs in where the CDI does to test basic issues, basically a multi meter in a box for people that have a hard time with electronics.
That would be a good idea, basically like an electrical outlet test tool. If it could identify the problem it would be excellent.

[ps2fixer]

Yea, atleast in the context of what the CDI can "see". There's a lot of ways CDI's are wired, so sadly it's not a super universal tool with out a ton of adapters, so kind of like a break out box. One thing I'd have to figure out is how to protect the tester if someone attempts to kick start the machine with it hooked up. Wouldn't be good to have a 100v spike sent to it from the exciter coil lol.

[SteveRoll]

Well I tried out the other 200e. The one with no compression, it’s about 60-70 psi. I gave it spark and it’s leaking air out around the exhaust. I think the head gasket is gone on that bike. I got one more engine to test it’s a 200m but the stator is off it and the recoil, it was used as a parts bike. I was told it’s a good engine but will need to put a stator on it to find out.

Also out of one 200m that ran earlier it died down shortly after running, I assume fuel issue cause if it’s primed it runs. It also has no airbox on it

[SteveRoll]

Hi guys: could use some help with carbs. I took off one of the carbs on one of the parts trikes and took it apart to learn and clean up the carb. Noticed a lot of dirt in the main and idle jet holes so I cleaned them, reassembled with the fuel ratio mixing screw 1 and 7/8 turns back from all the way screwed in that I read online. Ran up one of the engines and it’s revving extremely high. I had to kill the engine quickly because it ran up very high. I adjusted the choke and tried again and it’s still revving high. On the carb how much is the idle screw suppose to be adjusted? I think that’s the one on the side, I didn’t touch it yet it’s now high revving. Well the carbs are easy to work on, first carb job was almost a success

[Jim mac]

long time ago, I managed to install a slide 180* off and it screamed. if it's in correctly, just turn the screw out a full turn and just be ready to either feather the throttle up or down.
On your motor with low compression, take the valve cover off and check the valve adjustment. I got a trike cheap because it didnt run, the exhaust valve was out of adjustment and not closing all the way. jim

[SteveRoll]

long time ago, I managed to install a slide 180* off and it screamed. if it's in correctly, just turn the screw out a full turn and just be ready to either feather the throttle up or down.
On your motor with low compression, take the valve cover off and check the valve adjustment. I got a trike cheap because it didnt run, the exhaust valve was out of adjustment and not closing all the way. jim
Thanks, I’ll double check. I thought I had the slide in right cause it has a notch on one side for the idle screw so I made sure it lined up. But then again I never checked the otherside so it could have a notch on that side too on the slide.
I just got a clymer manual off a loan from a friend of mine. Haven’t had the chance to read it all yet but excited to.
I’ll check the valves like you mentioned, I haven’t done that yet but looks simple enough on this bike.

For the bike with no compression, when I tested it I put a lil oil in the cylinder since i don’t know whenever it last ever ran. When I attempted to start it, I seen smoke / white combustion gases coming out around the fins close to the exhaust. I’m very positive that the head gasket is gone there. I think it would be easy to just replace the top end on the bike. Only thing I’m kind of uncertain about is the timing of the engine again. I’ve been messing around learning about the carbs and cleaning all the ones here. Next will be taking that engine out and seeing the condition of it for future use. One thing I don’t like on that engine is the foot shift lever is off that bike and the splines look chewed up on it. Other then that it’s a complete bike with everything working ( aside from engine )

[MrConcdid]

Jim Mac is right, the slide can be installed 180 out, one side has a notch the other side has a ramp, the cover will screw back on, but the thumb throttle will have a lot of slop, also a leaking valve will cause one the idle high and or lean, be sure to check and set the valve lash BEFORE you start it. I set the valves now before I do much of anything.

Since you asked.
1. For me I pull the rope feel for compression or resistance.
2. check oil level and color and smell (i don't really know why I do that)
3. blip the throttle see if its frozen.
4. pull the plug, check color, wetness, broken, age
4.5 if you have a compression tester use it now, run test with throttle and choke fully open, look for between 120-150 psi
5. pull rope with plug out but coil wire on plug touching header, looking for spark
6. place a long wooded dowel in spark plug hole, remove pluse cover, remove cap in recoil cover, pull rope slowly watch stick, watch rotor find TDC F-T on the flywheel in the inspection hole on the recoil cover, pulser is indexed and pointing toward the black pick up, stick is at top of stroke this is TDC.
7. Remove valve cover caps check, set valve lash .005ish.
8. Open choke, spray a little carb cleaner in carb and open throttle all the way and pull rope firmly. (if you had spark in step 5, and only after you remove the dowel and replace the plug cleaned)
9. Motor should hit and run a bit, if so remove carb, clean and replace IT, run new fresh gas from new container.
10. Motor should run, if it smokes its either rings or valves
11. Let it run a bit, it could clear out (some of these have set for 25 years) Remove the baffle in the muffler it could have a blockage
12. Check compression again if low its more than likely rings, if compression is 120-150 and it smoked, its valves..

I am not a mechanic (I manage a funeral home), but this is how I do every engine I have.
It works for me, I hope it can work for you.
MrC.