LM1000 top end work

[Mr. Breeze]

Hi All! About 82K now on my '86 LeMans 1000. Valve guides need replacing as it's blowing smoke at start up and soiling the plugs a bit. I assume it's time to have the heads rebuilt, valves ground, etc? What other "might as well" issues should I consider? What can I expect to pay to have the heads done if I pull 'em off. I haven't gone this far into an engine before :shock: but looking forward to the experience. Any and all help is much appreciated! Thanks!

 

[john zibell]

Instead of replacing the guides, have them K-lined. If in the US, these guys http://www.sbintl.com/ may be able to tell you of a local machine shop that can do the job.

Don't just do the valves, also do the rings. Measure the pistons and cylinders at the same time to see if they are within limits. With the increased compression from the valve work, the rings won't hold out long and you will be doing them at a not so later date. With just 86K on the bike, the bottom end should be OK.

 

[guzzibob]

I had pretty much what you describe done on my big valve 1000S (same motor as your LM 1000) at 74k miles last year. Work done by MG Classics In Long Beach, CA. Job included "head rebuild, blast, hot tank, re-surface, guides, valves, seats, test." New exhaust valves, 4 valve guides & rings. Rings were still (just barely) within specs, but would have been foolish to not replace while in there. They also pulled the heads off the bike for me & did a couple of unrelated relatively minor jobs. Grand total came to a bit under $1000, including the unrelated stuff. Before work bike wasn't smoking but was soiling the plugs in a half moon pattern, also gradually becoming more & more prone to pinging. Post work no plug soiling, can't make the bike ping no matter how hot & how much I lug it to try, & runs wonderfully well (aided by my finally completing correcting grossly bad factory jetting).

 

[double.d]

I've had all the same done to mine except I added a flow job on the heads, makes a big difference.

 

[Mr. Breeze]

Thanks for the replies! How are the pistons/rings/cylinders measured? I'll be doing as much of the work as feasible to keep the costs down but also for the experience and my own curiosity.
Thanks again!

 

[john zibell]

Thanks for the replies! How are the pistons/rings/cylinders measured? I'll be doing as much of the work as feasible to keep the costs down but also for the experience and my own curiosity.
Thanks again!

For a one time job, it isn't worth buying the telescoping gauges and micrometers the size you would need. Take the specifications and parts to the machine shop that will do the heads and they will do it for you much cheaper than you can buy the tools.

 

[Mr. Breeze]

Thanks for the replies! How are the pistons/rings/cylinders measured? I'll be doing as much of the work as feasible to keep the costs down but also for the experience and my own curiosity.
Thanks again!

For a one time job, it isn't worth buying the telescoping gauges and micrometers the size you would need. Take the specifications and parts to the machine shop that will do the heads and they will do it for you much cheaper than you can buy the tools.

Okay. So the cylinders and pistons come off and I'll take those to the shop to measure, yes? At that point a new piston ring size can be determined?
Concerning valve springs-Do they get measured for tension and reused if good or do they typically get replaced? A new set for all eight is about $83.00 from MG Cycle.

Thanks again this is helping me get my brain around the procedure!

 

[Penis Rotor]

Measure 'em. If they check out OK re-use em. with a low mileage donk like yours it is unlikely they'll of fatigued unless it has been raced or thrashed mercilessly.

My rebuild instructions are in the link below.

http://www.thisoldtractor.com/guzzitech ... ctures.htm

Pete