lukemillar - NC30 Post Classic race bike

[crazyman]

Hows it going luke , finey got the brothers gprnc30 going again , building my self one now .cheers scott

[lukemillar]

Been hibernating!. Work got busy, then Jess got pregnant and so all racing got put on pause for a while. Had to sell some stuff to make a bit of $$ and clear out the garage, so now I am back onto the racebike. Have a list of stuff to get a race ready again and a list of engine dev stuff. Can only work late in the evenings so progress is slow but I'm getting there!

[benny]

Great thread. Shame the first few photos aren't working any or ever a good read. Thankyou!

[lukemillar]

Finally... an update!

It has been a long time since I posted an update. First work got busy and I had to blow off the rest of the season which was a shame. It had ended on a high though with 1x first place and 2x second places in the last round I competed in. Better still was I got into the 19s at Manfeild which is a barrier I have been trying to break! Watching the onboard footage and the data acquisition stuff, I can see where I made up the time as well as other areas for improvement. This was how the season ended up:



However, another life changing thing happened - Jess got pregnant! This threw up so many unknowns that I decided to hang up my leathers for a bit until things settled down. In the meantime, I realised that from the race bike build, I had enough parts left over to build a second bike! After a few dramas with frames and swingarms, finished the 2nd road bike to sell to re-coup some of the costs of racing. It was a pretty satisfying project for sure!:


The twins

Josie was born on 14th September 2013 and after just over a year, I decided it was time to get back in the saddle so I booked a track day at Manfeild with motoTT. The day was looking great and the bike started up without any issues. I went out for the first session but the bike didn't sound right so I came in after about 5 laps and discovered that I had lost both bolts to the front exhaust header! I hadn't overly tightened then as the Tyga exhaust plates kept bending (to be fixed soon) and they had obviously rattled loose. A quick fix later and the bike was running great. Went out for the 2nd session and after 2 laps, one cylinder keeps dropping out. Something is definitely up and after coming out of the hairpin and looking down at my boot, it is covered in oil. Crap. I pull off the track as safely as I can but not before leaving a long oil trail down the middle straight (sorry guys!). I lose the front just before I almost stop and drop the bike about 10km - nothing major beyond a bent crash bung bolt.


When things were going better!

At first I think the header has just burnt through the oil filter as they get pretty close with the HRC oil cooler and I had just been working in that area, but further diagnoses shows this:


Holes in the cases

I assume it has thrown a rod and is terminal. It wasn't until I got home and removed the rear rocker cover that the picture becomes clear.... The cause actually started about 6 months ago when I snapped a corner camshaft holder bolt from mis-setting the torque wrench. I got the old bolt out and sourced a replacement (thanks Cammo!). This was on my spare engine that would eventually go into the road bike build so as to not hold that up, I borrow a bolt from my race engine. Unfortunately, due to a garage break in and loss of other bikes around the same time, it slipped my mind completely and when I thought about it again, I assumed I had done it. Big mistake. I actually think the 7 remaining bolts were enough to hold the camshaft in place. The deal breaker was the shim that I had installed to offset the cams from skimming the head. Each one is held in place by the 2 bolts so with 1 missing, the shim was free to pivot around. At some point it got caught in the valve spring, the collets dropped out, the valve dropped into cylinder 1 and all hell broke loose. The rod then snapped and ripped through the liner and the cases. The resulting carnage was this:


Destroyed cyl1 piston


The mess in the head


Cracked piston


Smashed cylinder liner

I was kicking myself as this was completely avoidable. However, the one small consolation was that the engine hadn't blown up from the build itself, just my own retardedness. There really wasn't much left to do but start looking for a new engine. Unfortunately, in NZ they are few and far between. I really didn't want to ship one from the UK again as the cost is immense. Luckily a local chap called Andrew Eckersley had a spare oil starved engine which he wasn't using and donated it to my cause as well as boxes and boxes of spares! The generosity of some people really blows me away. I stripped it down hoping it wouldn't be too bad and was looking good until I got to the last big end:


Scored journal


Munted bearing

The bearing hadn't actually spun but they had scored the crank journal enough that it was a paperweight. I sourced a 2nd hand one from Japan and in the meantime, got the cases cleaned and my spare heads skimmed. Taking what I had learnt from the 1st build, I was trying to avoid the cost of having the crank balanced as it was expensive and didn't add much. However, with no idea of what weight rods came off the crank from Japan, I had no choice. At least it gives me piece of mind that this one will be as good/better than the last:


Rebuilt bottom end

I did get smarted when ordering parts though and any part that was used across many Honda's was available in the US for a lot less money than the UK. I ordered a lot of parts from partzilla.com (piston rings for instance) at a much reduced cost which was great!


