Penyakit yang terkenal dari CBR 250 adalah getaran yang mengganggu saat RPM tinggi (setidaknya itu yang saya rasakan selama menunggangi CiBoRi). Menurut sumber yang saya baca, di indikasikan penyebab getaran itu berasal dari rantai keteng yang tegang kendur. Juga, selain getaran yang tinggi juga suara mesin yang kasar di RPM bawah saat berakselerasi.
So, setelah iseng-iseng nyari informasi, ketemulah sebuah solusi, check this out :
Well the CCT went again, spring is shot…beyond help. The thread above can be disregarded. Use the technique in this thread instead.
So being the cheap bastard that I am, I tried to figure out another way to keep the CCT tight against the timing chain. You’ll need a 10mm bolt 20mm long and a nut and washer. Preferably stainless steel, so it doesnt rust although not terribly important.
First you have to remove the allen head that is in the center of the CCT, then tighten the worm gear against the timing chain, stick a small flathead inside the hole and turn counterclockwise. Until it doesnt go anymore. Refer to link above for info on how to do this, you have to read it, go to the bottom of the pictures.
***This next step is optional – ride the bike for a couple days until it feels the quickest, the timing chain is just like the chain to the rear sprocket, if its too tight youll lose power and the bike will rev down to quick and accelerate slower than at optimal slack ( or just back off the wormgear a bit). The reason for doing this is – the CCT is a spring and if its old it will turn the wormgear backwards . New CCT ‘s may not have this problem, but if you are experiencing inconsistent performance eg; shaky one day with absurd vibration and smooth the next, chances are it’s the CCT, it literally has a mind of its own…it’s a stupid fuc_king design. Some days the timing chain will be tight and some days it will be loose causing harmonic vibrations.***
Once you feel the bike is performing the best, insert the 10mm x 20mm bolt into the hole and finger tighten it until it wont turn anymore, then give it a little wack with a 10mm wrench just to set it in place. The nut should be on the bolt when you screw in the bolt, the washer should be between the nut and surface of the CCT. If you turn the bolt too much with the wrench its possible that you may end up loosening the CCT against the timing chain, resulting in more slack. Once the bolt is in place tighten the nut to lock the bolt in place.
The bolt you just put in will prevent the wormgear from turning or atleast slow it wayyyy down by putting pressure on it. Its been a week since I did this and its holding and running very consistently everyday so far. The famous engine vibration seems to have vanished.
Thats it, your done and you just saved 600 baht. Cost of bolt, nut and washer : 7 baht.
Allen head on CCT – allen #5
10mm x 20mm stainless bolt, nut and washer – the bolt on the bottom is only 10mm long i bought both because i wasnt sure how long i needed. You need 20mm length.
Bolt, nut and washer in place on CCT
Source : http://www.thaivisa.com/forum/topic/663312-cbr-250-cct-cam-chain-tensioner-repair-part-2/
Ide-nya unik dan murah. Intinya, agar CCT gak mengendur, dipasanglah baut penahan.