Practice 11: best laps and breakages

The second of back-to-back Saturdays. Once again I found myself awake in the early hours, brain totally engaged thinking about the day. Having found the benefits of an early arrival (i.e. plenty of time to get ready for the first session without rushing) to my liking last week, we arrived an hour before the track opened. Unlike last week however, I hadn’t really been able to do as much of the preparation at home the night before owing to the poor weather (the garage has insufficient space to actually work in it and the lighting is awful) so the tyres (a fairly decent ‘new’ used set bought from the forums some time ago) hadn’t been inflated, I hadn’t gotten the new carb gaskets fitted, nor check everything over properly after I had stripped the back end down to dry it last week. The preparation hour was a bit of a rush; I put the new 3l fuel tank on, corrected the kind of mistakes you make when working in the dark (i.e. a front wheel with three wheel nuts but only two bolts used!) and got everything set. We were on the grid when the cadets came off at 10:10.

Our first problem of the day: the kart wouldn’t fire. I gave it a couple of aborted push start attempts but there wasn’t even the hint of it starting. I took it back to the pits and checked the ignition box wire connectors were ok and then checked the spark plug and found that we were not getting a spark. I whipped out the new plug that I had bought in the week for just this purpose and things looked more promising. Hastily, I tossed the old plug in the bin and we went for another attempt at getting on track. Once again the kart is showing no signs of starting so back to the pits again – it seemed the sparking was intermittent. I had used my only spare HT lead at a recent practice at Dunks. Good job that Clay has a shop… only the shop didn’t have one! Fortunately, I was able to borrow one (from my good friend also known as KartingDad’s Karting Dad!), swap the lead over and get the kart starting reliably on the stand and running fine (shame about the plug I threw in the bin full of wasps but never mind).

Junior was on the grid for the start of the second session but only managed three laps before coming in to complain about his brakes. I could see that one pad was rubbing the disc engine-side and there was quite a gap brake-side but assumed, as he had been running ok, that it I could just adjust it at the end of the session. He did another 15 laps but with a slow best time of 39.3s and still complaining about the brake. Back in the pits, I was surprised to see the brake-side pad was rubbing the disc and the gap was now engine-side. If you are thinking “grub screws”, you would be correct: the grub screws had abandoned ship! Pleasingly, I figured that one out straight away too. Disappointingly, this was a mechanic error – I wasn’t overly tightening the grub screws knowing grub screw damage can severely weaken an axle. I have to admit that I hadn’t checked the grub screws at the start of the day so it could well have been that I hadn’t tightened them enough (even for my liking) after refitting the axle. Everything else was still aligned and looking good so it was just the grub screws required – you’d think these would be in stock wouldn’t you? As far as shop stock went, today wasn’t my lucky day so they gave me the only one they had. Having lost a couple at home recently, I only had one spare and my Karting Dad had one also. Cue wandering around the pits trying to buy spares! I managed to get some but it wrote off the remainder of the morning with only 18 laps under our belt and a best (and faulty brake affected) time of 39.1s.

The third session was more like it: 23 laps with a best of 36.6 and lots of time still evident in Junior’s lines. The fourth was better again: running with the camera on-board for first time of the day, Junior managed a 36.5s before the camera mount snapped :S See if you can spot the moment in my YouTube video. I am not convinced this punt on the camera is working – the camera itself is fine but the case and mounts haven’t looked up to the massive vibration that karting poses. For this session we were also running with the MyTach GPS watch. I’ve still not really read up on this but the watch gives you top speed readings and we were looking to test sprocket sizes. Running a 78 sprocket (what we had always run at Clay although I know the quicker guys run a fair bit smaller), we did a fastest lap of 36.57 with a top speed of 64.6mph (ironically analysis at home showed this was not on the fastest lap, which included a top speed of 60.8mph). With our problems seemingly behind us, we switched to a 76 sprocket and ran the GPS again. This time Junior put in a 36.42, the top speed on that lap was 63.8mph and his maximum speed during the session was 64.7mph. Not much in it, I am sure you will agree – I put this down to inconsistency, particularly out of the Top Bend but there was some interesting data in there: he was 3mph quicker down the straight into The Hairpin on the smaller sprocket.

