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Discussion Starter #1
Hello guys,
My bike have cold starting,and when i visited service center,they said my bike have valve guide problem and it cannot be replaced,or else i have to replace the head assembly,and they said they will try to fix it in lathe.
CAN VALVE GUIDE BE REPLACED? OR SHOULD I DO AS THEY SAY? PLEASE HELP
 

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Probably less money to just replace the entire cylinder head in this bike. Whereas a lot more labor involved to replace valve guides.
 

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What year? How many miles?

It would be odd to have the guides wear out with any reasonable miles on the engine. The valve seals will usually wear first and allow oil to run down the valve and into the cylinder, which usually makes the engine smoke on cold start.

We replaced a couple valves on one of our Honda singles (CRF150R) and when it was all said and done we probably should have purchased a head assembly that had valves and cam installed at a reasonable price.

If you do need to replace the valve guides a head assembly may be the best bet, but if the engine has a lot of miles I'd probably look for a good used one instead of buying new.
 

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Discussion Starter #4
2015 model,ok guys thanks i will try to get a 2nd hand one instead of new
Bike has only covered 32k kilometres in odo.
Dont know why it worn out so fast
 

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2015 model,ok guys thanks i will try to get a 2nd hand one instead of new
Bike has only covered 32k kilometres in odo.
Dont know why it worn out so fast
It would be very unusual to have to replace valve guides at that point.

What are the symptoms you are experiencing that led you to take it in?

I'd be very surprised if worn valve guides were the actual problem.
 

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Replacement of head costs less. i had replaced entire head of my 250R with authorised CBR mechanic it costed me around 10k. But after replacement there will be vibrations for first 700 to 1k km and don't panic! after around 1000 km your bike will become normal and vibrations free before. I replaced entire head at 31000km on ODO recently last year in month of November. Don't compromise on spares.
 

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Discussion Starter #7
Thanks chethan,
Can you please tell me the parts you have changed.and cost of it,i dont trust service center guys here
 

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Discussion Starter #9
Bike will turn off if i let go the acceleration,on morning time,if engine is heated enough then no problem,A missing feeling at lower speed,
Fuel system has been checked and it is fine.they have checked the head assembly and told me valve guides has worn out
 

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Bike will turn off if i let go the acceleration,on morning time,if engine is heated enough then no problem,A missing feeling at lower speed,
Fuel system has been checked and it is fine.they have checked the head assembly and told me valve guides has worn out
Can you describe it in more detail?

Not sure how they came up with that diagnosis, but there are other things that could cause what you described.

Did they tell you anything about how they determined it was valve guides?

I'd get a second opinion before buying parts.
 

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Discussion Starter #11
Symptoms are
1. Cold starting
2.rpm dropping below 1500 if i let go acceleration suddenly
3.missing below 3k rpm
4.at near red rpm tik tik noise from head
5.all fuel system where cheked, timing chain is fine
6.the mechanic some how fixed 95% issues mentioned above,but tik tik noise can hear always now,and it annoying.
 

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Symptoms are
1. Cold starting
2.rpm dropping below 1500 if i let go acceleration suddenly
3.missing below 3k rpm
4.at near red rpm tik tik noise from head
5.all fuel system where cheked, timing chain is fine
6.the mechanic some how fixed 95% issues mentioned above,but tik tik noise can hear always now,and it annoying.
I'm not sure how they got worn valve guides out of that.

As far as the top-end noise, the cam chain tensioner and cam chain guides might be something I would look into, in addition to confirming the valve clearances are correct.

Is it smoking? Does it use oil?

What does the plug look like, and is it a new exact replacement?

What is the condition of the air filter? Try temporarily removing it and going for a ride to see if it runs better or worse.

Something else is the problem from the sound of it.
 

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Discussion Starter #13
Air filter is good,new spark plug,no smoke is coming from exhaust.any way they just fixed it almost but sound is so annoying.
 

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Air filter is good,new spark plug,no smoke is coming from exhaust.any way they just fixed it almost but sound is so annoying.
If all else is good, I don't see how it could need valve guides replaced.

New Cam Chain Tensioner or valve clearance adjustment may cure the top-end noise problem IMO.

Plug is exact stock replacement, correct?
 

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Cold starting can be due to a lot of factors, right from out of spec valve clearances to dirty injectors/throttle body. Valve guides as such don't pose a problem, they leak oil into combustion chamber and burn oil that's when you have problem. Start off by inspecting your throttle body, get your throttle body cleaned, injectors cleaned, spark plug cleaned and considering the fuel in India and your KMS clocked, it's better to start off with the cleaning process and see if it helps.

Cheers!
VJ :cool:
 
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