[JoeysDad]

Hello, I am Jim. My wife and I have 2 children, Joey and Ciera which have been riding since they were 4 and 5. They started out on a pair of 1984 Suzuki LT50s that I found, not running, on Craigslist. With a little bit of tinkering I was able to get both of them running good and they have terrorized the county on a daily basis every since...lol.

A few weeks ago the boy's stopped running and locked up while trying to restart it. He has outgrown it both physically and mentally so instead of fixing it I went back to Craigslist to see what I could find for his fast approaching 7th birthday. I didn't have much time or money, but I found an 87 trx125 that was in my price range and went to take a look. When I got there, the guy explained that it was his sons first quad and it had sat in the barn for a couple years after his son got his new 300ex. We put a battery charger on it as I checked it over. The gas in the tank was very old and stunk, a couple cables were froze up, it showed signs of being rode pretty hard, but other than that it wasn't in too bad of shape. We had to crank on it for about 30 minutes or so but when she came back to life sounded good and ran strong when I rode it. I bought it.

The next day, while Joey was at school, I drained all the old gas out, changed the oil, and put a new spark plug in it. It fired right up and I rode it for about 2 hrs. It ran well and seemed like it would be great for him once I cut the throttle back. The quad sat all week as his birthday weekend approached. The night before his party, I went to get it to move it closer to the house and it wouldn't start! It took an hour of messing with it to get it to fire up and when it did, it smoked like a freight train for a few minutes. As the bile rose in my throat I told myself the the Seafoam that I put into the fresh gas has done its job and it just needed to be blown out. I rode it a little and after it choked out the smoke, it ran good, idled perfectly, and no more smoke.

The next day, his birthday party, I went up to the barn to ride it back to the house and it did the same thing again. Took an hour to get it started, belched out a nasty cloud, and came to life. I rode it around and warmed it up then drove it behind the house and parked it for him to find after opening his other gifts. When he "found" the quad his eyes lit up like the 4th of July! But, after sitting for an hour,and cooling off, it was back to the same game. This time it took 2 hours to get it started! My son turned 7 and even so, he is very patient, he knows I can't afford to buy new quads, but non of that made the fact that I had given my son a broke toy for his birthday any easier to swallow! I made him a promise that night, that no matter what it takes, I will get it running right.

This past weekend we took the carb off, tore it apart, and have it soaking in laquer thinner. After removing the carb, I ran a compression check. It was not good at all. Cold engine, 70 psi, put a plop of oil in it and it came up to 100 briefly then back to 70. I called the local Honda shop, they said it should be 180!! Looks like I am in for a crash course in rebuilding a 4 stroke motor now.

I am on my second Honda, I have 98 trx300 4x4 that has never missed a beat! I have never had to work on it at all other than maintenance. I can't afford to take the 125 to the Honda shop and have them go through it, I will have to do it myself. Any and all suggestions and advice any of you can give will be greatly appreciated! I don't have a clue what all it may need. At this point, I am planning on boring it and new piston and rings. Any other suggestions on what to check?

Thanks, Jim. (A very heartbroke father, of a very optimistic 7 year old...lol!)

 

[Redracer]

Welcome to the family, I can only imagine the sorrow you felt for your son but at the same time you must have been very proud of him for acting mature(especially for his age) and understanding.

That being said, you came to the right place. We have many members here who enjoy helping others out. Between everyone on this site you can probably just about get step by step instructions...

 

[Helmut]

Welcome to the forums. Sounds like you're on the right track with the carb cleaning and the cylinder bore and new piston and rings. I believe that will take care of the problem.

 

[mud99]

Welcome to the forums.

 

[69quadracer]

Welcome to the forums!

 

[94300ex]

welcome to the forums! since your motor was so low on compression you should probably check your valves and make sure they haven't been pulled. bad rings will cause a lot of compression loss but if one of the valves is pulled it will cause most of it. but other than that you've got it covered.

 

[JoeysDad]

Thanks for the warm welcome! I found out today that all of the parts I will need are still available. That was a relief! I hope to get time to remove the motor this weekend, and to let Joey help me as much as possible. We'll kind of make a project out of it. I will probably take pics along the way and post them up. Hopefully the story will have a happy ending!...lol!

 

[Redracer]

Good deal, we love seeing pics. Get him in there doing the work with you, he will appreciate it more... plus the memories you will have with your son and he will have with his dad

 

[JoeysDad]

94300ex: What exactly do you mean by "pulled a valve"? I have never heard that before. When the quad sits, it leaks oil through the valve seals down onto the piston, but when we can get it started it runs great. It actually has more get up and go than I figured it would. I was shocked to find out that the compression was so low. It don't hesitate to carry my 220lbs up long hills in 3rd gear.


Redracer: I will enjoy every hour that Joey and I spend working on this together. I plan to let him do as much as he can and not making time an issue. I am sure we will take many pics and I will be happy to post them. I can't wait to get home and explore this site better from a computer rather than my phone. Should I put the rebuild thread into the "TRX" section?

Thanks, Jim

 

[shadetree]

welcome to the forums joey..you came to the right place for help ! i'm sure your son we'll love you more than ever when we help you get that bike running like new !..first off..just pull the motor..pull the top end off..inspect the piston..ring's..valves..cylinder..have the cylinder mic'd..this will tell you if you need the cylinder bored or not ?..just because it smokes..does not mean it needs to be bored over. as for it smoking..bad oil rings..leaking valve guide seals..more than likely..probally both !..sooo..first thing..pull the motor..take it from there..keep us posted..if you have any questions..ask away !.