The track then seemed to cool a little and I think my not increasing the tyre pressures a fraction may have cost us a few tenths as we drifted in the 36.6/36.7s laps before we encountered our biggest problem of the day: Junior had been holding up a couple of RotaxMax’s for a few laps and ran wide at The Horseshoe, matey decided to stick his nose up on the outside and, as Junior moved wider to get a line for the bend, they hit – flicking our back end up and causing Junior to run onto the grass. He rejoined the track and ran for another 8 laps. I was very surprised when he came in and I took the chainguard off – the chain looked blackened and dry (it had been freshly lubed) and was missing a few chunks, then I noticed the teeth on the rear sprocket (a brand, spanking new one that day) were wrecked which lead me to a front sprocket with some nice sharp spurs! At this point I needed KartingDad’s Karting Dad (again) as I had no idea how to remove a front sprocket and have learnt I need to buy some new tools :S With hindsight, either of two changes I made during the day may have contributed to this: I removed the sprocket protectors after deciding to use 6 sprocket bolts instead of three (it looked like the front sprocket alignment was a little uneven as the rear sprocket was rotated so I add the extra bolts in case this was the cause and the protectors have three warped holes that no longer easily facilitate the extra bolts) and the chain was running a little looser than I normally have it (on advice!). We went back to the 78 sprocket (now my smallest), a 110  chain (also now my smallest) and fitted a spare front sprocket (thanks again, spares :)).

The track was quieter now and Junior spent the last couple of sessions racing his friends. His lines through the afternoon had really come on – a screech and a lift entering Billies always looks good, taking The Esses with a decent amount of kerb was becoming more of the norm and, although his exit from The Hairpin was still a little tight and he had acquired a new, slower line through The Horseshoe, he was carrying [a little] more speed into and out of the Top Bend. New PB!!! 36.11 🙂 Racing was obviously paying off. For the final session of the day, he spent a few laps following the South West Junior TKM champion 😉 until said champion decided he had enough and wanted to put Junior in his place. Junior didn’t mind though, he was chuffed to bits with another new PB – 36.06s.

So we got off to the worst possible start, endured a pretty expensive day, breakage wise but ended up clocking 166 laps and Junior making further progress.He is definitely quick enough to race. I have no lofty goals/dreams about exactly how competitive he will be, it would be nice to be close enough to the pack to race someone but I doubt that will be the case initially. Whether I am ready to race is another question. I am still making mistakes but I think that is just human nature – I’ll make more than most mechanics, I just need to make sure I learn from them! The troubleshooting is a worry as, if things go wrong, there is no second engine to pull out the trailer, nor is there likely to be for some time. We’re just going to have to see how we get on 🙂

Cost of day: £12 petrol, £7 fuel for the kart, £35 practice fee, £5 grub screws

Cost of replacement stuff: £10 ‘new’ chainguard from eBay, £100 new spark plug cap/spark plug/HT lead/6 grub screws/10-tooth front sprocket/Talon size 76 rear sprocket/Panther (I know I could have spent less but I am keen to see if it is stronger and longer lasting) 108 link chain (from Kart Parts UK/Spellfame)

Total spent so far: £3,396

I plan to limit outgoings to race weekends and associated running costs/repairs only for the remainder of the year so kick me if you see me post about new bits and pieces!

Practice 9: Hmmm…..

A fair amount had changed on the kart since our problems at Dunkeswell; the back end had had some attention as I had fitted and subsequently returned a used axle, I had also fitted the OTK foot rest in the expectation that it would give Junior something to press his heels into when braking and I had ‘expertly’ created a foam insert for the seat after Junior had complained that he was uncomfortable in the seat in longer sessions. I had some things to test too: I had tightened the nassau in a bid to improve upon the vibration suffered by the ActionPro and I had also been lent a MyTach GPS watch to test (thanks, Colin!).

