cbr 250 ticking update

[KRS1]

went to inspect the bike today, amazingly they were going to throw the old shim back in without reshimming all of them back to spec as requested...amazing (maybe they were trying to save me money, but they could have let me know)

failure was due to one missing side of the cotter valve, dont know how it went missing....side to side play and the shim slipped out...bike has been ridden hard for the past 25k kilos, and just now failed.

so it needs cotter valves and a new retainer and shims...gaskets etc....so i have to wait another week to reorder the shims fark !

#13 (cotter valves) & #11 (retainer) - see below

actual valve face and seats looked ok, cylinder barrel wasnt scarred...piston was extremely carbonized....theres a YZF-R3 in my future sooooo...left it as is. with the airflow modifications i performed i was curious how lean it was running, after seeing the piston - its not running too lean at all.

Edited March 25, 2014 by KRS1

[transam]

They are called Valve stem locks. They can fail. can lead to dropped valves. In high performance high revving engines you can buy them made of a different type of treated steel or titanium to eliminate the problem, I am talking about car engines now but the principle is the same.

[Familyonthemove]

Fascinating posts ..... a blown motor is like a detective novel for petrol heads!

Hope you get the parts and are back on the road soon.

I have a theory that racers and tuners improve the breed by stressing components to breaking point and hopefully the info gets back to Honda - and so eventually the engines get stronger for us 'normal' users who keep things stock.

A bit OT - but in a standard state of tune is the 250 motor reasonably reliable?

[yankee99]

You are very lucky the valve didnt drop and destroy the engine. Did you disable the rev limiter previously?

[KRS1]

Fascinating posts ..... a blown motor is like a detective novel for petrol heads!

Hope you get the parts and are back on the road soon.

I have a theory that racers and tuners improve the breed by stressing components to breaking point and hopefully the info gets back to Honda - and so eventually the engines get stronger for us 'normal' users who keep things stock.

A bit OT - but in a standard state of tune is the 250 motor reasonably reliable?

I would say yes, for normal riding and long distance travel....and not redlining constantly its pretty bulletproof, except for the cam chain tensioner which is prone to a lousy ribbon spring inside, even then it wont break down, itll just be loud clacking (not ticking)...the plunger only travels one way, so the tension wont loosen.

The clutch has minor slipping issues every once in a while, but thats contributed to hard riding/choice of oil and isnt a serious issue, as all bikes at some time will slip...But after you push it hard, it hiccups.

The rear brake pads wear a little too fast though, im on my 2nd set within a year, but thats do to my riding style.

The gearbox is getting loud when shifting also. But this seems to be the case for all small displacement hondas with manual gears.

This bike is heavily detuned, once you remove the things honda did to detune it...its a totally different bike...and makes the need to upgrade to the cbr 500 pointless...unless of course you derestrict the 500 as well.

semicheap to repair if the dealer doesnt rape you. All the repairs in this post will cost 2300 baht, but they know im keeping an eye on them and what they change/charge. A normal person wouldve gotten charged for a sparkplug and air filter and CCT as well, bringing the bill up to 4000 baht or more.

Edited March 25, 2014 by KRS1

[KRS1]

You are very lucky the valve didnt drop and destroy the engine. Did you disable the rev limiter previously?

yeah thank got it didnt drop.

No mod on the rev limiter, its the stock ECU.

[transam]

Should add that over revving to the point of valve bounce will be very detrimental to all your valve train, thats why you can buy stronger springs if you want to increase rpm.

[KRS1]

Should add that over revving to the point of valve bounce will be very detrimental to all your valve train, thats why you can buy stronger springs if you want to increase rpm.

was just looking at titanium valves and springs last night.

But is titanium meant to be for prolonged/daily use?

[transam]

Should add that over revving to the point of valve bounce will be very detrimental to all your valve train, thats why you can buy stronger springs if you want to increase rpm.

was just looking at titanium valves and springs last night.

But is titanium meant to be for prolonged/daily use?

Usually titanium locks and keepers are used. Stainless steel valves and descent springs do the job. Increased tension (poundage) springs can cause premature cam wear.

PS. Synthetic oil a must.

Edited March 25, 2014 by transam

[KRS1]

Should add that over revving to the point of valve bounce will be very detrimental to all your valve train, thats why you can buy stronger springs if you want to increase rpm.

was just looking at titanium valves and springs last night.

But is titanium meant to be for prolonged/daily use?

Usually titanium locks and keepers are used. Stainless steel valves and descent springs do the job. Increased tension (poundage) springs can cause premature cam wear.

PS. Synthetic oil a must.

thanks.

[seedy]

was just looking at titanium valves and springs last night.

But is titanium meant to be for prolonged/daily use?

I think at a cost/benefit ratio for your intended use, Transam advice is good. SS plenty good, with Ti keepers and retainers.

Only benefit to Titanium valves for a street bike - or any other - is a reduction in weight, so a corresponding lighter valve spring can be used and still allow adequate valve return

By the by - what do they want for a titanium valve ??? I am sitting down !!

