Thanks for the detailed response.
As per both mechanics, the compression readings for my bike and my friend's bike are similar so they didn't go beyond that (i'm not sure about this one as I did not see the readings myself).
Plug has a light-ish brown colour. No sign of excessive carbon or soot.
The spark plug was fine when it was tested. Getting FE of 32-34 in city and 38-44 on the highway (at 90-100kmph and depending on the wind).
For comparison, my friend's FZ25 (the first black one in Bengaluru) gives ~34 in city and 36-40 on the highway with the same riding style.

But the main issue is that valve clearances keep changing (tighter) every 500-1000kms. For eg. 0.07/0.10 changed to 0.04/0.09 after 1500kms with a big loss in performance.
If I left it as is, then the loss in performance would make it perform somewhat like a 125-150cc 2 valve bike.
I still remember the moment when a Gixxer 150 was able to out-accelerate my FZ25 with ease when it was at its worst.

Shshank, when you adjust the clearance, is it performs like a beast it should be?

Asking this question, because, if the reduction of clearence is the only parameter, then we can overlook the other parameters.

Please confirm. If it's only that problem, we can discuss about probbale solutions. May be tighter locknuts, rocker arm, and a tighter torque spec.

Regards
SomrajSG

Performance is close, not the same. It felt best for around 300kms when I set it to 0.06/0.08, but even then it did not match the performance on my friend's bike. I actually didn't mind as the performance was close enough for me.

My bike was excellent till some 7500kms or so when I gave it to the service centre. They claimed that the clearances were loose, so they adjusted it. Probably they made some mistake while doing it.

The tightening of clearances happened even when my friend tightened the lock nut with the torque specified unfortunately.

Shashank, it is possible that the compression of the engine can go down slightly over time. That's normal, till there is no significant loss of power. However as you said, once the clearances adjusted properly the bike behave almost normally, my suspect is the rocker arms got damaged while doing the clearance adjustment for the first time. They may have over-tighten the bolt and the locknut with the more than specified torque and have damaged the thread. Hence repetitive issues are occurring.

I want to suggest you to replace the rocker am for the both valves along with the adjuster and the lock nut. You already have done many things, why not try this too. It will not cost much I guess. Plus, use a torque wrench. It's must.

I have some little understanding of IC engine, and believe me, there is nothing that we cant solve. All we need, is patience, knowledge and competency. I have build some worst damaged engine(cars), and have fair amount of experience.

Come to my issue, I yesterday I removed the throttle body and cleaned it thoroughly. Adjuated the AFR and increased the idle rpm a little (Around 1500). I am yet to adjust the valve clearance. The bike is now feeling much better. With crisp throttle response and the brutality is almost back! Hope it will improve more after the valve adjustment.

Regards
SomrajSG

Probably that or they didn't set it correctly at TDC.

I have already replaced the lock nut and adjusters (believe it or not, this was actually suggested by Ari Henning to JyotishmanS). I may get the rocker arms replaced after a month or so.

Also the mechanic used a torque wrench with the torque specified in the manual which they had.

Also how did you adjust AFR? As far as I know, the ECU adjusts AFR dynamically and we can't do anything to that.

This is partially true. The O2 sensor feedback control is inactive at idle condition in this bike. So, when we adjust the idle by adjusting the screw on the throttle body it actually fiddles with the AFR ratio, and make that value as a base.

A reference from the service manual, Page no 2-5


​​​​
The ECU controlled mapping comes fully into action when the value from TPS increase (there are other parameters too), and the ECU takes the control of injector pulses.

So yes, we can fiddle with the AFR to an extent, but NOT completely.

Hope this helps

Regards
SomrajSG

I have come across many posts, youtube videos, where its showing a top speed of 140+kmph.
Many members also have claimed to touch 142 145. But what's the fact? What is the top speed of this bike? Let's calculate...

Here are some numbers.

