Planet Minis

storminnorman07

anyone know if tb guides will fit in this 70 head. i dont know what year or model. all i know its old and the 25/22 valve set up none bearing cam.

firepower354

Looking to update to 5mm stems? Measure the hole ID?

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storminnorman07

yea i would like to. ill get a id tonight think you might be able to hook a brother up?

cyclerider57

Haven't heard from you in a long time stormin... good to see you're still doing some work. Should be standard 10mm hole size (+.10mm -.01mm). Measure to find out if you need oversize. Normally .001" (.025mm) over will do the trick if your hole is slightly oversize from pressing the old one out. Make sure the hole has a good surface finish or you'll need to hone it a little. I have ampco45 guides but you can get stock crf50/70 oversize in .001" steps to .005" over. Kibblewhite sells them in ampco45 as well. Don't forget to ream the valve guide once you have it installed.

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storminnorman07

jordan what the hell is up man i haven't heard from you in a long time. last i heard you was working for harley i think it was. i can't find my mic right now buddy must of borrowed it but i would say that your right looking at the holes they have a good finish and look good but would feel better to get a actual reading on it.

cyclerider57

Settled back down for a few months right now. Harley Manufacturing Engineer, Honda R&D Associate, Dirt track race team... I try to keep it moving around.

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Paxracing

Honda R&D Associate you working with Dave Arnold now.

cyclerider57

Don't want to clutter the thread... pm'ed.

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storminnorman07

i dont mind the clutter most of the time my threads dont get any attention any how and i end up having to figure something out on my own. sounds like you have been busy whats ur next move?

Kurlon

I *THINK* that head uses the same valves and guides as my 'DRP Ultra' head, in which case Beatrice Cycle may have them, if for some bizarre reason you want to stick with thicker valve stems and non KW guides? : )

50rider340

This is awesome. I love the port job. Yesss more tech jobs/threads We need more of these than those dumb polls on what china bike is most improved.

storminnorman07

thanks kurlon but i wanna go with the newer setup with the 5mill stems and the newer style valve seals. the guides that came out there was nothing wrong with them. a while back when cycle and i was talking alot on here i was kicking around the idea of doing a light bore 88-106cc and then kinda gave up on the idea. well just last week i did a tb 88 for my buddies girlfriend did a lil head work and uped the intake valve to a 26mill. but being i was on a budget and couldn't go all out on it we just stuck with a xr 80 carb the mani that comes with the yx motor and a hermaphadite exhaust half china half 2 bros. and after playing with it for a lil bit i was kinda impressed with it and now i am curious what i can do with a lil cc motor without any restrictions and i have two of these old 70 heads laying around so i figured i'll build off that so thats where i am at now. o and by the way that fincher head a i was thinking about selling a while back you wanted to do a lil trading for a clutch be glad i decided not to let anyone else have that bomb i ran it for a while all the epox that was on the intake port floor lifted and sucked into the motor. and if your curious it ran pretty decent but no where near as bad a$$ as he claimed it if he wouldn't took me up on the bet to race my 4 valve he would of went home w/ his tail between his legs.

Kurlon

Hah, hopefully it didn't do too much damage when the epoxy decided to free itself...

I miss my 72cc screamer. Never took it quite to the level you're at right now, but it was a fun 7hp lil mill. I know of another Honda 72cc mill in a modern remake of a 60's 50cc GP racer, pulls 85+ mph, last dyno was a touch over 8hp. Beautiful bike, and there's so much stuff out there for these motors that the guy hasn't seen yet... : )

Does the old 70 head you're playing with have a steel insert for the combustion chamber? I would think that would polish up nicely, hopefully reflect a ton of heat back into the chamber rather than wicking it up into the head itself?

storminnorman07

o it wreck the motor it locked up and tore it up o well its china...lol yeah it has the steel inserti haven't decided if i am going to polish it or not yet. deciding on what to do with guides and i can not find my inside calipers for the life of me to get a id so jordan or terry can tell me if they have something i can pick up.

storminnorman07

best i can do is give a od on the old guide which is .3950 jordan you have anything a brother can work with?

storminnorman07

no one?

Kurlon

.3950 in = 10.03300 millimeters
So ream for 2nd oversize?

cyclerider57

I really need the hole diameters to make sure you have the right press fit. That's a pretty standard size. I should have ampco45 guides laying around in that or slightly oversize. Kibblewhite sells them straight out of their book as well.

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slimbo

what cam and piston are you going to use?

storminnorman07

damn ok thanks jordan i'll have to find the ol trusty kibble white cateolog.