[KRS1]

was just looking at titanium valves and springs last night.

But is titanium meant to be for prolonged/daily use?

I think at a cost/benefit ratio for your intended use, Transam advice is good. SS plenty good, with Ti keepers and retainers.

Only benefit to Titanium valves for a street bike - or any other - is a reduction in weight, so a corresponding lighter valve spring can be used and still allow adequate valve return

By the by - what do they want for a titanium valve ??? I am sitting down !!

it was like $150 for a set of 6 on ebay... just skimming prices, those are for engines with 7mm stems. Although its a possibility they can be sourced for a cbr1000 to be used on the 250.

[transam]

I don't know much about bike upgrade stuff, but, can you source "roller tip" rockers for your application ?

[seedy]

it was like $150 for a set of 6 on ebay... just skimming prices, those are for engines with 7mm stems. Although its a possibility they can be sourced for a cbr1000 to be used on the 250.

WOW - price of Ti coming down big time, due to more use of it most likely.

[seedy]

I don't know much about bike upgrade stuff, but, can you source "roller tip" rockers for your application ?

Nothing like removing a set of tall rocker arm covers, and seeing a set of needle bearing roller rockers and a billet stud griddle !!!

Those were the days !!

[transam]

I don't know much about bike upgrade stuff, but, can you source "roller tip" rockers for your application ?

Nothing like removing a set of tall rocker arm covers, and seeing a set of needle bearing roller rockers and a billet stud griddle !!!

Those were the days !!

Weeeeeeeeeeeeeeeell, was thinking about talking tech ....... .........How I solved stuff with valve train probs.......

[KRS1]

I don't know much about bike upgrade stuff, but, can you source "roller tip" rockers for your application ?

i dont know...but...'roller tip' rockers just sounds badass !

[transam]

I don't know much about bike upgrade stuff, but, can you source "roller tip" rockers for your application ?

i dont know...but...'roller tip' rockers just sounds badass !

[metisdead]

Troll posts have been removed.

[transam]

Ok some tech.......

The rocker pushes the valve down, but unfortunately it also creates sideways pressure with stock rockers, this is why valve guides wear. So, a bright spark came up with the idea of a roller tip rocker arm that did away with this sideways pressure to illuminate valve guide wear and "friction". The roller tip pushes down to open the valve but the roller tip "rolls" on the valve head. Great weeee invention. I had the Harland Sharp rockers on my Pontiac combined with bronze valve guides. Can't get better than that.

[KRS1]

ok, now to find dual rocker arms...

[KRS1]

bikes back, lost some power does not move like it did 6k rpm up...

mechanic did not reshim, he actually took the old shims and took material off...he must be a real ninja if he can take off 0.??? mm of material

and this contradicts with my measurements, there would have to be thicker shims put in, not skinnier ones...measurements were probably taken with a hot/warm engine...marvelous.

Plus for some reason they removed the steering stem nut, and now theres another washer underneath thats too thin and the stem is loud. One of the gas tank mounting rubbers is also missing and loud over bumps.

Nat motors Huay Kaew road CNX, avoid if your into peak performance...go if you want to save money.

great just farking great...now i have to do myself, what i paid them to do...god this is irritating.

Edited March 27, 2014 by KRS1

[yankee99]

Like you said No! way they can use the old shims...You need to do it yourself or see if ricco will do it...you need to check they have the chain aligned up correctly with the crank markings and cam gear markings.

[yankee99]

bikes back, lost some power does not move like it did 6k rpm up...

mechanic did not reshim, he actually took the old shims and took material off...he must be a real ninja if he can take off 0.??? mm of material

and this contradicts with my measurements, there would have to be thicker shims put in, not skinnier ones...measurements were probably taken with a hot/warm engine...marvelous.

Plus for some reason they removed the steering stem nut, and now theres another washer underneath thats too thin and the stem is loud. One of the gas tank mounting rubbers is also missing and loud over bumps.

Nat motors Huay Kaew road CNX, avoid if your into peak performance...go if you want to save money.

great just farking great...now i have to do myself, what i paid them to do...god this is irritating.

You mean go if you want to pay twice?. Is that a big wing dealer that superior always complains about?

[KRS1]

no its a regular dealer, bastards.

and they KNOW i have a race on the 5th, if they detuned my bike on purpose im going to be really pissed.

Edited March 27, 2014 by KRS1

[yankee99]

My understanding is kawasaki big bike will sell individual shims ....

[KRS1]

i coudve gotten shims at Saengchai Honda, Nat motors is the worst at stocking inventory.

you know if kawa and honda shims are the same width? just curious.

[KRS1]

and why the hell they have to take off my steering stem nut ????

the new washer isnt even the right size, you can see the abrasion marks from the original one and the width it should be.

damnit

[wantan]

Guess the mechanic just wanted to offer a special tuning. Better steering makmak, better fuelflow with racing shims. You shouldn't have told him about racing

[seedy]

Sorry to hear your troubles.

Nat Motors always been good for me. Came recommended by a long time friend who has bought a few bikes from them, recently a CRF250.