DAN696 Posted August 9, 2017 Report Share Posted August 9, 2017 Hello I'm rebuilding a 240 engine fitting new bearings to the bottom end has anyone got any tips which bearings to fit in cases first do I build crank and gearbox into right hand case then fit left hand case with bearings already in it to crank and gearbox Thanks in advance Dan Quote Link to comment Share on other sites More sharing options...
grib Posted August 14, 2017 Report Share Posted August 14, 2017 Build it in the left hand case. Put all the bearings and LH seal in the cases first (heat cases to fit bearings), pull the crank in to the LH bearing using the primary drive nut and spacers, slot the gear clusters etc. in and then put the RH case on and pull it down evenly on to the crank with the case screws. Don't hit anything with a hammer, fit the RH seal last. Quote Link to comment Share on other sites More sharing options...
DAN696 Posted August 15, 2017 Author Report Share Posted August 15, 2017 (edited) Thanks for your advise I'll give it ago at weekend. I'm surprised I couldn't get all the oil seals to match correct sizes. Old ones don't seem too worn and are still flexible without any cracks etc so I'll re use and see how goes cheers again Dan Edited August 15, 2017 by DAN696 Spelling Quote Link to comment Share on other sites More sharing options...
DAN696 Posted August 15, 2017 Author Report Share Posted August 15, 2017 Do I fit right hand main bearing into case first and pull onto crank or fit bearing to crank and pull case onto bearing Cheers Dan Quote Link to comment Share on other sites More sharing options...
grib Posted August 15, 2017 Report Share Posted August 15, 2017 I wouldn't recommend re using oil seals, the one behind the flywheel can be replaced fairly easily with the engine in situ but the left hand one can only be done by taking the crank out. Seals are available from Simply Bearings, get Viton seals for the crank, others can be nitrile. Quote Link to comment Share on other sites More sharing options...
grib Posted August 15, 2017 Report Share Posted August 15, 2017 (edited) I put the bearing in the case first, either heat the case up with a hot air gun or put it in the oven until the bearing will drop in easily, I usually put the bearing in a plastic bag in the freezer too. Edited August 17, 2017 by grib clarity Quote Link to comment Share on other sites More sharing options...
grib Posted August 15, 2017 Report Share Posted August 15, 2017 After pulling the RH case down with the case screws the crank bearings will feel tight - I use a tubular spacer on the inner race of the RH bearing and gently ease the inner race in using the flywheel nut until it feels free. I have tapped the inner race with a drift & hammer in the past but the spacer & nut works better. Quote Link to comment Share on other sites More sharing options...
vintagenut Posted August 17, 2017 Report Share Posted August 17, 2017 Hey Grib - thank you for your detailed tips in answer to Dan's questions. I picked up a severely beaten 240 parts bike recently that I'm hoping to rebuild sometime soon. What I'm wondering is if there was ever a shop/repair manual available with complete motor teardown/rebuild procedures, tool use (I was fortunate to acquire some Fantic specific tools of late), and engine specs/tolerances etc. ? Sadly, I'm very manual dependent when it comes to my rebuilds and attempting to fly without one can mean all the difference between doing the job right the first time and having to repeat the process because of a silly mistake! I've scoured the internet but, to this point, haven't seen any reference of one. If anyone has a lead or copy available, it'd certainly be a great resource for us budding mechanics trying to keep these old bike alive and well! Thanks again for all of the information you've provided here. Very much appreciated! Best regards, Christian 1 Quote Link to comment Share on other sites More sharing options...
grib Posted August 17, 2017 Report Share Posted August 17, 2017 There has never been workshop manuals for Fantic trials bikes. There is a parts list which shows exploded views of the whole bike, and there is the handbook that came with the bikes when new which has some specs for torques etc., both of these are attached to this post. The 240 is a fairly straightforward engine to work on, its the first one I ever rebuilt without a manual, and common sense should see you through it. It probably helps if you have built engines before and already have an idea of what goes where, just remember - if you are having to apply a lot of force to anything to get it to fit, something is probably not right. I have done lots of Fantic engines and am happy to answer any queries. Fantic 240 OM.PDF Fantic 240 PM.PDF Quote Link to comment Share on other sites More sharing options...
