RobbieRobot Cafe Racer Project in pictures

Good news regarding the stripped spark plug thread. I ordered a spark plug thread repair kit off eBay.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 1420677579

It arrived yesterday lunch time. Job completed within an hour and managed a 50 mile ride to check it out. It would be rude not to take advantage of this unseasonably warm, sunny weather. Bike performed good as new.

 

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It arrived yesterday lunch time. Job completed within an hour
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so, how do you stop the "bits" from dropping into the cylinder,
or fish them out after?
stu :?

 

You can't, that worried me too when I saw it done but a blast of air removes all the swarf back through the plug hole

 

I grease my tap (fill the flutes) to catch all the metal chips. it works a treat!

CN

 

Hi Stu. I had my reservations about this kind of repair but after watching this vid

http://www.youtube.com/watch?v=Cqid0tfLzEg

I felt more confident. Having said that I did improvise a little. First of all I set the piston about half way up on it's compression stroke. This ensures both valves are closed so that swarf can't get trapped behind the seat. Next I pushed an industrial wipe (a square sheet of clean white cloth) into the plug hole and pulled it back to a point just below the bottom of the thread with some pointy nose pliers. I then started tapping the thread with the reamer/tap supplied in the kit. I used a vacuum cleaner at frequent intervals to clear the swarf as it was produced. This ensured minimal swarf entry into the cylinder. I used WD40 to lubricate the tap rather than grease as I didn't want a lump of swarf laden grease dropping into the cylinder. This would be very difficult to suck or blow out. After the new thread had been cut I pulled the cloth out with the pointy pliers, making sure it had all come out. I then taped about an eight inch length of rubber fuel line to the nozzle of my vacuum cleaner. I tested it's ability to pick up a largish piece of swarf - and it did. I then proceeded to suck out the remaining swarf from inside the cylinder. Finally, I blew out the cylinder with compressed air although I wasn't aware that there was even any left at this stage. That only left the insert to be fitted to the spark plug, smeared with thread locking compound and screwed into the new thread. It worked reasonably well although the new thread wasn't the best I've ever produced. The main thing is that the spark plug tightened up firmly and the bike ran well afterwards. I'm still working on my spare head just in case.

 

My spare head had a broken header stud that the PO has tried to drill out but his poor workmanship had caused the hole to drift off centre. I rigged up my electric drill and stand and clamped it to the bench above the vice with the head securely fastened at the correct angle. Using a tri-cut slot drill I produced a new, larger hole roughly in the centre of the cast boss. I then tapped the hole and screwed a length of stud into the tapped hole. I then cut the stud off and ground the excess back so that it was flush with the original cast face. All that's required now is to drill and tap a hole for the new stud.

 

After centre punching the position of the new hole I drilled it deep enough to pass right through the repair plug (which was 10mm long) and a further 10mm into the parent metal of the cylinder head.

 

Next step, tap the M6 thread 20mm deep from top face.

 

New, longer stud purchased here

http://www.ebay.co.uk/itm/191085831960? ... 1439.l2649

screwed home 20mm deep. The new stud is threaded through the repair plug and into the cylinder head meaning there is less risk of the repair plug working loose.

 

Valve lapping in progress.

 

Setting the spare head valve clearances on the bench.

 

I was looking at that exhaust stud repair - i caught myself wondering if you shouldn't hit that steel insert you made with a punch in a few places (peen) to force some thread interference to allow easier stud removal down the road? Just a thought.. If it comes out and you torque it down to a different spec, the threads might not line up properly with the aluminum threads.. at least enough to cut into them a bit..

 

Good thinking Pr0zac. I'll definitely do that. Thanks.

 

That is the most beautyful well designed XJ café, I have ever seen!
Fantastic work and energy!

 

Thank you jrutgers. Your comment is very encouraging.

 

Been fascinated reading/following this thread. I do have a spare XJ 750 in the shed that I would like to mod something very similar to your bike, but I need to first complete another restoration XJ 750 project that I have in progress at the moment. What year Darmah tank is that? I read in he thread tha it has been modified by the previous owner. Did this increase the fuel capacity by much?
Cheers
Phil

 

Thanks Phil. I'm afraid I don't know much detail about the tank other than it's originally from a Darmah but was modified to increase capacity to. 4.5 UK gallons. PO originally posted it on eBay but withdrew it when he realized it was modified. I persuaded him to let me buy it. When he saw what it was for he told me he had always loved XJ's and so only asked for £20. I couldn't believe my luck. Just chilling in the Algarve for a few days at the moment. Cheers. Rob.

 

Chilling in the Algarve, that's an oxymoron, surely.

 

Well I'm back from a refreshing break in Portugal and straight back in the garage.

Spare head prepared for painting.

 

Spare head in etch primer.