Making my 426 more durable.


4 replies to this topic
  • kubamtx

Posted July 15, 2007 - 11:35 PM

#1

Hello
I ride 4 times a week, 30-40 km per ride. Half on the track and half in trials. I would like to make my yzf 426 more solid. I mean do something to make my engne going longer without maintance.
Of course changing oil each 5 rides.
My question is what to do with the engine to make it more durable.
I was thinking about increasing valve clearance from 0,1-0,15 to 0,12-0,17 and from 0,15-0,20 to 0,17-0,22.
And I have no ideas what else I can do. I don't need al HPs. So lowering the compresion can be done.
What do you think?

  • SRT426

Posted July 16, 2007 - 04:01 AM

#2

I think you'd have and easier time making it less durable than more durable. The 426 motor is about the most solid motocross engine ever produced. I would say it's the XR400 of motorcross bikes. Adjust the valves to Yamaha specs, CHANGE THE OIL OFTEN, maybe throw some rings in it to freshen it up every now and then along with basic maintenace (clean/lube chain, tightening bolts, cable maint. and greasing bearings) and ride the hell out of it :thumbsup:

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • Ga426owner

Posted July 16, 2007 - 04:16 AM

#3

Hello
I ride 4 times a week, 30-40 km per ride. Half on the track and half in trials. I would like to make my yzf 426 more solid. I mean do something to make my engne going longer without maintance.
Of course changing oil each 5 rides.
My question is what to do with the engine to make it more durable.
I was thinking about increasing valve clearance from 0,1-0,15 to 0,12-0,17 and from 0,15-0,20 to 0,17-0,22.
And I have no ideas what else I can do. I don't need al HPs. So lowering the compresion can be done.
What do you think?


I think it is already very durable stock ... but be aware of the worst possible case...:busted:
Your quote:
"I mean do something to make my engne going longer without maintance"
I hate to sound arrogant....and I really wish this was the case but unfortunately, this is a pipe dream......:thumbsup:
They all need maintenance and the older/more hrs on them makes maintenance a requirement to keep them running w/o blowing up and costing you more than the 426 is worth. Valves will need to be replaced, along with all valve componets and valve seats. Topends need to be replaced, Cam chains and gears and CCTs need to be replaced....how many hrs total are on your 426?
5 rides between oil changes......how many hrs do you equate to this? 5hrs? 10hrs?
I recommend changing oil no more than 5hrs max....most do 3-4hrs max...this will help keep maintenance cost down to. :thumbsup:

  • kubamtx

Posted July 16, 2007 - 08:10 AM

#4

Hehe.
Ok. So I'll change the oil each 5 hrs and check the valve clearances each 4th ride. In my case it is 1,6 liters of oil 2 times a week and a filter.
So that's 3 bottles for two weeks so that's 23$ a week. Not bad.
So I'm going to garage to change the oil. ;-) thanks for advice. I was only thinking that there is and recipe for my cylinder head last forever (with propor maintance of course)

  • grayracer513

Posted July 16, 2007 - 08:12 AM

#5

Do not start thinking that you know better than Yamaha what is good for the engine. Healthy 426 valves will go for hundreds of hours with needing to be adjusted. Furthermore, increasing the valve lash beyond specification will SHORTEN their service life, not extend it. Stay with the recommended settings.

I should also point out that you are incorrect about the exhaust valve clearance:

2001/2002 models with Ti valves call for the exhaust valves to be set to .20-25mm

2000 models with SS valves call for .25-.30mm

I understand that oil is very expensive in Europe compared with the U.S., but it's still cheaper than rebuilding the engine.

In so far as the oil goes, there are two main problems with running it for an extended period in these engines. First is that there is not much of it in the system, and it must not only absorb the wear particles and fuel waste from the engine, but also the metal shed from the transmission, and the debris from the clutch as well, so it gets contaminated fairly quickly compared with an engine only application.

The other problem also relates to using the oil to lube the gears. Multi grade oils are thin oils that are kept from thinning out excessively at high heat by using additives called viscosity improvers. Most of these that are used in engine oils can be physically torn up by the transmission very quickly, which turns a 10w-40 oil into a 10w-30 or a 10w-20 in just a very few hours time. There are VI additives available for use in multigrade gear oil that will withstand the thrashing they get in a gearbox, but these cost more, and blenders of engine oils will not usually use them. But some oils intended for motorcycles with shared oil in engines and transmissions
do use the better additives, and those can be used for longer periods without breaking down. I would still say no more than 9-10 hours even then, because you still have the contamination problem.

Some oils that do retain their viscosity by actual test are Amsoil MCF and MCV, Mobil 1 Racing 4T and V-Twin, Bel-Ray EXS, Torco T45-R, Maxima Maxum 4, and Golden Spectro 4. Whether any of these are available to you in Poland, I don't know. If you need to research this for yourself, the issue is the oil's shear stability.





Related Content

Forums
Photo

yz250x vs 450 4t comparisons (preferably desert riding) needed by JakeNorthrupYZ450F


Dirt Bike   Make / Model Specific   Yamaha   Yamaha 2-Stroke
  • 9 replies
Forums
Photo

2016 YZ450 by CaptainKnobby


Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  59 replies
Forums
Photo

Chubby dad, looking at bikes , First trip to the orange/black forum ! by Slow_ride


Dirt Bike   Make / Model Specific   KTM   250-530 EXC/MXC/SXC/XC-W/XCR-W (4-Strokes)
  • Hot  28 replies
Forums
Photo

Michigan Motocross Tires by 288yz450


Dirt Bike   Dirt Bike Regional Discussion   North
  • 1 reply
Forums
Photo

Megabomb Fitment by 288yz450


Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 1 reply
 
x

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.