Engine build prep (2014)

Lovely bike, the blue is my favourite, even though I am stuck with a Black and Gold one.
The front brake is interesting. I thought Madass had the only modern caliper setup not requiring a bracket.
Did the disc and caliper come as a kit?
Also, is the disc a full floating type?

Glen

worntorn said:

Lovely bike, the blue is my favourite, even though I am stuck with a Black and Gold one.
The front brake is interesting. I thought Madass had the only modern caliper setup not requiring a bracket.
Did the disc and caliper come as a kit?
Also, is the disc a full floating type?

Glen

Click to expand...

The blue is growing on me too Glen, I very nearly stripped it for a JPN red-white-blue job, but the simplicity of the single colour, sans pinstripes even, is growing on me now.

The front brake is all UK made! Disc is RGM, its a full floater although the pins are tight, I was going to relieve them, but will see if the 'bed in' first as I'm assured they do.

The caliper is from a firm called Pretech in Reading, England. It's very nicely made. They get fitted a lot to modern specials. Late Heskeths had them as standard fitment too! I do think that 6 pots is a tad unnecessary on a Commando in terms of outright braking power, but I wanted modern day feel and good braking without massive lever pressure.

I've not ridden it yet, so can't say what it's like. I can tell you it's a bastard to bleed though!!

Looks awesome, beautiful job! Nice build.

Nige,
Thats a real scrumpish bit of kit, been out yet?

john robert bould said:

Nige,
Thats a real scrumpish bit of kit, been out yet?

Click to expand...

Not yet John, have only run it.

Gotta torque down the head next, but my current challenge is bleeding that fancy front caliper !!

Try sucking on the nipple. NO, NO the bleed nipple! really i heard some where that a sucks better than a squeese...your mind here isnt helping
Get a grip! try a pump and suck the fluid out..its supposed to dislodge trapped air. suck it and see...sorry could'nt ressist.

john robert bould said:

Try sucking on the nipple. NO, NO the bleed nipple! really i heard some where that a sucks better than a squeese...your mind here isnt helping
Get a grip! try a pump and suck the fluid out..its supposed to dislodge trapped air. suck it and see...sorry could'nt ressist.

Click to expand...

I've got a large syringe, I was gonna try pushing fluid backwards though the nipple. But I could also use it to try and suck fluid out.
Will have another go on the morrow.

Congratulations on a great bike!!
Hope it goes as well as it looks! Looking forward to the description of how the engine works. Will you test it on dyno?

Eddie , have you tried disconnecting the calipier from the leg and turning it upside down whilish beeding it? this moves the air pocket about.

Fast Eddie said:

john robert bould said:

Try sucking on the nipple. NO, NO the bleed nipple! really i heard some where that a sucks better than a squeese...your mind here isnt helping
Get a grip! try a pump and suck the fluid out..its supposed to dislodge trapped air. suck it and see...sorry could'nt ressist.

Click to expand...

I've got a large syringe, I was gonna try pushing fluid backwards though the nipple. But I could also use it to try and suck fluid out.
Will have another go on the morrow.

Click to expand...

The usual method for bleeding 'difficult' systems is to back bleed the fluid line from caliper to master cylinder. A small plastic bottle containing fluid is connected by a tube to the caliper bleed nipple, and the nipple is carefully released as gentle pressure is applied to the bottle. Care has to be taken to avoid the master cylinder over flowing. I used to have such a bottle, but it got lost years ago. Most advertised are intended for pressurizing from the master cylinder to the caliper. For some reason I never bothered to investigate, most difficult to bleed systems were those on motor cycles, and the real problem ones often had to be removed from the motor cycle and laid out on a bench so that the flow lines were rising from caliper to master cylinder. At least doing it this way avoids accidental fluid spillage over paint work.

Nothing at all to do with engine prep, but as the problem was mentioned ......

Kvinnhering said:

Congratulations on a great bike!!
Hope it goes as well as it looks! Looking forward to the description of how the engine works. Will you test it on dyno?

