Motorcycle cylinder head

[Screwdriver]

I welded an old KZ1000 head up on the exhaust studs with 150A (air cooled and off the engine. If you want to re-drill and tap for the stud make a jig up before welding using the other stud and locating in the exhaust port , bolting to the other stud and a drill guide made up for the one you want to re-drill after welding it up. Saves the guesswork.

Yes, thanks.

When you say welded "on the exhaust studs" you mean alloy welded with the steel/SS studs in place?

There is a slight additional problem that the reason this broke off is that it had been badly helicoiled off centre. So the other stud which is still in place, is in fact still in the wrong place. They were both slightly off centre/wonky. So I may take a look at it and decide to do both.

S.

 

[Member 66061]

Years ago Hotrodder welded up a clutch release arm housing for my stepson's motocrosser. The chain had snapped and wiped out the casing but after the repair it worked as good as new.

Ditto, thats what happened to me. I got a time served welder to repair it. Didnt bother getting the guard mount welded back on, just wanted to keep the repair simple

 

[Richard.]

Zeppelin has it regarding preparing that part. A carbide burr in a dremel type tool to clean it up and smooth it over. Lots of degreaser, scrubbing, files etc don't be tempted to use abrasives.
Put a prep where possible.
Set your machine up to bios the AC balance further into the positive to aid further with lifting/moving any thick oxide layers that may be present.
Most of these casts are Alsi and assuming this is no different I'd be selecting a filler to match. 4043 would be my choice.

 

[penfold]

I need some advice regarding welding this:

It's a mates bike and I have said I'd have a go.

The plan is to weld it in situ. Just taking the cylinder head off will cost hundreds. I am planing to grind it back and clean the area thoroughly of course. Then hit it hard and fast with the TIG set to 100-150 amps (??), get some rod in as quickly as possible, then let it cool a bit, hit it again, repeat until filled.

I am assuming I couldn't fit the steel/stainless stud and weld over it?

So either drill and tap or fit a helicoil. It's not a structural item so I'm happy to have a go, it just needs to hold one of two studs. If it fails in service, the exhaust will not fall off. In any case, if it doesn't work, he's going to buy a new head for it. I have an old dead cylinder head to practice on.

Any tips?

Screwd.

Taking a head off costs nothing but time and the tools to do it; if he's intent on buying a new casting if it doesn't work that will require removal. I don't understand why you'd make life so difficult.

 

[Screwdriver]

Taking a head off costs nothing but time and the tools to do it; if he's intent on buying a new casting if it doesn't work that will require removal. I don't understand why you'd make life so difficult.

Whats so difficult about not taking an engine out?

While it costs "nothing but time", that's in short supply around here and I am not whipping out an engine then stripping it apart just to reach something thats right in front of me. Plus there are oils and gaskets on top of all that "free" time before muggins gets to put it all back together.

He's not intent on buying a new casting, he was quoted over £500 to have the work done at a Suzuki dealer so I said I could do it for him. Its a shot to nothing, even if I fail, he's no worse off than he started

S.

 

[Pete.]

Taking a head off costs nothing but time and the tools to do it

And fifty quid for a head gasket.

 

[Richard.]

And fifty quid for a head gasket.

More if it needs a set of head bolts.

 

[Pete.]

No reason why it should need head bolts. They don't tend to use stretch bolts like some cars do, in fact I can't think of a single example nor a single case of anyone replacing them.

Ditto, thats what happened to me. I got a time served welder to repair it. Didnt bother getting the guard mount welded back on, just wanted to keep the repair simple

That looks identical to the one HR repaired for us, except ours had the whole bearing housing smashed off right down to the waisted bit.

 

[Member 66061]

No reason why it should need head bolts. They don't tend to use stretch bolts like some cars do, in fact I can't think of a single example nor a single case of anyone replacing them.



That looks identical to the one HR repaired for us, except ours had the whole bearing housing smashed off right down to the waisted bit.

That sounds like a very skilled repair job, hats off to Hotrodder for making it work. Would have been interesting to see pictures of the job.

 

[Pete.]

I never took any photos of it, sorry. It's probably 15 years ago now.