Again, we left late – only 15 mins but it meant that we didn’t make the first session although only because went on the track before it opened in order to set the GPS position and decided to walk the track since we were out there. Our first lap lasted all of about 30 seconds as Junior complained that his brakes weren’t working. What he actually meant was he didn’t like the heel rests and they restricted his use of the brake! Our second session ended with the kart stopping on track; I had hand-tightened the spark plug having noticed it wasn’t seated as we were pushing the kart to the pit lane and so we had lost compression (Noob Lesson 1 for the day).

We then had some decent track time mixed with some more mistakes on my part: a loose floor tray, lost nassau bracket bolts, another [different] loose nassau bolt. These are things I have to admit I’d never checked mid-session but, as Junior was starting to [sporadically] hit the kerbs through The Esses, the kart was starting to get a little roughed up (Noob Lesson 2 – check bodywork through the day). The seat insert of which I was very proud was a flop – the sides had to be removed in order for Junior to fit in, then he decided he preferred the seating position without it! We never captured any data on the MyTach, either through user error (not hitting the ‘Start’ button) or taking it off whilst we found some reliability and forgetting to put it back on again! The ActionPro still suffered vibration although tightening the nassau did help a little.

The biggest disappointment was the times we were producing – 37.x throughout the day, a second off of our best at our last visit in June. Conditions were pretty similar; the weather was warm and although the kart setup was not identical (the rear axle was at it’s middle height whereas it was low last time, we may have had a different carb and the tyres had obviously seen a little action at Dunks in July) but I didn’t feel that explained such a loss of pace. You could see that it was taking longer for the regulars to catch Junior on our last visit but that wasn’t the case this time. Junior was working on his lines but there is still a lot of room for improvement, most significantly in his lines and his braking points. Don’t get me wrong I very rarely criticise him; it would be a bit hypocritical as I am still making noob mistakes! He wants to race and we’ll do that when he is ready. I came hoping to confirm our readiness and left knowing that we still weren’t there yet. When we bought the kart I said we’d look to get a few races in at the end of the year. I thought we were a little ahead of plan but maybe that isn’t the case.

On the positive side, Junior ran for 170 laps despite the mishaps, did improve his line through The Esses a little and nothing unexplainable happened to the kart. Remember there is no such thing as bad seat time… 🙂

Cost of day: £12 petrol, £7 fuel for the kart (still plenty left from last time), £35 practice fee

6 nassau bracket bolts: £3!!!

Total spent so far: £3,143

 

The kart… it works (I think)

I had been meaning to investigate the cause of the problem that caused an early end to our day at Dunkeswell the following day. I needed Junior to be home to help me get the kart off the trailer lid and onto the trolley (the wife refuses after hurting her back the only other time she tried – I won’t take that one any further!) and I had the kart all ready for his teatime arrival so that I could replace the fuel tank and try starting the kart. It was pretty dark when he got home at 9:30pm!!! Barely light enough to get everything replaced/checked never mind starting at 2-stroke go-kart in the front garden at such an unsociable hour. It had to be done though although a couple of quick starting attempts proved fruitless and I quickly threw in the towel.

Ten days passed (is it just me or is the kart easy to ignore when you know you have a problem to resolve?) and I mustered just enough enthusiasm to try again. The carb was holding the fuel ok but the kart just wasn’t firing up. I rested the plug on top of the engine and tried starting again to gauge the health (or otherwise) of the spark – there was no spark! I replaced the spark plug with a couple of the spares although one of the few pitfalls in buying a retirement package is that you’ve no idea as to the quality of the spares. Could three spark plugs all be bad? I made a note to myself to buy a new plug just to keep for troubleshooting and wondered what I could next. I’m still not great at engine problems but the only things I could test were the PVL coil and the ignition HT lead – both of which I had 🙂 The HT lead was the quicker win so that got replaced first. I was very pleasantly surprised to see a spark and then subsequently hear the engine fire up. I couldn’t run it for very long but it started a couple of times. The HT lead did suffer some damage when Junior had a Rotax drive over him but it had been fine until now. Ho hum…

Our race plans have been set back though – we need another good practice day now so it’s looking likely that we’ll head to Clay this week and hope for the best.