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trx_dave 05-13-2018 05:45 PM

400ex manual timing chain tensioner
hello all so i traded my blown up trx450 for a 400ex bored to 440 runs and rides great plenty of power came with a spare motor and 2 good 440 cylinders and pistons. but it has a slight tick i checked the timing chain tensioner and its maxed so i assume it needs a timing chain no big deal. but my question is will a manual chain adjuster allow me to take the slack out and quiet up the chain until next winter??? i dont ride to often and i dont abuse mt quads. im hoping its possible to modify a stock tensioner or order a manual one i have a spare stock one to modify for now if need be. i know and understand that a manual tensioner can cause damage if over done the stock unit is fine but will not extend enough to take out the chain noise and i dont feel like doing a chain at the moment so a manual unit should give me that little bit more to take away the tick and avoid jumping time.

Here 2 help 05-14-2018 04:18 PM

You can buy a manual tensioner or (if you are handy) modify the stock tensioner into a manual one.

Take a stock tensioner, remove all the parts, drill it out and thread it to 8x1.25mm - find a fully threaded bolt of adequate length (or get a piece of 8x1.25 threaded rod) and a 8x1.25mm nut - you might weld a wing nut or hex nut on the end of the threaded rod, but you should not tighten the tensioner more than finger tight (I just use a piece of threaded rod with a hacksaw cut slot in the end so I can use a screwdriver to speedily back off the tensioner when necessary, but this is just for the cheapskates that refuse to install a new cam chain and don't care if it might cause damage cause they are only going to ride it the rest of the season and sell it. "Then it will be somebody else's problem!"

Now I hate to burst your bubble, but when the cam chain is worn to the point the tensioner will not take up the slack, just installing a manual tensioner will not always stop the ticking or keep the chain from jumping time - when the chain is worn past the point the automatic tensioner can take up the slack, the chain no longer fits the sprockets properly. The noise you hear may be the ill fitting chain trying to climb the teeth on the sprocket and then snapping back to the bottom of the teeth as the chain gets tight from the climbing action. If you over tighten the chain, the chain will wear faster and may jump time even though it's tight. Try it and good luck.

I just put in a new chain when it's needed and stay with the auto tensioner, but that's me - I spent $4000 to get the machine - a couple hundred every 3 or 4 years is just maintenance and insurance it's not going to leave me stranded somewhere that I don't want to be stranded.

trx_dave 05-14-2018 04:50 PM

I found most of my tick was an exhaust leak which I fixed I did make a tensioner which I didnt install I'm gonna order a chain

trx_dave 05-15-2018 11:11 PM

I also found out after changing my oil the clutch slips badly to the point its unrideable so im gonna order a clutch and chain for it and do it all at once. Now I'm very mechanically inclined so that's not an issue I'm a mechanic for a living. As far as replacing the chain ca I get away with leaving the cam installed and take off just the head cover??? And I know that the clutch basket and drive gears needs to he removed for the chain. Also how often do the guides wear out on these motors I'm new to the 400 only ridden this one once I recently just got it since I traded my blown up 450 for it.

Here 2 help 05-16-2018 03:28 PM

Taking the head cover off releases the cam and the cam has to be removed to install the chain - I remove the bearing retainer dowel pins, slide the bearings off the cam, lift the chain off the cam sprocket and remove the cam from the chain. Pay attention to the cam bearings - one is sealed on one side and the other is open on both sides - they have to go back in correct way or cam, head and rocker arm damage will occur.

The tensioner and guide do not wear out at a high rate unless they have been over tensioned, run with a bad chain for a long time or run with the wrong cam chain (theres a "high performance" modification that some people do using a cam chain for a CRF450 which is the same length but wider and cheaper than the TRX/XR400 cam chain - they mistakenly think that since it's wider it's heavy duty when in fact it is made of lighter plates and smaller pins. It's cheaper construction and the race bikes are expected to have the parts replaced more frequently.

Plan on replacing the crankshaft and clutch nuts - they have a collar on them that has to be deformed into a slot on the shaft to lock them in place. There's a thin metal gasket between the head cover and the head - get a new one - it's necessary for clearance on the cam bearings. Might as well get a new clutch cable also - the cable is the cause of most clutch failures next to the use of incorrect oil - be sure to use an oil that is JASO rated. I suggest you get a manual (if you don't already have one) for torque values, disassembly and assembly instructions.

trx_dave 05-16-2018 03:36 PM

Thanks for the info yeah the guy I got the 400 from gave me 2 gasket kits so I should have those. And a complete spare motor the clutch nut looks good on that motor havent seen the one on my motor yet. And as far as the chain I'll stick to the 400ex one dont want any issues lol. And yes I'm gonna order a tusk clutch kit and new cable for it while I'm in there and change the chain. Now I've seen chains for like 30 bucks would you stay away from those??? I'm on alittle bit of a budget

Here 2 help 05-17-2018 02:22 AM

Get the $100 OEM chain or a DID chain for $69 or a Wiseco for $64.50 or a Pro-X for $63.20

trx_dave 05-17-2018 03:44 PM

I'll go to the local honda dealer and pick one up. I noticed that after changing my oil to valvoline 20w50 motorcycle it's much much quieter and I adjusted the valves to spec and now the clutch dont slip as bad so I'm gonna ride it alittle and see how it is. I'll still order a new clutch on Friday

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