 

[lchris21]

Similar repair, but I had the advantage of being able to take the casing off. Broken stud boss. Used some 4043 filler, and prepped with a carbide burr as previously mentioned. Little porosity at the surface on the thinner parts but I didn't want to force the issue and have a complete melt down!!!Get stuck in......

 

[Chris Stevens]

Whats so difficult about not taking an engine out?

While it costs "nothing but time", that's in short supply around here and I am not whipping out an engine then stripping it apart just to reach something thats right in front of me. Plus there are oils and gaskets on top of all that "free" time before muggins gets to put it all back together.

He's not intent on buying a new casting, he was quoted over £500 to have the work done at a Suzuki dealer so I said I could do it for him. Its a shot to nothing, even if I fail, he's no worse off than he started

S.

Very easy to repair if you can get the torch in at the right angle, and can access to drill and tap after welding. I do loads of this type of repair, and you will find 1.6mm 5356 rod, and slowly building up a new boss to tap thread into will work best. Take care to avoid inclusions, and if you are repairing both sides, make up a simple drill jig to keep the holes in the proper place.

Castings with more zinc are far more difficult, but all the Jap ones I have done have all been very easy to weld, just use 5356 rod, which is easier to drill and tap, and you will have no issues at all. However if not possible to get right torch angles/position you might have to take motor out to get access................but again not a major problem.

 

[Paul99]

Years ago Hotrodder welded up a clutch release arm housing for my stepson's motocrosser. The chain had snapped and wiped out the casing but after the repair it worked as good as new.

Ditto, thats what happened to me. I got a time served welder to repair it. Didnt bother getting the guard mount welded back on, just wanted to keep the repair simple

Very same happened to my brothers CR250 - a brand new chain fitted for that meeting so he wasn't very happy. After all the scare stories about it being scrap it can't be welded he found a guy down Somerset way who charged £30-£40 including postage to get it welded up and machined back - you couldn't tell it had been repaired.

 

[RichardM]

Yes, thanks.

When you say welded "on the exhaust studs" you mean alloy welded with the steel/SS studs in place?

There is a slight additional problem that the reason this broke off is that it had been badly helicoiled off centre. So the other stud which is still in place, is in fact still in the wrong place. They were both slightly off centre/wonky. So I may take a look at it and decide to do both.

S.

No stud, welded it up then made a jig up, re-drilled it then tapped out

 

[arthur]

All the talk of chains snapping I make up simple case savers, like this one modelled on the OEM's, hugs the chain and guides it back out when it snaps, essential for MX/Enduro/oh and Ducati's, this one for my WR450F Supermoto.

 

[blenkie1]

Lots of degreaser, scrubbing, files etc don't be tempted to use abrasives

What's the reason you don't use abrasives?

 

[Member 66061]

All the talk of chains snapping I make up simple case savers, like this one modelled on the OEM's, hugs the chain and guides it back out when it snaps, essential for MX/Enduro/oh and Ducati's, this one for my WR450F Supermoto.

A poxxy little case saver wouldnt have helped at all. My chain wrapped round the sprocket twice and it wasnt any impact that caused damage, it was the pressure of the chain being forced between the sprocket and the casing. You can see one of the mounts that would be used to fit a case saver broke off because it wasnt robust enough to withstand the pressure. Any case saver will have to be a robust item and use robust mounts, theyre going to be big mounting points to withstand the force of a chain wrapping, mine looped up between the swingarm pivot and the sprocket. A case saver will do heehaw if the mounts its bolted to are weak.

 

[Screwdriver]

In fairness, case savers are designed to prevent the chain from wrapping around the sprocket so....

 

[Member 66061]

In fairness, case savers are designed to prevent the chain from wrapping around the sprocket so....

In fairness, between the swingarm pivot and sprocket? so....
I found this looking for a similar example of what happened to me - http://www.moddedraptor.com/communi...do-you-need-case-saver-your-raptor-700-a.html Theres not many case savers going to stop a chain wrapping this way.....

 

[Screwdriver]

Once again though, you refer to a "poxxy little case saver" and link to a cheap plastic thing, which has failed to prevent wrap, though it did stop the chain eating through the crankcases.

Chain savers are designed to stop chains from wrapping around the sprocket. Space shuttles are designed to fly into orbit. Enough said I think. Now, what about my little welding job...

S.