CBR 250 CCT (cam chain tensioner ) Repair Part 2

[KRS1]

Continued from this thread http://www.thaivisa.com/forum/topic/657561-cbr-250-cct-cam-chain-tensioner-repair-step-by-step/

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

Edited August 25, 2013 by KRS1

[ib1b4]

KRS ; Iam starting to think you have been here too long! It is very Thai approach to fixing a problem but with a farang improvement via the stainless bolt, Please dont take offence it will probabally the method I will use on my CRF when the time comes. ps........ Great update.

Edited August 25, 2013 by ib1b4

[KRS1]

KRS ; Iam starting to think you have been here too long! It is very Thai approach to fixing a problem but with a farang improvement via the stainless bolt, Please dont take offence it will probabally the method I will use on my CRF when the time comes. ps........ Great update.

lol..no offense taken...riding it a few days until it's in the sweet spot is also farangish, to get it just right.

To do it right though , id remove the spring, back the worm gear all the way up into the plunger ( or remove the wormgear), and go the full length with a longer bolt.

If it loosens up, thats what im going to do next. But doing it the way i posted only takes 10 minutes. Will update in another week if it is holding.

[schondie]

Thanks for these insights into CBR related matters, better than any garage or Honda dealer.

KRS1, you are a fount of all of knowledge.

[KRS1]

Im just cheap

[KRS1]

Did a top speed run today, just past Promenade (CNX) outbound, full crouch looking through windshield.

170 kph

[mania]

Did a top speed run today, just past Promenade (CNX) outbound, full crouch looking through windshield.

170 kph

When you say 170 kph

Can you describe approaching it?

Meaning, I am pretty sure you rev each gear to RL or near it

So when you click into 6th from 5th what speed were you at

when 5th was maxed out.?

Then,

After clicking 6th how long till you hit 170?

Just curious

Edited August 26, 2013 by mania

[KRS1]

Did a top speed run today, just past Promenade (CNX) outbound, full crouch looking through windshield.

170 kph

When you say 170 kph

Can you describe approaching it?

Meaning, I am pretty sure you rev each gear to RL or near it

So when you click into 6th from 5th what speed were you at

when 5th was maxed out.?

Then,

After clicking 6th how long till you hit 170?

Just curious

I'll try and remember, but i was concentrating more on staying alive.

I think 5th hit the rev limiter around 156-158 kph'ish...gets there respectably, not too slow. Then shift into 6th.

162 kph comes on about 10 seconds later

165 kph about another 10 seconds later

168 kph about another 15 seconds later

170 kph about 15 seconds later

I forgot to look at the rpms at 170 kph again, but i think i had around 700rpm left before cut out... This was as far as i went, the rev limiter didnt hit and could 'maybe' still climb...but traffic was coming up and i ran out of road, maybe another 30 seconds could have reached 172kph.

edit : I weigh 75.4 kilos

Edited August 26, 2013 by KRS1

[mania]

I'll try and remember, but i was concentrating more on staying alive.

I think 5th hit the rev limiter around 156-158 kph'ish...gets there respectably, not too slow. Then shift into 6th.

162 kph comes on about 10 seconds later

165 kph about another 10 seconds later

168 kph about another 15 seconds later

170 kph about 15 seconds later

I forgot to look at the rpms at 170 kph again, but i think i had around 700rpm left before cut out... This was as far as i went, the rev limiter didnt hit and could 'maybe' still climb...but traffic was coming up and i ran out of road, maybe another 30 seconds could have reached 172kph.

edit : I weigh 75.4 kilos

That is the thing with smaller bikes.

They are never going to be top end monsters

Yet Moto3 250's do 240+kph in a short time which is quite impressive

for a 250 single cylinder

With the N250 I have I like to note the quickness.

I have no situation for traveling 3 km or more pinning the throttle for

a minute trying to see absolute attainable type top speed. As there are no places I ride

that really have such long straights. But it is interesting to hear what your Honda

could reach over x distance (which I think was about 2.3-2.6 km while in 6th gear).

I am always most interested in how fast the bike will rev to RL in each gear & what

speeds are at each shift.

Once I shift into 6th which truthfully I actually rarely do on the N250

I am only interested in what speed it sweeps to in probably the next 10 seconds or less.

The best I saw on my N250 in that type of situation was 168kph

But I saw it as soon as I shifted into 6th but I had the Devil full exhaust on it then.

Now back with the stock pipe 5th goes to somewhere around 156-158

After that the climb in 6th is too slow to be of interest.

Also climbs to RL in all gears are slower time wise than with the devil exhaust.

It obviously wants a free flowing pipe back on

Thanks for your feedback always interesting to read

Edited August 26, 2013 by mania

[ll2]

cbr 250 is theoretically capable of doing 169,6 kph max at 10500 rpm with stock gearing and sprockets according to gearing commander.com. do you have aftermarket sprockets?

but i just have seen 162 kph once on it with it and never reached it again - maybe there were wind behind me, i am not sure.

good solution for CCT, congrats.

[KRS1]

cbr 250 is theoretically capable of doing 169,6 kph max at 10500 rpm with stock gearing and sprockets according to gearing commander.com. do you have aftermarket sprockets?

but i just have seen 162 kph once on it with it and never reached it again - maybe there were wind behind me, i am not sure.

good solution for CCT, congrats.