Click to expand...

Yes, I'll Dyno it, but only after its had a proper 'shake down' and a good fettling.

john robert bould said:

Try sucking on the nipple. NO, NO the bleed nipple! really i heard some where that a sucks better than a squeese...your mind here isnt helping
Get a grip! try a pump and suck the fluid out..its supposed to dislodge trapped air. suck it and see...sorry could'nt ressist.

Click to expand...

Looks like I've cracked it. I had to do all the usual tricks, ended up spending hours on bleeding just the one caliper!
Once air had been dislodged and reduced, a good suck really did the final trick.
Then I had to sort out the fact that the floating disc wasn't actually floating, or running true, and pushed the brake pads back into the caliper as the wheel turned (resulting on no brake)!!

Fast Eddie wrote;

I had to do all the usual tricks, ended up spending hours on bleeding just the one caliper!
Once air had been dislodged and reduced, a good suck really did the final trick.
Then I had to sort out the fact that the floating disc wasn't actually floating, or running true, and pushed the brake pads back into the caliper as the wheel turned (resulting on no brake)!!

Click to expand...

AAhhh the joys of a newly rebuilt m/cycle. It usually takes me about a year to iron out all of the faults. Maybe I'm just slow.
Looks great. I'm sure you'll let us know how it goes?

Just read the whole thread. a credit to you sir.

i need a trip up to see this and talk turkey over cc's cylinder heads etc.

Well that is looking nice. Guessed it was going to turn out something like that. Look forward to seeing it on the road.

Re: Engine build prep second round!

Right then girls...

I got this back on the road in summer 2014. Since then I've done a few track days and probably around 2,000 miles, which is not a lot, but they have been quite hard miles.

The engine dyno'd at 56rwhp with 50ftlbs torque, so hardly an R1 beater, but a very healthy increase on prior. It revs to 6,000+ so quickly, this is almost its 'normal' riding! When being 'spirited' it is sweet to 7,000 but there is no benefit in trying to go beyond this (which I have).

I rebuilt it with the RH10 head in box stock spec last time and eventually got around to pulling the head this winter. It will be going to Sir Comnoz for his full attention and treatment, I'll then re-dyno it and road test it for an effective 'back to back' comparison.

So, some update on the motor's conditions:

The bottom end looks and feels perfect. The JS1 cam looks like new:



The barrel doesn't have any perceptible wear, but it does have some scores. These could be because 1) I have been running on unfiltered velocity stacks 2) some of the ceramic coating applied to the combustion chambers came away, this stuff must be very abrasive and could be the guilty culprit:



Jim Comstock did forewarn that he has seen ceramic coating flake off and cause problems. And this would seem to support that. The thickness is uneven and is particularly thick around the valve seat area. Maybe this caused a difference in expansion rates? Whatever the reason, you can see that large parts have flaked away, this has happened on both pots, but much worse on the drive side for some reason. Jim will be removing this coating for me and I do not intend to re-coat:



This ceramic coating failing in the drive side combustion may have been partly the cause of this rather poorly looking piston. Also, when first built, the carbs were very weak on the needle. Having accelerator pumps really hides this (making it difficult to detect) and it will only be apparent on a steady mid throttle cruise. I believe it mildly 'nipped up' on me at one stage and this would appear to support that. Interestingly, the compression, oil consumption and general performance of the engine was all fine. I only saw this because I removed the top end for the head work and 'had a look':



It is only fair to point out again that I have ridden this bike quite hard and its done several track days. I also ran it weak on the needle for a while, the ceramic coating flaked into the bore and I ran it on an entire track day and dyno session with the ign timing accidentally very retarded. That's abuse by anyone's standards I think! Nevertheless, the general wear of the undamaged piston looks very good IMHO:



For those interested in such things (nerds!) here is a pic of a sectioned JS piston, I cut through the centre of the valve cut outs to see what the metal thickness etc looked like:



So there we are. I thought long and hard about taking the motor right down and going the Maney 920 route. But the motor is SO sweet as is, the time, effort and cost involved in such are things I can't really afford right now, plus I really want to see what difference a good head job makes. Therefore, dissuaded, the only other difference will be going from +0.020" to +0.040" oversize pistons, which I doubt would show as a meaningful increase on the dyno.

