ATC 350x Head issues

[Fixer_Upper]

Hello! I’m 14, and have been working on and riding an 85 350x. I typically work on it with my grandfather, he’s really good at machining and engine repair etc. But anyways, a couple years ago we made the completely wrong decision with my 350x head and reamed out one of the valve guide holes (where the valve guide drops into the head). We didn’t even think about freezing the valve guide to get it to fit, I know that it was a dumb decision. Well, since then it hasn’t been an issue until it started leaking oil REALLY bad. Nevertheless, since this is just a project bike I really don’t want to spend $400+ on a head that could be in worse condition than the one I have. I really only have a few options that I can think of, if you guys have more PLEASE REPLY. Option #1, find an valve guide that is 5 thousandths oversized or make one. If you know anyone who makes these, let me know. Option #2, make a sleeve for the valve guide to go into, therefore making it the size it originally was. Option #3, find a better way to glue in the valve guide again. We used loctite last time, and it didn’t hold. Also remember, my valve guide hole is 5 thousandths over, so it would need to take up that space, and be resistant to heat. Please mention any ideas you have regarding that option. I mentioned the possibility of making a valve guide or sleeve, but I need to know the hardness and heat resistance of the original valve guide. I’d imagine they aren’t designed to resist heat, but they are designed to transfer heat. If you have any experience with this or just want to put in your opinion, please reply! It would be greatly appreciated!

[Jim mac]

have you talked to a machine shop and asked about knurling the OD of the guide to make it a little larger? jim

[Fixer_Upper]

Thanks for the reply! I have heard that knurling is only a temporary solution and it doesn’t last. Have you tried this? If so, how has it held up? Is there a high temperature glue you used to hold it in?

[Jim mac]

knurling the inside of the guide is a budget fix, but I think if you do it on the outside of the guide to make the fit tighter it would become permanent. but would need some sort of sealer jim

[Fixer_Upper]

I’m thinking I’ll use loctite 640. Thanks!

[Dirtcrasher]

Cylindrical Loctite is amazing stuff. IDK if it would hold a spring backed valve from walking around though.

I have absolutely seen oversized valve guides for just this issue. Even better because usually the hole is worn out unevenly, it sounds like you guys reamed it perfectly on center but the hole is just too big.

I'm fairly sure you can find an oversized guide. Worst case scenario you make one. Quite a few of the dimensions are plus/minus allot based on what they do, wouldn't be too terrible to make IMO...

[Fixer_Upper]

That was another idea. Have you found any oversized valve guides? The only way I’ve found I can get them is to either make them, or get them custom. I’ve decided not to use the loctite brand, it’s like 70 dollars for an industrial bottle, that of which I I definitely don’t need for this application. I have however, decided to use the permatex brand. It’s essentially the same exact thing, the only difference is that I can get a small tube for about $7 instead of $70 for a industrial sized bottle. Nonetheless, if you have seen any oversized guides, let me know. Another opinion if the knurling doesn’t last and I can’t get oversized guides, I will possibly sleeve it so I can put normal sized guides in.

[Fixer_Upper]

Update! I knurled the valve guide, and got it in. I changed my mind AGAIN about which glue to use, and finally decided on Loctite 648. It’s readily available, cheap, and supposedly the best stuff out there. Everything seems to be going well, it will take 48 hours to fully harden. It should be noted I used the loctite primer too. Thanks for all of the information, I might have saved myself 400 bucks because of you guys!