I promise you i hit 170 kph on the speedo today. Sprockets are stock, paper element cut out of air filter, fuel gauge about to blink.

You have to be fully crouched, chin of helmet HAS to be touching the gas tank. If i peek over the windshield only 165 kph.

Bike has 31k kilometers.

edit: fuel was PURE gasohol 91

Edited August 26, 2013 by KRS1

[KRS1]

I'll try and remember, but i was concentrating more on staying alive.

I think 5th hit the rev limiter around 156-158 kph'ish...gets there respectably, not too slow. Then shift into 6th.

162 kph comes on about 10 seconds later

165 kph about another 10 seconds later

168 kph about another 15 seconds later

170 kph about 15 seconds later

I forgot to look at the rpms at 170 kph again, but i think i had around 700rpm left before cut out... This was as far as i went, the rev limiter didnt hit and could 'maybe' still climb...but traffic was coming up and i ran out of road, maybe another 30 seconds could have reached 172kph.

edit : I weigh 75.4 kilos

That is the thing with smaller bikes.

They are never going to be top end monsters

Yet Moto3 250's do 240+kph in a short time which is quite impressive

for a 250 single cylinder

With the N250 I have I like to note the quickness.

I have no situation for traveling 3 km or more pinning the throttle for

a minute trying to see absolute attainable type top speed. As there are no places I ride

that really have such long straights. But it is interesting to hear what your Honda

could reach over x distance (which I think was about 2.3-2.6 km while in 6th gear).

I am always most interested in how fast the bike will rev to RL in each gear & what

speeds are at each shift.

Once I shift into 6th which truthfully I actually rarely do on the N250

I am only interested in what speed it sweeps to in probably the next 10 seconds or less.

The best I saw on my N250 in that type of situation was 168kph

But I saw it as soon as I shifted into 6th but I had the Devil full exhaust on it then.

Now back with the stock pipe 5th goes to somewhere around 156-158

After that the climb in 6th is too slow to be of interest.

Also climbs to RL in all gears are slower time wise than with the devil exhaust.

It obviously wants a free flowing pipe back on

Thanks for your feedback always interesting to read

Just wanted to mention that i didnt crouch until i was in 6th.

[ib1b4]

That is very quick for a basically stock single cyl 250 engine, certainally no drag created at the cam chain.

[KRS1]

if you look on youtube there are people hitting the same speeds with all stock bikes.,

[yankee99]

when i had my dtracker is was going to order one from here. http://www.kriegercamchaintensioners.com/

Looks ok but if something fails well you know already..

[KRS1]

This is the 10 day update i promised.

Bike is still running the same as the day i put the bolt in and has not loosened, and there are no mishaps so far....

will update in another 2 weeks.

[Garry]

KRS ; Iam starting to think you have been here too long! It is very Thai approach to fixing a problem but with a farang improvement via the stainless bolt, Please dont take offence it will probabally the method I will use on my CRF when the time comes. ps........ Great update.

My dragbike engine (GSX1166 (Katana 1100) had a pure mechanical tensioner, in the same principal as what the OP made. They are a valid idea, but they just require more regular adjustment checks.

I based my intervals on 'lube the drive chain, check the camchain tensioner at the same time'. I was also going to bring up how to rebuild an OEM camchain tensioner and also how to reload OEM ones (reset the spring), but thought better of it if someone were to blame me for something going wrong.

and there any many styles out there. Below is just a couple of different variants:

Edited September 3, 2013 by Garry

[Sung Ham]

Of course that's barely over 150kph in actual speed.

Which is fine. Nothing wrong with that.

Edited September 3, 2013 by Sung Ham

[KRS1]

Tightened up the bolt on the cct yesterday on a hunch and extra vibration that the wormgear had turned itself clockwise (retracted).

All good now. Im going to pull the spring out and turn the wormgear all the way into the plunger and use a longer bolt on next tuneup, and should solve the problem of the wormgear retracting the plunger.

On another note, i also checked the acid level in the 'sealed' battery and acid level was below half on a 3 month old Yuasa battery, refilled it with battery acid and the starter motor spins up faster now. If anyone wants to check the battery ( you have to ride a bit to get the charge up), the best way is to pull up one end of the cell caps and the rest will follow, you'll need something like a thin pocket knife to lift the cell cap, dont start in the middle.

The cell caps say " Do not open, never fill with water" - dont pay it any attention, theyre just trying to scare you so you have to buy a new battery, dealers love it. The battery should be removed when doing this, it requires an 8mm or a philips to remove the terminals, they are in the tool kit. The battery should also be wiped clean before opening it, especially in the crevices, there will be dirt close to the holes. Go to an autoparts store and ask for : nahm grun, that means battery acid, say 'bat' for battery.

To reset the clock hold both buttons down at the same time.

[KRS1]

hit 174kph today with about 400-600 rpm left...

180kph in my sites ! Going to try to eliminate one of the chambers (middle one) in the muffler, theres 3....and i think its slowing the exhaust velocity down.

Edited September 14, 2013 by KRS1

[ll2]

Go on krs.

Interesting progress.

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