Newbie Hello --- 350LC Head Gasket and other Frustrations

[dalew750]

Hi RD LC Crazy Forum,

I'm a Newbie on here and this is my first post.
I'm Based in the Welsh Border area and I purchased a 1981 350LC Bounty Colour scheme LC last Year.

Most of the bike was done, paint ok and the engine was rebuilt and required running in. Did 600kms (import / speedo still in Kms) to run in and seems to go well enough. Since its been Parked up I have noticed there is a coolant weep from the cylinder head gasket ..... I assume it was fitted with a non gen gasket. Is there anything else I should look at when we pull the head off?

Should a gen gasket be used or is there a way Non Gen can be used successfully?



The other frustration is the bike had Bacolite - hard original Metzler tyres on, I got a pair of new Avons from the Stafford show and thought how hard can it be (having fitted loads of trials / enduro tyres on). No gap between rim and tyre bead to fit your hand through to push the valve through it's hole ..... Mmm one split tube later



Wheels and tyres will go to the local bike shop to be swapped over this week, then I can give the rear wheel a refresh of satin black and brighten up the rim and spokes.





Well that's where I'm upto with the LC so far, loved riding it last year and looking forwards to getting her a little better and more S/miles this year.



Cheers

Nick

[tacky1]

You could try torquing the head. The manual calls for 17ft/lbs.
I always set mine at 20ft/lbs. I had a few leak at 17, none at 20.

[dusty350]

+1 on what Tacky said regards head torque. If you've not checked it after running in after a rebuild, you might find it's looser than it should be. I do mine to 20ftlb too and never had an issue. I always use genuine Yam, but guys get good results with Athena gaskets too. A genuine head gasket is £65 now - seem to go up every year without fail
Did you get any rebuild receipts that would indicate what gasket was used ?
And, welcome to the forum

Dusty

[dalew750]

Cheers tacky1,will give it a go at 20ft/lbs and try it before pulling the head off and checking surfaces (which did look good on engine build pics).

[dalew750]

Hi Dusty,
Thanks for the welcome, reply and advice. Seems 20ft/lb is the way to go, sadly no mention on the build receipts regards the gasket make.
Will re-torque it down and update.

Cheers
Nick

[beardy]

Welcome in. May 24th will be smoking the Beacons LC rally if you fancy a blast with loads of LC’s 👍🏻

[dalew750]

Hi Beardy, Where can I get details of that rally?

[shaunthe2nd]

Welcome to the forum Nick.
Some good advice for the head gasket.
Often need retorquing after a few heat cycles, so hopefully that will sort it.

I convert a lot of clocks from km to miles if this is something you are looking for, if so just drop me a PM.

Enjoy the bike, you made a good choice!
Shaun.

[beardy]

Jan 8, 2024 23:05:40 GMT 1 dalew750 said:

Hi Beardy, Where can I get details of that rally?

Have a look on faceache for the “LC club”. If you don’t have it I’ll pm the details to you 👍🏻

[4l04ever]

Welcome in

[midlifecrisisrd]

Hi

Firstly I'd say check it is actually the head gasket

I did have a leak on one last year so replaced it with a gen Yam one

Left it overnight and then found a small puddle under the bike and was livid

On closer inspection it was the top water hose housing gasket that was leaking and running down the front of the head

Sorted that but 2 days later found a drip on the floor. Was the barrel drain bolt this time 🤣

Steve

[seanclarky]

+1 for 20ftlbs

[dougw]

Head gaskets is a controversial topic.

Mate and I Proddie raced LC`s in the 80s, I used to rebuild a few local guys LC motors too.

Never used a genuine yam gasket back then and never had a problem , probably did around 20 top end rebuilds.

Current 4L0 rebuilt first time using a pattern gasket with a smear of stag wellseal , no problems , then rebuilt after 500 miles running and ports corrected using a home made gasket made out of copper to get squish a bit tighter, sprayed with permatex copper gasket spray.
2,500 miles later no problems.

Make sure surfaces are clean and flat , torque to 20lb/ft and usually OK , but Dave Whattam has mentioned some barrels/heads have an issue that causes leaks, and mismatched barrels with different heights will cause problems( not unusual apparently ) .

Edit , warped heads too won`t help.

[steeley]

Welcome in . Yep 20ft/lbs for head bolts .

