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  1. #61
    CB750 Addict joe p's Avatar
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    We just had a thunderstorm, rained it's ass off. lost power for about 2 hr.

  2. #62
    Moderator dirtdigger's Avatar
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    Well never got to the track this summer, worked 6 days a week because of all the rain putting us behind. Now its winter and snowing and cold so inside tinkering on the bike. Running around on the street the RC exhaust was hitting all the time on the speed bumps etc. So...thought I would build my own, based off of the sidewinder type headers everyone is using. Equal length and longer primary tubes. Got most of the tubes welded up before I ran out of argon gas. This is my prototype header pipe.
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  3. #63
    CB750 Addict joe p's Avatar
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    Looking good!

  4. #64
    CB750 Addict dan1951's Avatar
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    Looks like they will flow good by the looks of the bends, Nice job Digger

  5. #65
    K2750tracy K2750tracy's Avatar
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    You'll need to make a set of those for that 1234cc motor!
    old Honda junkie

  6. #66
    Moderator dirtdigger's Avatar
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    The big motor build has been shelved for the time being. Ran into a piston issue and an oddity with one journal on the crankshaft. Its not dead but its not going to be a priority for now. Still need to be able to get this one to the track!

  7. #67
    Moderator dirtdigger's Avatar
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    OK still never got to the track and have had some money issues this last winter so had to let some parts go. But I am not one to leave anything alone so the motor is back apart in the drag bike even though it has never made a pass. LOL Cycle X keeps coming out with nifty new parts I just have to have Pulled the head I had on it and going to go back on with a ported RC Eng head but doing some things to it first. Cycle X has come out with new cast iron valve guides that are shorter on top for higher lift cams. Have a set in hand but 2 of the bores in the head are slightly oversize so I have 3 .001 oversize guides on the way. I am going to give the iron guides a shot as have used only bronze in the past.
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    One on center is new iron guide, left is bronze and right is old bronze RC guide.

    Problem with the stock setup on the K heads is you can run much over .350 lift because of several things. Retainer to valve seal can get close but the biggest reason I have found is the design of the valve retainer groove on the valves. The groove is very wide...much wider then the keeper is. At lift around .350" the groove goes into the valve seal... so you have no oil control at the highest lift. These guides drop the seal closer to the head.

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    CycleX is coming out with some new cam profiles and I am going a high lift route. This head continues to flow past .400 lift so to utilize the head I am going high lift and modest duration...should help to keep combustion pressures up as well. Was running an old RC327 cam. Works good but new cam technology has to be better. I am hoping for something in the mid .4?? lift.

    Also now instead of driving guides in and out of the heads I built a setup to pull new guides in straight...no more beating on the guides with a driver and risking collapsing the guides. It also keeps the guides closer to center of the valve seats as the cone centers off of the valve seats. Much easier and no more hammers and drivers and hopefully easier valve jobs.
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  8. #68
    Moderator dirtdigger's Avatar
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    Cycle X has these high lift guides in .001 and .002 over size. Have 3 .001 on the way. Kens the man!

  9. #69
    CB750 Addict Medyo Bastos's Avatar
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    dana did you end up using the silver frame? i am interested in it if you didnt. give a shout~

    btw, that header is looking great!

  10. #70
    Moderator dirtdigger's Avatar
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    The welds on that silver frame...lets just say they were less then acceptable, some are down right laughable. Guess they never broke but I wasnt going to trust them. It would have been far more trouble to try and fix the frame then start over so I used a stock frame and built a long swingarm.


    I built the header from exhaust bends I get through Speedway Motors.

  11. #71
    CB750 Guru amc49's Avatar
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    Man, I would have been removing the clip or set ring in a second to get more lift room on the OEM guides, it looks super simple and BTDT on other engines. Then using your guide install tool have some idea of the desired set height and then cobble up washers, a custom length sleeve, or the like and pull the guide in to the chosen point and just repeat on all the others to get the same heights.

  12. #72
    Moderator dirtdigger's Avatar
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    Thats why they make these guides...no guessing,no cobbling with spacers.....seat to the ring done, good to go.

  13. #73
    CB750 Guru amc49's Avatar
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    I understand that, but you could have been there sooner if that was desired. Most of drag racing involves guessing. Back when we used to drag race AMC engines we did things like that all the time, there were practically zero high-perf parts for them and often you made up your own. Half the parts on the cars were modded GM or Ford parts made to fit AMC.

    Not trying to rib you at all, I guess it's just the modding side of me showing up, I tend to see things like how easy that ring removed instantly, it comes from years of searching for easy mods that cured problems, I still do it today, just to cure problems on modern cars when the makers (Ford in my case) refuse to do so unlike what they used to do. You don't really guess there, rather you make it happen and correctly once you determine it can be done. Currently modding a HVAC cam on a Focus to avoid the cable breaking problems they have with heater cables, the Ford official fix is another $850 airbox and $2000 + in charges to yank the entire dash to get to it. Ridiculous, my part mods costing maybe $10 and installed in 10 minutes, problem gone. I've got many other fixes on the two Focus cars I've got and never much more money involved doing them. The cars are utter junk as they rolled off the lines and a pile of endless problems.

    Shortening car engine valve guides was a given back in the old days, many designs required you to do it, Iskenderian Racing Cams back in the day rented out cutters to mod the guide tops on most engines back in the '60s.............

    High lift and shorter duration are a gangbusters combo and we did lots of them for the circle track dirt car people but you better have durable parts like springs, they get knocked about a lot more than long duration stuff does. If rocker arms any errant geometry issues will show up faster in breakage. I don't know what lobe center the SOHC cams use routinely but the combo is even better if the LC gets closer like 105 degree or so. Some Honda like the early DOHC use that low number really well, you get a big mid range boost without losing the top end revability at all. The wonderful thing with DOHC, you can then put that LC (both actually) exactly where you want it (them).

    About time somebody is making shorter duration high lift parts, the bane of bike engine modification for like forever is how most makers made cams too long in duration in relation to higher lift due to so many cam profiles coming from regrinding stock cams. The cam makers tend to stay with more reliable grinds and shorter duration hi-lift have their problems but dang do they run good.
    Last edited by amc49; 05-08-2017 at 11:05 PM.

  14. #74
    Moderator dirtdigger's Avatar
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    RC block just back from APE. Decided I wanted to use the RC block on the drag bike. Jay had to have custom sleeves made to fit the block..... not cheap but he helped me out. New sleeves fresh deck top and bottom for MLS gaskets, good to go and NO leaks. Now waiting on a set of APE wrist pins, Jay is doing a special run of them because the RC triple and Sorcerer needed wrist pins! Maybe some year I will actually get the bike on the strip instead of tearing it apart every year, spending money and not going racing lol

  15. #75
    CB750 Guru amc49's Avatar
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    We ain't getting any younger, my thoughts are the same.

    Got both a 985 and 955 (destroked 1100) DOHC projects sitting around doing nothing.

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