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Extrude Honing the Head

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by tmg, Nov 13, 2006.

  1. I was reading an automotive magazine a while back, and they had an article on extrude honing.

    For people who aren't too sure about what this is, it is where instead of porting and polishing the head, the technician uses a metal cutting paste, which flows in on end and out the other - through the intake or exaust and out through the valve openings taking any bad stuff with it.

    Education lesson over, I was wondering if you can do this with bike engine heads, as the engine I am working on has heaps of crap in the intakes and exausts adn this seems to be the best sounding option.

    If there's a way I can do the cleaning without doing this then that would help heaps, but I am asking about it just in case anyway.

  2. Seal one end and fill the ports with white vinegar, leave for a day, clean out crap. (I would just like to take this opportunity to tell the Queen that I never cleaned carbon out of one of her SLR's that way, no....never............ever....)
  3. And it's a good idea if you're going to use the white vinegar method to also give anything else that might come into contact with it a coating of wax - melt it and apply it with a brush.

    Inci - I never cleaned my 1943 MK3 SMLE like this, either....

  4. I like the idea of the white vinigar, but the wax seems a bit shady.

    I can just sit the head "valves down" and fill one side at a time with the white vinigar and put it on an angle so it doesn't spill out.

    :LOL: that's a good one man, I laughed heaps at that.

    what does the wax do anyway? what parts "might" need protecting :?:
  5. Valve seats, mostly, and any sealing faces.

    If you plug 'em you should be fine, but any time you leave something for a day or so, you'll want to be careful .

    Saw this done on an ancient speedway bike head years ago as a "full immersion" process - plan was to clean the head inside and out. Head was dunked in a bucket full of vinegar, and I seem to remember it being left for more than a day, then being given a good once-over with a tooth brush.

    All the best with this. Here's to no more head congestion!

  6. So did the head of the speedway bikes engine come out ok in the end? I can get a few litres cheap as it's not an expensive liquid to get. all in the aim of saving money I guess.
  7. Yup, the head came out fine.

    But here's the bit where I come over all un-helpful....I was the observer on this job, not the do-er, many years ago, and I cannot tell you for sure whether the head was alloy or steel.

    I can only assume that this would be a pretty important detail to take into consideration. All I remember is that it was a big-bore, classic era speedway bike, so probably a Jawa or some such. Jawas fall into the category of "bikes I know almost nothing about", unfortunately.

    Maybe Inci will know about the critical differences in how the treatment affects steel vs. alloy? Other option, I guess, is to go to a wreckers, get a stuffed head of the relevant material out of their skip, and give the method a test-fly with something you don't care about.

    Costs you a bucket of vinegar and you're away.

    I do remember that the head in question copped a very thorough degreasing before the vinegar treatment.

    Sorry about the steel/alloy thing - I don't want to take a guess and misinform you. Might cost you a head!


  8. maybe I can give my head a thorough degreasing too. just to see if that will help clean things easier first.
  9. Extrude honing is used solely to increase performance, you'd be better off finding an efficient way to clean it if that's all you're after.

    I've only ever seen extrude hone used on turbo car engines, where getting maximum airflow is paramount, and off boost driveability not considered.

    On a bike this is not always the case for performance (need to consider ehaust scavenging efficiency etc, unlike a turbo), many private race teams actually fill the intake ports (reducing the diameter/volume) and achieve a top end power increase.

    Extrude honing is also expensive (especially compared to a few bottles of vinegar!), you could achieve all you want with a dremel and some time.
  10. Cammo -

    Go the dremel! Talk about the most useful tool in the shed!

    Cleaning up ports, knife-edging transfer ports on strokers...used right there's just nothing better.

    Sorry. Got all excited there...

  11. Hi Guys i have lust picked up my spare set of CX500 heads from a mate of mine that has a head shop

    They where dunked in the paint stripper bath they dangerous one that has a blanket of water over it in the tank

    They looked as if they left the honda machine shop today
    No Carbon No Paint and No corrosion at all

    All Gone

    And sorry guys dremels are good but a proper desouter pencil grinder is better and yep it needs them hondas port designs are pretty good its just that when the production guys get to them they let all the dross etc lumps bumps and casting flashing go through and the ridge on the base of the inlet valve valves has to be seen to be believed

    I use a couple of the emery flap wheels ground down on the grinder with some oil and kero as lube to finish my ports if i get the chance iwill post some pictures
  12. You mean Trichlorethylene? That stuff is good, but it's as dangerous as being first in line at Grace Brothers on day one of the January sales.....
  13. Yep, and yet it's what they use to use to make decaffinated coffee :shock:.
  14. No Inci I dont mean Trico we have a bath of it here at work its what we / I degrease everything with its steam heated and works as a vapour within the tank

    No Trico is chicken feed to this stuff metheylene chloride rings a bell

    It sits in the tank at the bottom and a layer of water is kept over it to keep the fumes at bay its not nice you lift your parts out of it very slowly
  15. I didn't even know that stuff was still legal. It is highly carcinogenic, even at very small concentrations, and it cause hypoxia by preventing oxygen absorption. (similar to Carbon Monoxide poisoning).
  16. Most chemicals can still be obtained legally if there is the appropriate safety precautions

    Ie MSDS available , proper storage , appropriate equipment, trained personnel, legally bought and disposed of via the EPA rules and regs.

    A proffesional company will still offer the sevice

    PS ie i do not do this / cannot do this at home

    And the mates rates involved ie Beer o clock time on a friday arvo a great to

    Jesus the heads come up like they had just left the production line no fancy water jet blasting
  17. I don't know exactley what you ar trying to achive but soot deposits should come off in a parts washer or with engine degreaser ($2 supercheap) with a brush, any thing harder should come off with careful use of a wire brush or bead blaster. anything on a finished surface can be cleaned up with some emery cloth or a scotch brite...

    cleaning a head should cost you less than $5 and take less than an hour.

    acid bathing and similar would only be extreme measures for a restoration or FBS (fussy bastard sindrome).
  18. Yeah sobil i agree with what you said mate

    but the fact is TMG and i are playing with bikes that are at least 25 -30 years old and lets face it i can slap up fix heads in less than half an hour get them running again to get me to work the next day

    But in this case i choose not to