Head repair options

[Kurlon]

Anyone have suggestions for a shop that can do head repair? I've got a 2v head that stuck an exhaust valve with less than 15 minutes of runtime on the clock. Based on the scoring on the valve stems the working theory is the guides were too tight.

I've got new internals, including valves/rockers and a cam, but I don't have the tools or expertise to ream out and clearance the guides, cut new valve seats or grind the valve stems to length.

Oh, and to make things more fun this is a pitbike head so we're talking tiny valve stems (4.5mm or 5mm).

[Stromper]

Lapping compound and go at it

[Kurlon]

Heh... ummm... it needs much more than lapping compound unfortunately. : )

[tls25rs]

You could try Harry's Machine in Northboro Ma. It might be a little far from you but they are highly skilled and have helped me out recently.

[Kurlon]

I'll give them a ring Monday. At this point I fully expect to have to mail the head out. I've been without the bike for a year thanks to this head, so waiting a little while longer for the postal service to do it's thing doesn't bother me as long as the end result is the head being right and reliable when I get it back.

[Expat]

+1 for Harrys, excellent reputation.
If you want to use Harrys and are going to BoMo or to Tonys on the 4th, I could take the head and drop off / pick up for you. Not sure how I would get it back to you but it would at least save to some shipping!

[butcher bergs]

What are the chances that the guide ends are the issue rather than the entire guide needing to be reamed? Maybe look into smoothing out both ends? I dunno....just thinking out loud.

Perhaps take an oversized drill bit and lightly go over the guide ends then check valve movement.

[Kurlon]

I've considered that as a possibility, given the scoring it appears that the whole length of the guide was involved? This is why I want a professional to look it over rather than me guessing and potentially doing even more damage by trying to hack it.

[KB]

Kurlon my guy Jim Pidgeon will hook you up. Lemme know if you want his number.

KB

[Kurlon]

Kurlon my guy Jim Pidgeon will hook you up. Lemme know if you want his number.

KB

Much appreciated KB, if I don't make any progress this weekend I'll take you up on that.

[Kurlon]

Welp, a bit of investigating later...

The new valves are slightly smaller diameter, so yeah it was a guide clearance issue, got that sorted.

New valve springs don't work with the old guides and guide seals, the inners are tight enough that you have to twist them on to get past the seals. So.... I'll be running seal-less till I can figure out a single beehive style spring setup I guess.