Bit of a sore point xb12r but what happened as far as I can work out is this. At xmas I had the valves done, then I did a couple of races and a couple of practise sessions, so maybe 80 to 100 laps. Heading into the back straight (can't remember the revs but maybe half) the bike gave a bit of a cough, then went to half power. When I removed the cam belt covers the front belt was missing half it's teeth and the other one was very loose. I can only assume that the belts weren't tensioned correctly after the cams were done. My assumption is that the belt jumped some teeth, the valves hit the piston, the exhaust valves jammed in the quides seizing the exhaust cam and then the driving pulley stripped the teeth off the belt. :frown: I could be completely wrong though. Both covers were full of rubber powder and the remaining belt looked pretty tattered as well. Belts were coming up to 2 years and about 4000kms. I was planning on changing them after this race. The really sad thing was that the day before I had been looking at race bike pictures and had seen that a lot of the guys were running without covers. I though that looks kind of cool and would make it easy to check the belt condition but as I was busy putting the rear of the bike back together and didn't have much time, I thought I would leave it till after that weekends race. Anyway, it's a race bike and I should have checked, so can only blame myself! I would love to send my engine to one of the UK builders but don't have the budget for that. Freight is so expensive and our currency is worthless as well. Possibly I could send the cases by slow boat to the UK later and get them sorted as spares but I want to get back on the track asap. I think I have found a set of cases and have been assured the bushes are good so think that is the way I will go. Also onto a set of cylinders and pistons. So plan is to balance everything, replace all bearings and seals, new rings, adjustable cam pulleys, skim the heads, replace the valves in the front head and a remap. Come on 1037, get her on a track, it is sooooooooooooooooooooooooooooooo much funbut you have to be prepared to throw her down the track :frown:
One of the best machinists I have seen was in South Africa, during the years of embargo they developed ways to fix rather than replace. Incidentally on the two engines JHP did for me they routinely replaced the bushings. Dave Martin was the engine man at the time.
I hope you can go back on track asap and i wish you a best as i can. I know how you feel i just finished my 999 before few weeks the engine block was cracked and i needed to change the engine.But you can already read my all sotry under topic 999(03-04) vs 999(05-06) All the best!!
A small pin will induce a higher stress concentration than a large pin. Due to the high frequency cyclic loading in the crankcase, the greater the stress concentration , the lower the fatigue life before crack initiation. Unless you can calculate the effect of the "notch" in the casing on the fatigue life, well, I wouldn't recommend messing with pins etc.
of course the loading will be even wether it be a large pin or small pin if it is designed to have the same interference fit as the bush that sits in the case. the loading in this case is not concentrated acting upon the 'pin area' exclusively. rather it is acting evenly across the whole area and of course if you remove too much material to accomodate a large pin. then you are potentially inducing a weakness into the load area. it has to be just large enough to do the job intended. but if the case is badly scored then that is asking for stress cracks to propagate through time. if it was mine id take the cases to work. have the relevant area peened and remeasured and have new bushes made to hold the bearings
I wouldn't pin them. If you machine the cases (minimum clean-up) you will need to bolt them together and line bore them. So the bores are concentric.
The bushes are flanged, yes, like a top hat. Bolting the cases together is the only way that they could be bored accurately. There is an issue with one side having half a flange, see pic but I think you could bore them from the other side. 2 different size bores though. At the moment waiting on the engineer to measure the bores and the seller of a second hand set of cases to get back to me. I've been scared off the pinning idea. From the photo's I've seen, the bores look like they have very little scoring but lets see what the engineer comes up with. The bushes are quite worn though. The one bearing was half out of the bush and was able to be removed by hand.
Ok got the measurements back. The bores are out of round by a tiny amount, 0.002mm and 0.001mm which I think is insignificant. Then there is the interference fit of the bushes into the cases. Ducati call for the main bearings to already be inserted in the bushes and there must be a minimum interference of 0.03mm. Inserting the bearings into the bushes would make the OD of the bushes bigger. My interference is 0.1mm without the bearings fitted so all good there as well. Therefore, I think my cases are good and the plan is to fit new bushes and Locktite for good luck. I'm also going to change the one cylinder and piston for a second hand pair I'm getting from Gotham in the states. They are also supplying a set of MBP light weight adjustable cam pulleys. Then it will be balancing the crank etc. sorting the squish, rebuilding the heads, all new bearings and seals, new rings and setting the cams. Then I should have a near new engine. Does anyone have any good ideas about things like, valve grind angles, clearances, cam angles and squish or anything else I can do at this point? Many thanks, Bront
Out of round by 1 and 2 microns isn't worth worrying about. That would fall within the tolerances for that measurement.
I know bront. It'll be out soon, just trying to get a house move sorted, and everything ready for my first child in October. Sadly my track fun is what's suffering. Is Kayalami still open as a circuit? I don't hear of any real track action from SA, and certainly didn't know there'd be club racing. Guess i'm a bit ignorant really cos its quite a big country really isn't it.
A baby, that will put the hand brake on for sure, :tongue: Yep Kyalami still very active. On the bike racing in South Africa scene, it is pretty busy. Lots of tracks around the country. There is National racing, Provincial racing and then local Club racing. I've started racing in the club group which has 3 classes, Power Sports, which is 650 or less I think, Classic Superbikes and thirdly, Clubmans, which is everything else and the one I'm in. We have about 30 entries on a fair weather day. Only 8 last weekend in the rain though and 3/4 of them fell off. Once I break the 1:22 twice in one meeting, I get kicked out of that and into Provincial racing. Provincial requires a different licence, more expensive of course. It has 3 groups, A, B and C. At the moment I can race in C but if I break out of Clubmans I go straight to class B. I think this will happen quite soon although I don't feel ready for that yet. I rely on passing down the straights, which is pretty easy seeing as I am the only one with more than 650cc. This bike is so quick that I am having trouble getting my braking and cornering sorted and as a result have my lines all over the place. I'm very tempted to restrict the throttle opening a bit once the engine is back so that I can improve in these areas before moving forward. wessel kruger - YouTube if you want to see some of my track, Killarney from my nearest competitor, Wessel Kruger on his CBR600 F3. He caught 4 of the crashes I think last weekend and damn lucky not to come off himself. Quite a few of the guys were on wet's for the first time and he had his pressures way too low. South Africa is pretty big compared to the UK but I come from Australia so it seems pretty small to me. It is 1/7 the size of Oz but a fair bit bigger than the UK for sure. I'm off to Angola for a month tomorrow so will miss the next meeting as well, although I don't think my engine would have been done by then. By the time I get back my new ISR brake discs for my BST wheels should be here as well so really looking forward to getting her all back together and on the track again. I will be quite a long way down the points board by then though :frown:. I really appreciate all the good advice you guys have been giving me, thanks a million. And just a little pic to show off my new race fairings, pity they didn't get the 996 in the right place but for 150 quid to paint everything, except the tank and front fender, I can't complain too much. Off course she lives in the lounge at the moment, thanks GF
All interesting stuff. Nice to hear about things we just get no news of over hear so i for one would be interested to hear how you get on through the year. I've never done any organised racing, but i have found the best way to improve in areas is to get with faster guys and try to follow them until you become fast enough to start overtaking. Then, try and find faster guys again. Best way to get to your or the bikes limits. Certainly wouldn't hold myself back in any area as then the next class will come as a big shock. I managed to get on a practice day with some endurance racers years ago at Jerez. Following one of them was mental fast compared to my comfort zone, but after 3 laps, less than 6 minutes i was physically knackered and had to back off. They could carry on all day. Lots of respect.
if you are after track performance I think that you'll be better to go Testastretta. The 996 SPS cams are pretty sharp and you inevitably run into flaking rocker issue. The stretta engine is more robust and revs a lot more which is good on track. If you are after upgrades, you should also consider the bigger airbox. Your frame won't work with the RS airboxes as you need the lower cross member. But I think that EVR or VeeTwo have something for SPS.
You're right 1037 but my ego likes it better coming first as opposed to last. I will probably get kicked into class B soon anyway once I have my new engine and sexy BST's fitted. I think I have plenty of performance Phil and want to keep her as close to a pucker 996 SPS as possible or be able to turn her back into one easily. Just waiting on parts to arrive but I am out of country for another 3 weeks or so anyway so no real rush.