[crigar]

Refit only with a new seal. Tighten in the order shown in the manual to 1 mkg. Tighten a second time to 2.4 mkg. Warm up the engine to operating temperature. Allow to cool completely. Check tightening to 2.4 mkg. I've never had a problem with this solution in 40 years. (Sorry, I don't know how to translate mkg into ft/lb)

[arrow]

Jan 9, 2024 13:58:21 GMT 1 crigar said:

Refit only with a new seal. Tighten in the order shown in the manual to 1 mkg. Tighten a second time to 2.4 mkg. Warm up the engine to operating temperature. Allow to cool completely. Check tightening to 2.4 mkg. I've never had a problem with this solution in 40 years. (Sorry, I don't know how to translate mkg into ft/lb)

17.36 ft/lb. 👍

[Gitram]

Jan 9, 2024 10:00:11 GMT 1 midlifecrisisrd said:

Hi

Firstly I'd say check it is actually the head gasket

I did have a leak on one last year so replaced it with a gen Yam one

Left it overnight and then found a small puddle under the bike and was livid

On closer inspection it was the top water hose housing gasket that was leaking and running down the front of the head

Sorted that but 2 days later found a drip on the floor. Was the barrel drain bolt this time 🤣

Steve

the exact same thing happened to me last year... pipe between the water pump and head, one bolt went through the bolt hole in the gasket between the head and the spigot? but the gasket wasn't straight and the other bolt went past the gasket, cue the puddle and the tantrum.. took the head off wasting a perfectly good (athena) gasket to find the wee gasket was misalined... there's probably a moral to this story, but...

marti

[peter1962]

welcome aboard

[alankelly]

Hi

First welcome in

Not sure if this is of help but I had a very small weep and this solved it

Best wishes Al

[arrow]

Welcome in.

[arrdy350]

Welcome to the forum 👍

[stusco]

Jan 9, 2024 22:43:15 GMT 1 alankelly said:

Hi

First welcome in

Not sure if this is of help but I had a very small weep and this solved it

Best wishes Al

Before i scrolled down I thought you had fixed it with draft excludeder tape😄

[dalew750]

Many thanks for all the replies and great advice on the head gasket / coolant weep .... I've come to the right place to get the bike right. I'll check the head gasket and the top coolant gasket this weekend and update.  

Regards
Nick

[JonW]

I always use copper spray now-a-days. Our bike parts are all old and this ensures less hassle.

[4l04ever]

You need to make sure the tops of the two cylinders are parallel to each other and are both flat. I used some short pieces of copper tube over the standard bolts so I could fasten the cylinders down without the head on, then I could check with a straight edge.

[Tobyjugs]

I use two YPVS cylinder head nuts to hold the barrel in place. Just don't tighten them too much.

[lcmarky]

Welcome along Nick..

[muttsnuts]

first off welcome to the forum

now to your head issue, things to check

1. Do you have the correct washers under the head bolts - if you don't get some as the head bolts can "bottom" out on the studs so the torque wrench will click, but the head isn't clamped - its a fairly common problem
2. If you have the head off, lift one of the barrels off and check the studs are fitted the correct way round - they have a long thread and a short threaded end, the short threaded end should go into the crank cases, if they are fitted the wrong way round then the head bolts can "bottom" out and again the head won't get torqued done even though the torque wrench will click
3. Check the barrels are level and have even "deck heights"
4. Check if the barrels have been relined, if they have, you may need to have these checked for it being done correctly - ones done by SEP engineering where known to have issues
5. Check the head isn't warped, if in doubt, get it checked or skimmed to be sure
6. head gaskets, if using a genuine one, then torque down to 20/22ftlb's is perfectly fine and what I use (ignore the haynes book of lies), 18ftlbs is a little light, if using a pattern head gasket, fit it dry, don't fill the engine with coolant, run it up until the barrels are warm to the touch - you won't damage anything, let it cool down, retorque the head bolts, fill with coolant, run up until at working temperature, turn off and let it cool down again,. retorque the head, then you should be fine

HTH

[urbantangleweed]

Welcome to the best RD forum around.

I mainly do YPVS engines, but if you're using the black type gasket like on those, like Dave says above, warm it up a little without coolant. This will allow the black coating to soften and do its job making a seal. Then you can add coolant. I always do it this way and have had success with all the gaskets I've ever used which includes OE, Athena, Vertex, NE among others.

[dalew750]

Dear Forum Members that have replied to my post,

Thank you all so much for all the brilliant advice for checking initially if it is the Head Gasket that is the culprit of the coolant weep. Also great advice (if it is), with reference to checking the the cylinder studs, nuts, matched height barrels etc and running up dry if using a black Gasket. 

Weather (freezing) has not given me the appetite to go out in the garage to do this investigation this week so far. Wheels were removed previously and Avon Road Rider 2 tyres fitted .... they have just come back today so they will need to go back in.
I need to freshen the satin black paint on the rear wheel before it goes back in and also clean up the zinc parts (axle, adjusters, nuts etc) as well ..... to improve the looks a bit.

Hope to check the coolant issue at weekend again .....  hope it warms up a bit.


Cheers

Nick