Any common problems with 98 WR400's?

[MAXPOWER_WR_450]

I'm looking into buying a 98 WR400. I know this was the first year for them and there are usually problems with bikes when they're new. Anyone know of any major, common problems with them?

Also, what would be a good price for one in good condition?

[Yamahondaha]

The most major problem with the bike is that it needs regular maintenance and most people put it off till the bike stops running.

I am no exception, I had a 99 WR400 and a 99 YZ400, the WR had a rod failure and that seems to be the most common major problem with putting off maintenance (I was told it is common on the 400's but the 426's got a bigger rod end) My rod failure was at the big end and caused the motor to seize but I pulled the clutch in the instant I felt the motor loose power so it just stalled. I hear a lot of people loose the piston, jug and the motor cases when the rod breaks at the small end (not a pretty sight)

The timing chain should also be replaced every season or you risk wearing out the permanent drive sprocket on the crank shaft and then you will have to replace the $300 crank as well as the $40 chain. My YZ400 had the counter balancer come loose on it and that was an easy fix and not that expensive ($150).

The valves should be checked often and adjusted to the larger end of the spec since they loose clearance as the valves stretch and wear.

When my motor failed I rebuilt it with a new crank and bearings, piston, rings and new valves in the rebuilt head. I did all the work myself and spent $1,000 on the rebuild. I loved my WR but wanted electric start for use in traffic (in case I stalled)

I would strongly recommend the YZ or WR426 over the 400 for the level of performance and reliability you get. I recommend you get the repair manual and stay on top of the maintenance no matter what bike you get.

If you are not willing to do regular maintenance and don't need a high performance bike I suggest you buy an XR400 and just change the oil. I owned two XR400's before the Yamaha 400's and they are great ultra reliable bikes that seldom break when they have oil in them but The performance of the WR/YZ400's that I have owned in the past are the reason I ride an 06 WR450 today, they are very durable high performance bikes with great suspension and great handling...

[bluebike1999]

Max

just repeating what i've read here.(i have very little knowledge of my own)

apparently the slide plate in the carb is prone to cracking and sending bits into the engine, replace slide in carb.

some report suffering a knock or worse due to a 'weak small end' in the conrod, replace rod,piston, rings if required. the 426 has a larger small end which i believe may have elininated that problem. some are doing 400-426 conversion by either honing original barrle or getting 426 barrell. several good reports on that process.

counterbalance key can wear creating concerning noises, cheap fix if done early.

chain, if not closely monitored can chew into swingarm, glob of silicon under slider helps reduce/avoid that and quiets down slap when lugging or using too high a gear.

again, just repeating whats already on here, other than that, change your oil and filters regularly(i go every 500ks) keep an eye on the valves. i get mine checked at least every 1000ks (costs me $30) only ever had one adjusted, but have peace of mind.

Dont know about price there. $3500-$5000 aus

enjoy what was the beginning of the new era of dirt bikes, one that honda is still trying to match. best selling bikes in Aust and no wonder.

hope that helps

[bluebike1999]

ha Yamahahonda, we must have been typing at the same time. at least the info is consistant.

max if you do a search under the headings like 'carb slide', 'counterbalance' 'small end' etc there should be enough reading for you to also sound like an expert when you front up to buy one of these. It should be noted that these issues are not across the board and dont effect every wr 400, but it has occurred enough to realise a pattern.

good luck

let us know what you get

[YamahaWR450FMike]

The most major problem with the bike is that it needs regular maintenance and most people put it off till the bike stops running.

I am no exception, I had a 99 WR400 and a 99 YZ400, the WR had a rod failure and that seems to be the most common major problem with putting off maintenance (I was told it is common on the 400's but the 426's got a bigger rod end) My rod failure was at the big end and caused the motor to seize but I pulled the clutch in the instant I felt the motor loose power so it just stalled. I hear a lot of people loose the piston, jug and the motor cases when the rod breaks at the small end (not a pretty sight)

The timing chain should also be replaced every season or you risk wearing out the permanent drive sprocket on the crank shaft and then you will have to replace the $300 crank as well as the $40 chain. My YZ400 had the counter balancer come loose on it and that was an easy fix and not that expensive ($150).

The valves should be checked often and adjusted to the larger end of the spec since they loose clearance as the valves stretch and wear.

When my motor failed I rebuilt it with a new crank and bearings, piston, rings and new valves in the rebuilt head. I did all the work myself and spent $1,000 on the rebuild. I loved my WR but wanted electric start for use in traffic (in case I stalled)

I would strongly recommend the YZ or WR426 over the 400 for the level of performance and reliability you get. I recommend you get the repair manual and stay on top of the maintenance no matter what bike you get.

If you are not willing to do regular maintenance and don't need a high performance bike I suggest you buy an XR400 and just change the oil. I owned two XR400's before the Yamaha 400's and they are great ultra reliable bikes that seldom break when they have oil in them but The performance of the WR/YZ400's that I have owned in the past are the reason I ride an 06 WR450 today, they are very durable high performance bikes with great suspension and great handling...

huh? my brother has a 98 YZ400F with close to 20,000 miles of dirt miles on it and it hasn't had one single thing done to it execpt for oil changes. No valve adjustments, trans problems or anything. That bike amazes me everytime we go riding.

[bluebike1999]

Mike

does your brothers bike have the 'free mods' done as i'm starting to wonder whether some of the issues created are due to more power.....

maybe those little japanese engineers are smarter than what we realise.

