[ebonho]

Originally Posted by b16h22

The assumption by the intl 390 forum members is that the number denotes the MC piston size. I guess it makes a lot of sense. The number on my Gixxer 250 Bybre MC is 12. It certainly can't be 2012 batch of manufacturing The bike is a 2021

Thats what my mech believes too.

Anyways, now thankfully I have the exact part number.

Cheers, Doc

[VijayAnand1]

Originally Posted by b16h22

The assumption by the intl 390 forum members is that the number denotes the MC piston size. I guess it makes a lot of sense. The number on my Gixxer 250 Bybre MC is 12. It certainly can't be 2012 batch of manufacturing The bike is a 2021

My V-Strom's master cylinder reads 12 and so does my 390's master cylinder and not 13. As far as I know of, most 2014 to 2015 Duke 390's came with the reading 12 on the master cylinder. Interestingly enough, the ADV 390s (current 2020 -2023) front master cylinder does read 13 and the marking underneath "B" "12" or "B" "13" denotes which I guess is for "Bore" that of piston/plunger diameter.

Came across this wonderful chart, which denotes the interesting topic of Front Master Cylinder ratio chart.

https://www.vintagebrake.com/mastercylinder.htm




Cheers!
VJ

[b16h22]

Originally Posted by VijayAnand1

My V-Strom's master cylinder reads 12 and so does my 390's master cylinder and not 13. As far as I know of, most 2014 to 2015 Duke 390's came with the reading 12 on the master cylinder. Interestingly enough, the ADV 390s (current 2020 -2023) front master cylinder does read 13 and the marking underneath "B" "12" or "B" "13" denotes which I guess is for "Bore" that of piston/plunger diameter.
Cheers!
VJ

I don't remember the number on my old 390 but I enquired a mechanic friend of mine and he said the number on his first gen RC390 is 13, weirdly. I got a first gen Dominar MC rebuild kit back in 2022 to rebuild the 390 MC but the piston didn't fit. Domi piston measured 13mm.

Out of curiosity, I asked him the MC number on the new shape Gixxer 150 SF in his garage and he said it was 13. Weird from Suzuki considering the Calipers are similar for both 250 and 150. I was doing a bit of research on the MC Piston and caliper piston size relation.

[VijayAnand1]

Originally Posted by b16h22

I don't remember the number on my old 390 but I enquired a mechanic friend of mine and he said the number on his first gen RC390 is 13, weirdly. I got a first gen Dominar MC rebuild kit back in 2022 to rebuild the 390 MC but the piston didn't fit. Domi piston measured 13mm.

Out of curiosity, I asked him the MC number on the new shape Gixxer 150 SF in his garage and he said it was 13. Weird from Suzuki considering the Calipers are similar for both 250 and 150. I was doing a bit of research on the MC Piston and caliper piston size relation.

Right. The variables are aplenty. Considering the pad and caliper is the same for the Strom, 250 and 155 as I've detailedly elaborated on my Strom thread.

Secondly, this is precisely why one needs to mention the MY or cross check with parts catalogue (if handy) for the right part compatibility. Though, most master cylinder parts of the gamut of bikes here in India F&R are backwards/forward compatible considering one gathers which bike has which matching part -- and that's where the devil is -- in the details..

I'll try to post a detailed photo excavation of the front and rear cylinder kit replacement I did a long while ago measuring things as they came apart, I'll try to fetch the pictures if I can.

Cheers!
VJ

[shadowrider]

Last week I replaced the airfilter box for my Gen 1 390 2013 and it seems the part number has changed. The new part number is JY581079 and the price was around 1569 rs. The only difference I can spot compared to the old af box is that this one doesn't have that long drain tube with the white rubber cap, but just a black cap similar to the 2017 D390s.

[ebonho]

Got hold of the rebuild kit.





Saturday will be a busy day.

Cheers, Doc

[ebonho]

P.S. Just spoke to Sachin at Wagholi. I currently have a perfectly working front brake with no fade, no leaks, no bubbles. Yes it does not have the kadak feel I like, and it comes a bit too close to my fingers on hard braking. Numerous posts on the international Duke 390 forums and elsewhere (not Duke specific) talk about botched up rebuild jobs, where the bore gets scratched, wrong/incorrect tools, new seals harder and leaky compared to well set old one, etc. So for now the decision is to bleed the current MC "as is" properly, and replace the brake fluid with a fresh lot only. No kit rebuild. Don't fix what aint broken paradigm. If not happy, later on I will go in for the latest non adjustable lever MC directly instead of trying to rebuild an old tech design from 11 years ago. Hope that is the right call. For now.

Cheers, Doc

[shadowrider]

Hey Doc, any update on your erratic idle? Is it the fuel pump, spark plug, or anything else?

[SunnyBoi]

Originally Posted by ebonho

botched up rebuild jobs, where the bore gets scratched, wrong/incorrect tools, new seals harder and leaky compared to well set old one, etc.

These concerns are not valid. All you need to do is remove the brake lever, take off the black boot, remove one circlip, pull out the old plunger, replace with new and other steps in reverse. There is no risk of scratching the bore anywhere. Your kit is manufactured 3 months ago so the seals will be as fresh as they can be.

Originally Posted by ebonho

If not happy, later on I will go in for the latest non adjustable lever MC directly instead of trying to rebuild an old tech design from 11 years ago. Hope that is the right call. For now.