DAN696 Posted August 17, 2017 Author Report Share Posted August 17, 2017 Thanks for advice again. I think it was gear lever seal I couldn't get think it was 15 mm I.D instead of 14 mm. I'm just waiting for them to be delivered. I'll replace both crank seals and see how I go on with the ones I couldn't get. I should be able to change them without splitting cases. I'll let you know how I get on Cheers Quote Link to comment Share on other sites More sharing options...
vintagenut Posted August 17, 2017 Report Share Posted August 17, 2017 Thank you, Grib - much appreciated! Yes - I do have a bit of motor experience - Bultacos, CanAms and a few Japanese motors - but, as mentioned, none with Fantics... and always had a manual to refer to when the work goes into the early hours when concentration and patience begin to wear thin. Guess there's no better time than the present to jump in and trust some of that experience to see me through! Hey - just to clarify on your earlier reassembly tips (seating the right side bearing and case together onto the crank), is there any crank end float measurement I need to be concerned with in case the replacement bearings aren't exactly of the same width dimension as the OEM bearings? I didn't see any crank shims in the parts manual so hopefully not! By the way, which replacement bearings have you used that you might recommend? Thank you again - truly helpful! Christian Quote Link to comment Share on other sites More sharing options...
grib Posted August 17, 2017 Report Share Posted August 17, 2017 There isn't a crank end float measurement published anywhere, and there are no shims on the crank (the only 'shim' is a spacer about 0.5mm thick behind the LH bearing on the output shaft in the gearbox). If you pull the RH case down using the case screws then obviously all of the clearance in the bearings is taken up with the inner races being pushed outwards, to counteract this I use a spacer under the flywheel nut to ease the RH inner race inwards and centralise the crank in the bearings by feel. The crank bearings are per the parts list - 6305 C3 and 6304 C3 (the C3 clearance spec is important), I usually use branded bearings like SKF, Koyo or similar as they don't cost much more in real terms than 'budget' parts. Not sure where you are in the world but I am in the UK and use the Simply Bearings website for all bearings, seals, o rings etc. Quote Link to comment Share on other sites More sharing options...
alberto Posted August 18, 2017 Report Share Posted August 18, 2017 8 hours ago, grib said: There isn't a crank end float measurement published anywhere, and there are no shims on the crank (the only 'shim' is a spacer about 0.5mm thick behind the LH bearing on the output shaft in the gearbox). If you pull the RH case down using the case screws then obviously all of the clearance in the bearings is taken up with the inner races being pushed outwards, to counteract this I use a spacer under the flywheel nut to ease the RH inner race inwards and centralise the crank in the bearings by feel. The crank bearings are per the parts list - 6305 C3 and 6304 C3 (the C3 clearance spec is important), I usually use branded bearings like SKF, Koyo or similar as they don't cost much more in real terms than 'budget' parts. Not sure where you are in the world but I am in the UK and use the Simply Bearings website for all bearings, seals, o rings etc. but on the ignition side, original is NU305ECP not 6305C3 Quote Link to comment Share on other sites More sharing options...
grib Posted August 18, 2017 Report Share Posted August 18, 2017 I haven't seen a Fantic engine with a roller bearing on the ignition side, but the 'newest' one I have taken apart would be about 15 years old at the time... I am just going off the parts list and what I have taken out. Quote Link to comment Share on other sites More sharing options...
vintagenut Posted August 18, 2017 Report Share Posted August 18, 2017 Much appreciated, Grib - and thank you, too, Alberto! Interesting that Fantic would choose a roller bearing for that application. Considering the cost of replacement (US $45.00), I can understand why substituting the NU305 for the 6305 may be a viable cost-cutting choice. I wonder if there's any notable performance or reliability difference between the two? (Not that I'd be able to tell given my unfamiliarity with the bike. At this point I'm still uncertain if she was even a runner at the time it was disassembled and boxed up in the early 1990's.) I'm also contemplating replacing the big end bearing with an In Motion or similar con rod kit while I'm at it. If either of you have any familiarity with the quality of these replacements, your thoughts would be most welcome! I'll be ordering some seals and outer bearings very soon and, after tearing into her, will definitely report back with my findings. Thanks again and have a great weekend! Quote Link to comment Share on other sites More sharing options...
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