Primary reduction ratio = 3.083 (74/24)
Transmission ratio of 5th gear = 0.852(23/27)
Secondary reduction ratio = 3.067 (46/15)
Max engine RPM = 9250
Number of Min = 60
Circumference of tyre 140/70 17 = 1971mm

So the top speed will be

(9250×60×1971)÷(3.083×0.852×3.067) mm/h
=135785286.18 mm/h
=135.79 km/h

So, whoever is getting a top speed reading of more than 135, consider it as speedo error!

Attacing a screenshot from the service manual.

Cheers
SomrajSG

Yes, the FZ25 has speedo error like most other bikes.
I've noted the below error (note that it is using a phone, so it will never be 100% accurate)-
60-80kmph - 7kmph
80-90kmph - ~8kmph
90-100kmph - ~9kmph
100-120kmph - ~10kmph
120kmph+ - 12kmph

This translates to approximately ~8.5-9% speedo error. I've noticed that Honda/Hero Honda/KTM speedos are more accurate than TVS, Yamaha and Suzuki.

The bike can touch 145kmph when all conditions are in its favour, which is approx. 133kmph (powerdrift recorded 134kmph with vbox). The maximum I have seen is 140kmph (true speed 128kmph), although my friend who is just 55kg could touch 145kmph on a downslope. Normally ~125kmph (around 113 true) can be touched any day.

However, there's hardly any point pushing it that much seeing that the top end is mediocre.

Hello,

Anybody is using any seat cover/cushion to soften the seating a bit? If yes, please share details.

Can anybody help me to get a 16T front sproket in Mumbai?

​​​​​is there any improvement in the throw and intensity? i am not satisfied with the headlight of my fz25. looking to get aux lights for my bike.
aux lamps are a must. this set up looks neat.
eagerly waiting for this diy tutorial.

Intensity is increased to 135-144k candela (each projector @20w) from the stock headlight's 55k candela. and width is 3-4x more. also since leds are 5000k color, it gives no visibility issues in rain or fog.

Diy should be up this weekend. been busy alot thus its taking time.

Hello everyone. I discovered by accident that just applying chain spray without cleaning is working better. Even after 6000km of doing it this way, the chain is not showing any wear. Usually every 4-5000km I would need to adjust it. I apply motul chain lube spray every 1000 kilometres.

Before I used to do a fair amount of cleaning with the motul cleaning spray. The whole process used to take 30 mins. Now not even a few minutes to apply. No noticeable decrease in performance or acceleration. My usage is in high dust but not much rains at least for the last few months. And ride from heavy traffic to 75-100kmph open stretches. Only known drawback is chain looks dirty. But that's okay for me.

Edit : After 8-9000km of no cleaning only lubricating, the chain has not changed its length much. Still no need to adjust. However the swingarm rubber chain guard has worn through prematurely. Its less than 200rs. Still easier to carry on with this method for me than clean often.

HOW to fit bi-leds in FZ25's headlight.

* Requirements -
1. bi-led projectors (maximum width 75mm, maximum length should be 12cm). ex- 1 , 2 , 3.
2. 50x150x3mm aluminum sheet. 6000/7000 series preferred because of hardness.
3. 4pcs of m3 or m4 bolts length should be 30-35mm.
4. jb weld. and or araldite (don't use any quick epoxy)
5. 3pcs of 12vmicro relays. and its connectors.
6.18awg silicon copper wires. 4-5mtrs.
7. high quality 4pin socket set. preferably waterproof.
8.1N5408 1W Diode 4pcs.
9. hot air gun.
10. 2 step switch.
11. File tool, or Dremel for grinding out heatsink.
12. soldering iron.
13. heatshrink
14. pvc cable sleeving.
15. moderate diy skills.
And obviously fz25's headlight assembly.