 

[94300ex]

94300ex: What exactly do you mean by "pulled a valve"? I have never heard that before. When the quad sits, it leaks oil through the valve seals down onto the piston, but when we can get it started it runs great. It actually has more get up and go than I figured it would. I was shocked to find out that the compression was so low. It don't hesitate to carry my 220lbs up long hills in 3rd gear.


Redracer: I will enjoy every hour that Joey and I spend working on this together. I plan to let him do as much as he can and not making time an issue. I am sure we will take many pics and I will be happy to post them. I can't wait to get home and explore this site better from a computer rather than my phone. Should I put the rebuild thread into the "TRX" section?

Thanks, Jim

what i mean by pulled a valve is that over time the valve springs along with heat and pressure will try to pull the valve through the seat which wears a groove on the valve where it seals against the seat and it will let the valve stay slightly open causing the compression loss. i hope this makes sense, I'm not the best at describing things sometimes. anyway good luck with the project, it sounds like a fun one.

 

[ostrx250]

welcome joeys dad share the pics cant wait to see it completed

 

[JoeysDad]

94300ex: you did a great job explaining it! I know what your talking about. Suggestions like this is what I was hoping to get when I joined the forum. I am new to working on ATVs and don't know what to look for. If it has pulled the valves, how do I go about fixing it? Can I replace the seats or will the whole head need to be replaced? I am figuring on replacing the valve guides, seals, and the timing chain. I am really hoping I don't have to change the crank bearings, I think splitting the lower case halves maybe over my head at this point.


Ostrx250: Thanks! We'll be more than happy to share the pics. Joey and I are going to start tearing her down this Saturday morning after football practice.

 

[shadetree]

94300ex: you did a great job explaining it! I know what your talking about. Suggestions like this is what I was hoping to get when I joined the forum. I am new to working on ATVs and don't know what to look for. If it has pulled the valves, how do I go about fixing it? Can I replace the seats or will the whole head need to be replaced? I am figuring on replacing the valve guides, seals, and the timing chain. I am really hoping I don't have to change the crank bearings, I think splitting the lower case halves maybe over my head at this point.


Ostrx250: Thanks! We'll be more than happy to share the pics. Joey and I are going to start tearing her down this Saturday morning after football practice.

you really don't need to replace the valve guides..you can re-cut..or better known as..re-surface the guide seat area with some cutting compound..i wouldn't replace the valve guides unless you had no choice..for now..just do a top end job..new rings..new timming chain..check to see if your valves are bent ??..if not..use them..that is..if you don't have to re-surface the seating area ??. some new valve guide seals..head gasket...bottom gasket..you should be good to go..of course..you may need a side cover gasket once you go to replace the timming chain ??..depends if you tear the old one up..taking the cover off ?..other than that..you should be good to go.

 

[MNRedneck]

Welcome to the Forums!

 

[JoeysDad]

Thanks MNRedneck.


Shadetree: I am hoping that the valvetrain isn't shot. If I find something suspicious, I have a friend that has rebuilt a few 4 strokes that I can have take a look.

It is most important to me, at this point, that we do this right the first time so that it will last many more years. Joey will ride it everyday that the weather permits. When we are done, I hope its as bullitproof as the other Hondas I have owned.

 

[Inglorious BSTRD]

Welcome. Just a suggestion but the way I usually check my valves for a leak is just take the head of and dump gas into the intake and see if it leaks out through the valves, then do the same on the exhaust. Those old hondas are so tuff you could probably just replace the rings that are more than likely stuck from setting so long and it would be fine, but while you got it apart might as well check it over good.

 

[shadetree]

Thanks MNRedneck.


Shadetree: I am hoping that the valvetrain isn't shot. If I find something suspicious, I have a friend that has rebuilt a few 4 strokes that I can have take a look.

It is most important to me, at this point, that we do this right the first time so that it will last many more years. Joey will ride it everyday that the weather permits. When we are done, I hope its as bullitproof as the other Hondas I have owned.

as long as you have a service manual..i think you'll do just fine..those trx125's are easy to work on....if you get stumped..feal free to ask any questions you have..i'm sure one of us can point you in the right direction...also..even if you don't get it right the first time...this is called a learning process..thats the best kind you will ever get..this is how me..and probally every other person on here has learned what we know..from doing it..trying it..or just flat out get'n it done !..good luck..keep us posted.

 

[shadetree]

Welcome. Just a suggestion but the way I usually check my valves for a leak is just take the head of and dump gas into the intake and see if it leaks out through the valves, then do the same on the exhaust. Those old hondas are so tuff you could probably just replace the rings that are more than likely stuck from setting so long and it would be fine, but while you got it apart might as well check it over good.

thats valve trick works really good for checking bent valves without taking them out...been doing that for many years after i replace the valve guide seals and put it back together..i do it that way..just to make sure they are seating good...glad you know this inglorious...keep passing the info along..other ppl will gain from this.

 

[94300ex]

94300ex: you did a great job explaining it! I know what your talking about. Suggestions like this is what I was hoping to get when I joined the forum. I am new to working on ATVs and don't know what to look for. If it has pulled the valves, how do I go about fixing it? Can I replace the seats or will the whole head need to be replaced? I am figuring on replacing the valve guides, seals, and the timing chain. I am really hoping I don't have to change the crank bearings, I think splitting the lower case halves maybe over my head at this point.


Ostrx250: Thanks! We'll be more than happy to share the pics. Joey and I are going to start tearing her down this Saturday morning after football practice.

worst case if it has pulled valves is you just have to replace the valve but do the trick that inglorious bstrd said and if the valves don't leak they are probably not pulled. shadetree is right you really don't need to replace the valve guides and seats unless they are really worn out, and your valve train (cam, rockers, chain, etc) should be okay as long as there are no tapping or rattling noises on the top end. keep us posted im looking forward to seeing the pics. :icon_ peace: