Post your general FAQs, comments & questions regarding all Ducati engine & transmission restoration here. [Specific engine FAQs should go in the 'BevelHeaven Garage' section.]
hashashan wrote: <snip> ..does anyone know if it fits?
Nope, sorry. The Darmah crank is different in a number of ways from the earlier bikes.
And buying a second-hand crank is pretty risky too. For example, you'll see that the seller writes, "feels and mesures within limits, but sat for years..... it would need new pin & bearings to be 100% sure."
I stand to be corrected, but as I understand it, it is very difficult to accurately check the condition of a roller bearing big-end simply by pulling on the connecting rod. You need to split it and and measure the components; so you end up re-building the crank anyway.
e-bay : No, that's a DucatiElletronica crank, not a Bosch.
Difference visible in the lenght of the primary side for fitting the Bosch rotor.
Sending a crank to a specialist in Europe isn't going to make a huge difference in the cost, so think twice about buying some non checked secondhand stuff.
That unaccessible screw is put there with engine out and a gear selected so better to reach.
Don't know (can't remember) how much the crankcases can be pulled apart before the kickstartermechanism interferes, but try again (gentle) with turning the kick and sliding the cases open.
My last rebuilds were racers, so no kickstart and currently no engine on the bench to check.
Same again, can't remember, but unscrew the big bolt at the rear of the engine : the ball-springloaded stop for the gears. Not sure if it REALLY is important but it does no harm when You take it out.
Didn't go through all the previous posts to look but : did You take out the mechanism that rotates the gear-selector drum : the springloaded arm with the hooks. This could hold the gear-drum in place.
You have to make sure that all shafts and gears and drums stay in the lefthand crankcase. If one goes left and the other right : the gears interfere and you can't open the case. Light tapping on the shafts (woody) can get things going.
Feel free to correct me, so I get reminded why RC racers were more fun to work on :-)
cu
joseph
That plastic thing is indeed for the ignition-wires, but it should be in the lefthand cover, and I think it's to big to float around.
Guess someone dropped it in the lower oil sump (no harm there).
Nego i ricordi peggiori
Richiamo i migliori pensieri
Your crank may well be Ok. There is a fair amount of side play on the rods when everything is normal. Holding the rod against the thrust washer and feeling for up and down play can give some indication of wear but it is very hard to do accurately. There is a spec. in the service manual for side clearance but I don't have one handy, you could look in the svc. manual index on this site. The piece you found in the case,is it definitely plastic or could it be hard,aged rubber? On the right side of the cases there is a rubber bushing that the nose of the oil strainer goes into which is the inlet for the oil pump. If your oil strainer was bent or wrinkled it probably wasn't seated in the bushing and it could have come adrift. One has to take care when installing the strainer to engage the nipple. As to getting the cases apart you are past the point of engagement on the k/s so it is probable the shafts are binding in the bearing races. Tap the shafts while pulling up on the case to free it.
ok, I now can see what is the problem.
when I try to pull the cases apart the kickstart is pulled to the right side right?
when I pull the right side away the kickstart is pulling some sort of a big sprocket with it and the sprocket is stuck in the gear.
should the k/s pull any sprockets? should it be on the right side at all?
when I turn it the sprocket doesnt turn.
G'day Hashashan,
Just came back on list after an absence. The other boys have helped you through the hard bits already but 2 pieces of advice for you.
1. Don't muck around with the crank. Send it to a RECOGNISED crank rebuilder who can rebuild it to proper specs with proper bits and you will never have to worry about it again (providing you use the "right" oil and change it very regularly). I won't start an oil thread here!
A few dollars spent here (and it can be expensive) is well worth not having the nightmare of the crank failing after the rebuild. A friend did his own to save money and ending up destroying a Sport motor. His other roundcase engine crank rebuilt previously by a professional is still going strong.
2. Do yourself a favour and get one of Steve's Case Saver kits as I noticed in your photos that the chain has gouged some serious channels in the case. While the cases are split, get a welding expert to fill it in and clean it up. I know that is just for looks but you have the oportunity while the cases are split to tackle it. Well worth the job.
well o course I cant rebuild the crank by myself. however we dont have anyone in Israel who rebuilds old ducati cranks, so ill have to send it to a random crank rebuilder.
I know it because one of the israeli members on this forum already tried to rebuild his own crank and ended up buing a used one instead.
sending it abroad or a rebuild would be too expensive.
about the case savers, it might be a good idea. I will probably do it after I make sure all my mechanics is in proper shape.
BTW, I wanted to put wiseco overbore pistons instead o my own. It is possible to machine down the sleeves right? (of course ill send it to a proper place to do this work) I mean no need to buy new sleeves? or am I mistaking?
re your pistons and cylinders: How much wear is present? There are all sorts of issues with aftermarket pistons,and depending on what you are trying to accomplish,you may be far better off with standard parts,(including,just possibly,all the old parts,rings and all)and,for all bevels,a careful confirmation or adjustment of your squish band clearance.
actually the pistons and rings are in ine condition
but I want to replace all the parts that can be replaced just or a resh start
the wiseco cylinder seemed like a fine choice, being bigger, and having a higher compression then the original ones.
it is also cheaper or some reason then the original. and rom what ive heard o this company they are very good. so I see no reason not to change these.
as or the pistons that are currently in my cylinder they are 86mm, the cylinder is 86.4 i think
the ones id like to put in are 87, so some machining should be done
Well,it's your money. Regardless of the nominal compression ratio of any piston you decide to use:be sure,on re-assembly to confirm or correct squish band clearance to no more than .060.I'd suggest .035 for an 860 not in racing use.
The Wiseco pistons will work fine and the cylinders can be bored by any competent machine shop or dealer.As for the squish clearance it usually winds up in the .040"-.050" range with std. cylinders but it is worthwhile to check when you reassemble and have the bottom of the cyls. skimmed if needed.
The wisecoes are very heavy. Most of the extra weight is in the wrist pin, its a lot longer than the stock ones.
79 Darmah
78 900 GTS
86 F1B
80 SSD
02 Harley FXD
72 H2 750 triple
08 KTM 300XC
there has yet to be a motorcycle line made that is as satisfying to ride, hear and look at as the ducati bevels
you will need to rebalamce things after going to the heavier pistons as well, do not forget this step!
I've often wondered - do you also need to rebalance if going to lighter pistons e.g. from standard 750 GT to Sport pistons? I have been advised by some reputable people that this isn't necessary.
Thanks,
Steve.
Last edited by Steve Foster on Tue Feb 01, 2011 2:00 pm, edited 1 time in total.