For more reliability -
1. 2x led drivers.
2. 2x cree XHP35 leds.
3. 40x40x15mm 12v dual ball bearing fans.



procedure -

1. use hot air gun and open the front clear lens from headlight assembly. video for reference.
2. once that's done, screw the beam adjusting nut in counter clockwise direction until the reflector units comes out from top, then just pull it out from bottom side. ( sorry for lack of pictures of this part but i forgot to take pictures ). after this, just cut the wires from inside ( green, white/black, yellow ). after this just keep everything aside and move on to the projectors.

when you get the projectors it will look like this -



open all those screws to get to the heatsink part so we can modify it. in below picture we have to cut/grind out the part after that from that yellow line. to get it to the shape like in second image- also make an m3 threaded hole like shown in picture. do this for both projectors.



Now we have to cut the side part of each projector ( for right and another left side so that we can attach both without a gap. like this -


Now make that side hole a little big in any one of the heatsink and then use an m3 bolt to tighten both heatsinks together like this - ( don't forget to beak/grind that part in red circle ) also you can use thread locker or epoxy between both heatsinks if you want so that they never move. also make sure both perfectly level.

Now this step is for those who have got an LHD beam projector, inside you will get a part like this - you have to remove it and make it flat like the second image.( this will produce the completely flat cutout in low beam.



Once that is done, fix back the high beam solenoid and those above parts. and adjust it so that the both are completely in a horizontal line. otherwise you will get non synchronized two low beam cutouts.



after that connect both solenoid in parallel. this is your high beam connection. solder it and use heatshrink tube to isolate it instead of electrical tape.



​
Now take the leds and fan, and solder it like shown below ( do it for both projectors )


After that, use a good quality thermal paste on both heatsinks and fix both leds back -


Make sure those screws don't touch the negative/ positive terminals of mcpcb.

pass the wires from below like this so that fans don't touch them.


Now measure the distance between both m3 holes you have on the back side of heatsinks. and now cut the aluminum sheet like this -



And drill 4 holes- and then fix it on back side of the heatsinks like this-

once that is done. fix both fans in such way that they blow air towards heatsink.


Now pass those wires from top to below like this -



Now fix back both reflector bowls.



now use a pvc cable sleeve or something similar ( but no tape) to shield the wires-



Now fix back both lens+ holders. and don't forget to clean them from inside otherwise it will look bad and also affects the output.



Now come back to the headlight, you see that beam adjustment screw, you can either remove it or break it as we don't need it and it will not let the projectors fit inside.
also cut that red circled part so we can pass the wires from there to outside. in the second image, those big cutouts in red circle are for reflector bowls, since we are moving both projectors up within the housing. this is not necessary if you don't want to move up the projectors. i will explain it detail later.


now take the projector assembly and put it inside the housing.



Now use the leftover aluminum sheet(plate) and put it on the back like the cardboard piece in the picture. also use silicon glue or something like that between aluminum piece and housing to make it water tight.



now, those cutouts in the circled area, we need to seal it properly from water entering inside. so use masking tape as a base layer. and on top of it, use lots of jb weld and layer it, after that use a lot of araldite or something similar to completely seal it.



After layer of jb-weld, araldite. it would look like this - you can even paint it if you want but it's not necessary.


Once everything is dried up, its now time to fix back the clear lens. for that just reheat the outer channel where the glue is by using hot air gun, and then press back the lens into the channel. also make sure that the outer tabs actually secure the lens.



now just fix back all the outer parts and then you are almost done.



Now only the wiring part is left. which I'll explain in the next post along with some explanation for moving the projector up inside. and also the reason why i'm not using the led that comes stock with the projector.

Till thn you can ask any questions you have.

FZ25 bs6 owners kindly help me! What is the Payload (maximum load carrying capacity) of FZ25 bs6? I've taken the test drive with a pillion and our total weight is 160Kgs. What we had encountered is the rear suspension is kinda wallow, bottoms out qickly and rebounds weirdly which causes back pain for the rider very fast. What is the cause? Payload constraints or is it the bike's actual setting?
Also how is the tank fibre quality?
Any other reliability issues like engine noise, exhaust rusting, chain noise in FZ25 BS6?