Although I will definitely not be ceramic coating the combustion chambers again, I am still deciding what to do with the pistons and am currently thinking hard anodised 'DiamonDyze' treatment. I may also get Laystall to apply their Silicone Carbide Impregnation to the bores.

I'll keep ya'll updated.

Now, back t' shed ...

Laystall charged me a very reasonable £70 for carbide coating on my 850 bores about two years ago. They completed the job in less than a week and were very pleasant to deal with for what after all is only a small odd job for them. Not enough miles on the motor yet (unfortunately life gets in yhe way) but no problems with their service or workmanship.

Thanks for the update - I hope it all goes together nicely - in the meantime, please keep the pics coming!

Re: Engine build prep second round!

Fast Eddie said:

2) some of the ceramic coating applied to the combustion chambers came away, this stuff must be very abrasive and could be the guilty culprit:

Click to expand...

Care to expound on this a bit? In th epicture it looks like most of the ceramic coating came away. There was no mention of any treatent on the piston crowns; were the piston crowns bare medal?

What product did you use for the ceramic coating. I have seen here on the forum a semi metalllic matt gray type coating. I have also seen (elsewhere) a light blue to off white ceramic coating that I used in one instance.

In concept, the barrier that a ceramic coating should provide is great but in practice, I am not sure how well it performs due to durrability. Your case is an example. I am speculating here but the flaking off can be due to a variety of things including: substrate compatibility, substrate cleanliness, substrate preparation, different thermal coefficients of expansion, mis application (air cooled versus water cooled).

Thanks for sharing.

Re: Engine build prep second round!

Dances with Shrapnel said:

Fast Eddie said:

2) some of the ceramic coating applied to the combustion chambers came away, this stuff must be very abrasive and could be the guilty culprit:

Click to expand...

Care to expound on this a bit? In th epicture it looks like most of the ceramic coating came away. There was no mention of any treatent on the piston crowns; were the piston crowns bare medal?

What product did you use for the ceramic coating. I have seen here on the forum a semi metalllic matt gray type coating. I have also seen (elsewhere) a light blue to off white ceramic coating that I used in one instance.

In concept, the barrier that a ceramic coating should provide is great but in practice, I am not sure how well it performs due to durrability. Your case is an example. I am speculating here but the flaking off can be due to a variety of things including: substrate compatibility, substrate cleanliness, substrate preparation, different thermal coefficients of expansion, mis application (air cooled versus water cooled).

Thanks for sharing.

Click to expand...

Hi Dances,

If you refer back to page 3 of this thread you'll see the pics I posted after having the coating done.

I had the piston crowns, combustion chambers and valve faces coated in a ceramic thermal barrier coating that is a light grey colour, you are supposed to polish it with fine steel wool and when this is done, it looks like polished alloy. The finish on the valve faces and piston crowns still looks good, its only the combustion chambers that have suffered flaking.

You are kinda looking at the picture in reverse Dances! The smaller / darker areas are where it has flaked, the bigger shinier areas is the coating.

I also had the exhaust ports coated in a different type of ceramic, this stuff was thick and black. Haven't had a good look at that yet.

And finally, I had the piston skirts and valve stems coated with a very thin Teflon based anti friticion coating. Most of this seems to wear off very quickly, but the idea is that it soaks into the poors of the material and thus does its job.

I've done dozens of pistons like this, I used to do it DIY, but lately get it done professionally. I've only had maybe 4 or 5 heads done though and this is the first failure I've seen.

I therefore think it is basically due to poor application of the nature you have described.

And that's why I'm thinking of having the pistons anodised this time instead, I think there is less chance of operator error / shoddy workmanship this way. Well, I hope so at least!