400 engine repair or replace

[AndyD]

Hi,
Assessing the engine that came with my latest bargain basket case and would really appreciate advice etc. now it's stripped.
Clocks show 36k miles and bike generally looks to have had a pretty hard life.
Bought it partially stripped but dry stored.
Bores are worn and pistons all had broken top rings so I guess rebore is needed - any idea on cost and where to get it done?
Bottom end seems OK at first look - are there known problems I should look for / things to check?
I guess key question is whether it's sane to refurbish the old engine or look out for a running one instead - any opinion?
Cheers
Andy

[Trigger]

Hard to say without a up close and personal inspection. The last one i fully rebuilt at a cost of £820. If you do not want to go down that road. Contact a ebayer bike-pusher. Neil specializes in braking low milage 400/4 and i know all his stuff is good and honest.   

[Bryanj]

Full 400 good engines are not easy to find, pistons/rebore probably cost £250, only known bottom end problem is cam chain tensione horseshoe and tensioner bolt

[AndyD]

Guys,
Got the engine fully stripped and am deciding whether to bin or rebuild as the general condition isn't very good inside.
Cosmetically all is OK on the outside and joint faces, fixings etc. are all OK which is the good bit.
Pistons / bores are badly worn - clocks show 56k miles so maybe original and just run into the ground by previous owner(s) - I've had great advice and help from one forum member already so think this can be solved quite easily / economically with new liners and pistons.
Camchain guides all look quite worn but I guess are easy replacement.
I think the deciding factor is whether the non-easy replacement bits are serviceable so I'm after a bit of advice on the crankshaft as start.
The crank and bearing areas all look visually OK but I think the big-end side clearance may be over limit - from the old Haynes manual I've got it looks like this is simply a feeler gauge measurement and if so mine is quite a bit looser than it says it should be. Is this the best quick check on condition or would the engine be OK even if there is some excessive wear here?
I'm guessing the crank will be the deciding factor on the fate of the old girl so any advice etc. welcome on how to assess this will really help the decision.
Cheers,
Andy

[Trigger]

Andy, The big end side clearance can not really be that far out. Are you talking about the float on the crank?. Everything on a engine is serviceable.  I would replace all big end shell's and con rod shell's. The primary chain will need a inspection and the oil pump would need a re=build. All parts of the gear box can be checked but, i have never found much wrong in that area.
I did point you to Neil (ebay name: bike- pusher) i know that he had a 16,000 mile engine in at £300.

[matthewmosse]

I tend to just buy a new engine, they are genrally cheaper then fixing an engine and the failed spare often has lots of good spares on it for future fixing issues, just dont bin anything as eventually everything gets hard to source and stuff that was easyer to replace suddenly is worth having a go at reclaiming. I have a kl250 project and it had 5 heads for the engine, all with shot bearings, but the reconditioning guy opted to fix the worst one with an insert bearing - logic of using the worst example being that if it didn't work then no loss. Thiss approach can have a downside though, my loft has at least 10 550 and 500 engines in it and I have few ideas about if they are good uns or dead uns for parts- easy enough to check if they run though.

[Trigger]

Matthew, i have been restoring motorcycle engines for the past 24 years and what you must look at is every engine is different. I have had engines that only needed new ring's, and i have built engines that needed every bearing,every shell and totally re-machined. The worst engine's are the ones that have sat about for years. Unless you fill them with diesel, which i do to store engines over a long period.

[SteveD CB500K0]

I have this picture in my head of Matthew's ceiling joists bending under the combined weight of stored CB500/550 engines - and now he's going to fill them all with diesel!

 

[matthewmosse]

I tend to agree on both counts, I had a few USA inport engines, very low milage apparently, looked immaculate, but totally crap in service, kept destrying camchain tensioners in 1 instance. I try to turn the engines over on the kickstart every now and again and store them full of oil. I have a few stationary engines around on rotorvators, dumpers etc and a fair few suffered from rusted valves sticking. Striping them off and cleaning - then oiling and re assembling can get them running again at minimal cost. I'd not go to the cost ing an engine with diesel, not something I've seen suggested before. Clean engine oil and a oil change at 500 miles has always been my thing. Plus remove tappet covers to check valves are moving, and clearences are right. A shot of oil to the exposed valve stem would seem a good idea too. One day I'll take a time out to see why the USA bike engine that kept killing tensioners would be interesting - Oil was clean every change, appart from when tensioner got lunched.

[Trigger]

Don't worry Matthew, I do use red diesel. And today i took a tank out of storage which has been filled with diesel since 1989. It is like a new pin inside.