Yamaha

Brand Yamaha Brand 12oClockLabs Yamaha WR400F 1999 Brand Honda KTM 450SX

10 replies to this topic
  • Tobyperkins17

Posted March 28, 2016 - 12:59 AM

#1

Gday

 

A guy wants to swap a Freshly rebuilt wr400 99 model with a high compression piston for my 1990 dr350

 

I rode the bike and is great, very smooth and nice power delivery 

 

It isn't in best shape tho

 

That isn't my reason for the topic tho how ever this is... I'm 65kg and I can start it, Nor could he so we tow started it, is there a tequnique for starting these beasts is question 1 and number two is do I have to use premuim petrol instead of normal unleaded to prevent the motor detonating from high comp piston... Will it blow the bottom up anyway??

 

 

Any advice would be muchly appreciated because i have to make my mind up within 5 days!

 

Cheers toby



  • Krannie McKranface

Posted March 28, 2016 - 07:21 AM

#2

Run away from it
Unless you want to learn about rebuilding the head....sounds like the classic leaking intake vale problem

  • Tobyperkins17

Posted March 28, 2016 - 04:22 PM

#3

Run away from it
Unless you want to learn about rebuilding the head....sounds like the classic leaking intake vale problem

Valve? If the valve is leaking wouldn't it have little compression? It has very high compression



  • Krannie McKranface

Posted March 28, 2016 - 04:59 PM

#4

Valve? If the valve is leaking wouldn't it have little compression? It has very high compression

 

You mean, if feels hard to kick.....that has nothing to do with it.

 

If this 17 year old motor has not had a complete valve job yet, and you buy it, you will have to do it, because everything wears out....including the valve train.

 

If it starts by towing/bumping, then runs and idles fine, that is a classic symptom of a intake valve the is either leaking, or more likely, sinking into the head from age and not opening enough, and leaking.



  • Tobyperkins17

Posted March 28, 2016 - 05:43 PM

#5

O

 

You mean, if feels hard to kick.....that has nothing to do with it.

 

If this 17 year old motor has not had a complete valve job yet, and you buy it, you will have to do it, because everything wears out....including the valve train.

 

If it starts by towing/bumping, then runs and idles fine, that is a classic symptom of a intake valve the is either leaking, or more likely, sinking into the head from age and not opening enough, and leaking.

Ok thanks makes sense

 

 

The original owner was heavier and could start it easily apparently tho



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  • Krannie McKranface

Posted March 28, 2016 - 06:32 PM

#6

O

 

Ok thanks makes sense

 

 

The original owner was heavier and could start it easily apparently tho

 

You said he had to tow it 



  • Tobyperkins17

Posted March 28, 2016 - 07:54 PM

#7

You said he had to tow it 

The guy I'm buying it off has only had it for a week as he is way to short for it and only weighs 62kg and so had to tow start it for me, the guy he bought it off could start it because he was a lot heavier, however idk this could be a lie so am trying to find out if there is a specific technique for starting it

 

That should make more sense 



  • chelder

Posted March 30, 2016 - 05:48 AM

#8

So you roll it just past TDC pull the decompression leaver and give it a kick.... is that what you are doing and it wont start?



  • Tobyperkins17

Posted March 30, 2016 - 05:55 PM

#9

So you roll it just past TDC pull the decompression leaver and give it a kick.... is that what you are doing and it wont start?

I think the guy was trying that 

 

Correct me if I am wrong but apparently you push kicker down till it hits compression without decomp. Then Pull in decomp. and push the kicker 1-2 inches down, let decomp. out and let the kicker all the way up then give her a big kick in the guts

 

E start would be great



  • chelder

Posted March 31, 2016 - 04:55 AM

#10

I think the guy was trying that 

 

Correct me if I am wrong but apparently you push kicker down till it hits compression without decomp. Then Pull in decomp. and push the kicker 1-2 inches down, let decomp. out and let the kicker all the way up then give her a big kick in the guts

 

E start would be great

Yeah mate that's it, been a long time since i have done it hahaha! if you cant feel any difference could be a problem the the decompression mechanism.  



  • Tobyperkins17

Posted March 31, 2016 - 01:06 PM

#11

Yeah mate that's it, been a long time since i have done it hahaha! if you cant feel any difference could be a problem the the decompression mechanism.  

Yeah fair enough!

 

Decomp does work, could be spark plug







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