[mrpj6]

Hi, to you all.
I have a TRX 300 4x4, It was bought from a company that sells machines from auction sites, and police recovery compounds so i have no proof of the age. I am told it is around 1995/6?. I changed all the oils on it., new battery and filters, brakes and all the usual things and started it! It really surprised me to be honest.... sounded good, went well and pulled like a steam train, all in all i was really happy. I gave it quite light use for about three months and changed the engine oil again, Still fine. Some time later a tapping started. Top end of the engine. To my untrained ear it sounded like it could be the timing chain, i asked around and was told of the nut on the adjuster trick. I did this, but no luck. I bought a manual and decided to start stripping it down. I am no mechanic, but i can follow step by step instructions with pictures and got on ok. First thing i found was what i can only describe as swarf in the gauze filter located in the side cover of the gearbox. This was curly swarf, the sort you would get from drilling steel on a pillar drill!! The oil filter felt gritty but not too bad. The strip down continued. The cam shaft was badly warn on both ends. I sent that off to have it machined and shells fitted. to cut a long story short i stripped every thing out and cleaned it.... The lot, gears clutch, every thing. All except the big end, as i understand you cant split that? I tested as i went and all came out ok as to the manual apart from the oil pump, so i got a new one. As i worked through i looked for any signs where the curly swarf could have come from, I found no signs. As the bike has a mystery past i can only think this was put in the sump maybe?? Like i say i have no idea of its past. The engine and box went together well and i replaced it in the frame. The electrical stuff was connected. And by god it fired up!! no one was more surprised than me!! Now the down side, the tapping is still there. Top end, sounds like one tap per revolution and is there from cold, and gets faster the more you rev. Rightly or wrongly i rode the old gal., and she went fine. Thats where i am now. I am not happy to use it like this. Has anyone got any ideas where to start looking? Honda parts are ridiculously expensive to me so i dont really want to start buying stuff to eliminate things with out some sort of pointers in the right direction. Thanks in advance.........Pete, Bristol UK

 

[honda300trx]

How about pistion rings and vavles maybe im sure some one will chime in soon

 

[mrpj6]

I will be off out for a pint soon..... To help me think!! But i will see if there is any thing to go on in the morning. Thanks for your quick reply. Pete.

 

[submarine 300]

My guess would be a rod bearing. If it is a slight ticking it could be a valve but my best guess is the bearing.

 

[Helmut]

Did you check the rod bearing while it was apart? Did the wrist pin and piston look OK? Were your rocker arms in good condition, since the cam was worn? I've never had a cam machined like that. I always just replace the cam with a new one. Also, was the "cradle" damaged in the head where the cam sits, since the cam was worn and the 300 doesn't have cam bearings? It just sits in the aluminum head and runs on a thin layer of oil from your oil pressure.

 

[mrpj6]

Con rod? Small end? big end? I am not too sure what you mean when you say rod bearing. If its the big end bearing, thats not replaceable..... is it?

 

[Helmut]

Con rod? Small end? big end? I am not too sure what you mean when you say rod bearing. If its the big end bearing, thats not replaceable..... is it?

Rod bearing=big end of the connecting rod. The crankshaft can be pressed apart and the rod bearing can be replaced, but they usually don't hold up too good. You're better off just buying a new crankshaft assembly, so you don't waist your time and money.

 

[mrpj6]

Did you check the rod bearing while it was apart? Did the wrist pin and piston look OK? Were your rocker arms in good condition, since the cam was worn? I've never had a cam machined like that. I always just replace the cam with a new one. Also, was the "cradle" damaged in the head where the cam sits, since the cam was worn and the 300 doesn't have cam bearings? It just sits in the aluminum head and runs on a thin layer of oil from your oil pressure.

The wrist pin was ok.... some movement but slight. the manual says to put it in the piston and check it by looking for movement? Rocker arms ok and the lobes of the cam. The cam was machined down and shells put in the aluminum halves. The place that did it says he has done loads of them... not sure how true that was but who do you believe. oil ways were put in the shells so the cam shaft still runs in oil,

 

[mrpj6]

Have you any idea of a price for a new crankshaft? I would think i am nearly at the point of cut and run if it is the crank!

 

[Helmut]

So what about the rod bearing? Did you check it while you had it apart? If you get a hold of the rod, it shouldn't have any up and down movement. A little side to side movement is OK.

 

[Helmut]

Have you any idea of a price for a new crankshaft? I would think i am nearly at the point of cut and run if it is the crank!

About $700 from the dealer, but you should be able to find one on Ebay for $100 or less. It's a pretty big job to put the crankshaft in, because you have to split the cases.

 

[mrpj6]

The noise is a definite tap. I was led to believe the big end bearing was more of a rumble if it was on its way out. I did test it by looking for movement when it was out, the con rod moved from side to side a bit but not really much play up and down, i mean if you held the crank and tried to pull it up from the crank there was not much movement . if any.

 

[submarine 300]

I don't have a clue what it would cost in the UK but after all the work you have in it I would not give up now.

 

[Helmut]

The noise is a definite tap. I was led to believe the big end bearing was more of a rumble if it was on its way out. I did test it by looking for movement when it was out, the con rod moved from side to side a bit but not really much play up and down, i mean if you held the crank and tried to pull it up from the crank there was not much movement . if any.

If it didn't have any up and down movement, it should be OK. I would associate a bad rod bearing as more of a knock. I would associate a ticking sound more as what the valves sound like when they need to be adjusted. I would probably associate a tapping sound as more like a bad rocker arm or something. I'm not saying that's your problem, I'm just saying that's what I associate those sounds with.

 

[mud99]

Welcome to the forums

 

[mrpj6]

Have you any idea of a price for a new crankshaft? I would think i am nearly at the point of cut and run if it is the crank!

About $700 from the dealer, but you should be able to find one on Ebay for $100 or less. It's a pretty big job to put the crankshaft in, because you have to split the cases.

I am not too worried about splitting the case again, bit of a long job but worth it if it works. Just want to check the easy stuff first if there is any. Not much comes up on ebay. there are breakers yards in wales but they want big money for parts too. As new is so expensive.

 

[Helmut]

I don't have a clue what it would cost in the UK but after all the work you have in it I would not give up now.

Yeah, I quoted $700 for a local US Honda dealer, but prices in the UK might be different.

Yeah, definitely make sure the rod bearing is bad, before you buy a crank. That is too much money to waist on a part that you don't need.

 

[mrpj6]

The noise is a definite tap. I was led to believe the big end bearing was more of a rumble if it was on its way out. I did test it by looking for movement when it was out, the con rod moved from side to side a bit but not really much play up and down, i mean if you held the crank and tried to pull it up from the crank there was not much movement . if any.

If it didn't have any up and down movement, it should be OK. I would associate a bad rod bearing as more of a knock. I would associate a ticking sound more as what the valves sound like when they need to be adjusted. I would probably associate a tapping sound as more like a bad rocker arm or something. I'm not saying that's your problem, I'm just saying that's what I associate those sounds with.

Right. My plan i think will be to start by taking the head off and all the stuff i can do with the engine in. have another look at the rockers ans see how the work on the cam shaft is standing up. To my ear it sounds top end, it may be wishful thinking but it does sound more up top than lower in the engine.

 

[mrpj6]

Welcome to the forums

Thanks mud!!

 

[mrpj6]

Right.... As Homer would say Beeeer!! Thats Marge's husband, not the bloke that wrote the Iliad.
I will return to the dark shed tomorrow night with renewed enthusiasm to start work on it!
Thanks to you all for all your thoughts. I will keep you posted, and be back for more help no doubt. Thanks again..... Pete.