[Yamahondaha]

huh? my brother has a 98 YZ400F with close to 20,000 miles of dirt miles on it and it hasn't had one single thing done to it execpt for oil changes. No valve adjustments, trans problems or anything. That bike amazes me everytime we go riding.

I am happy for him, he must have got a good bike that was not built on a Friday (like mine) and has been maintained on schedule. The valves will tighten if dirt and grit get in through the intake and the rod will fail if bits of metal in the oil flow through the bearings. The plating on the cylinder wears off if the oil breaks down from excessive heat (especially if the bike is jetted too lean). Since these bikes can rev to 13,500 they need to have the oil changed often. The better you do the maintenance the longer the bike will live. I got mine used and feel the past owner didn't do regular maintenance but still it was an awesome bike worth rebuilding...

[Yamahondaha]

ha Yamahahonda, we must have been typing at the same time. at least the info is consistant.

max if you do a search under the headings like 'carb slide', 'counterbalance' 'small end' etc there should be enough reading for you to also sound like an expert when you front up to buy one of these. It should be noted that these issues are not across the board and dont effect every wr 400, but it has occurred enough to realise a pattern.

good luck

let us know what you get

Great minds think alike My 99 YZ400 I bought for $700 because the throttle plate that fits into the carb slide was cracked (I think that is what you are mentioning). I replaced the entire carb with a spare I got for my WR off Ebay for $150 and had it running within an hour of getting it home. I ran better with a Wr carb because it has that air cut off valve to eliminate backfiring during deceleration. I loved riding the YZ in the dirt with the close ratio gear box and the WR with the wide ratios for dual sport rides that started on pavement. You can't beat these bikes for the money, You can buy two for the price of a new bike.

[YamahaWR450FMike]

Mike

does your brothers bike have the 'free mods' done as i'm starting to wonder whether some of the issues created are due to more power.....

maybe those little japanese engineers are smarter than what we realise.

He had done no mods to that bike. All stock and very fast from the factory.

[bluebike1999]

hmmm i think there is something in that for us all.

free mods = problems sooner??????

for every action there is a equal opposite.......

[bluebike1999]

at least we beat japan in the world cup.

[MAXPOWER_WR_450]

Thanks for all the info. Ill have to do more reading on this

[standup rider]

You have a external rod on your carb that is part of the Accelerator Pump (AP). That rod can get dirt and grit around it and keep it from working. The AP is what gives you a quick squirt of fuel when you first turn the throttle to make the bike get fuel immediately for a quick response. Only problem is that it comes from the factory with about a 5 second squirt duration when you only really need a 1/2 second squirt and therefore can cause the bike to bog because of to much fuel. There is info in this forum on how to correct this.

I have a 99 WR400 and with all the free mods done and I do not see where it should effect the bikes longevity much as long as I don't keep it pegged for extended periods of time. I read that the earlier 400's are the more bullet proof engines do to the valves being stainless steel and less prone to go out of adjustment then the Titanium valves that are on the 426 & 450's.

You have come to the right place to know the facts about this bike. I could have never known near as much as I do if I hadn't found this place. My Best advice, change oil filter and oil and keep your air filter maintained as well and you should have many miles of trouble free riding. Its a great bike.

[kieethes]

Check that carb slide/throttle plate close. I had 2 break on me in my 98 wr400. Sounds like a common thing. I had some stronger slides made at a machine shop. They should last way longer than the stock one, or the updated stock one, which is the exact same as the old one. Let me know if you are interested in one of my slides. I have a few extra. If anyone with a 426 or 450 had a slide break and still has the old one, I would like to have it for comparison. Maybe my stronger slide will fit the newer carbs as well.

[trikeflyer]

10,000 miles of mostly single track vales needed adj when new and still in spec today absoutley nothing to fix amzoil every 200 miles

[Conan_'dale]

Check that carb slide/throttle plate close. I had 2 break on me in my 98 wr400. Sounds like a common thing. I had some stronger slides made at a machine shop. They should last way longer than the stock one, or the updated stock one, which is the exact same as the old one. Let me know if you are interested in one of my slides. I have a few extra. If anyone with a 426 or 450 had a slide break and still has the old one, I would like to have it for comparison. Maybe my stronger slide will fit the newer carbs as well.

I sent you a PM, I would be interested in one of your slide plates! Let me know, I'll be in Portland over Christmas.

[427fastback]

I have a 99WR 400 (Canadian version) that i have had since new.Aside from replacing the throttle cables a few times,cleaning out the acc pump every year and the odd valve setting I have had Zero problems with this bike.

[xr_rider1]

my 2000 wr400 pretty much self destructed. the conrod snapped just under the piston pin and put a hole through the engine cases at the front of the motor and punched another hole through the back of the cylinder. the rod also smashed the balancer. we got a quote for parts here in australia and it was going to cost around $4000 australian dollars and that does not include a new crank and balancer and that is with me doing the labour. if i were you i would not buy an early model wr. the only way iw ould buy a wr is if i bought one brand new.

[Bamster]

Mike

does your brothers bike have the 'free mods' done as i'm starting to wonder whether some of the issues created are due to more power.....

um, It's a YZ.

[Randy Nilles]

I had a 98 yz and never had a single problem. I geased it from time to time but ran the piss out of it pretty much every weekend until I got my new bike. The guy I sold it to still says it is running great and hasnt done anthing to it either.? I sold it to him for $2600. in good condition with a White Bros pipe and Aceribis hand guards.