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Discussion Starter · #1 ·
What I think I have is a 2004 TRX350 rancher FM (I haven't ran the numbers yet) I have owned this atv for better than 12 years. I bought it from a local dealer, it has been an awesome machine. Always ran very strong, pulling better than a few larger machines in the family. My son was a cycle kind of guy when he was young, never liked atv's until all his buddies started riding them. So once he hit the age I knew he could handle it, I let him start taking it riding with them. To make a long story short, it was sunk...several times. I put a new top end in it several years ago, but as you all know, it didn't last long, maybe a year....started smoking. Fast forward to last year, put another top end in it, with a new cylinder, got 6 months out of it, started smoking. This is when I found this forum and started reading that having being sunk, cases needed to be cracked, cleaned, rebuilt. Soooo this is where Im at, I've got the machine apart, plan on replacing a few things and doing some painting before It goes back together. My sons got his own 420 now so I can keep him off mine. I want the machine I used to have, reliable, dependable and strong.
Im confident in the wrenching needed, I am a mechanic by trade, I've rebuilt motors ranging from Nissan trucks to Farmall tractors.

Here's were we are as of last night......
 

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I would guess you are going to need a crankshaft , cause the connecting rod end has slack where the wrist pin rides , allowing the piston to rock and that is why the upper rebuilds are not lasting , so check the play on the wrist pin to connecting rod connection

the connecting rod is pressed onto the crank , it is sold as an assembly from Honda , Mr Crankshaft is one company that will press a new rod onto your crank
 

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I talked for a long time with Vince (Mr Crankshaft) and he uses Vesrah rods which he said are superior to the OEM rods. If you need a crank I'd send your old one to him for a rebuild rather than get a new OEM crank assembly.

The long ways motors apparently don't oil as well as the old sideways motors. That came up when I pointed out that you don't see people with ruined cranks very often on the old 300's and 350 Foremans, but the 350 and 420 Ranchers and 500 Foremen seem to eat cranks.

I could definitely tell that his rebuild crank was tighter than a new OEM crank.
 

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its a shame you have to learn the hard way, sunken motors just dont last unless you split the cases, clean them out, rebuild them. been down this road many times with owners. your off to a good start, down load the service manual, read it, tear the motor down, rebuild it. one good tip: check to see if that year model has the bad shift drum ?, if it did/does ?, replace it with the newer upgraded shift drum !. they are very prone to snap off at the rear of the shift drum.
 

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Discussion Starter · #6 ·
I would guess you are going to need a crankshaft , cause the connecting rod end has slack where the wrist pin rides , allowing the piston to rock and that is why the upper rebuilds are not lasting
Exactly what I was told by a guy at the local shop. Didn't know you could rebuild them though, thought they were a plug and play deal, and honestly was sweating the 400 bucks for just the crank and rod assembly.

I already have the service manual, printed it off, put it in a binder so I can have it at my finger tips. Thanks for the heads up on the shift drum, I'll be checking into that.
 

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Dearl , Mr Crankshaft has done a couple of 300's for me , they will use a Versah rod if you ask , I have heard nothing but good about the Versah , a Honda rod use to be available thru Honda direct and was not even offered thru parts , but that supply dried up , so it is either new OEM crankshaft or a company like Mr Crankshaft


hyper link :
MrCrankshaft ATV Crankshaft repair site.
 

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For the upper , G+H gives a really good deal , machine work to bore , Shindy piston and all parts needed to do the job for right over $200 , they will do the head for another $150 , they will also sell you a new Taiwanese jug with parts
 

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its a shame you have to learn the hard way, sunken motors just dont last unless you split the cases, clean them out, rebuild them. been down this road many times with owners. your off to a good start, down load the service manual, read it, tear the motor down, rebuild it. one good tip: check to see if that year model has the bad shift drum ?, if it did/does ?, replace it with the newer upgraded shift drum !. they are very prone to snap off at the rear of the shift drum.
Think that was only 2000 that did that. The 01-up schematics have a different part number for the drum.
 