This is something i realised early in my Duke journey. Try to save pennies on the dollar and end up spending more that what it would have if done right the first time. This is why I was suggesting you straight away get a new MC.

[ebonho]

Originally Posted by SunnyBoi

This is something i realised early in my Duke journey. Try to save pennies on the dollar and end up spending more that what it would have if done right the first time. This is why I was suggesting you straight away get a new MC.

I too realised rhis as a occupational hazard of my approach to bike maintenance a long time ago. Not just with my KTM but my Bullets as well. My first instinct is to salvage a part, and get the full use/life out of it that I paid for. So repair or refurbish first. If that does not work, yes tou need to replace/upgrade anyway. And the money you spent on the repair then becomes a wasted sunk cost. As in the case recently with my fuel pump. So sometimes this risk is there. Other times your salvage is successful, and tou often get more than 10,000 additional kilometres or two riding years of life out of it. Whereas otherwise you would have simply chucked it away. Wastefully. So these are the peos and cons of this approach, and my frugal biker nature gels with it best. Till now. And will likely not change in the future either.

Cheers, Doc

[b16h22]

Originally Posted by ebonho

P.S. Just spoke to Sachin at Wagholi. I currently have a perfectly working front brake with no fade, no leaks, no bubbles. Yes it does not have the kadak feel I like, and it comes a bit too close to my fingers on hard braking. Numerous posts on the international Duke 390 forums and elsewhere (not Duke specific) talk about botched up rebuild jobs, where the bore gets scratched, wrong/incorrect tools, new seals harder and leaky compared to well set old one, etc. So for now the decision is to bleed the current MC "as is" properly, and replace the brake fluid with a fresh lot only. No kit rebuild. Don't fix what aint broken paradigm. If not happy, later on I will go in for the latest non adjustable lever MC directly instead of trying to rebuild an old tech design from 11 years ago. Hope that is the right call. For now.

Cheers, Doc

Just make sure they use the right circlip pliers to remove the circlip and there is not much to go wrong here imo. I have done it myself. Since you got the kit, it is wiser to rebuild it.

[ebonho]

Originally Posted by b16h22

Just make sure they use the right circlip pliers to remove the circlip and there is not much to go wrong here imo. I have done it myself. Since you got the kit, it is wiser to rebuild it.

I located the kit. I did not get it yet. Its in Kothrud Sai Service. About 10 km away.

Cheers, Doc

[SunnyBoi]

Originally Posted by ebonho

I too realised rhis as a occupational hazard of my approach to bike maintenance a long time ago. Not just with my KTM but my Bullets as well. My first instinct is to salvage a part, and get the full use/life out of it that I paid for. So repair or refurbish first. If that does not work, yes tou need to replace/upgrade anyway. And the money you spent on the repair then becomes a wasted sunk cost.

I was of the same opinion as you, why replace a part when I can rebuild it cheaper? A good friend with a 2013 Duke gave me his freshly rebuilt MC, told me he got it rebuilt but still didnt feel right so ended up buying the latest MC. I plonked the rebuilt one on my Apache - got a stiff lever as expected and let him ride my bike, showed him, see it wasnt the MC fault but it was the incompetent mechanic. He wasnt convinced but I stuck to my guns.

Later on when I got my Duke, I realised what he was on about. So this time I did not waste time or money, straight away bought the latest MC.

Sunk cost is a very real fallacy in our line. One has to learn when to draw the line and replace a part instead of trying to repair and hope for the best.

Originally Posted by ebonho

I located the kit. I did not get it yet. Its in Kothrud Sai Service. About 10 km away.

Good that you did not buy it. Get the brakes bled and see if it improves the situation, if not, get a new MC.

[ebonho]

Originally Posted by SunnyBoi

Good that you did not buy it. Get the brakes bled and see if it improves the situation, if not, get a new MC.

Yeah, that's actually the bottom line. I'm convinced about the superiority of braking for the 1051 spend compared to the 400 spend (kit + petrol). And more importantly, I eventually "want" the superior MC. Plus I have a lot of other more critical jobs lined up for this visit, so this can wait out a trial of a simple bleed + new brake fluid this time around.

1) New cone set
2) New chain sprocket kit
3) New hub cush rubbers set
4) New rear sprocket bearing ?
5) New rear wheel bearings ?
6) New chain slider ?
7) New swingarm rubber(?) bushes ?
8) Front brake MC bleed + new brake fluid
9) New brake pads - Front ? Rear ?
10) Check sensors for hesitant/long cold start cranking (Re: shadowrider - the idling searching is much better now, if I wait a bit, and press in the clutch a few times)
11) New engine oil
12) New oil filter + O ring
13) Clean air filter

Cheers, Doc

[shadowrider]

Originally Posted by ebonho

1) New cone set
2) New chain sprocket kit
3) New hub cush rubbers set
4) New rear sprocket bearing ?
5) New rear wheel bearings ?
6) New chain slider ?
7) New swingarm rubber(?) bushes ?
8) Front brake MC bleed + new brake fluid
9) New brake pads - Front ? Rear ?
10) Check sensors for hesitant/long cold start cranking (Re: shadowrider - the idling searching is much better now, if I wait a bit, and press in the clutch a few times)
11) New engine oil
12) New oil filter + O ring
13) Clean air filter

Cheers, Doc

Do you remember when was the last time you changed the water pump seal? I'd add that to this list too for keeping my overthinking mind at bay.