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TRX Student

1995 fourtrax 300 4x4 rebuild

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Hey guys,

 

Some of you may have seen this build from the old forum. I haven’t updated in a long while because I’ve been waiting on some machining on the jug, broke a bolt :(

Now that I’m expecting to be ready to put the motor back in, I have a question about the state of my valves.

This first photo is the machine back when I picked it up last spring. I stripped it down because the frame was rotten. The second photo is the old valve head that I’ve had to replace (because of broken fins and seized exhaust) notice the jurnals are clean. The next photo is the one I bought , it has brownish stains in it. What is that indicating, and what are my options? 

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Looks like the engine got really hot and cooked the oil.

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I was told the new head doesn’t smoke.

sorta doubting that.

Does this mean I need new seals? Or I need to lap the valves? This is my first go at a 4stroke motor work.

should I just slap it together and see if it smokes?

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If it were me , I would take the extra steps and lap the valves and replace the stem seals  while it is taken apart , start fresh , don't take that chance of having to do the work again  but it is very easy for me as I have to the tools , so it is only about an hour to do it ------- unspring'ing the valves and getting the retainers out is super easy , place a deep dish socket over the retainer plate  and hit it with a hammer , the retainers will pop right out ,  valve clamp tool makes putting them back in a snap , and I cheat with the lapping of the valves ,have a lapping suction cup that fits in a drill and spin them with the drill

 

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I agree with tb. Either cooked oil. Or it is possible they short tripped it alot and condensation built up there and dried after sitting for a long time. Lapping valves is easy and requires few very cheap tools. I would lap them if it was me. And replace the valve seals that will be in your topend gasket kit. Expecially if it sat those valve seals are gunna be dry rotted. My .02

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Thanks guys, I’ll be ordering a gasket kit and will make sure it comes with the stem seals, and will order some lapping tools, and do the proper work.

 

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2 minutes ago, TRX Student said:

Thanks guys, I’ll be ordering a gasket kit and will make sure it comes with the stem seals, and will order some lapping tools, and do the proper work.

 

You can get lapping tools at any auto parts store. And the compound course and fine grit. And prussion blue. Thats all you need. I just picked mine up at oreilly autoparts. They had both big and small valve lapping tools and all the compounds for around 25 bucks total.

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Thanks for the tips, I’ll be ordering everything online though, I live in a very isolated place with no stores. eBay is usually my go-to.

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No worries man. Understood. I can walk to oreilly. Autozone or advanced in about 10 minutes. 3 minute drive at most. I always forget eveeyone doesnt have that luxury. One last thing i would suggest for your first time lapping in valves to do it by hand. It will give you the sound and feel a whole lot better. The drill trick is easy but is for someone who has done them many times. Doing it by hand isnt really even crazy amount of work. And your only doing 2 valves. Its kinda like trying to start a primative fire in the woods. Real light pressure and a back and fourth motion. You will start with course compound and you will here it get gritty sound then will get quiter and quieter. Then lift the valve up a bit and do it again. A few times then go to the fine grit. Do the same. When its good and seated it will be almost silent. And feel nice and smooth. Wipe compound off in between the 2. Keep it out of the stem area. Just on the contacting edge of the valve. And always keep the stem oiled so you dont wear out the guide. Once you thing its smooth and quiet go to prussion blue instead of compound. Just push the valve straight down to seat. No turning. Pull it out and measure your contact area. Your manual will tell you what is spec. It should be even thickness all the way.

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still Waiting for the jug, the gaskets, compounds , valve tool etc, but I’m itching move ahead.

Before Christmas I realized that I was going to need a few miscellaneous bolts to be replaced so I nabbed a box of bolts off eBay from a 300. They’ve already come in handy and I haven’t even put the motor back together yet.

 

I cleaned up and painted the rear diff this week. Contemplating whether or not I want to do the same for the motor...

Next I think I’ll just continue to get little things out of the way, route the harness properly, change the air filter, clean the carb.

I still have to order a rear axle and hubs. That might be the next thing on the wish list. 

It’s coming along nice.

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Looking good ---- did you buy a nut , bolt , hardware lot from one of the dismantlers 

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People will take a atv apart for parts , all the hardware left over goes in a pile ,  they sell the pile for usually $20-30 ,it is a good deal if you need a few pieces and then have some spare bolts and nuts , brackets , etc 

 

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13 hours ago, Fishfiles said:

People will take a atv apart for parts , all the hardware left over goes in a pile ,  they sell the pile for usually $20-30 ,it is a good deal if you need a few pieces and then have some spare bolts and nuts , brackets , etc 

 

 

If you really look at the pics, sometimes you can get stuff you want as part of one of those hardware piles.

 

I got the secondary gears for a 420FM in one, which is an 15% GR for the 420AT.  Those two gears would have run me about $60 from Honda.

 

I also bought a set from a dismantled TRX125 that had the front fender support in it, which is no longer available new and usually bring $40-50 used on ebay. 

 

I tend to try to really look closely at the pics.  You can get wheel center caps in them if you watch carefully too.

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I need to find one of those yellow toboggans for behind a sled here...

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1 hour ago, TBRider said:

I need to find one of those yellow toboggans for behind a sled here...

Hard to find in the south, store called 'the northern' or 'nord select' carry them. Not something you can find at Canadian Tire.....

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I think I should be able to find one in quebec.

 

An aluminum boat is too cold to sit in.....lol

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Calf sleds are similar. You would just have to build the tongue for it instead of the ropes they come with.

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