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its a shame you have to learn the hard way, sunken motors just dont last unless you split the cases, clean them out, rebuild them. been down this road many times with owners. your off to a good start, down load the service manual, read it, tear the motor down, rebuild it. one good tip: check to see if that year model has the bad shift drum ?, if it did/does ?, replace it with the newer upgraded shift drum !. they are very prone to snap off at the rear of the shift drum.
Think that was only 2000 that did that. The 01-up schematics have a different part number for the drum.
yeah, wasn't for sure where they changed shift drums :).
 

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Shift drum breakage occurred on '00 & '01 models. The fix is an '02 & up drum and rear bearing delete:

Yeah the extra motor I have in the shop is a 2000ES, so I ordered a whole transmission from PSN from an 05 simply because it included teh shift drum and was cheaper than buying only the drum anywhere else I could find one. Going to do that, new timing chain, seals, and crank in the bottom end, and of course, convert the shifter to a footshift splined shifter.

I'm stuck working on the house for the foreseeable future. In-laws are coming in right before Christmas and the wife wants the dining room painted before they get here.

Out of curiosity though, wouldn't a drum end sitting in a needle bearing be better than a larger drum end not sitting in a bearing/ wearing on the crankcase, or is there still a bearing in the case on the 02-up?
 

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Shift drum breakage occurred on '00 & '01 models. The fix is an '02 & up drum and rear bearing delete:

Yeah the extra motor I have in the shop is a 2000ES, so I ordered a whole transmission from PSN from an 05 simply because it included teh shift drum and was cheaper than buying only the drum anywhere else I could find one. Going to do that, new timing chain, seals, and crank in the bottom end, and of course, convert the shifter to a footshift splined shifter.

I'm stuck working on the house for the foreseeable future. In-laws are coming in right before Christmas and the wife wants the dining room painted before they get here.

Out of curiosity though, wouldn't a drum end sitting in a needle bearing be better than a larger drum end not sitting in a bearing/ wearing on the crankcase, or is there still a bearing in the case on the 02-up?
no bearing in the case, you have to remove the bearing in order to fit new updated shift drum in case. will it wear over time ?, more than likely. but if I had to choose between shift drum breaking ?, or case wearing ?, i'd go with case wearing. there are a few spots in motors from way back, up to today that also does not use bearings in the case.
 

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Discussion Starter · #16 ·
Got the motor washed before I started tearing into it. Well I didn't expect what I found once a got the cylinder off. Seems one of the circlips on the wrist pin broke, and allowed the wrist pin to cut into my cylinder wall. this explains the severe smoking just before I put it In the barn. I checked the side to side on the connecting rod to crank play and Im sure there is some tolerance there, but I didn't like the movement I seen. The plan is still to split the cases (I gotta find the broken circlip) clean everything out, check for wear on internal parts, I know I'm replacing the connecting rod (Mr. Crankshaft style), crank bearings, and the timing chain, slack adjuster, and cam bearings. I wont know what else till I get into it. I do know its going to need a new cylinder, no amount of boring is gonna fix this one. I got everything else soaking in the parts washer right now, looks like Im going to have plenty of time to clean everything.
 

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before you go Mr crankshaft route ?, you might want to check the price on a brand new crank from partzilla ?, from what i've seen on his website ?, its best to just buy a brand new oem crank, your call :).
 

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Vince rebuilds Honda cranks using Vesrah rod kits, which are much better quality than OEM. Plus, his assembly is tighter spec'd than OEM. Much cheaper than lesser quality OEM cranks too.
 

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Discussion Starter · #19 ·
Im going to look at both options real careful, I do know partzilla crank/Rod assembly goes for like $396, the bottom end kit from Rocky mountain was like $490 something with the crank, and you still don't get the cam bearings or timing chain. I have found with several engines I have rebuilt over the years, sometimes its better (not always cheaper) to source individual parts and go OEM were you can, and stay away from cheap "kits" their cheap for a reason. I think if I can get the crank re-built for $200.00 or less than that is the most economic route, if its much more than that then I will go OEM.
 

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Yep, OEM parts are the best available 99% of the time, unless the motor is being built for high performance. In the case of the crankshaft for the 350 Rancher motor, Mr Crankshaft rebuilt is the superior quality part though, by far.
 
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