Cases sealed up


Clutch was all good, so reinstalled

Fortunately, the engine had run for very little time after letting go so despite a lot of debris going through the engine, a lot of parts like the clutch, generator etc. were unaffected and could be transferred straight onto the new build.

I was now at the point where I was about to install the heads but decided that since the engine is on the bench, this is a great time to spend some time porting the heads and dialling in the HRC cam grind that I have had sitting on the shelf for like 3 years! I had the porting plan established a long time ago (thank to advice and images from Mike Norman at G-Force) and had really just started. This is:

-Blend intake valve guides to port without reducing functionally
-Radius the valve seat to 1mm* blend the port to seat area with minimal material removed
-De-shroud the valves
-Match the inlet rubbers
-Leave the exhausts as is

* Mike actually said they could be taken to 0.8mm but I want to allow a little margin of error!

My previous porting had been literally to remove casting flash which in all honesty, I think the results were negligible. I had always been nervous about working on the valve seats but fortunately, I now had a busted head to practice on!:


Left = Standard, Right = Seat reworked


Engineers Blue to check the work

It took me all morning to do the practice valve and 1x inlet! I'm sure I will get faster as time goes on but it is really delicate work so I don't want to rush it. Putting in that much time only to fuck up the last valve and have to throw the head away would be gutting. However, valve seats are pretty hard so it is a little more forgiving than you might expect. As soon as the heads are done, I can move onto the cam dialling and checking piston/valve clearances.

[lukemillar]

Great thread. Shame the first few photos aren't working any or ever a good read. Thankyou!

Thanks!

Those images are all before I signed up to an imageshack account so I guess they just ditch them after X amount of time. I'll re-upload them at some point!

[Tim400GB]

Welcome back buddy.

Congratulations on the baby.

Very interesting read, glad to see you've not let the failure get you down.

[28hodge]

Luke nice to see this back up and getting running again, I guessed you'd had a blow up when you were looking for a crank couple months back.

I can beat your blow up through stupidity though, unfortunately!!

I took mine to a dyno to get sorted and set up ready for this year, all going well then it does the crank and blows up, didn't smash any cases thankfully but nailed a couple rods and the crank!

The cause, oil starvation due to me leaving paper towelling in the top of the engine in the cam gears last time I shimmed the engine to avoid dropping a shim down into the bottom of the engine.

Worse still I travelled 6hrs to brands gp and did a full weekend racing with it like this, I'd have been sick if I had travelled 6 hours to blow up in morning quali! God know how it survived that weekend with the paper in there.

All rebuilt now and back in the frame, shitting myself to start it up for the first time!

[crazyman]

what a bugger , let me know if you need a hand on the engine

[lukemillar]

Cheers Scott

I actually got a very kind donation of a couple of broken engines that I havebuilt a good one out of. Almost got it back together - just changed direction recently on the porting as I just can't quantify what I am doing and it is bugging me. Switched back to non-skimmed heads for extra piston/valve clearance to dial in those HRC grinds.

Where did you land in the end? How much head skim and what numbers did you dial those cams in to without getting too tight on piston/valve clearance?

[crazyman]

[quote="lukemillar"]Cheers Scott

I actually got a very kind donation of a couple of broken engines that I havebuilt a good one out of. Almost got it back together - just changed direction recently on the porting as I just can't quantify what I am doing and it is bugging me. Switched back to non-skimmed heads for extra piston/valve clearance to dial in those HRC grinds.

Where did you land in the end? How much head skim and what numbers did you dial those cams in to without getting too tight on piston/valve clearance?[/quote]i removed .3 off the head , i did not dail in , just pressed the gears off and back on to give the piston to valve clearance to around 1.2 mm , can't remember if it was the exhaust or inlet cams , i would not be surprized if it ended up around 120 degrees (-; , if the pistons were out i would do it right as mine will be (-;